6 human physiology Flashcards
what is chyme
food churned with acid
what enzymes does the pancreas excrete
amylase
lipase
protease
what does the liver secrete
bile to emulsify lipids
the gall bladder stores…
bile
what is bile
Bile is not an enzyme. Bile breaks large lipid globules into smaller lipid globules (this is what emulsify means). Bile does not facilitate hydrolysis reactions as enzymes do.
what is the serosa
the outermost layer consisting of connective tissue that is in contact with body cavities.
what is the longitudinal muscles
responsible for peristalsis.
what are the circular muscles
responsible for peristalsis.
what is the submucosa
connective tissue that supports the mucosa and that contains large veins and arteries which give rise to the capillary bed of the mucosa.
what is the mucosa
innermost layer forming the soft lining of the tube comprised of epithelium (which lines the lumen of the digestive track), connective tissue and smooth muscle (villi form part of this layer).
what does the pancreatic duct do
duct cells transport the enzymes produced by the acinar cells and secrete sodium hydrogen carbonate, which neutralises stomach acid
what do acinar cells do
secrete digestive enzymes
what do the islets of langerhoans do
produce the hormones insulin and glucagon
amylase:
breaks down starch into maltose
endopeptidase (trypsin) do
breaks down proteins into smaller polypeptides
lipases and phosopholipase
break down lipids and phospholipids, respectively, to glycerol and fatty acids. in case of the phospholipid, phosphate is also produced.
nucleases
break down dna into rna
maltase
breaks down maltose into glucose
lactase
breaks down lactose into galactose and glucose
exopeptidases
remove a single amino acid from the end of the small polypeptides
dipeptidases
break down a dipeptide into two amino acids.
stucture of a villus
where does absorption take place
epithelial cells
what do goblet cells produce
mucus
what carries nutrients away from the intestine
the capillary network and the lacteal
what is the lamina propria
connective tissue of the villus
absorption
the taking in of digested food substances as well as minerals and vitamins from the lumen of the small intestine into the blood.
what is directly absorbed by the villus
Bases and phosphates from nucleic acids
Fatty acids and glycerol
Amino acids
Monomeric carbohydrates, such as fructose, glucose, galactose and ribose.
what is assimilation
end products of digestion that are used by cells for anabolic processes or for respiration
methods of absorption
substances to be absorbed move from the lumen into the epithelial villi
Amino acids and monosaccharides move from the villi into the capillaries and monoglycerides move into the lacteals.
what mode of transport when molecules are small and hydrophobic
simple diffusion (they can pass through phospholipid bilayers)
facilitate diffusion
Fructose, glucose and other hydrophilic monomers are moved by protein channels. Be aware, this still requires a concentration gradient.
active transport
Is needed when the concentrations are lower in the lumen of the small intestine. Thus, the movement needs to occur against a concentration gradient. Glucose, amino acids and some mineral ions are transported out of the lumen in this way, which requires ATP. The cells of the epithelium have many mitochondria that can synthesise ATP for this process.
pinocytosis
Draws in small droplets of liquid surrounded by a small section of the phospholipid membrane, as shown in Figure 2. This is most likely to occur with fat droplets in the lumen of the small intestine.
describe the digestion of starch
Digestion of starch begins the moment you start chewing your food. Amylase is an enzyme present in saliva. Once the saliva and the food have been mixed, amylase starts breaking down the α-1,4 glycosidic bonds that connect the glucose monomers in amylose and amylopectin. The numbers 1 and 4 refer to specific carbon atoms within the two glucose molecules that are joined by the bond: refer to Figure 2 below. The end products are maltose, a dimer of glucose connected by α-1,4 bonds, and maltotriose, which is comprised of three glucose molecules also connected by α-1,4 bonds. Amylopectin also possesses a slightly different type of bond, called α-1,6 glycosidic bonds, however, these cannot be broken down by amylase.
amyolpctin vs amylose
what needs ot happen to the di- and tri-saccharides produced from the starch molecules
they are too large to pass through membranes, so they need to be broken down into monomers (monosaccharides) before they can be absorbed.
what enters the small intestine during the digestion of starch
a mixture of maltose, maltotriose and dextrins. Dextrins are very small polymers still containing the α-1,6 glycosidic bond.
what happens to the three enzymes that are immobilised in the epithelial cells of the small intestine
maltase, glucosidase and dextrinase, break down these molecules into glucose, which can then be absorbed by the villi.
All absorbed monomers from food are
transported via the hepatic portal vein from the small intestine to the liver, from there it enters the general circulation.
what happens to excess glucose
taken up by the liver and converted into glycogen, the animal equivalent of starch. resembles amylopectin but has moe alpha-1,6, glycosidic bonds
dialysis
the separation of smaller molecules from larger molecules in solution by selective diffusion through a partially permeable (also known as selectively permeable or semipermeable) membrane.
use of dialysis tubing to model absorption?
