UNIT 6/11 + OPTION D - Human Physiology Flashcards
Define nutrition
the process by which an organism acquires the matter and energy it requires from its environment
State and define two types of nutrition
autotrophic nutrition - synthesis of organic molecules from simple inorganic substances
heterotrophic nutrition - obtaining organic molecules from other organisms
List the types of heterotrophic nutrition
saprotrophic nutrition - feeding on dead organic matter
parasitic nutrition - feeding on the host’s tissues
holozoic nutrition - the ingestion of liquid or solid organic material from the bodies of other organisms, digestion in the alimentary canal or gut and then absorption and assimilation of it
List the types of animals performing holozoic nutrition
herbivores - animals feeding directly and exclusively on plants
omnivores - animals eating both animal and plant material
carnivores - animals eating other animals
List and define the five steps of holozoic nutrition
- ingestion - food taken into mouth for processing in the gut
- digestion - mechanical digestion by the action of teeth and the muscular walls of the gut & chemical digestion by enzymes, mainly in the stomach and intestine
- absorption - soluble products of digestion absorbed from blood circulation system (lymphatic system if fat droplets)
- assimilation - products of digestion absorbed from blood into body cells (liver and muscle cells) and used or stored
- egestion - undigested food and dead cells from the lining of the gut, together with bacteria from the gut flora, expelled from the body as feces
State the reason for digestion
food taken in consists of insoluble molecules that are too large to cross the gut wall themselves and enter the blood stream
by breaking down the food the body can obtain the subunits it needs to builds up its own macromolecules
Describe the process of mechanical digestion
mastication (chewing) of food by teeth to break the ingested food into smaller pieces that are more readily digested through chemical digestion
peristalsis and segmentation
Define peristalsis and segmentation
involuntary contraction of circular and longitudinal muscle layers of gastro intestinal tract mixes the food with enzymes and moves it along the gut
Describe the process of chemical digestion
breakdown of complex molecules (fats, proteins, carbohydrates) into smaller molecules through water and digestive enzymes
List the 3 most popular human digestive enzymes and what they digest, the products of this reaction and their optimum pH and where they are produced
- amylase - carbohydrates - ex. salivary amylase - substrate: starch -> product: maltose - source: salivary glands - pH: 7-7.8
- protease - proteins - ex. trypsin - substrate: polypeptides -> product: amino acids - source: duodenum glands - pH: 8
- lipase - lipids - ex. pancreatic lipase - substrate: triglycerides -> product: fatty acids & glycerol - source: pancreas - pH: 7.2-7.5
Describe the process of carbohydrate digestion.
…
Describe the process of lipid digestion.
lipids (fat and oils) (usually triglycerides) are emuslificated through bile salts into smaller droplets of triglycerides and then broken down by lipases into fatty acids and glycerol
Why do triglycerides need emulsification
lipase is water-soluble but its substrates aren’t and so the enzymes can only attack the fat molecules at the surface of a mass of fat
emulsification increases the surface area of fat exposed to the action of pancreatic lipase and so increase the rate of lipid digestion
Describe and distinguish between the two types of enzymes digesting proteins
endopeptidases (e.g. pepsin, trypsin) - hydrolyze bonds in polypeptide chains and so it breaks down large polypeptides into smaller ones increasing surface area for action of exopeptidases
exopeptidases (e.g. dipeptidase) - remove terminal amino acids which are then available for absorption
Label the parts of digestive system.
- mouth
- salivary glands
- esophagus
- liver
- gallbladder
- stomach
- pancreas
- large intestine
- duodenum
- ileum
- rectum
- anus
List the places with the processes where digestion happens in human body in the correct sequence
- Mouth - mechanical digestion (chewing) and chemical digestion of starch (salivary amylase)
- Esophagus - peristalsis
- Stomach - mechanical digestion - muscular contractions (acid kills bacteria, pepsin digests proteins).
- duodenum - bile from the liver and gall bladder neutralizes acid and emulsifies fats (pancreatic amylase and lipase digests carbohydrates and fats, trypsin digests polypeptides)
- ileum - absorbs nutrients into the blood via the villi.
- large intestine - water is reclaimed and returned to the blood leaving feces.
- egestion - feces is forced out of the anus
Label the structure of the stomach
- duodenum
- pyloric sphincter
- pyloric canal
- cardia
- esophagus
- muscularis externa ( longitudinal, circular and oblique layers)
- lumen
- body
- rugae of mucosa
- fundus
- serosa
Describe and list the functions of the stomach
- killing bacteria and denaturing - proteins through hydrochloric acid (pH 2)
- protein digestion commencement - pepsin
- mechanical digestion - muscular actions
- food storage in the lumen
- control of entry of food and exit of chyme with muscular sphincters
- mixing enzymes with food through muscular wall contractions
How does the stomach trigger the release of enzymes
stretch receptors in the muscular wall
List the components and their function of the gastric juice
hydrochloric acid - creates an acid environment of pH 1.5-2 which is optimum for protein digestion by the protease enzymes, activates inactive enzymes, kills many bacteria present in the food
protease enzymes - secreted in inactive state, begin the digestion of proteins
State the function of gastric glands
present in the wall of the stomach and secrete the components of gastric juice
Define goblet cells
cells present in the stomach lining and secrete mucus
State the function of mucus
bathing of the interior lining of the stomach, forming an effective barrier to both hydrochloric acid and the protease, preventing autolysis of the stomach wall
Define chyme
semi-liquid resulting from the squeezing of the food and mixing it with the gastric juice
State the two main functions of the small intestine
digestion of carbohydrates, lipids and proteins
the absorption of useful products of digestion
Describe the processes occurring in the small intestine
- chyme enters the duodenum
bile from the gallbladder and liver is emptied into the duodenum, neutralizing the acid and emulsifying fats - pancreatic enzymes are released and further released into the jejunum
- the ileum conducts the absorption of digested food molecules through villi
- a wave of muscle contractions (peristalsis) keeps the mixture of digested and undigested food moving through the intestine
State the function of the bile and where it is produced and stored
produced: liver cells
stored: gall bladder
is strongly alkaline and neutralizes the acidity of the chyme also emulsifies lipids
State what forms pancreas
acini - large number of lobules with central lumen (pancreatic capillary)
Define absorption in the small intestine
uptake into the body (blood circulation or lacteals) of the useful products of digestion, from the gut lumen
State the adaptation of villi to its function
single layer of epithelial cells - short diffusion path
rich blood supply - maintains a concentration gradient down which nutrients can diffuse across the membranes
lymph vessels (lacteals) close to the surface - allows lipids to be easily absorbed
mucus from goblet cells in epithelium - lubricates the movement of digested food among the villi and protects plasma membrane of epithelial cells
epithelium cells packed with mitochondria - source of ATP for active uptake across the plasma membrane
Describe the process of absorption of fats
- triglycerides in the lumen are exposed to enzymatic hydrolysis by lipase breaking down the triglycerides into fatty acids and monoglycerides.
- those products diffuse into epithelial cells, the monoglycerides and fatty acids are reformed into triglycerides (some of them)
- triglycerides are incorporated into water-soluble globules - chylomicrons.
- chylomicrons leave epithelial cells by exocytosis and enter lacteals where they are carried away by the lymph and later pass into large veins
Describe the process and state the name of absorption mechanism of glucose through the epithelium
in the kidney or intestine (only) the sodium-glucose symporter binds both glucose and Na+
(the coupling with Na+ relies on it and allows to get glucose out of the lumen even at very low concentrations, and the gradient of Na+ is maintained constantly because of the sodium potassium pump)
and because of that it is passive facilitated diffusion
Describe the process or amino acid and short chain polypeptides uptake into the bloodstream
- proteins and their fragments are digested to amino acids by pancreatic proteases (trypsin, chymotrypsin and carboxypeptidase) along with the brush border enzymes of mucosal cells (carboxypeptidase, aminopeptidase and dipeptidase)
- the amino acids are absorbed by primary active transport to the absorptive cells and moved toward its opposite side
- the amino acids leave the villus epithelial cell by facilitated diffusion and enter the capillary via intercellular clefts
List the pancreatic proteases
- trypsin
- chymotrypsin
- carboxypeptidase
Define assimilation
uptake of nutrients into cells and tissues
Describe the steps of assimilation
absorbed nutrients are transported from the intestine into the villi:
- sugars into capillary network and from them into the liver.
- amino acids too are transported into the capillary network and transported into the liver.
- the lipids are absorbed as fatty acids and glycerol and are largely absorbed into the lacteal vessels then carried by the lymphatic system to blood
State the role of the large intestine
- walt and mineral salts are absorbed
- undigested and undigestible food (e.g. cellulose), bacteria, dead cells, mucus, bile pigments form the feces which is stored and consolidated in the rectum and then passed out periodically by the anus controlled by anal sphincters
List the general functions of the liver
- secretes bile - important in mechanical digestion of fats
- helps maintain homeostasis by regulating nutrient concentration in the blood
- converts excess glucose to glycogen and stores it
- converts excess amino acids to fatty acids and urea
- stores iron and certain vitamins
- detoxifies alcohol and other drugs and poisons
Label the tissue map of a section through the stomach wall
- serosa
- longitudinal muscle
- circular muscle
- oblique muscle
- submucosa
- glandular epithelium
- connective tissue with gastric glands
- muscle
Label the section of the villus
- lacteal
- capillary network
- epithelial cell
- arteriole
- lymphatic vessel
- venule
List the digestive exocrine glands present in human digestive system
- salivary glands
- pyloric glands (stomach)
- exocrine pancreas
- goblet cells (small intestine)
List the contents of saliva with their corresponding functions
- amylase - starch digestion
- lingual lipase - breaks triglycerides into fatty acids
- water and electrolytes - moistens and lubricates
- mucus - lubricates food bolus
- antibacterial compounds and bacteria
List the contents of the gastric juice with their functions
contents:
- hydrochloric acid - begins protein digestion and activates pepsin
- mucus - protects the stomach lining
- enzymes - pepsin and rennin - digest
State where is the gastric juice produced by and when
where:
by the parietal cells in the stomach wall
when:
when polypeptides are detected
List the cell types present in the stomach and the substance secreted by them and their function
- goblet cells - mucus - protects stomach lining
- parietal cells - gastric acid
- chief cells - pepsinogen
- D cells - somatostatin - inhibits acid secretion
- G cells - gastrin - stimulates acid secretion
List the contents of the pancreatic juice and its pH
basic pH because the bicarbonate ions neutralize acidic gastric products
contains many different enzymes: pancreatic lipase and amylase, endopeptidases (trypsin and chymotrypsin) and exopeptidases (carboxypeptidase and elastase)
Determine why the enzymes are excreted in a different form (name it)
secretion as active enzymes would cause damage to the exocrine cells - autodigestion
thus they are excreted as inactive precursors which are harmless and become activated under the right conditions
State the name and describe how the enzyme acidifying the stomach works
hydrogen potassium (H+/K+) ATPase
exchanges potassium from the intestinal lumen with cytoplasmic hydronium and thus creates acidic environment in the stomach contents allowing for pepsin activation
State the purpose of using PPIs and their mechanism of functioning
Proton Pump Inhibitors irreversibly bind to the proton pumps and prevent H+ ion secretion which is sometimes increased by certain medications or diseases
they raise the pH of the stomach consequently and thus prevent gastric discomfort (acid reflux f. e.) caused by high acidity
Discuss the roles of gastric acid and Heliobacter pylori in the development of stomach cancers
..
State the stages of control of gastric juice secretion with the nerves and hormones involved
Cephalic phase - reflex response to visual, smell or thought stimulus via the vagus nerve causing gastric juices to be released.
Gastric phase - in response to mechano- (stretch) and chemo- (protein) receptor stimuli the medulla oblongata sends a signal to the gastric pit to start secreting digestive juices.
Intestinal phase - reduces secretions: low pH or arrival of lipids in the small intestines is detected by the medulla oblongata and thus secretes a hormone stopping the production of gastric juices and moves food to the small intestine.
