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.