Mucous membranes are made up of
a surface layer of epithelial cells over a deeper layer of connective tissue. They produce mucus for protection and lubrication.
what do the skin and mucous membarnes act as
physical barries forming a primary defence against pathogens that cause infectious disease
how does blood clotting occur
Platelets release chemicals to start these reactions.
The first reaction triggers the second reaction by producing a chemical required for the second reaction.
This continues through a series of several reactions including up to 12 factors.
People who have the most common form of hemophilia are missing clotting factor VIII.
Each reaction takes an inactive protein in the blood called a clotting factor and activates it.
The last step of this cascade of reactions is the conversion of fibrinogen, a soluble and inactive clotting factor in blood, to insoluble fibrin.
This reaction is catalysed by an enzyme called thrombin which itself had to be activated by the cascade of reactions.
The result is a network of fibers that traps red blood cells and platelets to form a scab,
what is a thrombus
a blood clot that forms in a vessel and remains in the place where it was formed.
what is a coronary thrombus
a blood clot in the coronary arteries
what is atherosclerosis
narrows the lumen of arteries and slows down blood flow; thus increasing the chance of a clot occluding (blocking) a coronary artery. This will lead to certain parts of the heart not receiving any oxygen and nutrients, causing that part of the heart to die, resulting in a heart attack.
what happens as a result of blood clots
When a blood clot reduces the amount of blood reaching the heart muscles rather than stopping it completely, it causes angina or chest pain due to heart muscles not getting enough oxygen-rich blood.
Thrombosis of coronary arteries or formation of a clot within the coronary artery starts when the fatty deposit (plaque) in artery walls rupture the lining of the vessel. The clot that began at the site of the rupture can grow larger with time and completely block the artery.
what contributes to blood clots
atherosclerosis
obesity
smoking
hypertension
divide the immune system
Non-specific immune system involving phagocytes.
Specific immune system made up of lymphocytes and antibodies.
how many types of leukocyte are there
5
macrophages are often called
phagocytes because one of their main functions is phagocytosis
what can phagocytes do
Phagocytes can squeeze past the leaky endothelial cells of the capillaries and invade the tissue where an infection has occurred, for example, in a small wound in your skin. This is an example of non-specific immunity to diseases as the phagocytes can respond equally well to a variety of organisms.
pathogen
a disease-causing virus or microorganism. Examples of pathogens are: viruses, bacteria, protozoans, prions and fungi.
label parts of the antibody
what do lymphocytes have the capbability for
they have the capability to recognise millions of different antigens through receptors on their surfaces. These receptors are essentially an antibody that is attached to its cell surface as an integral protein so that the antigen binding site points outwards. An antibody is a protein molecule made by lymphocytes with a specific structure (as shown in Figure 2 ) and the function of recognising antigens
when a b cell encounters an antigen…
Firstly, the B cell divides repeatedly through mitosis to create many copies of the B cell that can recognise the antigen. This process is called clonal selection: ‘clonal’ comes from the fact that mitosis exactly duplicates, or clones, the B cells, and ‘selection’ comes from the idea that only one type of B cell, the one matching the antigen, has been ‘chosen’ to divide.
Most of these B cells become plasma cells which make and secrete large quantities of the antibody to circulate in the blood. Some of the B cells become memory cells: a long-lived pool of cells capable of responding quickly to the same antigen in case you encounter it again.
what do antibodies do (that are produced by plasma cells)
They can bind to the antigen, which allows phagocytes to recognise and then destroy the pathogen.
They can bind to proteins in the coat of a virus, which will prevent the virus from entering other (human) cells.
Where do memory cells remain
Bloodstream and lymph nodes
Antigens to antibodies pathway
Where are B cells produced
Bone marrow
What is a leukocyte
A leukocyte is any type of white blood cell. A lymphocyte is a particular type of white blood cell that produces antibodies.
What is a t cell
A type of lymphocyte
What is an apc
Antigen presenting cell
Once the antigen has been recognised by the T helper cell, the immune system is
activated to fight against the antigen. It triggers the production of antibodies and activates macrophages and killer T cells, which will engulf and destroy the antigen.
What does HIV do
The infected T helper cells are destroyed leading to a reduced number in the body. Since T helper cells are needed to activate B cells to produce antibodies, infection with HIV causes a loss in the ability to produce antibodies which can lead to the development of AIDS (acquired immune deficiency syndrome). It should be noted that HIV causes an overall reduction of active lymphocytes in the body, including both T and B cells: activated T cells decrease as infected T helper cells are destroyed and activated B cells decrease because there are fewer T helper cells to cause their activation.
HIV diagram
What is a retrovirus
HIV is a retrovirus that has RNA as its genetic material. Once HIV infects a cell through the proteins on the surface of its envelope, it makes a DNA copy from its RNA, with the help of an enzyme called reverse transcriptase. The cDNA that is produced is inserted into the host cell’s genome. These days the infection can be slowed down, or even stopped, with the use of antiviral drugs specifically targeting reverse transcriptase activity.