Describe how the acidic chyme from the stomach is neutralized when it moves to small intestine
duodenum responds to amino acids and fatty acids in the chyme by releasing the digestive hormones cholecystokinin and secretin
CKK stimulates the release of digestive enzymes from the pancreas and of bile from the gallbladder
secretin stimulates the pancreas to release bicarbonate (HCO3-) which neutralizes chyme
Describe the nervous mechanism triggered by food
the sight and smell of food triggers an immediate response by which gastric juice is secreted by the stomach pre-ingestion and when food enters the stomach it causes distension which is recognized by the stretch receptors in the stomach lining which send signals to the medulla oblongata in the brain which triggers the release of digestive hormones sustaining gastric stimulation
Describe and define the mechanism of action of cholera toxin
Vibrio cholerae is a bacterial pathogen infecting the intestines and causing acute diarrhea and dehydration - cholera - it can kill within hours unless treated with oral rehydration therapies
- V. cholerae releases a toxin that binds to ganglioside receptors on the surface of intestinal epithelium cells which is then internalized by endocytosis and triggers the production of cyclic AMP within the cell
- cAMP activates specific ion channels within the cell membrane, causing an efflux of ions from the cell and thus the build up of ions in the intestinal lumen which draws water from the cells and tissues via osmosis (causing diarrhea)
- water being removed from the body tissues and thus causes severe dehydration
State the role of tight junctions in the epithelial cells of the small intestine
prevents the movement of molecules between neighboring cells
State the role of fiber in the digestive process
helps move food along the alimentary canal especially cellulose fiber
List the functions of the large intestine
- recovery of water and electrolytes from ingesta
- formation and storage of feces - as ingesta is moved through the large intestine it is dehydrated, mixed with bacteria and mucus and formed into feces
- microbial fermentation - microbes in feces produce enzymes capable of digesting many molecules that to vertebrates are indigestible (cellulose for example)
List materials not absorbed and thus egested by feces
- lignin and cellulose from plant foods
- dead cells from the intestine
- bacteria
- bile pigments
Describe the unique blood supply of the liver
- receives oxygenated blood via the hepatic artery which is used to sustain liver cells
- receives nutrient rich blood from the gut via the portal vein
- deoxygenated blood is transported form the liver via the hepatic vein
List the functions of the liver
many others, its the most complex organ in the body
- secretes bile - important for mechanical digestion of fats (emulsification)
- helps maintain homeostasis by regulating nutrient content in the blood
- converts excess glucose to glycogen and stores it
- synthetizes glucose from non-carbohydrate sources (gluconeogenesis)
- converts excess amino acids to fatty acids and urea
- manufactures heparin and plasma proteins f. e. albumin
stores iron and certain vitamins (A, D, E, K, B12) - detoxifies alcohol and other drugs and poisons that enter the body
- synthetizes cholesterol from acetyl CoA
State the name of the structural and functional units of liver and their cell composition and structure
liver lobules - hexagonal in structure consists of plates of hepatocytes radiating outwards from the central vein
at each six corners of a lobules there is the portal triad (portal tract region)
List the structures and their functions that the portal triad consists of
- branch of hepatic artery - supplies oxygen-rich arterial blood to the liver
- hepatic portal vein - carries venous blood laden with nutrients from the digestive viscera
- bile duct
Define a sinusoid
small blood vessel found in the liver perfoming a similar function to capillaries - material exchange
State and describe the adaptation of sinusoid
increased permeability allowing larger molecules
for example: plasma protein to enter and leave the bloodstream
structurally:
surrounding diaphragm (basement membrane) is incomplete or discontinuous in sinusoids (but not in capillaries ) endothelial layer contains large intercellular gaps and fewer tight junctions
State the main difference between the sinusoids in the liver and capillaries in most organs
in capillaries because they do not have walls separating blood from the liver cells the two are in direct contact
State how the blood is transported in hepatocytes from the hepatic portal vein
from hepatic portal vein and the hepatic artery percolates from the triad regions through these sinusoids and empties in the central vein from where it eventually enters the hepatic veins (draining the liver) and empties into the inferior vena cava
List the adaptations of liver sinusoids to detoxify the blood
- hepatocytes in general
- Kupffer cells - engulfing microbes and breaking down RBC
- Stellate cells - forming a scar tissue in response to liver damage
State the names of two circulating hormones regulating glucose related metabolic activities in the liver
- insulin
- glucagon
Define gluconeogenesis
synthesis of glucose from other compounds
Describe the process of glucose regulation by negative feedback
List and state the function of the nutrients stored in the hepatocytes
- calciferol (vit D) - helps uptake of calcium
- retinol (vit A, from carotene) - used to make other vitamins
- iron - used to make hemoglobin
Describe how the liver metabolizes the stored fats
they are broken down into smaller compounds and combined with coenzyme A to form molecules (through B-oxidation) of acetyl coenzyme A which will enter the citric acid cycle
List the contents of bile
- hydrogen carbonate ions
- bile pigment
- bile salts
- cholesterol
Describe how bile is released
- produced by hepatocytes and secreted into narrow bile canaliculi.
- it is carried in larger ducts to the gall bladder where it is stored and the water is re-absorbed.
- bile is released into the duodenum via the bile duct.
State the function of bile
- elimination of cholesterol because it makes it soluble by bile acids and lipids
- emulsification of lipid aggregates through the bile acids
- solubilization and transport of lipids in an aqueous environment - bile acids are lipid carriers and so able to solubilize many lipids forming micelles
- transport and absorption of fat-soluble vitamins
State how gallstones form
result from processes that allow cholesterol to precipitate from solution in bile
Describe the breakdown of red blood cells
- phagocytosis by Kupffer cells in the liver.
- hemoglobin is converted to a yellow pigment - bilirubin - and transferred to the bile.
- iron is transferred to the blood through binding to transferrin protein - stored as ferritin or incorporated into the heme molecule.
- protein is broken down to amino acids which are released into the blood.
- bilirubin is converted to a yellow pigment in the intestine which gives feces the characteristic yellow colour.
Define Jaundice
term used to describe a yellowish tinge to the skin and sclerae and body fluids that is caused by hyperbilirubinemia
Define hyperbilirubinemia
excess of bilirubin in the blood
Define bilirubin
waste product remaining in the bloodstream after the iron is removed from the hemoglobin during the degradation of erythrocytes
List the causes of jaundice
- acute inflammation of the liver - impairs the ability to conjugate and secrete bilirubin resulting in its buildup.
- inflammation of the bile duct - prevents the secretion of bile and removal of bilirubin.
- obstruction of the bile duct - prevents the liver from disposing of bilirubin.
- hemolytic anemia - large quantities of erythrocytes are broken down and thus the production of bilirubin increases.
Label the structures of the circulation system.
- head and upper limb capillaries
- superior vena cava
- inferior vena cava
- aorta
- hepatic artery
- hepatic portal vein
- splenic artery
- mesenteric artery
- renal afferent arterioles
- common iliac artery
- common iliac vein
- trunk capillaries
- lower limb capillaries
- renal efferent arterioles
Label the diagram of the upper abdomen
- inferior vena cava
- right lobe of liver
- right hepatic duct
- common bile duct
- gallbladder
- stomach
- pancreas
- hepatic portal vein
-duodenum
Label the diagram of a hepatocyte
- interlobular veins
- central vein
- bile canaliculi
- bile duct
- fenestrated lining
- portal venule
- portal arteriole
- stellate macrophages in sinusoid walls
- portal vein
- sinusoids
- plates of hepatocytes
Label the diagram of sinusoid and hepatocyte
- hepatic artery
- hepatic vein
- bile duct
- sinusoid blood-filled channel
- phagocytic cells
Differentiate between the needs of small and larger organisms for a transport system
small - simple diffusion across body surface or active transport
larger - require a circulatory system to transport materials because diffusion is too inefficient and slow to supply all the cells of the body
State the reason for the name double circulation in mammalian circulation
blood passes twice through the heart in every single circulation of the body
List the components of mammalian blood with their abbreviated functions
- water - solvent
- ions (blood electrolytes) - osmotic balance, pH buffering, regulation of membrane permeability
- plasma proteins - albumin - pH Buffering and osmotic balance, immunoglobulins - defense, fibrinogen - clotting etc.
- substances transported by blood such as nutrients, respiratory gases, hormones or waste products of metabolism
- leukocytes - defense and immunity
- platelets - blood clotting
- erythrocytes - transport of O2 and some CO2
State two advantages of mammalian circulation
simultaneous high-pressure delivery of oxygenated blood to all regions of the body
oxygenated blood reaches the respiring tissues, undiluted by deoxygenated blood
Define blood
specialized tissue consisting of liquid medium - plasma - and blood cells
Distinguish the types of leukocytes
phagocytes
- granulocytes (basophil, neutrophil, eosinophil)
- monocytes -> macrophages
lymphocytes (T or B)
State the shape of erythrocytes
biconcave
List the components of hemoglobin
- 2x beta globin chain
- 2x alpha globin chain
- iron-containing heme group
List the functions of blood plasma
transport of:
- nutrients from gut or liver to all cells
- excretory products (for example - urea) from the liver to the kidneys
- hormones from the endocrine glands to all tissues and organs
- dissolved proteins - osmotic concentration regulation
- antibodies
- heat distribution to all tissues
List the functions of blood erythrocytes
transport of:
- oxygen from lungs to respiring tissues
- carbon dioxide from respiring cells to lungs
List the function of blood lymphocytes
forming antibodies
List the functions of blood phagocytes
ingestion of bacteria or other cell fragments
List the functions of blood platelets
play a part in the blood clotting mechanism
List and briefly define the types of vessels in the mammalian circulation system
- arteries - carry blood away from the heart
- veins - carry blood back to the heart
- capillaries - fine networks of tiny tubes linking arteries and veins
List the structural differences between arteries, veins and capillaries
CAPILLARY - site of exchange between blood and body tissues
- outer layer (collagen fibres) = absent
- middle layer (elastic fibres and involuntary muscle fibres) = absent
- inner layer or endothelium (pavement epithelium) = present
- valves = absent
ARTERY - carries blood under high pressure away from the heart
- outer layer (collagen fibres) = present
- middle layer (elastic fibres and involuntary muscle fibres) = thick layer
- inner layer or endothelium (pavement epithelium) = present
- valves = absent
VEIN - carries blood under low pressure back to the heart
- outer layer (collagen fibres) = present
- middle layer (elastic fibres and involuntary muscle fibres) = thin layer
- inner layer or endothelium (pavement epithelium) = present
- valves = present
State the function and list the adaptations of arteries
to convey blood at high pressure from the heart ventricles to the tissues of the body and lungs
- narrow lumen (relatively to the wall thickness)- maintaining high blood pressure
- thick wall (outer collagen layer) - prevention of rupturing under the high pressure
- inner layer of muscle and elastic fibers - help maintain pulse flow (can contract and stretch)
State the function and list the adaptations of capillaries
to exchange materials between the cells in tissues and blood travelling at low pressure
- splitting of arteries -> arterioles -> capillaries - decreasing arterial pressure and increasing the total vessel volume, ensuring thorough blood supply to all cells
- capillaries pool into venules and then larger veins after the material exchange occurred
- very small diameter - passage of only one single blood cell at the time
- wall made of a single cell layer - minimizing diffusion distance for permeable materials
- basement membrane - permeable to necessary materials
- contain pores - aid the transport of materials between the tissue fluid and blood
List the types of capillary wall possible and its location in the body
- continuous (endothelial cells held by tight junctions to limit permeability)
- fenestrated (with pores) - in tissues specialized for absorption (e.g. intestines, kidneys)
- sinusoidal (have open spaces between cells) - permeable to large molecules and cells - e. g. liver
Compare the three blood vessel types under the following categories: function, pressure, lumen diameter, wall thickness, wall layers, muscle & elastic fibers, valves
ARTERY
function = send blood from heart
Pressure = high
Lumen diameter = narrow
Wall thickness = thick
Wall layers = 3 (tunica adventitia, media, intima)
Muscle and elastic fibres = large amounts
Valves = no
VEIN
function = send blood to heart
Pressure = low
Lumen diameter = wide
Wall thickness = thin
Wall layers = 3 (tunica adventitia, media, intima)
Muscle and elastic fibres = small amounts
Valves = yes
CAPILLARY
function = material exchange with tissues
Pressure = low
Lumen diameter = very narrow (1 cell wide)
Wall thickness = very thin
Wall layers = 1 (tunica intima)
Muscle and elastic fibres = none
Valves = no
State to common placement of valves in veins and their function there
veins of the limbs
prevents reversed blood flow caused by the pressure from movements of the surrounding tissues including the contractions of the muscles, which compress the vein
valve is closed by blood pressure from in front and opened by that from behind
State and briefly distinguish the two types of circulation present in double circulation
pulmonary circulation - to and from lungs
systemic circulation - to and from all other organs including the wall of the heart
Briefly describe the process of pulmonary circulation
right side of the heart (right ventricle) pumps deoxygenated blood through pulmonary artery to the lungs where it is oxygenated
then the blood flows in pulmonary veins to the left side of the heart (left atrium)
Briefly describe the process of systemic circulation
organs are supplied with blood through and artery branching from the main aorta.
within organs the artery branches into numerous arterioles and the smallest arterioles supply the capillary networks which allow the efficient exchange of nutrients, oxygen and wastes between the blood and tissues.
capillaries drain into venules and venules join to form veins which consequently join the vena cava carrying blood back to the right atrium.
State the branching sequence in the circulation
aorta -> artery -> arteriole -> capillary -> venule -> vein -> vena cava
State the names of the blood vessels supplying the liver and what they carry
- hepatic artery
- hepatic portal vein - products of digestion after they have been absorbed into the capillaries of the villi
State the location of the human heart
in the thorax between the lungs and beneath the sternum (breast bone)
State the general structure of the human heart
- surrounded by the pericardium
- divided into four chambers (two upper atria and two lower ventricles)
- muscular wall of the left ventricle is much thicker than the right ventricle though volumes of both ventricles are identical
Define pericardium
strong, non-elastic sac anchoring the heart within the thorax
State the function and types of valves present in the human heart, distinguish them
prevent the backflow of blood, maintaining the direction of flow through the heart
- atrio-ventricular valves - larger valves preventing backflow from ventricles to atria while the ventricles contract, their edges are supported by tendons
- semilunar valves - separation of the ventricles from the pulmonary artery (right) and aorta (left), cut out the backflow from aorta and pulmonary artery into the ventricles as the ventricles relax between heartbeats
State the reason for the atrio-ventricular valves to be supported by tendons
prevention of the folding back of the valves due to huge pressure developing with each heart beat
State an alternative name for the heart muscle
myocardium
Define coronary circulation
circulation of blood in the blood vessels of the heart muscle
State and distinguish between the types of vessels present in the coronary circulation
- coronary arteries - deliver oxygen-rich blood o the myocardium
- cardiac veins - remove the deoxygenated blood from the cardiac muscle
- coronary sinus - returns the collected deoxygenated blood from the cardiac veins to the right atrium
List the general steps of the cardiac cycle
- atrium muscles contract pushing blood past the bicuspid valve into the ventricles.
