physiology Flashcards
Which hormone stimulates the seminal vesicles? and what is the function?
testosterone. aid sperm by adding 50%-70% of the seminal fluid that nourishes sperm. adds sugars etc. DOES NOT STORE SPERM
Which hormone stimulates the seminal vesicles? and what is the function?
testosterone. adds acid phosphotase.
what is ectopic pregnancy?
fertilised egg doesn’t reach the uterus and tries to implant in uterine tube. PREG COMPLICATION
where does fertilisation occur?
ampulla
describe the function of epithelial squames
cells of the epithelium of the vagina and cervix collect glycogen and break off (desquamate) after ovulation. Bacteria then feed on the glycogen to create lactic acid. this creates an acidic environment and protects against microorganisms.
which two hormones are released by the thyroid gland?
thyroxine and calcitonin
How is the release of thyroxine controlled?
the hypothalamus releases thyro-tropin releasing hormone which then triggers a release of thyroid stimulating hormone from the anterior pituitary which in turn stimulates the release of thyroxine and triodethyronine from the thyroid gland.
what does thyroxine do?
plays an important role in metabolism, digestion, heart, brain development, bone maintenance and muscle control.
What does calcitonin do? where is it released from?
calcitonin helps to regulate calcium levels in the blood. it acts to lower the calcium levels by inhibiting osteoclasts, preventing the breakdown of bone. It is released from the thyroid gland from the C cells.
What does parathyroid hormone do? where is it released from?
opposes calcitonin. promotes the break down of bone and inhibits the formation of new bone. also promotes vitamin D production in the kidneys. It is released from the parathyroid glands.
What is released by the adrenal medulla?
adrenaline and noradrenaline.
what are the main constituents of skin?
keratinocytes and melanocytes.
what does multipotent mean?
cells that can differentiate into any type of blood cell. multi potent cells are in the bone marrow
what does pluripotent mean?
cells that can differentiate into any type of body cell
what does totipotent mean?
cells that are present at embryonic stage, they can differentiate into the placenta as well as body cells.
what are the two types of sweat gland and where do they secrete?
eccrine - small glands that secrete directly onto the skin, found in most places. apocrine - found at the armpits and anus, larger glands that secrete into the canal of a hair follicle.
what are spinous cells?
keratin producing cells with many intercellular connection found in the epidermis of the skin.
what is the outermost layer of the epidermis and what is its function?
striatum corneum = 10-30 layers of cells thick, corneocytes connected by corneodesmosomes, tough outer layer which is the first line of protection against foreign bodies.
name the other layers of the epidermis.
(striatum lutium), striatum granulosum - keratinocytes have lost their nucleus and have granules, striatum spinosum - granules are joined by desmosomes and langerhans cells are present here, and basal layer.
what are langerhan cells
immune cells located in the striatum spinosum of the epidermis.
why is the rate of corneodesmosome breakdown important?
too little = psoriasis, too much = atopic eczema
describe the physiology behind acne.
hair follicles narrow by hypercornification. this increases sebaceous fluid production. the increased sebum makes skin oily and the hair follicle becomes completely blocked. this leads to stagnation of sebum which causes the multiplication of the propioni bacterium acne. the p. acne break down triglyerides into fatty acids and cause inflammation. the p. acne then attack neurophils and pus formation begins.
give the percentages of blood that different organs receive.
lungs = 100%, liver and digestive system = 27%, skeletal muscle = 21%, kidneys = 20%, brain = 14%, bone and other = 9%, skin = 5%, heart = 4%
where is ADH synthesised?
paraventricular and supraoptic nuclei
which section of the loop of hence is impermeable to water?
thick ascending limb
describe the process of bicarbonate reabsorption. where does it take place?
proximal convoluted tubule. An Na/H+ antiporter on the luminal membrance moves H+ into the tubule. This H+ combines with bicarbonate to produce carbonic acid. This is then converted into water and carbon dioxide by carbonic anhydrase enzyme. carbon dioxide can now diffuse into the cell. Within the cell, the CO2 then recombines with water to make carbonic acid. Carbonic anhydrase then forms H+ and bicarbonate. H+ is recycled by the original antiporter back into the luminal membrane and bicarbonate is moved across the basolateral membrane by a Na/3HCO3- symporter into the blood.
which part of the tubule has leaky epithelium?