HIV symptoms
High fever
Headaches
Mood swings
Cough
Joint pain
High heart rate
Clammy skin
Nausea
Fatigue
When untreated aids develops into
AIDS
HIV can be transmitted via
Sexual intercourse
Transfusion of infected blood
Sharing of hypodermic needles by drug users
From mother to child during pregnancy, birth or breastfeeding.
HIV cannot be transmitted through ordinary day-to-day contact such as shaking hands, hugging and kissing or via sharing food, drink or personal items.
What do antibiotics do
Antibiotics block processes that occur in prokaryotic cells but not in eukaryotic cells. Thus, antibiotics can be used to treat bacterial infections in humans and animals (because they are eukaryotes) without harming their body cells.
What do antibiotics target
A ntibiotics do not have an effect on human cellular processes. The drugs target bacterial cell wall and membrane formation, ribosome function or DNA replication, transcription and translation. None of these may directly kill the bacteria, but it will slow down or stop growth and prevent cellular division.
Fungi and bacteria can compete for the same food resources so
fungi often secrete antibiotics to inhibit the growth of the competing bacteria. The best known example of an antibiotic is penicillin.
Florey and chain and streptococcus
Florey and Chain infected eight mice with Streptococcus . This bacterium causes pneumonia in mice. Eight mice were kept under identical conditions, but four of the eight were given an injection of penicillin. The four mice that were not treated with penicillin died within 24 hours, but the treated mice stayed alive. This experiment does not prove a causal relationship but gives a very strong indication that penicillin may have played a role in the recovery of the mice.
The next step was to test the drug on humans. Florey and Chain proceeded to test penicillin on very sick patients with infections. Most survived, and the commercial production of the drug in the 1940s allowed testing on more and more patients; eventually confirming it as a very effective weapon against infections.
Label the heart
Pulmonary circulation
From the heart to the lungs and back
Systemic circulation
From the heart to the body tissues and back
Which side is responsible for pulmonary circulation
Right
What side is responsible for systemic circukatuon
Left
The heart is myogenic which means
that the heart muscle can generate its own contractions. There is a group of specialised muscle cells in the wall of the right atrium called the sinoatrial (SA) node. This SA node initiates (starts) each heartbeat and it sets the heart rate, so it is often called the pacemaker. The SA node ‘fires’ (sends electrical signals) at regular intervals to cause the heart to beat with a rhythm of about 60 to 70 beats per minute for a healthy, resting heart.
Summary of the propagation through the heart of the electrical signal initiated in the SA node
The SA node sends out an electrical signal that stimulates contraction as it is propagated through the walls of the atria.
The signal then passes via interatrial septum to reach the atrioventricular (AV) node.
From the AV node, the signal is relayed via the bundle of His located in the interventricular septum to the top of each ventricle (confusingly, the top of the heart, or apex, is the bottom-most part where the two ventricles meet in a shape somewhat like a point).
At the top of the ventricles, the signal spreads from the bundle of His (also called the atrioventricular (AV) bundle), to the ventricles via the Purkinje fibres located in its wall.
Order of valves in the cardiac cycle
Left AV closes
Aortic valve opens
Aortic valve closes
Left AV valve opens
what controls the SA node to speed up the heart or slow it down
Two nerves that originate in the medulla oblongata of your brain
The nerve that stimulates the heart to beat faster is called the
cardiac accelerator nerve
the nerve that stimulates the heart to beat faster is called the
cardiac accelerator nerve
the nerve that reduces heart rate is called
the vagus nerve
what is monitored by the cv centre to determine whether impulses should be sent along the cardiac accelerator nerve or vagus nerve to the heart
Blood pressure, pH and carbon dioxide concentration of the blood
what is epinephrine
adrenalin, the fight or flight hormone. increases the heart rate by stimulating the sa node to emit electrical signals at a faster rate as well as by increasing the conduction speed of impulses generated by both SA and AV nodes.
epinephrine also increases
muscle strength, blood pressure, sugar metabolism
what produes epinephrine
the medulla of the adrenal glands
atheromas
fatty deposits caused by high blood concentrations of low density lipoprotein (LDL) in the arterial alls next to the endothelial cells.
what does LDL consist of
cholesterol and fats
what is the thrombosis
the forming of a clot in the blood vessel that can block the blood vessel entirely.
what happens if a coronary artery becomes blocked
the cells in that part of the heart will die, and the result is a myocardial infarction (heart attack). The buildup of plaque takes time and, initially, the restricted flow of blood in such an artery will cause pain due to heart cells being deprived of oxygen and nutrients. Medically, the pain is known as angina.
waht increases the chance of plaque formation leading to atherosclerosis and the increase in cv disease e
High blood concentrations of LDL
Diabetes causing high blood glucose concentrations
Smoking and stress causing high blood pressure
Diets containing high levels of trans fats
Recent research indicates that certain infections with bacteria, such as Chlamydia pneumoniae , can also play a role.
what does the ski nhave pores for
for sweating, hair follicles and sebaceous glands that produce oils (called sebum) to keep the skin supple and at a slightly lower pH. The oil and low pH both act as growth inhibitors for certain bacteria.