- atrium muscles relax
- ventricle muscles contract causing the blood pressure to close the bicuspid valve and open the semilunar valve forcing blood into the aorta.
- ventricle and atrium muscles relax while the pressure of blood in the aorta causes the semilunar valves to shut.
- blood flows into the atrium and opens the bicuspid valve as it starts to flow into the ventricle.
Define the cardiac cycle and its two phases
one complete sequence of pumping the blood and filling the chambers
systole - contraction phase of the cycle
diastole - relaxation phase
List and describe the cardiac cycle in three steps
- atrial and ventricular diastole (0.4 s) - relaxation phase where blood returning from large veins flows into the atria and then into the ventricles through the AV valves.
- atrial systole and ventricular diastole (0.1 s) - atrial contraction forcing all blood remaining in the atria into the ventricles.
- ventricular systole and atrial diastole (0.3 s) - ventricular contraction pumps blood into the large arteries through the semilunar valves.
State the duration of a complete cardiac cycle in an adult human and the bpm
72 beats per minute
0.8 s of the cycle
Describe in detail the process of atrio-ventricular and semilunar valve functioning
- blood returning to the heart fills atria pressing against the AV vales which pressure caused them to open.
- as the ventricles fill up the AV valve flaps hang limply into ventricles.
- atria contract forcing additional blood into the ventricle.
- ventricles contract forcing blood against the AV valve cusps and thus to close the AV valves.
- papillary muscles contract and chordae tendinea tighten preventing valve flaps from everting into atria.
- as the ventricles contract and intraventricular pressure rises the blood is pushed up against the semilunar valves forcing them to open.
- as the ventricles relax blood flows back from arteries filling the cusps of semilunar valves and forcing them to close.
Compare the diastole, atrial systole and ventricular systole phases of the cardiac cycle taking into account: the state of atria and ventricles, blood positioning, AV and SL valves state
DIASTOLE
- atria and ventricles relaxed
- blood flows into heart from veins
- AV valves open
- SL valves closed (heart sound 2)
ATRIAL SYSTOLE
- atria contract
- ventricles relaxed
- blood pushed into atria
- AV valves open
- SL valves closed
VENTRICULAR SYSTOLE
- atria relaxed
- ventricles contract
- blood pushed into arteries
- AV valves closed (heart sound 1)
- SL valves open
State and define the characteristic of the heart beat
myogenic in origin
origin of each beat is within the heart itself
State the component of the intrinsic cardiac conduction system
noncontractile cardiac cells specialized to initiate and distribute impulses throughout the heart so that it depolarizes and contracts in an orderly, sequential manner
State and describe the sequence of electrical excitation in the human heart
- sinoatrial node (pacemaker) generates impulses.
- the impulses pause (0.1 s) at the atrioventricular node.
- the atrioventricular bundle connects the atria to the ventricles.
- the bundle branches conduct the impulses through the interventricular septum.
- subendocardial conducting network (Purkinje fibers) depolarizes the contractile cells of both ventricles.
Define an ECG
electrocardiogram
graphic record of heart activity
State the function of the delay of the electrical impulse before spreading to the heart apex.
allows the atria to empty completely before the ventricles contract
Relate the stages of the electrical excitation of the heart with the waves on the electrocardiogram.
- atrial depolarization initiated by the SA node - P wave.
- impulse delayed at the AV node - space between finish of the P wave and Q dip.
- ventricular depolarization being at apex along with atrial repolarization - QRS complex.
- ventricular depolarization - space between QRS and T wave.
5.ventricular repolarization begins - T wave
6.ventricular repolarization is complete - end.
Give examples of heart conditions
- tachycardia - elevated resting heart rate >120 bpm
- bradycardia - depressed resting heart rate <40 bpm
- arrhythmias - irregular heartbeats (very common in young people)
- fibrillations - unsynchronized contractions of either atria or ventricles leading to dangerously spasmodic heart activity
State the location and distinguish between the two types of the human heart cardiovascular center
located in the medulla oblongata
cardioacceleratory center - projects to sympathetic neurons via the spinal cord which in turn synapse with neurons in the sympathetic trunk, from there the fibers run to the heart where they innervate the SA and AV nodes, heart muscle and coronary arteries.
cardioinhibitory center - sends impulses to the parasympathetic dorsal vagus nucleus in the medulla oblongata which in turn sends inhibitory impulses to the heart via branches of the vagus nerves
List the parts of the nerve signaling controlling the human heart activity
- medulla oblongata involuntarily controls the pacemaker
- sympathetic nerve releasing noradrenaline (norepinephrine) increases the heart rate
- parasympathetic nerve (vagus nerve) releases the neurotransmitter acetylcholine to decrease heart rate
List the parts of the hormone signaling controlling the human heart activity
release of the adrenaline hormone (epinephrine) from the adrenal glands (above the kidneys) and thus increasing heart rate by activating the same chemical pathways as the neurotransmitter noradrenaline
can happen in order to prepare for vigorous physical activity
Distinguish between the short-term and long-term response to stress of the adrenal glands
..
List the short-term (epinephrine and norepinephrine) and long-term (mineralocorticoids, glucocorticoids) effects of stress
epinephrine & norepinephrine:
- glycogen broken down to glucose, increased blood glucose level
- increased blood pressure
- increased breathing rate
- increased metabolic rate
- change in blood flow patterns -> increased alertness and decreased digestive, excretory and reproductive system activity
mineralocorticoids:
- retention of sodium ions and water by kidneys
- increased blood volume and pressure
glucocorticoids:
- proteins and fats broken down and converted to glucose, increased blood glucose
- partial suppression of the immune system
Describe the disease of atherosclerosis: its cause and effects
degenerative disease where areas of the artery wall become damaged
the macrophages will release growth factors encouraging the growth of fibrous tissue while the cholesterol builds up in the damaged areas eventually forming plaques and the arterial wall loses elasticity
plaques restrict blood flow and as the plaque ruptures blood clotting is triggered (coronary thrombosis)
State alternative name and define a heart attack
myocardial infraction
the coronary arteries become completely blocked leading to death of the coronary muscle tissue as a result of a lack of blood and oxygen
List the risk factors in coronary heart disease
- genetic predisposition for high cholesterol levels/blood pressure
- age
- sex - males at greater risk
- smoking - constricts blood vessels, increases blood pressure, decreases oxygenation of the heart muscle, increased clotting though increased fibrogen and platelets
- diet - increased fat/cholesterol/LDL in blood leads to plaque formation in arteries
- exercise and obesity - weakened circulation, increase in blood pressure, formation of plaques
- stress - increased cortisol causing increased atherosclerosis
State the types of leukocytes
GRANULOCYTES
- neutrophil: multilobed nucleus, pale red and blue cytoplasmic granules.
- eosinophil: bilobed nucleus, red cytoplasmic granules.
- basophil: bilobed nucleus, purplish-black, cytoplasmic granules.
AGRANULOCYTES
- lymphocytes: large spherical nucleus, thin rim of pale blue cytoplasm
- monocyte: kidney-shaped nucleus, abundant pale blue cytoplasm.
Label the structures of the blood vessels
Capillary
- endothelium
Artery + vein
- outer layer
- middle layer
- the hollow centre of a tube is the lumen
- endothelium
Label the structure of the heart.
- superior vena cava
- inferior vena cava
- right pulmonary trunk
- right atrium
- right pulmonary veins
- tricuspid valve
- right ventricle
- aorta
- left pulmonary artery
- left atrium
- left pulmonary veins
- mitral (bicuspid) valve
- aortic valve
- pulmonary valve
- left ventricle
- papillary muscle
- interventricular septum
- epicardium
- myocardium
- endocardium
Label the cardiac conduction system
- Sino-atrial node (SA)
- AV bundle
- atrio-ventricular node (AV)
- Purkinje fibres
- right and left bundle branches
List the ECG cardiac rhythms
- normal sinus rhythm
- arrhythmia
- bradycardia
- tachycardia
- atrial fibrillation
- ventricular fibrillation
State the reason for heart sounds
1st - closing of the AV valves at ventricular contraction
2nd - closing of SL valves after systole (pressure in the ventricle is lower than in aorta - backflow of blood closes valve)
Describe the meaning of A, B, #, *, +, x, y, z
- increase in atrial pressure due to atrial contraction
A - atrial contraction
B - ventricular contraction
- increase in ventricular pressure as ventricle contracts forcing blood into the aorta and increasing aortic pressure
+ - increase in atrial pressure due to the inflow of blood returning to heart from the veins following systole
ventricular volume:
x - increases as atrial contraction forces blood into the ventricle
y - decreases as ventricular contraction forces blood into the aorta
z - increases as blood returns to the heart following systole
Define ventilation
movement of air into and out of the lungs in two stages: inspiration and expiration, controlled by a movement of the diaphragm and ribcage
Define gas exchange
diffusion of oxygen and carbon dioxide to and from the blood at the alveoli and the respiring tissues
List the factors affecting diffusion
- size of the surface area available for gaseous exchange (respiratory surface)
- concentration gradient
- length of the diffusion path
State the factor necessary for the gas exchange to be efficient and what is it achieved by
high concentration gradients maintained in the alveoli
breathing in increases concentration gradients of oxygen between the alveoli and blood so that it diffuses into the blood while breathing out removes CO2 increasing the concentration gradients of CO2 between the blood and the alveolus so that CO2 will diffuse out
State the two factors that improve the condition for diffusion in mammals
a blood circulation system which transports oxygen into the body cells
a respiratory pigment (hemoglobin) which increases the oxygen carrying ability of the blood
Define human thorax
airtight chamber formed by the rib-cage and its muscles (intercostal muscles) and the diaphragm
Define a diaphragm
a sheet of muscles attached to the body wall separating thorax from abdomen
State the name and function for the membrane lining up the internal surface of the thorax
pleural membrane
secretes and maintains pleural fluid
Define pleural fluid
lubricating liquid that protects the lungs from friction during breathing movements
State the function of glottis and epiglottis
prevention of the entry of food into the trachea
State the function of incomplete rings of cartilage in the trachea
prevention of the collapse under pressure from the large boles of food passing down the esophagus
State the adaptation of bronchi and larger bronchioles to the pressure of a powerful inspiration of air
smooth muscles lining the walls and rings or tiny plates of cartilage
State the reason why lungs have a very large surface area
to increase the overall rate of gas exchange
State the structure of a bronchiole
a cluster of alveoli with a capillary system wrapped around the cluster and connected to a branch of the pulmonary artery and drained by a branch of the pulmonary veins
Define type I pneumocytes
extremely thin alveolar cells adapted to carry out gas exchange
State the adaptation of the alveolar cell wall to gas exchange
wall of alveoli consist of a single layer of flattened cells (pavement epithelium) with extremely narrow capillaries so that the distance over which oxygen and carbon dioxide has to diffuse is very small
Define the function of type II pneumocyte
secrete a solution containing surfactant reducing the surface tension and preventing the water from causing the sides of alveoli to adhere when air is exhaled from the lungs which helps prevent the collapse of the lung
State the structural adaptations of alveoli to their role
- very thin epithelial layer - minimize diffusion distance for respiratory gases
- rich capillary network - increased capacity for gas exchange with the blood
- spherical in shape - maximize the available surface area for gas exchange
- layer of fluid internally - facilitation of the diffusion of the dissolved gases into the bloodstream
State the mechanism of gas exchange by diffusion in the alveoli
oxygen dissolved in the surface film of water, diffuses across into the blood plasma and into red cells where it combines with haemoglobin to form oxyhaemoglobin
simultaneously carbon dioxide diffuses from blood into the alveoli
Describe the principle behind negative pressure breathing and its effect on human respiration
gases will move from a region of high pressure to a region of lower pressure
and thus
when the pressure in the chest is less than the atmospheric pressure the air will move into the lungs - inspiration
when the pressure in the chest is greater than the atmospheric pressure, air will move out of the lungs - expiration
List the human respiratory muscles
muscles of inspiration
core muscles:
- external intercostals (contracts to elevate ribs)
- diaphragm (contracts to expand thoracic cavity)
accessory muscles:
- sternocleidomastoid (contracts to elevate sternum)
- pectorialis minor (contracts to pull the ribs outwards)
Describe the ventilation mechanism of the lungs
INSPIRATION
- external intercostal muscles contract.
- internal intercostal muscles relax.
- thus the ribs are moved upwards and outwards and the diaphragm down.
- diaphragm muscles contract.
- diaphragm descends and thus the rib cage rises.
6.thoracid cavity and intrapulmonary volume increases and so the pressure is reduced below atmospheric pressure and air flows in.
EXPIRATION
- external intercostal muscles relax.
- internal intercostal muscles contract.
- thus the ribs are moved downwards and inwards and the diaphragm up and the rib cage descends due to recoil of costal cartilages.
- diaphragm muscles relax.
- the volume of thorax and thus lungs decreases (elastic lungs recoil passively) and so the pressure is increased above atmospheric pressure and air flows out.