PCT
describe the actions of atrial neurotic peptide? where is it synthesised?
in the atria. it is a vasodilator. it inhibits the release of aldosterone, inhibits Na reabsorption and closes ENaC channels.
what are EnaC channels, where are they located and how are they affected hormonally?
mainly at the distal convoluted tubule, some at the collecting duct. they are epithelial sodium channels. They are affected by Aldosterone released by the adrenal cortex. aldosterone has both cytoplasmic and cell surface receptors that can increase the number of ENaC and K+/Na+ anti porter channels, and increase the ENaCs respectively.
Give the percentage reabsorption’s of Na along the tubule.
100% filtered. 60% in PCT, 25% in ascending loop of hence by active transport. 10% in DCT. 4% in collecting duct. 1% is excreted in the urine!
what is reabsorbed at the PCT?
60% NaCl, 60% water, 100% glucose, 100% amino acids, 90% HCO3-
what is secreted at the PCT?
uric acid, organic acids
what is reabsorbed at the loop of hence?
25% NaCl by NKCC2 cotransporter, water
what is reabsorbed at the DCT?
10% NaCl, water
what is secreted at the DCT?
K+, H+
what is reabsorbed at the collecting duct?
urea, 4% NaCl, water
what is excreted from the collecting duct?
urea, creatinine, 1% NaCl, water
what is an average GFR, what is the GFR and how is it measured?
100 ml/min, glomerular filtration rate, creatinine levels in the urine. creatinine should not be reabsorbed, so it is a measure of direct GFR
What are the 3 components of the filtration membrane?
fenestrated endothelium of the glomerular filtrate, basement membrane, podocyte finger-like projections with filtration slits.
Which proteins are essential for the functioning of the slit diaphragm?
Nephrin, and Podocin
What are the normal Na levels in the extracellular and intracellular fluid?
140 mM and 5 mM
what are the actions of the macula densa if the Na conc of the DCT is too high?
constrict the afferent arteriole, so that the GFR is lower. the efferent hydrostatic pressure and therefore the vasa recta hydrostatic pressure will be lower so NaCl and water will be reabsorbed more in the PCT. This will lower the NaCl conc at the DCT.
What are the actions of the RAAS system?
efferent arteriole vasoconsriction to raise GFR, general vasoconstriction to raise BP, insertion and activation of ENaCs in DCT, increase in sympathetic stimulation, stimulation of ADH release from PP
What is tamm-horsfall protein? what is its alternative name? where is it produced?
produced in ascending loop of henle, uromodulin. is thought to reduce the risk of UTIs
what is a healthy amount of urinary protein? which are the most common?
40-80 mg/day, 20-30 = uromodulin,
Forces acting on the glomerular capillaries
hydrostatic, oncotic, Bowman’s space pressure.
Why do the pressures reach equilibrium half way along the glomerular capillary?
so that if you have eaten a high protein meal, there is time for further filtration.
what are mesangial cells?
extraglomerular mesingial cells are part of the juxtoglomerular apparatus. intraglomerular cells are pericytes, they cover 30% of the glomerular capillaries.
how much blood travels through the kidneys in a minute?
1L
what are the functions of the kidney?
maintaining water, K, NaCl, H+ balance. excretion of urea, uric acid, organic acid, creatinine. secrete hormones - erythropoietin, Renin, Vit D.
describe the passage of blood into the kidneys
renal artery, segmental arteries, interlobar arteries, arcuate arteries, interlobular arteries or vasa recta, afferent arterioles.