Mucous membranes are made up of
a surface layer of epithelial cells over a deeper layer of connective tissue. They produce mucus for protection and lubrication.
people who have the most common form of hemophilia are missing clotting factor…
VIII
The clotting process seen in Figure 1 is actually a cascade of reactions triggered by damage to a blood vessel.
Platelets release chemicals to start these reactions. The first reaction triggers the second reaction by producing a chemical required for the second reaction. This continues through a series of several reactions including up to 12 factors. Each reaction takes an inactive protein in the blood called a clotting factor and activates it. The last step of this cascade of reactions is the conversion of fibrinogen, a soluble and inactive clotting factor in blood, to insoluble fibrin. This reaction is catalysed by an enzyme called thrombin which itself had to be activated by the cascade of reactions. The result is a network of fibers that traps red blood cells and platelets to form a scab, as shown in Figure 2 .
a thrombus
a blood clot that forms in a vessel and remains in the place it was found
factors that increase risk of clot formation
smoking, obesity, hypertension (high blood pressure) and diabetees
the immune system can be subdivided into
non specific immune system involving phagocytes
specific immune system made up of lymphocytes and antibodies
the two types of leukocytes
macrophages (/phagocytes)
lymphocyte
what do phagocytes do and how
These cells engulf a pathogen that has entered the body and is found in the lymph nodes or the blood. Once inside the phagocyte, enzymes secreted by the lysosome will digest the pathogen.
Phagocytes can squeeze past the leaky endothelial cells of the capillaries and invade the tissue where an infection has occurred, for example, in a small wound in your skin. This is an example of non-specific immunity to diseases as the phagocytes can respond equally well to a variety of organisms.
pathogen def
a disease-causing virus or microorganism. Examples of pathogens are: viruses, bacteria, protozoans, prions and fungi.
antigen def
any molecule that enters the body and triggers an immune response
antibody
a large protein with variable regions produced by your own body that will bind to an antigen.
a protein molecule made by lymphocytes
when a b cell encounters an antigen…
the b cell divides repeatedly through mitoiss to create many copies of the b cell that can recognise the antigen. this is called clonal selection.
antibodies produced by plasma cells work in two ways:
They can bind to the antigen, which allows phagocytes to recognise and then destroy the pathogen.
They can bind to proteins in the coat of a virus, which will prevent the virus from entering other (human) cells.
after an infection, plasma cells… and specific antibodies…
decrease
decrease
but memory cells remian in the bloodstream an lymph nodes for a long period of time so that if the same pathogen invades the body again, the response will be much faster.
infection response
what is a t cell
a type of lymphocyte that helps b cells complete their function of making antibodies
central role of a t cell diagram
APC
antigen presenting cell
what is HIV
a retrovirus that has RNA as its genetic material.
hwo does hiv work
Once HIV infects a cell through the proteins on the surface of its envelope, it makes a DNA copy from its RNA, with the help of an enzyme called reverse transcriptase. The cDNA that is produced is inserted into the host cell’s genome.
why is HIV so bad
The infected T helper cells are destroyed leading to a reduced number in the body. Since T helper cells are needed to activate B cells to produce antibodies, infection with HIV causes a loss in the ability to produce antibodies which can lead to the development of AIDS (acquired immune deficiency syndrome). It should be noted that HIV causes an overall reduction of active lymphocytes in the body, including both T and B cells: activated T cells decrease as infected T helper cells are destroyed and activated B cells decrease because there are fewer T helper cells to cause their activation.
how can hiv be slowed down or stopped
antiviral drugs specifically targeting reverse transciptase activity
how can hiv be transmitted
Sexual intercourse
Transfusion of infected blood
Sharing of hypodermic needles by drug users
From mother to child during pregnancy, birth or breastfeeding.
why can antibiotics work without harming body cells
Antibiotics block processes that occur in prokaryotic cells but not in eukaryotic cells. Thus, antibiotics can be used to treat bacterial infections in humans and animals (because they are eukaryotes) without harming their body cells.
what do antibiotics target and not target
Antibiotics do not have an effect on human cellular processes. The drugs target bacterial cell wall and membrane formation, ribosome function or DNA replication, transcription and translation. None of these may directly kill the bacteria, but it will slow down or stop growth and prevent cellular division.
why are most antibiotics isolated from saprotrophic fungi
Fungi and bacteria can compete for the same food resources, so fungi often secrete antibiotics to inhibit the growth of the competing bacteria. The best known example of an antibiotic is penicillin.
effects of chlamydia
causes build up of scarring that can block fallopian tube and prevent fertilisation
how waspencillin tested
Florey and Chain infected eight mice with Streptococcus . This bacterium causes pneumonia in mice. Eight mice were kept under identical conditions, but four of the eight were given an injection of penicillin. The four mice that were not treated with penicillin died within 24 hours, but the treated mice stayed alive.