Define and describe the symptoms, causes and consequence of emphysema
lung condition whereby the walls of the alveoli lose their elasticity due to damage to the alveolar walls
symptoms:
- loss of elasticity results in the abnormal enlargement of the alveoli leading to lower total surface area for gas exchange
- degradation of the alveolar walls can cause holes to develop and alveoli to merge into huge air spaces (pulmonary bullae)
cause:
- major cause is smoking as the chemical irritants in cigarette smoke damage the alveolar walls
- small proportion due to a hereditary deficiency of the elastase enzyme which breaks down the elastic fibers in the alveolar wall
consequence:
- shortness of breath
- phlegm production
- expansion of the ribcage
- cyanosis
- increased susceptibility to chest infections
State the reason for human ventilation system
- as large organisms oxygen cannot diffuse into all the cells directly from the air
- as land-borne organisms the gases need moist surfaces (membranes) to diffuse
- to maintain a large concentration gradient between the alveoli and the blood
State the reason for hemoglobin in the human respiratory system and its structure
because of the low solubility of O2 in water (and thus blood) it has difficulty with transport itself in animals relying on the circulatory system to deliver O2
has four polypeptide subunit chains each with cofacyor called a haeme group with an iron atom at its center
each iron atom binds one molecule of O2 so one hemoglobin can carry four total
Define the partial pressure of oxygen
pressure exerted by oxygen in a mixture of gases
at low p02 hemoglobin is not fully saturated with O2 but at high full saturation occurs
at high p02 it is easier to attach oxygen molecules to hemoglobin
State the partial pressure of alveolar air and interpret it
about 100mmHg
most of the hemoglobin molecules are bound to four O2
Describe with reason the binding of O2 molecules to hemoglobin molecule
after the first O2 molecule binds to iron the hemoglobin molecule changes shape and thus more readily takes up two more molecules
State when is the O2 separated from the hemoglobin molecules
when the oxygenated blood encounters a region where the PO2 in the interstitial fluid and body cells is lower than that in blood and thus it will diffuse from the blood plasma into the interstitial fluid and then into body cells
State, name and explain the factor contributing to the release of O2 from hemoglobin
increased acidity in active tissues
caused by oxidative reaction releasing CO2 which combines with water to form carbonic acid
causing the Bhor effect - alteration of the hemoglobin conformation which will reduce the affinity for O2
State the adaptation of the fetal hemoglobin
fetal hemoglobin is able to take up oxygen at lower partial pressures than adult hemoglobin because of its higher affinity for oxygen
especially as the fetus obtains oxygen through the placenta as the oxygen dissociates from the mothers hemoglobin and is attached to the fetal hemoglobin
State the function and adaptation of myoglobin
storage of oxygen in muscle tissues and its release when needed in respiration (gives also the muscle tissues its characteristic red colour)
releases a lot of oxygen over a narrow range of low partial pressures in the tissues
as it is more sensitive to a change in pO2 (higher affinity for oxygen at low pO2) and thus releases the oxygen into the tissues rapidly
Describe the ways of carbon dioxide transport in the blood
- dissolved in plasma (just 7-10%)
- chemically bound to hemoglobin (just over 20%) - carries in the erythrocytes as carbaminohemoglobin (bound directly to the amino acids of globin not to the haeme) - CO2+Hb->HbCO2
- bicarbonate ions in plasma (about 70%) - when dissolved CO2 diffuses into erythrocytes it combines with water forming carbonic acid (H2CO3) which as an unstable molecules dissociates into hydrogen ions and bicarbonate ions (carbonic anhydrase)
CO2 + H20 -> H2CO3 -> H+ + HCO3-
(arrows going both ways for both)
Describe the export of hydrogen carbonate (and thus CO2) out of the red blood cell
hydrogen carbonate diffuses out through a carrier while chloride ions diffuse in (chloride shift) which maintains a balance of charges across the membrane
the hydrogen ions attach to Hb which maintains pH and is know as buffering (additionally helped by the plasma proteins)
State the importance of maintaining the blood pH and how that is achieved
pH 7.35-7.45 to avoid the onset of disease
maintained by plasma proteins acting as buffers as they resist changes to pH by removing excess H+ ions or OH- ions through
a) amino acids which are zwitterions - may have both a positive and negative charge and hence can buffer changes in pH
b) the amine group may take H+ ions while carboxyl group can release H+ ions
Describe the mechanism of homeostatic control of breathing
- raise in the [CO2] in the blood and cerebrospinal fluid because of the increased metabolism.
- increase in the [H+] lowering pH of the blood.
- medulla oblongata detects the change in pH.
- increase in the depth and rate of breathing through medulla’s control circuits and its control of the rib muscles and diaphragm.
- remain high until excess CO2 is eliminated in exhaled air and pH return to normal.
State and name the effect of altitude on gas exchange
hypoxia
thinner air at higher altitudes has a reduced pO2 and thus the uptake of oxygen will be reduced by normal ventilation since the hemoglobin cannot reach 100% saturation
compensation by increased heart and breathing rate
symptoms:
headache, nausea, vomiting, dizziness, loss of consciousness, muscle weakness, rapid pulse
State the remedy for altitude sickness
cclimatisation
which helps the body produce more erythrocytes , myoglobin and mitochondra and a more adequate circulation around the muscles
ventilation rate increases
people living there have bigger chests, more dense alveoli, more red blood cells and higher affinity for oxygen
Define an asthma attack
smooth muscle walls of the bronchi contract blocking air flow into the lungs
is an allergic response to dust, pollen or house mites
inhalers help through acting as bronchodilators
Define a lung cancer and its effects
abnormal cell growth in the lung tissues caused by among else inhaling carcinogens (e.g. asbestos or radioactive ores)
effects:
- reduced surface for gas exchange
- pressure on blood vessels and impeded transport
- damage to pleural membranes, diaphragm or intercostal muscles
Define sexual reproduction
process that creates a new organism by combining the genetic material of two organisms
List and define the two main processes during sexual reproduction in eukaryotes
meiosis - number of chromosomes reduced from diploid 2n to haploid n
fertilization - involves the fusion of two gametes to form a diploid zygote and the restoration of 2n chromosomes
Define fertilization in animals
fusion of gametes to produce a new organism
involves the fusion of an ovum (oocyte) with a sperm which leads to a development of an embryo
State where are the gametes formed with distinction on testis and ovaries
gametes in general - gonads
sperms in testis
oocytes in ovaries
Distinguish how the female vs male sexual characteristics (ovary and testis) are formed
female:
1. TDF is not produced in the absence of Y chromosome, which allows the cortex of the embryonic gonads to develop into ovaries
2. in the absence of testosterone the embryo develops female characteristics
male:
1. the TDF (testis-determining factor) is produced by a gene on the Y chromosome which induced the medulla of the embryonic gonads to develop into testes
2. the testes produce testosterone which initiates the development of male sexual characteristics
Define and list the three phases of gametogenesis and list its two “types”
the production of gametes
- multiplication phase
- growth phase
- maturation phase
spermatogenesis
oogenesis
Describe the process of spermatogenesis
- the primordial germ cell in embryo divides mitotically to produce spermatogonia
- some spermatogonia return to basement membrane and some grow to become primary spermatocytes.
- FSH stimulates meiosis and thus primary spermatocytes divide into secondary spermatocytes.
- LH stimulates testosterone production which induces meiosis II which produces 4 haploid spermatids.
- testosterone stimulates differentiation of early spermatids into sperm cells
List the processes counting as the differentiation of spermatids into sperm cells
- tail development
- midsection with mitochondria
- nourishment from Sertoli cells
- storage and motility development in the epididymis
Define ejaculation
passing of the sperm through the ejaculatory ducts and mixing of it with fluids from the seminal vesicles, the prostate and the bulbourethral glands to form semen
State the components of semen with their places of origin
- seminal vesicles - yellowish viscous fluid rich in fructose (70% of semen)
- prostatic secretion - whitish (clear sometimes), thin fluid containing proteolytic enzymes, citric acid, acid phosphate and lipids
- bulbourethral glands - clear lubricating secretion into the lumen of the urethrae
Describe the structure of the testis tissue
- testes composed of seminiferous tubules producing sperm.
- each tubule surrounded by a basement membrane lined with germline epithelium cells.
- germline epithelium will divide by mitosis to make spermatogonia.
- developing spermatozoa are nourished by Sertoli cells
- outside tubules the blood capillaries and interstitial cells (Leydig cells) produce testosterone.
List the components of a single sperm cell
- head: acrosome with hydrolytic enzymes, DNA in nucleus
- middle piece: helical mitochondria
- tail
Describe the process of oogenesis
- primordial germ cell differentiates into oogonium through mitotic divisions.
- oogonium undergoes mitosis to form a primary oocyte arrested in prophase of meiosis I until puberty (the ovary is functionally inactive).
- the completion of meiosis I and onset of meiosis II creates a secondary oocyte arrested at metaphase of meiosis II and a polar body.
- meiosis II is completed only if sperm penetrates the oocyte.
List the phases of the menstrual cycle
- follicular phase
- ovulation
- luteal phase
List the processes occurring during the follicular phase of the menstrual cycle
- stimulation of follicle growth by FSH
- secretion of estrogen by the dominant follicle
- inhibition of growth of other follicles by estrogen
- stimulation of the endometrium development by estrogen
List the processes occurring during the ovulatory phase of the menstrual cycle
- release of an egg through a surge of LH
- creation of corpus luteum through rupture of the follicle
List the processes occurring during the luteal phase of the menstrual cycle
- secretion of progesterone and estrogen by corpus luteum
- stimulation of endometrium development by progesterone
- inhibition of FSH and LH production by estrogen and progesterone
- degradation of corpus luteum over time and dropping of progesterone alongside it
- endometrium shedding in menstruation because of the lack of progesterone
- as the FSH is no longer inhibited the cycle can start again
State what hormone is released if a fertilization of an egg occurs in the menstrual cycle
release of HCG hormone by a zygote which maintains the corpus luteum
Define and list an example of negative feedback
control process where the response to a stimulus reduced such stimulus
e.g. LH is produced by pituitary (the stimulus) which promotes the formation of the corpus luteum which the produces progesterone (response)
progesterone will inhibit LH secretion
State the origin of the FSH hormone and its general function
o: pituitary gland
promotes the development of follicles in the ovary and thus estrogen secretion by the follicle cells
State the origin of the LH hormone and its general function
pituitary gland
promotes ovulation and the formation of corpus luteum and thus estrogen secretion by the developing follicle
State the origin of the estrogen hormone and its general function
o: developing follicle and corpus luteum in the ovary
promotes thickening of the uterus lining
inhibits secretion of FSH
stimulates pituitary to secrete LH
State the origin of the progesterone hormone and its general function
o: corpus luteum
maintaining the thickened uterus lining
inhibits secretion of both LH & FSH
Distinguish the time of occurrence of spermatogenesis and oogenesis
spermatogonia are formed from the time of puberty throughout adult life
oogonia formed in the embryonic ovaries long before birth
Distinguish the time of formation of sperms and primary oocytes
sperms: daily
primary oocytes: from puberty a few undergo meiosis II to become secondary oocytes each month but only one of them will become the ovulatory follicle the rest will degenerate
Distinguish the number of sperms and ovum’s formed in spermatogenesis and oogenesis
from 1 spermatogonium 4 sperms
from 1 oogonium 1 ovum
Distinguish the time of meiosis II completion in spermatogenesis and oogenesis
meiosis I and II go to completion during sperm production
meiosis II reaches prophase and then stops until a male nucleus enters the secondary oocyte, triggering completion of meiosis II
Distinguish the consequence for the egg if or if not fertilized
if:
zygote begins to divide as it travels through oviduct to implant into lining of uterus
if not:
egg travels through oviduct to uterus and will exit body with blood and tissues during menstruation
List the stages in the fertilization of a human egg
- arrival of the sperm
- binding
- acrosome reaction
Describe the stages of the fertilization of human egg
- Arrival of sperm
chemoattracted sperm swims up the oviduct to the egg. - Binding
binding to the zona pellucida by the first sperm to break through the layers of follicle cells
triggers acrosome reaction.
3.Acrosome reaction
release of the contents of the acrosome through separation of the acrosomal cap from the sperm
the proteases from the acrosome digest the route through the zona pellucida allowing the sperm to reach the plasma membrane of the egg
- Fusion
fusion of the plasma membranes of the egg and sperm and thus the nuclei of the egg and the sperm joins trigger of the cortical reaction - Cortical reaction
exocytotic release of the contents of cortical granules as they move to the plasma membrane of the egg and fuse with it
enzymes contained in them cause cross-linking of glycoproteins in the zona pellucida and thus making it hard (fertilization envelope forms) and preventing the entry of any more sperm - block to polyspermy
- Mitosis
a two cell embryo is produced through the sperate mitosis of both nuclei from the sperm and egg using the same centrioles and microtubular spindles
Define polyspermy
condition in which multiple sperm nuclei enter the egg and fatally disrupt development
Describe the process of early embryo development and implantation (until day 8-9)
- zygote produced by fertilization in the oviduct starts to divide by mitosis.
- formation of morula by several divisions.
- simultaneous transport into the uterus by the oviduct.
- morula develops into the blastocyst (hollow ball of cells).