Which channels are on the luminal membrane of the PCT?
glucose/Na symporter, phosphate/Na symporter and an Na+/H+ antiporter, K+ simply diffuses
Which channels are on the basolateral membrane of the PCT?
3Na+/2K+ ATPase, uses active transport to drive a gradient.
Which channels are on the luminal membrane of the Loop of Henle?
NKCC2 and ROMK (K+ recycled)
Which channels are on the basolateral membrane of the Loop of Henle?
3Na+/2K+ ATPase and CLCNKB (Cl- moves through to blood)
Which channels are on the luminal membrane of the DCT?
ENaCs can be inserted, Na/Cl symporter, Ca2+ channel stimulated by PTH which acts on the basolateral membrane.
Which channels are on the basolateral membrane of the DCT?
Ca2+ active transport channel, 3Na+/2K+ ATPase
Which channels are on the luminal membrane of the collecting tubule?
active transport of H+ into tubule. K+/H+ anti porter (H+ into tubule)
Which channels are on the basolateral membrane of the collecting tubule?
3Na+/2K+ ATPase, HCO3-/Cl- antiporter
how does thyroxine travel in the blood?
thyroxine binding globulin and albumin
how is thyroxine/tri-odothyronine made?
iodide moved from the blood into the follicular cell with Na. Na transported back out and K+ in. iodide then goes into colloid in exchange for a Cl-. here, iodide undergoes a per oxidation reaction to produce iodine. thyroperoxidase produces H2O2 in this reaction. meanwhile, thyroglobulin being manufactured in follicular cell. goes demo RER to golgi body then sent into colloid. iodines can attach to form monoiodothyronine or diiodothyronine. these can then esterify to form triodothyronine or thyroxine. then transported into the follicular cell by endocytosis. lysosomes are released and break the carbon chain»_space; hormones are ready. hormones travel in blood attached to thyroxine binding globulin or albumin. once at target tissue, thyroxine is activated to triodothyronine. Its receptor is in the nucleus on the actual DNA.
how does tirodothyronine act?
nucleus of the target cell.
what are the functions of thyroxine?
increase cardiac output, increase gluconeogenesis, increase metabolism of glucose, increase glycogenolysis, increase respiration rate.
what is thyrolobulin?
carson chain with multiple tyrosine attached.
how is thyroxine converted to triodothyronine?
iodithyronine deiodinase.
what is renal clearance?
the volume of plasma from which the si=ubstance in question is completely removed by the kidneys per unit time.
how do you work out renal clearance?
mass of X secreted per unit time/ total plasma conc of X
what are Th1 and Th2?
T helper cells. Th1 is pro-inflammatory and Th2 is anti-inflammatory.
what are IgM, IgE, and IgG?
IgE are immunoglobins released during allergies, they stimulate MAST cells. IgG are the only immunoglobins that can cross the placenta. IgM are the first response to tissue damage/pathogens.
what are mast cells? how are they stimulated?
they store histamine and become active in allergic reactions. they are the tissue version of basophils.
what does histamine do?
increases permeability of blood cells to allow WBCs in to fight the invasion.
what is red skin, itchy skin and dry skin caused by?
vasodilation, nerve irritation, lack of water.
what are the adnexae tissues of the skin?
sweat glands and follicosebaceous glands.
what do keratinocytes produce? 2 things.
keratin and interkeukins, a type of cytokine.
how long does it take to get from striatum basale to striatum corneum ?