The next step was to test the drug on humans. Florey and Chain proceeded to test penicillin on very sick patients with infections. Most survived, and the commercial production of the drug in the 1940s allowed testing on more and more patients; eventually confirming it as a very effective weapon against infections.
nowadays protocols for clinical trials
These include pre-clinical studies on individual cells and two mammalian species to investigate toxicity before any human trials begin. Clinical trials on humans should begin with testing on healthy subjects to further investigate any possible problems (such as possible side effects, and how quickly the drug is metabolised and excreted from the body) before sick patients receive the drug.
ventialation maintains
conc grad of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries
the longer air remains in the alveoli..
the lower the conc of oxygen in that air, thus decreasing the conc grad that drives diffusion of oxygen into the blood. Ventilation removes this lower oxygen air and replaces it with fresh, higher oxygen air. This is essential to ensure that oxygen continuously diffuses into the blood from the alveoli and carbon dioxide diffuses out of the blood into the alveoli. The exchange of gases that occurs at the alveoli is called gas exchange and is directly dependent on ventilation.
ventilation rate/breathing rate
number of breaths, including inhalation and exhalation taken per min
gas exchange depens on two conc grads.
one gradient of oxygen, and another gradient of carbon dioxide
describe the conc grads of the alveoli
the tiny air sacs of the lungs where gaseous exchange takes place – the oxygen concentration is higher than the concentration of oxygen in the blood that flows past the alveoli. The opposite is true for carbon dioxide, which is present in higher concentrations in the blood and lower concentrations in the freshly inhaled air in the alveoli. This gradient, as well as the thin walls and moisture of the alveoli and the short distance to the capillaries, facilitates gas exchange by diffusion.
alveolus diagram
types of alveolar celsl
type I pneumocytes
type II pneumocytes
type I pneumocytes
are extremely thin alveolar cells that are adapted to carry out gas exchange, as shown in Figure 2 . They are very flat and thin, increasing the surface area available for diffusion. This also speeds up diffusion by decreasing the distance between the inside of the alveolus and the capillary.
type II
secrete a solution containing surfactant, which is a water-based solution containing phospho-lipoproteins. Surfactants create a moist surface inside the alveoli (shown as a film of moisture in Figure 2 ) to prevent the sides of the alveoli from sticking to each other: they do this by reducing surface tension. The moisture also increases the speed gases dissolve, which helps gas exchange.
When breathing in, the thorax (the chest) ONE and the pressure inside the lungs is TWO,
ONE expands
TWO lowers
ensuring that thoracic pressure is lower than atmospheric pressure. This causes air to rush into the lungs.
When we breathe out, the thorax gets ONE, the pressure TWO and the air is forced out of the lungs.
ONE smaller
TWO rises
inspiration:
external intercostal muscles contrat
internal intercostal muscles relax
diaphragm contracts
abdominal muscles relax
pressure in lungs decreases while volume increases, air enters
rib cage expands as rib muscles contract
expiraiton
internal intercostal muscles contract
external intercostal muslces relax
diagphram relaxes (rises)
abdominal muscles contract
pressure in lungs increases while volume decreases,a ri escapes
muscle contraction makes rib cage smaller
muscles that work in pairs to move body parts in opposite directions are called
anatgonistic muscles
tidal volume
the amount of air that enters or leaves the lungs ina single breath at rest
causes of lung cancer
Asbestos dust particles lodge in the lungs and cannot be broken down
Smoking (cigarettes, cigars, pipe tobacco)
Passive smoking (breathing in someone else’s cigarette smoke); about 3% of all cases
Air pollution: diesel exhaust fumes contain many carcinogens (compounds causing cancer)
Radon gas: in some parts of the world there is a higher concentration of this radioactive gas. It emits alpha particles, which can cause mutations when inhaled.
consequences of lung cancer
Shortness of breath
Cough that does not go away
Coughing up blood
Pain (chest pain and pain in other areas if cancer spreads)
Accumulation of fluid in the chest
Spread of cancer to other parts of the body
Loss of appetite or weight loss
Fatigue
Repeated problems with pneumonia or bronchitis.
emphysema is caused by
long-term exposure to cigarette smoke and other pollutants.