- implantation of the embryo into the endometrium
Define morula
embryonic stage consisting of a solid, compact mass of 16 or more cells
Distinguish between an early blastocyst and an implanting blastocyst
at 4 days the early blastocyst is basically a morula hollowed out and filled with fluid and hatches from the zona pellucida
at 7 days the implanting blastocyst consists of a sphere of trophoblast cells (no zona pellucida) and an eccentric cell cluster called the inner cell mass
Define a cleavage
process of the division of the zygote into a mass of daughter cells increasing the number of cells but not the size of the zygote
Define a blastocyst
a hollow ball of cells developed from the morula
Define implantation of an embryo
7 days after fertilization the embryo starts to become embedded in the endometrium
State how the blastocyst embeds into the uterine wall
using enzymes to digest and penetrate the lining which will provide nourishment for the embryo until placenta develops
State when and list and state the function of the two types of embryonic membranes formed
five weeks after fertilisation
the amnion - encloses the embryo in a fluid - filled space
the allantochorion - forms the fetal portion of the placenta
State what happens with the 7,5 day blastocyst
the syncytiotophoblast is eroding the endometrium cells from the embryonic disc are now separated from the amnion by a fluid-filled space
State what happens with the 12 day blastocyst
implantation is complete
extraembryonic mesoderm is forming a discrete layer beneath the cytotrophoblast
State what happens with the 16 day embryo
cytotrophoblast and associated mesoderm have become the chorion, the chorionic villi are elaborating
embryo exhibits all three germ layers, a yolk sac, and an allantois (forms the basis of the umbilical cord)
State what happens with the 4,5 week embryo
decidua capsularis, decidua basalis, amnion and yolk sac are well formed
chorionic villi lie in blood-filled intervillous spaces within the endometrium
embryo nourished via the umbilical vessels that connect it through the umbilical cord to the placenta
Define the placenta
disc-shaped structure composed of maternal (endometrium) and fetal membrane tissues which form placental villi embedded in the uterus wall
State how the blood flows in the placenta (and thus its functioning)
blood of the fetus flows close to the blood of the mother but they do not mix
the umbilical cords conect the fetus to the placenta and maternal blood pools via open ended arterioles into intervillous spaces (lacunae)
the chorionic villi extend into these spaces and facilitate the exchange of materials between the maternal; blood and fetal capillaries -> nutrients, oxygen and antibodies will be taken up by the fetus while carbon dioxide and waste products will be removed
State the adaptations of placenta for diffusion
- huge surface area (lots of villi-like projections)
- only a few cells thick
- blood supplies keep the concentration gradients high
- counter-current system
Describe the placental circulation
maternal blood enters the placenta in the arteries,
flows through blood,
pools in the endometrium
leaves via veins
the embryonic blood remains which in vessels,
enters the placenta through arteries,
passes through capillaries in finger-like chorionic villi where it acquires oxygen and nutrients
leaves the placenta through veins back to the fetus
State how are materials exchanged between maternal and fetal blood
diffusion, active transport and selective absorption between the fetal capillary bed and the maternal blood pools
List the placental structural adaptations to aid in its function
- rich blood supply (in fetus’s blood vessels)
- mothers arteries deliver blood into the intervillous space, bathing the villi of the placenta for maximal exchange of materials
- few, thin membranes give a short diffusion path
- villi increasing the surface for exchange
- placenta equipped with a large surface area and many RER and vesicles for production of hormones
- placenta secretes anti-immune substances to avoid attack by the immune system
List the movements across the placenta
- respiratory gases (diffusion)
- water (osmosis)
- glucose (facilitated diffusion)
- excretory products like urea
- antibodies
Define the placental barrier
cells separating maternal and fetal blood (selective and permeable)
Define HCG and state its role
human chorionic gonadotropin
a sex hormne which is intially secreted by the cells of the plastocyst and later from placenta
maintaining the corpus luteum as an endocrine gland (secreting estrogen and progesterone) for the first 16 weeks of pregnancy
later placenta takes its role as the estrogen and progesterone maintain the endometrium
State the function progesterone and oxytocin during gestation
progesterone - inhibits secretion of oxytocin by the pituitary gland and inhibits contraction of the muscular outer wall of the uterus
oxytocin - stimulates contraction of the muscular fibres in the myometrium
State the mechanism of the role of hormones in parturition and the type of feedback it represents
positive feedback
- towards the end of pregnancy there is a fall in progesterone level.
- progesterone-driven inhibition of the uterus wall is removed & posterior pituitary releases oxytocin.
- muscle in the uterus wall contract (directed by stretch receptors and signal to the pituitary gland to increase oxytocin secretion).
- uterine contraction stimulate the secretion of more oxytocin.
- uterine contractions become stronger and stronger.
- cervix relaxes and becomes wider & amniotic sac bursts and the amniotic fluid is released.
- fetus is pushed out through the cervix and vagina.
List the steps of IVF
- induced stop of the normal menstrual cycle.
- hormone treatment to develop follicles (FSH to stimulate follicle growth and HCG for follicle maturation).
- extract multiple eggs from ovaries
- select the sperm and prepare (capacitate) and inject into egg via intra-cytoplasmic sperm injection
- fertilization occurs under controlled conditions in vitro.
- implantation of multiple embryos into uterus
- test for pregnancy
State the mechanism of pregnancy test functioning
a urine sample is applied -> hCG in the urine binds to the mouse antibodies and starts to travel up the paper into the test region.
Antibodies that do not bind to hCG (there are always more antibodies than there is hCG) also move into and through the test region, where they serve as a positive control.
In the Test Region, a second antibody to hCH (fixed to the paper so that it cannot move), stops the hCG and the original antibody bound to it. This is in the first window of the pregnancy test. Any antibodies that are not bound to hCH (‘unbound’ antibodies) continue to move up the test strip into the Control Region.
In the Control Region, (the second window of the pregnancy test) the third antibody is encountered. The ‘unbound’ mouse antibodies are recognized by the goat antibodies fixed in the paper, and they stop moving at the second window
Label the diagram of a male reproductive system.
- sperm duct
- urethra
- testis
- penis
- ureter
- seminal vesicle
- prostate gland
- rectum
- coiled tubes
- scrotum
- glans
- foreskin
- spermatic cord
- bladder
Label the diagram of a female reproductive system.
- right/left oviduct
- ovary
- uterus
- vagina
- bladder
- urethra
- clitoris
- labia
- vulva
- rectum
- vagina
- cervix
Explain what happens during spermatogenesis.
..
Explain what happens during oogensis.
..
Label the diagram of a sperm cell.
- acrosome
- plasma membrane
- haploid nucleus
- helical mitochondria
- microtubules in a 9+2 arrangement
- protein fibres to strengthen the tail
- tail
Explain what happens during follicular phase, ovulation, luteal phase and menses.
..
Label the structure of a female gamete.
- two centrioles
- haploid nucleus
- cytoplasm (or yolk) containing droplets of fat
- first polar cell
- plasma membrane
- layer of follicle cells (corona radiata)
- layer of gel composed of glycoproteins (zona pellucida)
- cortical granules
Label the diagram of fertilization and implantation process
- zygote
- 4-cell stage
- morula
- early blastocyst
- implanting blastocyst
- ovulation
- oocyte
- fertilization
Label the diagram of the uterus and placenta.
- uterus
- placenta
- umbilical cord
- maternal blood pool
- chorionic villus containing fetal capillaries
- maternal arteries
- maternal veins
- maternal portion of placenta
- fetal portion of placenta
- umbilical arteries
- umbilical vein
- fetal arteriole
- fetal venule
State the homeostatic level in the human body and the factors responsible for maintaining it
- blood glucose concentration - 80 mg/dl - 110 mg/dl - pancreas and liver: insulin and glucagon
- blood pH - 7.35-7.45 pH - buffering agents, kidneys through excretion and circulation breath and heart rate
- 90% of blood volume is water - kidneys and hormones (excretion)
- CO2 concentration 10-13 kPa - kidneys (excretion) & circulation
- body temperature - 36-38 degrees - vasodilation and sweating for hot or vasoconstriction and shivering for cold
State the general definition of the endocrine system
control system of ductless glands that secrete chemical messengers called hormones, which circulate within the body via the bloodstream to affect specific target cells at distant organs
(does not include exocrine glands, which are ducted and secrete substances for release into cavities, either inside the body or onto its outer surface)
State the three major chemical classes of hormones
- polypeptides
- steroids - lipids that contain four fused carbon rings (all derived from the steroid cholesterol)
- amines - synthesized from a single amino acid (tyrosine or tryptophan)
Distinguish the hormone classes taking into account their philic properties
steroid - lipophilic - can cross membrane - constitutive secretion
peptide and amine - hydrophilic - cannot cross the membrane - regulatory secretion
Define regulatory secretion of hormones
cell stores hormone in secretory granules and releases them in “bursts” when stimulated
Define constitutive secretion of human hormones
cell does not store hormone but secretes it from secretory vesicles as it is synthesized
Distinguish the water-soluble hormone secretion and absorption into the cell from the lipid-soluble hormones
water-soluble
- secreted by exocytosis and travel freely in the bloodstream.
- cannot diffuse through the plasma membrane of target cells and thus they bind to cell-surface receptors to alter gene transcription.
lipid-soluble hormones
- diffuses out across the membranes of endocrine cells.
- binds to transport proteins to keep them soluble in aqueous environment of the blood.
- diffuses into target cells and typically binds to receptors in the cytoplasm or nucleus which will trigger a change in gene transcription.
State the mechanism of functioning of steroids
- steroid hormone diffuses through the plasma membrane and binds an intracellular receptor.
- the receptor-hormone complex enters the nucleus.
- the receptor-hormone complex binds a specific DNA region.
- binding initiates transcription of the gene to mRNA.
- the mRNA directs protein synthesis
Describe the cyclic AMP second-messenger mechanism of water soluble hormones
- hormone (1st messenger) binds receptor
- receptor activates G protein (Gs)
- G protein activates adenylate cyclase which converts ATP to cAMP (2nd messenger)
- cAMP activates protein kinases which will trigger responses of target cells
State the possible consequence of binding of the water-soluble hormone to a receptor protein
triggering the events at the plasma membrane that results in a cellular response such as:
- the activation of an enzyme
- a change in the uptake/secretion of specific molecules
- rearrangement of the cytoskeleton
- alteration of transcription of particular genes
State the absorption pathway of the protein hormones
- (are lipophobic) binds to receptors on the surface of the plasma membrane.
- activates second messengers within the cell.
- acts indirectly to change cellular activity via signal transduction pathways.
State the main difference in the mode of hormone action
steroid hormones: cross the plasma membrane of their target cells and cause activation of a specific gene on a chromosome in the nucleus
protein/peptide hormones: bind to a receptor in the plasma membrane of the target cell and thus activated receptor causes the release of a secondary messenger on the inside of the plasma membrane
but the type of hormone remains outside the cell
State the function of the neurosecretory cells of the hypothalamus
synthesis of the two posterior pituitary hormones: antidiuretic hormone (ADH) and oxytocin
Define the posterior pituitary gland
an extension of the hypothalamus
State an alternative name and general function of the antidiuretic hormone (ADH)
vasopressin
regulates kidney function through increasing water retention in the kidneys, helping maintaining of normal blood osmolarity
Describe the mechanism of osmoregulation of vasopressin
- osmoreceptors in the hypothalamus monitor blood osmolarity via its effect on the net diffusion of water into/out of receptor cells.
- blood osmolarity increases (after sweating for example) -> signals from the osmoreceptors -> release of ADH from the posterior pituitary (& thirst).
- drinking water reduces blood osmolarity
- inhibits also ADH secretion
State the consequence of the failure in release of the sufficient ADH
condition: diabetes insipidus
in which large quantities of dilute urine are produced
Describe the consequence of ADH receptor binding to receptor molecules
increase in the number of aquaporin proteins inserted in the membranes of collecting duct cells
and aquaporin channels recapture more water, reducing urine volume
State the origin of secretion and function of oxytocin in female mammals
mammary glands
regulates uterine contractions during birth
stimulates the ejection of milk from the mammary glands of a nursing mother
Describe the mechanism behind the regulation of milk ejection in a nursing mother
- stimulation of nipples in suckling sends neuronal signals to the hypothalamus.
- release of oxytocin from the posterior pituitary.
- through positive feedback oxytocin stimulates more oxytocin secretion.
- oxytocin stimulates the contraction of the smooth muscle cells surrounding individual alveoli of the mammary glands to contract and thus forcibly expels the milk through the nipples.