12 days.
how many layers is each layer?
corneum = 20-30. granulosum = 2-3. spinosum = 2-3. basale = 1
what are merkel cells?
act are mechanoreceptors.
where does the dermis develop from? what are the two layers?
mesoderm. papillary and reticular.
where are lipid lamellar bodies present? what do they do?
striatum granulosum. form water lipid barriers.
why do we have the endocrine system?
communication between cells in different parts of the body. maintenance of metabolic environment. integration of whole body physiology.
how is GH stimulated?
starvation, hypoglycaemia, exercise, excitement.
what is DHEA?
dehydroepiandrosterone. most common circulating sterior hormone. precursor to androgens. produced in gonads, adrenals.
what does leptin do? where is it produced?
adipose tissue. inhibits hunger.
what does irisin do?
hormone produced by muscle that increases brown fat.
where do the anterior and posterior pituitary develop from?
anterior is from Rathke’s pouch so is from ectoderm and posterior is an out pouching of the hypothalamus so is from ectoderm.
where are the osmoreceptors in the body?
hypothalamus. V2 in collecting ducts. V1a in the vasculature and V1b in anterior pituitary.
where is all the fluid in the body?
42L. 28L is intracellular. 14L is ECF»_space;> 10.5L is interstitial. 3.5L is IVF.
what are the ICF and ECF cations and anions?
ICF = predominantly K+ and organic anions. ECF = predominantly Na+ and Cl-
what is the thyroxine axis?
TRH»>TSH»>T4 and T3 negativist feed back on ant. pituitary and hypothalamus.
what is the GH axis?
GHSH (or SMS)»>GH»>liver»>IGF-1 negatively feeds back on hypothalamus.
what is the cortisol axis?
CRH»>ACTH»>cortisol negatively feeds back on pituitary and hypothalamus.
what are the types of hormone and how do they differ receptor wise?
peptide = membrane receptor. steroid = intracellular receptor. amino acid = both
explain G-coupled receptors?
ligand attaches to a receopt on the membrane. this causes the g protein coupled receptor to exchange GDP for GTP. GTP causes the alpha subunit to break off and act on an effector protein, which will produce a secondary messenger.
what is a g protein coupled receptor?
a unit made up of an alpha, beta and gamma subunits. the alpha at rest has GDP bound to it.
explain the structure of the hypophyseal portal system.
in the infundibulum.
what are the embryological names for anterior pituitary and posterior pituitary?
adenohypophysis. neurohypophysis.
how is oxygenic release stimulated?
suckling and pressure on the uterine wall.
what are the layers of the adrenal cortex?
zona glomerulosa = mineralocorticoids e.g. aldosterone. zona fasiculata = glucocorticoids e.g. cortisol, zona reticularis = androgens e.g. dehydroepiandrosterone.
name all the endocrine glands of the body? 333
upper 3 = pituitary, pineal, hypothalamus. middle 3 = thyroid, thalamus, parathyroid. lower 3 = gonads, adrenals, pancreas.
where is the adrenal cortex/medulla derived from?
cortex = mesoderm. medulla = ectoderm.
what does cortisol do in relation to adrenaline?
activated the hormone that converts noradrenaline to adrenaline.
describe the production of cortisol.
cholesterol»_space;> pregnerolone»_space;> progesterone»_space;> cortisol»_space;> liver»_space;> cortisone.
what does cortisol do to the body?
induces stress response. increases adrenaline, increases protein and fat metabolism, increases gluconeogenesis, suppresses immune system.
describe the pathway for formation of adrenaline.
phenylalanine»_space;> tyrosine»_space;> dihydroxyphenylalanine»_space;> dopamine»_space;> noradrenaline»_space;> adrenaline.
adrenal catecholamines?
fast acting, short life. e.g. adrenaline, noradrenaline.
when does endocrine function begin? when does exocrine?