emphysema is
an inflammatory (swelling of tissues) response in the lungs, resulting in a narrowing of the small airways and breakdown of lung tissue. There is also evidence that the alveoli become less elastic, making ventilation more difficult. Furthermore, there is increased protease activity, which breaks down the alveolar wall, creating one larger air space instead of many small ones. This reduces the surface area of the lungs and results in a smaller amount of oxygen reaching the bloodstream. Normally, the proteases are inhibited by alpha-1-antitrypsin, but in emphysema patients, the activity of this enzyme inhibitor is reduced.
treatments of emphysema
These are all irreversible processes, resulting in a reduction of the oxygen saturation of the blood because gas exchange can no longer occur in the damaged alveoli. Patients with emphysema are always short of breath and cough frequently. In cases of severe emphysema, some patients may benefit from oxygen therapy or even a lung transplant.
consequences of emphysema
Shortness of breath
Persistent cough
Fatigue
Weight loss
Depression.
axons of some neurons are coated with
a myelin sheath
what is the mylin sheath
gap between adjacent schwann cells
node of ranvier
schwann cells
any of the cells in the peripheral nervous system that produce the myelin sheath around neuronal axons.
6.5.2, 6.5.3, 6.5.4, 6.5.5
RESTING AND ACTION POTENTIAL, PROPAGATION OF NERVE IMPULSES, SYNAPSES, NEONICTIONOIDS
what should blood lguose levels typically be
between 70 and 130 milligrams per decilitre
why most you maintain blood glucose levels
so your body has a certain osmotic balance as well as ensuring that the cells of your body, especially your brain cells, have an ample supply of glucose for cellular respiration.
insulin
produced and secreted by β-cells of Islets of Langerhans in the pancreas.
glucagon
produced and secreted by α-cells of Islets of Langerhans in the pancreas.
insulin effect on blood glucose conc
Levels fall : insulin stimulates glucose uptake into muscles and liver cells, where it is converted into glycogen.
glucagon effect on blood glucsoe conc
Levels rise : Glucagon stimulates glycogen hydrolysis to glucose in the liver, which in turn releases glucose into the blood.
when does insulin act
when levels are higher than normal
when does glucagon act
when elvels are lower than normal
blood glucose cycle
types of diabetes
Type I results from the body’s failure to produce insulin. Sometimes this form of diabetes is referred to as insulin-dependent diabetes mellitus (IDDM) or juvenile diabetes.
Type II results from insulin resistance, a condition in which body cells fail to use insulin properly. This form was previously referred to as non insulin-dependent diabetes mellitus (NIDDM), or adult-onset diabetes because it often begins later in life.
treatment for diabetes
The treatment of Type I diabetes involves injecting insulin into the body on a daily basis. Type II may be treated by eating food with low levels of carbohydrates, eating frequent but small meals and doing strenuous exercise, as well as losing weight.
thyroxin
the main hormone that regulates your metabolism and body temperature.
where is thyroxin produced
thyroid gland
The general effect of thyroxine is
to activate nuclear transcription of large numbers of genes for the synthesis of enzymes, structural proteins, transport proteins and other substances in virtually all cells of the body. Therefore, thyroxine increases the metabolic activities of almost all the tissues of the body.
effects of thyroxine
Increased rate of utilisation of foods for energy
Increased breathing rate to obtain oxygen and get rid of carbon dioxide
Increased rate of protein synthesis and protein catabolism
Increased number and size of mitochondria in most cells of the body
Increased growth rate of children and adolescents
Growth and development of the brain during fetal life and for the first few years of post-natal life
Enhanced carbohydrate metabolism
Enhanced fat metabolism.
what is the relationship between thyroxine and body temp
when the body’s metabolic rate increases, the rate of cellular respiration also increases producing a large amount of heat. Thus, elevated thyroxine production accounts for increased body temperature. This relationship between the two is used to help control body temperature. For instance, when body temperature is above normal, the thyroxine level is decreased to reduce cellular respiration, and thus reduce heat production.
what is required for thyroxine
four atoms of iodine and the amino acid tyrosine. In some areas of the world, iodine is not present in the diet, or is only available in amounts too low to produce sufficient amounts of thyroxine. People living in these regions often develop a goitre, an enlargement of the thyroid gland.
treatment of goitre
idodine tbalets
symotoms of thyroxine defiencecy
Fatigue
Depression
Forgetfulness
Feeling cold
Constipation.
When thyroxine deficiency is present in young children, it can also lead to impaired brain development.
where are leptin receptors
hypothalamus
onec leptin binds to the receptors in the hypothalamus, it causes
inhibition
when fat mass decreases, the level ofplasma leptin
falls so that appetite is stimulated until fat mass is recovered. body temp also suppressed
when fat mass increases,
leptin levels also icnrease so appetite is suppressed until weight loss occurs
what allele makes people obese (in that it increases appeittie)
ob allele. mice cna be given leptin injections but humans cant. Unlike mice, obese people have very high leptin levels in their blood. This implies that receptor cells in the hypothalamus may no longer be sensitive and responsive to leptin, thus they do not induce appetite inhibition.