State the factors controlling the release of anterior pituitary hormones and distinguish their types
hormones secreted by hypothalamus
hypothalamic hormones can either be:
- releasing hormone
- inhibiting hormone
depending on their role
State the location of the pituitary gland relative to the hypothalamus and its main structural division
below the hypothalamus but connected to it
two parts: anterior pituitary and the posterior pituitary lobe
State what and how controls the activity of the pituitary gland and an alternative name for it
master hormone gland
hypothalamus controls the endocrine activity of the pituitary gland
through:
releasing a number of hormones from neurosecretory cells into the portal vein running between the hypothalamus and anterior lobe
releasing nerve impulses via neurons
Distinguish the posterior pituitary from the anterior pituitary naming them, by which hormones they produce (list an example) and why are they released
posterior pituitary lobe - neurohypophysis
- releases hormones produced by neurosecretory cells of the hypothalamus
- released in response to nerve signals
- examples: ADH
anterior pituitary lobe - adenohypophysis
- synthesizes hormones called releasing factors which will cause endocrine cells to release specific hormones into the bloodstream
- are released into the portal vein extending to the anterior lobe
- GnRH - triggers release of LH and FSH
Describe the hormonal regulation of growth taking into account its hypo and hypersecretion
the growth hormone GH is secreted by the anterior pituitary and stimulates growth in humans
through targeting the liver which responds through releasing insulin-like growth factors (IGFs), which circulate in the blood and directly stimulate bone and cartilage growth as well as increase in muscle mass
hyposecretion: absence of GH the skeleton of an immature animal stops growing
hypersecretion: during childhood can lead to gigantism (unusually tall person but retaining relatively normal body proportions)
State the responsible agent for the release of melatonin and its control method
released by the pineal gland
control of the release by a group of neurons in the hypothalamus called the suprachiasmatic nucleus (SCN)
Describe the control of melatonin secretion by the SCN
- photons stimulate the retina of the eyes
- nerve impulse sent to SCN
- nerve signal from SCN carried to the spinal cord and eventually to the pineal gland
- inhibition of melatonin production
- blood levels of melatonin fall, promoting wakefulness
contrary if light levels decline melatonin production increases
State the primary function of the thyroid hormones
increase in the metabolic rate
control of the body temperature
State the location of the thyroid gland
neck region, in front of trachea, below the larynx
State the two hormones secreted by the thyroid gland and the amino acids they are synthesized from
thyroxine - T4
triiodothyronine - T3
synthesized from tyrosine and iodine
Describe the role of thyroid hormones in vertebrates
- essential for normal growth and development
- increase the rate of metabolism in the body tissues - generation of body heat
- help regulate the synthesis of proteins necessary for cellular differentiation :
- T3 binds with its receptor in the nucleus of target cell
- T3-receptor complex induces or suppresses synthesis of specific enzymes and proteins
Describe how the thyroid hormones regulate the temperature in the human body
HOTTER temperatures cause hypothalamus to inhibit thyroxin release (from thyroid), which decreases the metabolic rate of the body to reduce heat production (lower body temperature).
COLDER temperatures causes hypothalamus to stimulate thyroxin release (from thyroid) which increases metabolic rate of the body to generate heat (raising body temperature).
Define and describe the effects of hypothyroidism
thyroxin deficiency
during infancy and childhood results in low metabolic rate leading to cretinism
in adults drowsiness and sleepiness, mentally slow, little energy
Define cretinism
a condition of retarred mental and physical development especially in children with hypothyroidism
diagnosed early enough and treated with thyroid hormones can prevent the effects
Define myxedema
condition of slowing down of physical and mental activity caused by almost no thyroid function and thus a drop in the basal metabolic rate by about 40%
treated by oral administration of the hormone
Define hyperthyroidism and state its consequence
excessive production of thyroid hormone by the thyroid gland
consequence: Graves’ disease
an autoimmune disorder usually with symptomatic protruding eyes caused by fluid accumulation behind the eyes
the body produces antibodies that bind to and activate the receptor for TSH causing sustained thyroid hormone production
State the consequence of iodine deficiency
inability to synthesize adequate amounts of thyroid hormone
thus insufficient to provide the usual negative feedback on the hypothalamus and anterior pituitary to inhibit TSH
elevated TSH causes an enlargement of thyroid gland and thus neck swelling known as goitre
Define leptin and its place of origin
hormone produced by the fat tissue throughout the body and regulating appetite
Describe the leptin feedback control system
amount of leptin is proportional to the fat tissue
reduced caloric intake -> decrease in fat tissue -> leptin signal decrease -> hypothalamus -> increased desire to eat
State the organs and their corresponding actions regulating the appetite control center
pancreas -> carbohydrate/protein intake -> insulin released -> appetite inhibitory center activated
adipose tissue -> lipids stored in fat cells -> leptin released -> block of stimulatory centre
stomach -> empty -> release ghrelin -> stimulatory centre
intestine -> food arrival -> PYY3-36 hormone -> inhibitory centre
State the mechanism describing how resistance to insulin is related to obesity
type II diabetes could reduce the activity of the inhibitory neuron and reduce the amount of leptin released as such also
resistance to leptin can develop and thus the blocking of the stimulatory neuron may fail to work leading to overeating and weight gain
State how the hormones regulate the functioning of testes in males
FSH - initiates sperm production at puberty
LH - stimulates the endocrine cells secreting testosterone
State the normal blood glucose level in humans and how and why it can vary
90 mg/100 cm3 of blood
- fasting or physical activity - drop to 70 mg
- meal rich in carbohydrates - rise to 150 mg
Describe the mechanism for regulation of blood glucose
digestion of carbohydrates -> glucose absorbed across the epithelial cells of the villi -> hepatic portal vein -> liver
if too high levels -> withdrawn from the blood -> stored as glycogen
Define hypoglycemia
blood glucose levels falling below 60 mg per 100 cm3
possible fainting
if body and brain continue to be deprived of glucose -> convulsions and coma
Define and describe hyperglycemia
an abnormally high concentration of blood glucose
high concentration of blood glucose -> water potential of the blood plasma decreases -> water drawn from the cells and tissues by osmosis back to the blood -> volume of blood decreases -> water excreted by the kidney -> circulatory system deprived of fluid
State and define the detection mechanism for excess blood glucose in the pancreas
the islets of Langerhans (alpha and beta)
which are hormone secreting glands (endocrine glands) with rich capillary network but no ducts that would carry secretions away and thus their hormones are transported all over the blood by the body
State the cells in the pancreas secreting insulin into the blood
beta islets of Langerhans
State the cells in the pancreas secreting glucagon into the blood
alpha islets of Langerhans
State the basic role of insulin
enhancing the transport of glucose into body cells
stimulation of the liver to store glucose as glycogen (glucose levels falls)
State the basic role of glycogen
promotes the breakdown of glycogen in the liver and thus the release of glucose into the blood
List the sites of blood glucose regulation
- liver (storage as glycogen)
- pancreas (insulin & glucagon)
- muscles (can import glucose but nor export)
- brain cells (import and use of glucose)
- small intestine (glucose absorption)
- most tissues
State the molecular reason for type I diabetes
insulin is not produced by beta cells in the pancreas and hence glucose is not removed from the bloodstream causing diabetes
State the molecular reason for type II diabetes
prolonged overproduction of insulin leads to desensitization of the insulin receptors and hence glucose is not removed from the bloodstream, causing diabetes
(defect in signaling between the insulin receptor and the glucose transporter Glut-4)
State the normal molecular physiology of glucose removal from the bloodstream
insulin bind to insulin receptors and triggers the opening of glucose transporters in fat and muscle cells
glucose removal from the bloodstream
Define diabetes in general
name for the group of diseases in which the body fails to regulate blood glucose levels
carries an increased risk of circulatory disorders, renal failure, blindness, strokes and heat attacks
Distinguish type I diabetes from type II in terms of onset of disease and treatment type
type I: onset during childhood
type II: onset after childhood
type I: insulin injections to control glucose levels, diet is not enough
type II: insulin injections are not needed, low carbohydrate diet
Define an endotherm and list the two animal categories being such
organism producing heat through internal means such as muscle shivering or increasing its metabolism and controlling heat loss through the skin
mammals and birds
opposite of endothermy is exothermy.
How does the hypothalamus gather the signals from the body
constant monitoring of blood composition circulating through the capillary networks of the hypothalamus
sensory receptors located in key organs in the body
sensory neurons via the spinal cord
State the origin of heat production in the human body
biochemical reactions of metabolism generating heat as waste product and distributing it by the blood circulation
over 70% comes from the core organs (kidneys and heart) also lungs and brain
during physical activity the skeletal muscles also do a good job
List the factors controlling the body temperature in humans
- transfer of heat in the blood
- role of the hypothalamus
- role of sweat glands
- role of skin arterioles
- shivering
State the body part responsible for thermoregulation
hypothalamus
List the actions of the hypothalamus relating to the heat conversion and loss centre
CORE TEMPERATURE IN BLOOD
DECREASE
hypothalamus
- heat conversion centre
- vasoconstriction
- increased metabolic rate
- shivering
- hair raised
INCREASE
hypothalamus
- heat loss centre
- vasodilation
- decreased metabolic rate
- sweating
- hair lowered
State the role of the thyroid hormone
regulation of bioenergetics; maintaining normal blood pressure, heart rate and muscle tone, regulation of digestive and reproductive functions
Describe the hormone cascade pathway of thyroid regulation
- thyroid hormone levels drop below the normal range.
- hypothalamus secretes TRH (thyrotropin releasing hormone) into the blood.
- portal vessels carry TRH to the anterior pituitary.
- TRH causes anterior pituitary to secrete TSH (thyroid-stimulating hormone) into the circulatory system.
- TSH stimulates endocrine cells in the thyroid glands to secrete thyroid hormones (T3 and T4).
6.thyroid hormone levels increase in the blood returning to normal range.
- acts on target cells throughout the body to control bioenergetics.
- thyroid hormone blocks TRG release - negative feedback loop
List the main functions the nervous system
- coordination of information from the senses as well responses to the sensory information
- coordination of muscle activity
- monitoring of the functioning of the other organ systems
State the organization of neurons
into central nervous system and peripheral nerves linking sense organs, muscles and glands with the brain or spinal cord
State the specialization of neuron cells
for the transmission of information in the form of impulses
List the ways of conducting nerve impulses
- from receptors to the CNS by sensory neurons
- within the CNS by relay neurons
- from the CNS to effectors by motor neurons
State the overall structural components of each neuron
a cell body - with nucleus and most organelles
variable number of nerve fibres:
- dendrites
- axons
Distinguish dendrites from axons in terms of function
dendrites - conduct impulses toward the cell body
axons - conduct impulses away from the cell body (thinner than dendrites, longer)
Define a Schwann cell
supporting cell of the neuron which wraps around the axon of motor neurons and form myelin sheath
Define the node of Ranvier
junction along the myelin sheath, between the individual Schwann cells
List and define the main types of neurons
- sensory neurons - carry impulses from receptors to the spinal cord and the brain
- interneurons - relay impulses from one neuron to another in the brain and spinal cord
- motor neurons - carry impulses from the brain and spinal cord to effectors (usually muscles)
State the path of a nerve signal from the receptor to the effector
receptor (e. g. sense organ) -> sensory neurons -> CNS (relay neurons) -> motor neurons -> effectors
Define an effector
organ of the body (muscle/gland) responding to an impulse from a motor neuron
Define and state an exact value of the resting potential of the neuron
potential difference across a nerve cell membranes when it is not being stimulated
-70 mV (millivolts)
List the reasons for the existence of resting potential in neurons
- sodium/potassium pump actively transports Na+ ions out of the cell and K+ ions inside (3 Na+ for 2 K+)
- membrane more permeable (50 times) to K+ ions than Na+ ions and so the diffusion down the concentration gradient is facilitated
- higher concentration of organic anions found on the inside of the membrane
Define and state an exact value of the action potential of the neuron
potential difference produced across the plasma membrane of the nerve cells when stimulated (through depolarization)
+40 mV
Describe depolarization in the neuron
- brief opening of the sodium gated facilitated diffusion channel by the stimulus.
- few sodium ions diffuse into the axoplasm.
- axoplasm less negative
- a) insufficient sodium ions diffuse in it and thus failure of reaching of the threshold potential and return to the resting potential
b) reaching of the threshold potential and thus change from a negative potential to a positive potential
Distinguish initial recovery from complete recovery after the electric stimulus in a neuron
initial recovery:
- closing of the voltage gated sodium channels
- opening of the sodium gated potassium channels
- increased flow of potassium ions diffusing down the concentration gradient
full recovery:
- all voltage gated channels closed
- sodium-potassium pump removing sodium ions from axoplasm
- diffusion of potassium ions through open channel
- resting potential - both Na+ and K+ channels are closed.
- Na+ channels open and Na+ rush in by diffusion.
- interior of the axon more positively charged.
- Na+ ions close
- K+ ions open and K+ rush out by diffusion.
- interior of the axons starts to become less positive again.
- re-establishment of the resting potential by the Na+/K+ pump starting to work
State the steps of the nerve signal impulse
- Resting state. No ions move through voltage-gated channels.
- Depolarization is caused by Na+ flowing into the cell.
- Repolarization is caused by K+ flowing out of the cell.
- Hyperpolarization is caused by K+ continuing to leave the cell.
Define and state the function of the saltatory conduction
in myelinated axons, jumping of the action potential from node to node.
because the voltage-gated sodium channels are restricted to nodes of Ranvier and the extracellular fluid is in contact with the axon membrane only at the nodes
thus action potentials are not generated in the regions between the nodes (Myelin layer prevents the movement of Na+/K+ ions) which speeds up the rate of transmission
State and distinguish the two types of synapses
electrical synapse - gap junctions, formed from the presynaptic and postsynaptic cells, enable the flow of ions through them - directly passing impulses
chemical synapse - plasma membranes of the presynaptic and postsynaptic cells are separated by the synaptic cleft through which the neurotransmitter molecules diffuse and bind to receptors in the plasma membrane of the postsynaptic cell. binding opens channels to ion flow which may generate an impulse in the postsynaptic cell
State the structural parts of the chemical synapse
- synaptic knob - the swollen tip
- pre-synaptic neuron - axon of one neuron
- post-synaptic neuron - dendrite and cell body of another neuron
- synaptic cleft - gap between the neurons
Define transmitter substances
small diffusible molecules, produced in the golgi apparatus in the synaptic knob and held in tiny vesicles before crossing the synaptic cleft (with the action potential)
List the examples of transmitter substances in a human neuron
- acetylcholine - released by cholinergic neurons
- noradrenalin - adrenergic neurons
- glutamic acid
- dopamine
Describe in steps the chemical synapse transmission
- arrival of an action potential at the synaptic knob.