10-15 weeks. birth.
how do alpha and beta cells of the islets of langerhans communicate?
paracrine affect on each other. when insulin release, inhibits release of glucagon.
which other hormones have a similar effect to glucagon?
adrenaline, cortisol, GH
describe the process of insulin release from b cells.
when blood glucose is high, glucose diffuses into the cell but GLUT 2 transporters. glucose is then acted on by glucokinase enzyme and glycolysis occurs. this ATP generated from glycolysis causes the K+ channels to close. channel is called ATP sensitive K+ channel. this closure causes depolarisation of the cell and Ca2+ channels open, influx of Ca2+ causes secretory granules containing insulin to fuse with the cell membrane and release the insulin by exocytosis.
what form of insulin is initially produced?
proinsulin. which is an ABC chain. C gets removed to form insulin when inside the secretory granules. pro hormone convertases.
what are phase 1 and phase 2 of insulin release?
phase 1 is where stored insulin is released. if more insulin is required, more insulin is manufactured and then released.
what is the effect of insulin in fat and muscle?
insulin binds to a cell membrane receptor and causes GLUT 4 vesicles to fuse with the membrane and allow glucose to diffuse into the cell.
what is the short term buffering system to monitor glucose?
liver. if glusose is higher than 6, glycogenesis is stimulated. if it is lower than 4, glycogenolysis occurs.
what is the long term buffering system for glucose control?
adipose tissue. if glucose is higher than 6, triglyceride formation occurs. if glucose is lower than 4, glucose is made from AAs and lactate.
where are the glucose sensors?
primary sensors in pancreatic islets, medulla, hypothalamus and carotid bodies, inputs from eyes/nose, stimulated by incretins.
what are incretins?
insulin response is high following ingested glucose, not IV glucose going up. if it was relyand on endocrine detectors, the glucose would be too high. therefore, sensors in the gut detect insulin absorption and release incretins to stimulate insulin release in preparation. examples are glucagon-like-peptide-1 and gastric-inhibitory-peptide.
what are incretins inhibited by?
DPP4 which is necessary to prevent hypoglycaemia.
what is the anion gap? what is its normal value? how is it calculated? what is the strong ion difference?
difference between anions and cations. 10-16. Na+K-Cl-HCO3. Na+K+Ca+Mg-Cl-HCO3-any other strong anions.
what are the causes of metabolic acidosis?
ingestion of acids, kidney failure, excess H+ load from ketoacidosis or lactic acidosis. HCO3 loss in diarrhoea.
what would cause a high anion gap?
ingestion of acids, kidney failure, excess H+ load from ketoacidosis or lactic acidosis.
what would cause a small anion gap?
diarrhoea.
what are the causes of metabolic alkalosis?
ingestion of alkaline, vomitting.
what level should urinary albumin be?
what is podocyte effacement?
shortening and thinning of the podocytes.
how is pH calculated?
1/log10[H+]
what should the daily acid load secretion be?
50-100 mEq/day
where are your 3 types of vasopressin receptor located?
V2 = collecting tubules. V1 = vasculature. V3 = anterior pituitary.
what is osmolality?
a measure of the number of dissolved particles in a solution.
what is an effective/ineffective osmole?
effective = semi permeable membrane, solutes unable to move. ineffective = solutes able to move but do not affect movement of water.
what 3 things increase the production of renin?
sympathetic activity, low Na conc at macula dense, low bp at afferent arteriole.
whats happening in the descending limb?
H20 drawn out by hypertonic medulla.
whats happening in the thin ascending limb?
NaCl going out because following water.
whats happening in the thick ascending limb?
NaCl pumped out. impermeable to water.
describe the renal handling of K+
90% reabsorbed. pumped into cell in collecting tubule. recoiled at loop of henle.
how does the ammonia buffer work?
when all phosphate is in the phosphoric acid form, you must crease ammonia that will combine with H+ to make ammonium. this is done by the breakdown of glutamate into a-ketoglutarate and ammonium/ammonia. it diffuses into the lumen and combines with H+ and gets excreted. the aketoglutarate is important because it forms two bicarbonates!
how does the phosphoric acid buffer work?
HPO4- combines with H+ in the PCT and gets excreted.
if you aren’t urinating due to kidney failure what will happen?
pumponary oedema.
which gene is involved in the development of the kidney?
WT1
which gene is involved in the maintenance of the normal structure of the kidney?
PKD1