The pineal gland is
a small endocrine gland found near to the centre of the brain between the two hemispheres, it is reddish-grey and shaped like a pine cone about 0.8 cm long.
human circadian cycle
certain receptor cells in the retina that signal dawn and dusk to the pineal gland. Actually, the impulses from the retina are first channelled to a group of cells in your anterior hypothalamus named the suprachiasmatic nuclei (SCN), which then pass on the information to the pineal gland. The pineal gland then adapts the melatonin concentrations in the blood to coincide with a normal 24-hour cycle. It should be noted that melatonin receptors are also present on the neurons of the suprachiasmatic nuclei of most species, implying the possible involvement of a negative feedback loop in the regulation of melatonin.
melatonin is synthesised from
the amino acid tryptophan and its production is dictated by light. Exposure to light has a negative effect on the release of melatonin.
when is melatonin secretion low
Melatonin secretion is generally low when you are exposed to daylight and high during dark periods.
effects of melatonin
our body core temperature drops and receptors in the kidney cause decreased urine production, all of which increases sleepiness.
melatonin levels high-
sleepy
mealtonin levels low -
gets light again, start to wake up
what hormone triggers the embryo to be female
estrogen and prostereogne
what hormone trigges the embryro to be male
TDF (testis determining factor) triggers the development of testis and production of testosterone indirectly. around 8 weeks of preganancy
waht causes embryonic gonads to develop as testes and secrete testosterone
a gene on the y chromosome
ovary function
Estrogen, progesterone and ovum (egg) production
fallopian tubes / oviduct function
Collects eggs from ovary and carries them to uterus
uterus fucntion
Place for the gestation of the embryo and fetus
cervix function
Blocks the entry to the uterus during pregnancy and dilates during birth
vagina function
Canal connecting cervix and outside of body: forms birth canal and is the receptacle for penis during heterosexual intercourse
vulva function
External parts for the protection of the internal reproductive system
testis function
sperm and testosterone production
epididymis function
stores sperm until ejaculation
sperm duct function
transfers sperm during ejaculation
seminal vesicles function
Produce an alkaline, sugar-rich fluid (fructose) that provides sperm with a source of energy to help them move
prostate gland function
Produces an alkaline fluid, rich in proteins which together with seminal vesicles’ secretion and sperm makes semen
urethra function function
Transfers semen during ejaculation and is the passage of urine during urination
penis function
Becomes erect during sexual arousal: penetrates the vagina during heterosexual intercourse to deposit semen close to the cervix
puberty def
is the phase of adolescence when the individual reaches sexual maturity and becomes capable of reproducing. It is accompanied by maturation of the genital organs, development of secondary sexual characteristics and, in humans and some primates, by the first occurrence of menstruation in the female.
menopause def
the phase in a woman’s life (around the age of 45–50) when her menstruation stops.
menustration cycle
describe the follicular phase
FSH causes several follicles in the ovary to begin to develop. Usually, only one matures. As the follicle develops, it secretes estrogen. The estrogen stimulates the uterine lining (endometrium) to thicken with mucus and a rich supply of blood vessels. These changes last about 10 days and prepare the uterus for a possible pregnancy; the endometrium is where a fertilised ovum will implant in order to further develop during pregnancy.
describe ovulation phase
A high level of estrogen in the blood (produced by the follicle) causes the pituitary gland to reduce the secretion of FSH (by negative feedback) and begin secretion of LH (by positive feedback). The decrease in FSH will, in turn, decrease the production of estrogen. When the concentration of LH in the blood reaches a certain level, ovulation occurs; that is, one mature follicle (a Graafian follicle) ruptures, releasing a mature egg. Ovulation usually occurs at about the middle of the menstrual cycle.
describe the luteal stage
After ovulation, LH causes the ruptured follicle to fill with cells, forming the corpus luteum (yellow body). It begins to secrete the hormone progesterone, which maintains the continued growth of the endometrium. The corpus luteum also produces estrogen, which accounts for the rise in this hormone level after ovulation. As the concentration of estrogen and progesterone rise to a certain level, they in turn inhibit the secretion of FSH and LH, respectively (negative feedback). This stage lasts about 14 days.
describe menstruation phase
If fertilisation does not occur, the corpus luteum breaks down. This results in a decrease in the level of progesterone and estrogen. With a drop in the progesterone level, the thickened lining of the uterus can no longer be maintained, and it breaks down. As a result, the extra layers of the endometrium lining, the unfertilised egg and a small amount of blood pass out of the body through the vagina. This lasts about 3–5 days. While menstruation is occurring, the amount of estrogen in the blood falls, reducing the inhibitory effect of estrogen on FSH secretion. The pituitary gland then increases its output of FSH, a new follicle starts maturing, and the cycle starts again.