- calcium ion channels in the pre-synaptic membrane open.
- calcium ions flow in from the synaptic cleft.
- Ca2+ ions cause fusion of the vesicles of transmitter substance with the pre-synaptic membrane.
- release of the substance into the synaptic cleft
- diffusion of the transmitter substance across the synaptic cleft
- binding with receptor protein and thus triggering the entry of Na+ ions and thus action potential in the post-synaptic membrane.
- transmitter substance on the receptors is inactivated by enzyme action which closes the ion channel of the receptor protein
- re-establishment of the resting potential in the post-synaptic neuron.
- re-synthesis of the inactivated products from the transmitter into transmitter substance and their packaging for re-use.
Describe the blocking of the synaptic transmission and give a specific example
mimicking of the neurotransmitters and thus stimulating the synapse even in the absence of the normal neurotransmitter
inhibition - inhibitor molecule binds to he postsynaptic receptor but does not cause depolarization - normal neurotransmitter cannot bind
e.g. inhibitory neonicotinoid pesticide binding to acetyl choline receptors
State the all-or-nothing principle of neuronal stimulation
stimulus must be at or above minimum intensity - the threshold of stimulation - in order to initiate action potential
every subthreshold stimuli will cause the influx of sodium ions to be quickly reversed and the full resting potential to be re-established
State the way of the intensity of the stimulus increasing
increase in the frequency of the action potential passing along the fibers
(same strength of the individual action potentials)
recognized by the effector or the brain
Define and state the reason for the refractory period
the 5-10 millisecond period after the excitation of a neuron, when the neuron fibre is not excitable.
because large excess of sodium ions inside the fibre and thus impossible further influx
Distinguish the CNS from the PNS in terms of their components
CNS: brain and spinal cord
PNS: cranial and spinal nerves
State the function of the autonomic nervous system
visceral motor - involuntary
conducts impulses from the CNS to cardiac and smooth muscles and glands
Distinguish the sympathetic division from the parasympathetic division and state the system they are both part of
both part of ANS
sympathetic: mobilizes body systems during activity
parasympathetic: conserves energy and promotes house-keeping function during rest
State the cause of an infectious disease
another organism/virus invades the body and lives there parasitically
Distingusih communicable from non-comunicable diseases and list their alternative names
infectious diseases (communicable) - pathogens may pass from diseased host to a healthy organism
non-infectious diseases (non-communicable) - non infectious lol (cardiovascular etc)
List the types of pathogens
- microorganisms - some bacteria, fungi
- some protozoa - flatworms, roundworms
- all viruses
Define immunity
the ability to resist infection
State and define the two types of immunity
non-specific immunity - allows the body to resist infections by a wide range of pathogens
specific immunity - allows the body to resist infections by a specific pathogen
State the types of non-specific immunity
- external barrier - skin
- internal barriers
- phagocytic cells
State the two types of internal barriers
- mucous and cilia
- gastric juice containing hydrochloric acid killing many bacteria present in the food
Define specific immunity
proteins and other molecules on the surface of pathogens recognized as the foreign by the body and stimulate a specific immune response
State and define the two types of animal immunity
innate immunity - recognition of traits shared by broad ranges of pathogens, using a small set of receptors - rapid response
adaptive immunity - recognition of traits specific to particular pathogens, using a vast array of receptors - slower response
State the types of innate immunity
- barrier defenses
- internal defenses
List the types of barrier defenses
- skin
- mucous membranes
- secretions
List the types of internal defenses
- phagocytic cells
- natural killer cells
- antimicrobial proteins
- inflammatory response
List and define the types of adaptive response
humoral response - antibodies defend against infections in body fluids - B cells
cell-mediated response - cytotoxic cells defend against infections in body cells - T cells
State the types of barriers of the specific immune system
- physical - skin and mucus membranes
- chemical - stomach acidity, anti-microbial peptides
- cellular - macrophages, neutrophils
State the first line of defense against pathogens
skin
State and justify the type of barrier the skin is
physical - covered by keratinized protein of the dead cells of the epidermis - tough and impervious layer
chemical - sebum secreted by sebaceous glands - maintaining the skin moisture and lowering the skin pH which inhibits the growth of bacteria and fungi
List the examples of chemical barriers
- lysozyme - phospholipase A (saliva and tears)
- acid pH - stomach
- anti-fungal peptides - alpha-defenses - intestinal tract
- anti-microbial peptides - beta-defenses - respiratory, urogenital tract
State the steps of immunity direct response after tissue damage
- release of vasoactive and chemotactic factors (histamines) by the mast cells.
- triggering a local increase in blood flow and capillary permeability.
- influx of fluid (exudate) and cells.
- phagocytes migrate to the site of inflammation (chemotaxis).
- destroying of bacteria by phagocytes and antibacterial exudate.
Define platelets
small cell fragments, which form in the bone marrow and circulate in the blood stream until they stick to the damaged tissues and clump together
Describe the clotting cascade of events
- damage to the endothelium vessel exposing connective tissue in the vessel wall to blood.
- platelets adhere to the collagen fibers in the connective tissue.
- platelets release a substance that makes nearby platelets sticky.
- platelets form a plug providing immediate protection against blood loss.
- usually plug is reinforced by a fibrin clot
Describe the fibrin clot formation
- mixing of the clotting factors released from the clumped platelets or damaged cells with clotting factors in the plasma forming an enzymatic cascade.
- conversion of the plasma protein photothrombin to its active form thrombin (enzyme).
- catalysis of the final step of the clotting process - conversion of fibrinogen to fibrin.
- threads of fibrin become interwoven into the clot
List the players of innate immune responses
- neutrophils
- macrophages
- dendritic cells
- natural killer cells
State the function of neutrophils
phagocytosis of:
- reactive oxygen and nitrogen species
- antimicrobial peptides
State the function of macrophages
phagocytosis of
inflammatory mediators
antigen presentation
reactive oxygen and nitrogen species
cytokines
complement proteins
Define neutrophils
most abundant type of white blood cell, phagocytic upon encountering infectious material in the tissues
State the second line of immune defense
phagocytosis
Describe the steps of phagocytosis
- phagocytic leukocytes circulate in the blood and in response to infection move into body tissues - extravasation.
- because the damaged tissues release chemicals (f.e. histamine) which attracts leukocytes via chemotaxis.
- phagocyte adheres to pathogens or debris.
- phagocyte forms pseudopods that engulf the particles - formation of phagosome.
- lysosome fuses with the phagocytic vesicle forming a phagolysosome.
- lysosomal enzymes digest the particles leaving a residual body
- exocytosis of the vesicle removes indigestible and residual material.
- pathogen fragments on the surface of the phagocyte in order to stimulate the third line of defense.
State the third line of immune defense
specific immunity
Define and state the full name of MHC
major histocompatibility complex
a glycoprotein encoded by a large gene family in all vertebrates and unique to every individual (genetically determined)
each individual has unique MHC antigens present on the plasma membrane of most of ones body cells
State the mechanism through which lymphocytes differentiate their own antigens from the foreign ones
through antigen receptors recognizing the MHC receptors
each recognizes one specific antigen and in its presence will divide rapidly producing many clones of itself
then the cloned lymphocytes secrete the antibodies specific to that antigen
State the two categories of lymphocytes with their place of differentiation and function
B-lymphocytes - differentiate in the bone marrow - secrete antibodies (humoral immunity) as one particular B-cell produces one particular type of antibody
T-lymphocytes - differentiate in the thymus - cell mediated immunity - become activated when other cells of the immune system atack foreign cells directly and kills them
State the origin of B- and T- cells
in red bone marrow
Define immunocompetence
ability of the B- and T-cells to recognize one specific antigen
State the feature enabling immunocompetence
specific receptor protein on the cell surface capable of binding to one type of antigen
Describe the maturation of the B- and T-cells
- lymphocyte precursors destined to become T cells migrate in blood to the thymus and mature there
- B cells mature in the bone marrow
- development of immunocompetence and self-tolerance
State what happens within the lymph nodes
pathogens and foreign particles in the circulating lymph encounter and activate macrophages and other cells that carry out defensive actions
State the function and full name of APCs
antigen-presenting cells
engulf antigens and than present small fragments of them like signal flags on their own surfaces where T cells can recognize them
State how are T cells activated
by the antigens presented to them on MHC proteins by APCs
Describe the production of antibodies (in stages)
- antigen enters the body
- antigen binds to antibody on B-cell plasma membrane
- antigen is taken up by exocytosis of the B-cell
- is expressed on the plasma membrane at the MHC protein
- simultaneously macrophages engulf antigens by endocytosis and express it on their MHC proteins on the plasma membrane (antigen presentation)
- T-cell binds briefly to macrophage that presents an antigen causing activation (now is called activated helper T-cell)
- activated helper T-cell now binds to B-cell with the same expressed antigen causing its activation (activated B cell)
- the activated B-cell divides rapidly forming a clone of plasma cells.
- some activated B-cells and T-cells survive in the body as memory cells.
- each plasma cell now mass-produces antibody molecules and secretes them by exocytosis
antibodies overcome the antigen by f. e. neutralising it
State the function of memory B and T cells
initiating a more speedy response in the event of re-infections
State a way of overcoming an antigen by the antibodies through neutralization
clumping together of cells to aid engulfing by other macrophages
precipitation of soluble antigens
State when are cytokines released
after activation of helper T lymphocytes by the antigen presentation
State the function of cytokines
stimulation of a specific B-cell that produces antibodies to the antigen to divide and form clones
State the two main functions of the clones created by B-cells
development into short-lived plasm cells that produce large quantities of a specific antibody (most of them)
differentiation into long-lived memory cells that function to provide long-term immunity (some of them)
Define an antibody with its structure in mind
a special protein called immunoglobin
made of four polypeptide chains held together by disulphide bridges with a unique arrangement of amino acids residues in the polypeptide forming the fork region (binding site of the antigen)
State the initial location of antibodies
attached to the plasma membrane of B-cells
State the location of antibodies after B-cell activation
mass-produced and secreted by cells derived from the B-cells by exocytosis
Define clonal selection
product of vast numbers of identical plasma cells
Define a polyclonal response
because invading microorganisms have many different types of antigens
a typical pathogen activated many different types of B-cells and thus
triggers the secretion of many different antibodies all of which attach and attract that pathogen
State the consequence of a polyclonal response
more efficient destruction of the pathogen
List the types of modes of action of antibodies
- precipitation
- agglutination
- neutralization
- inflammation
- opsonization
- activation of the complement
Define opsonization
mode of action of antibodies - making a pathogen more recognizable to phagocytes so as they are more readily engulfed
Distinguish the neutralization of viruses/bacteria from the naturalization of toxins by the antibodies
viruses/bacteria - prevention of docking to host cells so that they cannot enter the cells
toxins - binding to toxins produced by pathogens, preventing them from affecting susceptible cells
Define agglutination by the antibodies
sticking together of pathogens so as to prevent them from entering cells and making them easier for phagocytes to ingest
the large agglutinated mass can be filtered by the lymphatic system and phagocytised
State the characteristics of the secondary immune response
faster, more prolonged and more effective
State what do memory cells provide
immunological memory
State the mechanism of function of vaccines
induction of long-term immunity to a specific pathogenic infection by stimulating the production of memory cells
Define a vaccine
weakened or attenuated form of the pathogen consisting of antigens but incapable of triggering the disease
State the function of an adjuvant in a vaccine
the antigenic determinants in the vaccine may be conjugated to it boosting the immune response
State the body’s response to a vaccine injection
initiation of the primary immune response an in consequence making of the memory cells
Distinguish the B from T lymphocytes in terms of type of immune response triggered
B-cells - humoral
T-cells - cellular
Distinguish the B from T lymphocytes in terms of primary targets of immune response
B-cells - extracellular pathogens (bacteria, fungi etc)
T-cells - intracellular pathogens (virus infected cells) and cancer cells
State the antigens present in the red blood cells and the blood compatibles for blood type A
A antigen
compatible: A, O
State the antigens present in the red blood cells and the blood compatibles for blood type B
B antigen
comp: B, O
State the antigens present in the red blood cells and the blood compatibles for blood type AB
both A and B antigens
compatible: A, B, AB, O (with AB+ as the universal recipient)
State the antigens present in the red blood cells and the blood compatibles for blood type O
none antigens
only O compatible (universal donor)
State the consequence of an incompatible blood transfusion
antigens on the surface of red blood cells stimulate antibody production in a person with a different blood group and thus trigger agglutination and hemolysis of the red blood cells
Distinguish the RH positive from negative blood group
Rh factor (spikes on rbc) which makes it positive
Rh negative = no spikes
Describe the serological conflict
..