negative feedback
generally has a stabilising effect on systems or processes. In this case, the product of a process controls the rate of its own production. For instance, the pituitary gland secretes FSH which stimulates the production of estrogen. But, an increased concentration of estrogen feeds back to inhibit the production of FSH. In this way no more estrogen is produced.
positive feedback
involves the enhancing or amplification of a product by its own effect on the process which gives rise to it. For example, positive feedback occurs during the follicular phase when rising LH levels in the blood cause the pituitary to release more LH to further increase the levels of that hormone so ovulation is triggered.
progesteone ovary
Rises at the start of the luteal phase; promotes thickening and maintenance of the endometrium (lining of the uterus)
estrogen ovary
Rises to a peak towards the end of the follicular phase; stimulates repair of the endometrium and an increase in FSH receptors on ovary cells
FSH (pituitary)
Starts to rise towards the end of the cycle (day 28); stimulates the development of follicles and the production of estrogen by the follicle wall
LH (pituitary)
Rises to a sudden peak towards the end of the follicular phase; stimulates completion of meiosis in the oocyte and thinning of the follicular wall, so that ovulation can occur. After ovulation, it stimulates the development of the remaining part of the Graafian follicle into the corpus luteum (by causing an increase in the number of follicle cells), which secretes estrogen (this is an example of positive feedback) and progesterone
reasons for IVF
Woman with blocked fallopian tubes
Woman cannot produce healthy eggs
Man does not produce enough sperm for fertilisation to take place
Man suffering from erection problems
Genetic predisposition of one parent toward certain health problems
Couple is unable to conceive normally.
steps of IVF
Step 1a: The woman is given a drug (or drugs) to suppress her natural cycle by suspending her normal secretion of hormones. She can administer them herself in the form of a daily injection or a nasal spray. The drug treatment continues for about 2 weeks.
Step 1b: FSH and LH are injected at a higher dose than normal for around 12 days to stimulate the production of a number of ova (egg cells), called superovulation. The clinic monitors progress throughout the drug treatment through vaginal ultrasound scans and, possibly, blood tests.
Step 2: Between 34 and 38 hours before the eggs are due to be collected, the woman will be given a hormone injection to help the eggs mature (this is likely to be human chorionic gonadotrophin). Eggs are then usually collected from the ovaries by using ultrasound guidance while the person is sedated. A hollow needle is attached to the ultrasound probe and is used to collect the eggs from the follicles in each ovary.
Step 3: A sperm sample is collected from the woman’s partner and checked for viability.
Step 4: The eggs are mixed with the partner’s or the donor’s sperm and cultured in the laboratory for 16–20 hours after which they are checked for signs of fertilisation. (Sperm can also be injected directly into the egg, as shown in the alternate picture on the right at number 4 in the diagram.) Eggs that are fertilised (now called embryos) are grown in the laboratory incubator for up to 6 days. The embryologist will monitor the development of the embryos and the best will then be chosen for transfer. The remaining embryos of suitable quality are frozen for future use.
Step 5: If the woman is under the age of 40, one or two embryos are implanted in the uterus at the appropriate time in her menstrual cycle. But, if she is older than 40 years, a maximum of three may be used. The number of embryos transferred is restricted because of the risks associated with multiple births.
arguements for IVF
Infertile families can have a baby
Embryos can be screened for genetic anomalies and other disorders
Increases understanding of human reproduction
arguments against IVF
Not all embryos are used, and some are destroyed
IVF often results in multiple births, which may be an increased risk for mother and babies
IVF is not considered ‘natural’, so it is not condoned by some religious groups
Women may be at risk because of hormonal injections
what did william harvey do
realise aristotles theroy coul dnot be true. (where the man produces a seed which develops into an egg, which then further develops into an embryo with the help of menstrual blood.
structure of the digestive system
transvesr section of small intestine with villi lining the small intestine
different tissue layers of the wall of thes mall intestine as seen under the light microscope
mucosa
submucosa
longitudinal muscle
what generates a nerve impulse on the post synaptic membrane
neurotransmitter binding with receptor sites
what is the myselin sheath made up of
a number of schwann cells, each separated by a nod eof ranvier. the dendrites are found protruding from the cell body of the neuron and their role is to receive impulses from other neurons.
What name is given to the movement of an action potential from one node of Ranvier to another in order to increase the speed of the impulse?
saltatory
State the name given to the cells that are extremely thin and make up most of the walls of the alveoli?
type I pneumocytes
During repolarisation, which voltage-gated channels open in order to allow the ions to flood out of the axon? (Answer with one word.)
potassium
Which ions move into the synaptic bulb in order to move the vesicles containing neurotransmitter to the presynaptic membrane?
calcium
Name the ion that is pumped into the axon to maintain a resting potential?
potassium
Which enzyme is responsible for breaking down acetylcholine in the synapse?
Acetylcholinesterase