Define active humoral immunity
B-cells encounter antigens and produce antibodies against them
Define passive humoral immunity
ready antibodies are introduced into your body
thus the B-cells are not challenged by antigens (immunological memory does not occur) and the protection provided by the “borrowed” antibodies ends when they naturally degrade in the body
List the two types of passive humoral immunity
naturally acquired - antibodies passed from mother to fetus via placenta or to infant in her milk
artificially acquired - injection of exogenous antibodies (gamme globulin)
List the two types of active humoral immunity
naturally acquired - infection (contact with pathogen)
artificially acquired - vaccine
Define an allergen
environmental substance that triggers an immune response despite not being intrinsically harmful
Define anaphylaxis
severe systemic allergic reaction, can be fatal if left untreated
State the location of the immune response to the allergen (allergic reaction)
localized at the region of exposure (e.g. airways and throat)
State the requirement for an allergic reaction to occur
pre-sensitized immune state (prior exposure to the allergen)
State the mechanism of an allergic reaction
- B-cell first encounters the allergen
- making of large quantities of antibody (IgE) through differentiating of the B cell into plasma cells
- IgE antibodies attach to mast cells priming them towards the allergen
- upon re-exposure to the allergen - release of large amounts of histamine by the IgE-primed mast cells
- inflammation as a cause
State the consequences of the histamine release from the IgE-primed mast cells in response to an allergen
- capillary widening - increased blood flow
- increased permeability - fluid release into tissues - redness and swelling
- attraction of leukocytes - extravasation of leukocytes to site of injury - tenderness
- systemic response - fever and proliferation of leukocytes - pain
Define a monoclonal antibody
artificially produced antibody to target one specific antigen
as usually the body produces a polyclonal response to an invasion by pathogen
State the possible use of a monoclonal antibody
cancer treatment
as the cancer cells carry specific antigens (tumor-associated antigens TAA) on their cell surfaces
thus if monoclonal antibodies to TAA are produced the drugs to kill cells or the inhibitors to block key tumor proteins can be attached and the cancer cells specifically targeted and killed
State the result of the use of monoclonal antibodies on cancer cells
hybridization of the tumor cell and the specific B cell resulting in hybridoma
capable of synthesizing large quantities of antibodies that can be used in various technologies
Define a myeloma cell
cancerous tumor of a plasma cell
which will divide rapidly but not produce antibodies
Define antibiotics
naturally occurring substances that slow or kill microorganisms
Define broad spectrum antibiotics
antibiotics effective over a wide range of pathogenic organisms
State the principle of the antibiotic mechanism of work
interfering with the specific metabolic processes, typically the synthesis and laying down of new wall materials
Describe the process of infection by an HIV virus
- binding of the virus to the T-lymphocyte cell and passing of the viral core into the cell
- RNA and viral enzymes are released
- reverse transcriptase catalyzes the copying of the genetic code of each of the viruses RNA strand into a DNA
- the DNA enters the host nucleus and is spliced into the hosts DNA of a chromosome
- may be replicated with the hosts genes every time the host cell divides (but remain latent giving no sign of presence)
- some events activate the HIV genes and the outcome is AIDS
- so the synthesis of the viral messenger RNA which passes out into the cytoplasm and codes for viral proteins at the ribosomes
- viral RNA, enzymes and coat proteins are formed into viral cores
- viral cores move against the cell membrane and bud-off new viruses which will infect other lymphocytes and repeat the cycle
State the consequence of the HIV infection
AIDS and thus
dramatic loss in the ability to produce antibodies to a wide range of common infections (e.g. pneumonia, meningitis)
List the possible ways of infecting with an HIV virus
- sexual intercourse
- sharing of hypodermic needles
- breast feeding of a newborn
- blood transfusion and organ transplants
State the current treatment for the HIV virus infection
drugs such as AZT and two protease inhibitors that reduce the number of HIV-infected cells by interrupting the steps of nucleic acid reverse transcription
State the consequence and function of the recognition of the self-antigens by the T cells
apoptosis as it eliminates the self-reactive T cells that could cause autoimmune diseases
State the consequence of the failure of the recognition of the self-antigens by the T cells
survival and continued maturation
State the consequence and function of the recognition of the self-MHC by the T cells
survival and proceeding to negative selection
State the consequence of the failure of the recognition of the self-MHC by the T cells
apoptosis
State the steps of the T-cell education in the thymus
- positive selection (self MHC)
- negative selection (self antigens)
Describe the diagnosis of an HIV infection using monoclonal antibodies
- HIV antigen attached to the plate.
- patients serum passed over the plate.
- HIV antibody would attach to the antigen on the plane.
- second antibody, specific to the HIV antibody, passed over the plate.
- antibody will attach to the concentrated HIV antibody on the plate (second antibody has an enzyme attached to its structure).
- Chromagen dye passed over the complex.
- enzyme will turn the Chromagen to a more intense colour
the more antibodies the greater the HIV antibody level
Define excretion and list main excretory compounds in mammals.
removal from the body of the waste products of metabolism
nitrogenous compounds such as urea, ammonia and uric acid coming from breakdown of proteins, nucleic acids and excess amino acids
Define osmoregulation
control of proper balance of water and dissolved
substances (inorganic ions) in the organism
List the main functions of the kidney
- excretion of urea
- regulation of the amount of water that is retained and excreted in the body.
- plasma filtration to get rid of certain ions and wastes while keeping other ions and maintaining water balance.
- maintaining the pH balance throughout the body.
- production of the EPO hormone.
- assisting with increased and decreased blood pressure.
State the full name and brief function of EPO hormone
erythropoietin
role in production of red blood cells
State the function of ureter
transport of urine to the bladder
State the way that blood is carried to the kidney and taken away
in by renal artery
away by renal vein
Define a nephron
basic unit structure of the kidney
List the steps of formation of urine
- ultrafiltration in the renal capsule.
- selective reabsorption in proximal convoluted tubule.
- water conservation in the loop of Henle.
- secretion in distal convoluted tubule.
- water reabsorption in the collecting ducts.
- ADH and the formation of concentrated/dilute urine.
State the three layers the ultrafiltration filtration takes place through
- endothelium of the blood capillary
- basement membrane of the blood capillaries
- epithelium of the renal capsule
Define glomerular filtration
blood from the renal artery enters the afferent arteriole which then turns into even smaller capillaries of the glomerulus
the diameter of the capillaries in the glomerulus is much smaller then arteriolar one and thus as the blood enters the narrow capillaries the pressure rises and forces a plasma-like fluid to filter from the blood in the glomerulus into the bowman’s capsule
Describe the ultrafiltration in the renal capsule
the large molecules in the blood enter through fenestrations between the capillary cell but are unable to pass through the basement membrane (the “ultra-filter”) which is the only barrier between the filtrate and the blood, allowing small solute molecules such as glucose and urea through but not large ones such as proteins
State the function of podocytes
allowing the filtrate to pass rapidly and easily into the space of Bowmans capsule as there are gaps between the cells
State with reason what functions as the “ultra-filter” in the renal capsule
the basement membrane
is the only barrier between the filtrate and the blood, allowing small solute molecules (e.g. glucose and urea) through but not large ones (proteins)
State the components of filtrate
water, glucose, amino acids, some salts and urea
very much like blood plasma but there are far less protein and no blood cells present
Define tubular reabsorption
reabsorption of useful substances from the filtrate within the renal tubules into the capillaries around the tubules
State the path of tubular reabsorption
starts at proximal tubules
Henle’s loop
distal tubule
collecting duct
State the percentage of the initial filtrate from the glomerulus that is reabsorbed by the nephron and returned to the blood in peritubal capillaries
99%
State the adaptation of the proximal convoluted tubule cells to reabsorption
- large surface due to microvilli
- numerous mitochondria
- closeness of blood capillaries
- intercellular and subcellular spaces increasing surface area for export
State the function of loop of Henle
creation and maintaining high concentration of salts in the tissue fluid in the medulla of the kidney through the countercurrent mechanism
State how the human kidney concentrated urine
through the two-solute model
Define the countercurrent system
depends energy to actively transport NaCl from the filtrate in the upper part of the ascending limb of the loop of Henle to create concentration gradients, which maintains a high concentration in the interior of the kidney enabling the kidney to form concentrated urine
Define the tubular secretion in distal convoluted tubule
involves substances which are secreted from the body and added to the tubular fluid such as K+, H+, NH4+, creatinine, some hormones and some drugs
State the function of ADH in relation to kidneys
increases the permeability of the distal convoluted tube and collecting ducts to water and urea
State the meaning of glucose in urine
common indicator of diabetes because it signalizes incomplete reabsorption
State the meaning of proteins in urine
can indicate for example:
PKU or hormonal conditions
Define kidney failure
kidney tubules fail to filter enough blood and hence fail to clear toxins from the blood
State two most popular methods of treatment of kidney failure
- hemodialysis
- transplant
Define the dialysis fluid
solution where the solutes are balanced to either cause or prevent diffusion
with zero concentration of urea so that it diffuses out of the blood
with glucose concentration equal of that to the blood so that no glucose leave the blood
Define hemodialysis
blood circulates through the dialysis machine and is returned to the arm vein
it passes along one side of a partially permeable membrane and dialysis fluid passes in the opposite direction on the other side of the membrane
List the types of skeleton systems
external - exoskeleton
internal - endoskeleton
absent - hydrostatic
State the function of bones
support and protection of the body parts
anchorage for muscles
State the brief function of joints
between bones permit movement
State the function of tendons
attach muscles to bones at their points of anchorage
Define the meaning that muscles are antagonistic and give example
when one contracts the other relaxes
in lower arm the extension of it is caused by the contraction of the triceps muscle and relaxation of the biceps muscle
Define with their function the ligaments
slightly elastic connective tissues connecting bone to bone and restricting the movement at joints and helping to prevent dislocation as they form a protective capsule around the joints
State what does the strength of the resulting contraction of the muscle depends on
on how many muscle fibers the motor neuron controls
Define a joint
junction between bones permitting controlled movement
State the function of the synovial fluid
lubrication of the joint, nourishment of the cartilage and removal of any harmful detritus from worn bone and cartilage surfaces
Define circumduction and state a type of joint permitting it
movement in all three planes
a ball and socket joint such as a hip joint
Define a hinge joint and give an example
one restricting movement to one plane
example: a knee joint
Compare and contrast the movement of the hip joint and the knee joint
Similarities:
- both are synovial joints
- both are involved in the movement of the leg
Differences:
HIP JOINT
- ball and socket joint
- capable of multi-axial
movement and rotation: - flexion and extension
- abduction and adduction
- circumduction and rotation
- Located between the pelvis and femur
KNEE JOINT
- hinge joint
capable of angular movement in one direction:
- flexion and extension
- small amount of rotation may be possible
- located between the femur and tibia
Define a muscle fibre
group of modified muscles cells where many cells have joined end to end to form a single mass of cytoplasm with many nuclei
Define a sarcomere
the basic unit of a muscle
State what are muscle cells composed of
tubular myofibrils
State what are myofibrils composed of
sarcomeres
appearing as dark and light bands under the microscope
State what are the thin and thick filaments of the muscles attached at
thin filaments - Z lines
thick filaments - M lines
State the positioning of the thick and thin filaments in a resting myofibril
partially overlapping
Define the position of a sarcomere
portion of the myofibril between the two z-line
State what are the thick and thin muscle filaments composed of
thin - actin protein
thick - myosin protein
State the reason for skeletal muscle shortening during contractions
the thick and thin filaments slide past one another
Define the H zone in the sarcomere
are occupied by the thick filaments
Define the I band (light) region in the sarcomere
region occupied by only thin (actin) filaments
Define the H band (dark) region in the sarcomere
region occupied by both filaments - overlapping
Define the Z band region in the sarcomere
extremities of a single sarcomere
State a structural characteristic making the shortening of the muscle possible
myosin thick filaments have bulbous heads protruding from the filaments
actin thin filaments have a complementary series of binding sites to which the bulbous heads fit
State what is present at muscle fibers at least making the binding and contraction not possible
the actin binding sites covered with blocking molecules - tropomyosin and the troponin complex
State the function of the calcium and regulatory proteins in muscle contractions
Ca2+ accumulates in the cytosol and binds to the troponin complex causing tropomyosin bound along the actin strands to shift position and expose the myosin-binding sites on the thin filament
thus if the Ca2+ concentration rise in the cytisik the muscle fibers will contract
State the effect of the motor neuron sending a signal to the muscle to contract that makes the muscle contract
causes a release of the Ca2+ ions by the sarcoplasmic reticulum
interaction of calcium with troponin triggers the removal of the blocking tropomyosin and exposes the binding sites
Label the neuron cell
- dendrites
- nucleus
- cell body (soma)
- node of Ranvier
- axon terminals
- myelin sheath
- Schwann cell
label the urinary system
- thorax
- renal vein
- renal artery
- vena cava
- diaphragm
- kidney (attached to dorsal wall)
- ureter
- dorsal aorta
- bladder
- urethra
- sphincter muscle under voluntary control
label the kidney
- nephrons
- fibrous capsule
- collecting duct
- renal artery
- pelvis - expanded origin of ureter
- cortex
- medulla
- ureter
Label the structure of a nephron
- afferent arteriole
- Bowmans capsule
- glomerulus
- efferent arteriole
- proximal convoluted tubule (PCT)
- renal cortex
- renal medulla
- descending limb of Henle
- loop of Henle
- ascending limb of Henle
- vasa recta
- distal convoluted tubule (DCT)
- collecting duct
Label the structure of an elbow joint
- humerus
- radius
- ulna
- cartilage
- tendon of biceps
- capsule of collagen fibres surrounds the joint
- tendon of triceps
- synovial membrane
- synovial fluid
Label the structure of an hip joint
- joint capsule
- femur
- pelvic girdle
- synovial membrane
- synovial fluid
- pad of fat
- ligament
- head of femur
- acetabulum
- cartilage
Label the structure of a muscle
- nucleus
- mitochondrion
- sarcoplasm
- sarcolemma
- z line
- sarcoplasmic reticulum
- thin actin filament
- thick myosin filament
- myosin head
- sarcomere
