homeostasis Flashcards
what is homeostasis
physiological control systems that maintain the internal environment within restricted limits in responce to extrenal change
why do endotherms(warm blooded) have greater range of tolerance
they have homeostatic controls to withstand more conditions
what are the advantages of intrinsic protein receptors
the hormone does not have to enter the cell
decribe the secondary messanger system for blood glucose regulation
adrenaline binds to intrinsic receptors in the plasma membrane
adenylate cyclase is activated
cyclic amp is formed by atp
protien kinase is activated
glycogen hydrolised to glucose
what is gluconeolysis
making new glucose from lipids and amino acids
what is glycogenolysis
splitting of glycogen
what is glycogenesis
making of glycogen
name the parts of the islets of langerhan and what they do
beta cells - secret insulin
alpha cells - secretes glucagon
describe what happens when there is a rise in glucose concentration
detection by beta cells in the islets of langerhans
insulin produced and secreted and travels in the blood to bind to receptors on target cell causing muscle and liver to take in glucose leads to glycogenesis
stops glycogenolysis and gluconeogenesis
short and long term concequences of low blood pressure
confused and fatigued because nerves cannot function lon term
short term water potential of cells increase
describe what happens when there is a fall in blood glucose concentration
detection by alpha cells which produce and secrete glucagon
it binds to receptor cell adrenaline cyclase is released making camp from atp which phosphorylises protien kinase converting glycogen to glucose
describe the actions of glucagon
active enzymes effect in liver hydrolysis of glycogen to glucose
synthesises glucose from amino acids and glycerol
describe the action of adrenaline
adenylate cyclase activated atp to camp
phosphorylation to activate protein kinase
glycogen to glucose
effects liver and muscles
type 1 diabetes
doesnt produce insulin
type 2 diabetes
resistant to your own insulin
what can diabetes cause
high blood pressure because more osmosis into plasma membrane
blindness
stroke
amputation
how do oral medications help diabetes
reduces glucose absorption in the ileum
stop starch digesion by inhibiting
amalyase
reduced glycogenolysis
increases insulin production from beta cells
5 molecules that move into glomerular filtrate
h2o , glucose , hormones , amino acids , o2
what 5 things that prevents the movement of small molecules out of capillaries into filtrate
enothelium and basement membrane
epithelial cells and renal capsual
podocytes
hydrostatic pressure in fluid of renal capsual space
osmotic pressure of glomerous filtrate
what % of water reabsorption happens in the proximal convoluted tube
85 % out the the total 99%
adaptations of the epithelial cell for reabsorption
micro villi to increase surface area so more diffusion happens
mitrochondria produces atp in oxidative phosphorylation
sodium potatsium pump
what is the structure and function of the ascending limb of the loop of henle
thicker wall
starts narrow and the widens
impermeable to water but permeabel to mineral ions
what is the structure and function in the decending limb in the loop of henle
thinner wall
narrow
permeable to water
explain counter current flow in the loop of henle
the ascending limb and decending limb flow in opposite directions to maintain conc gradient across the whole length of the loop
describe the distal convoluted tubule
final ajustments to water , salt to maintain pH of the blood
they have microvilli and many mitrochondria
reabsorbs by active transport
hormones affect the walls permeability
describe the collecting duct
found in the medulla
connects the nephron and the ureter
moves out of the collecting duct by osmosis due to the concentration gradient created by active transport of minerals in the ascending loop
water leaves by channel proteins
adh controls water loss
describe movement in the loop of henle
descending limb
water leaves by osmosis decreasing water potential in the tube
ascending limb
sodium moves out by facilitaed diffusion when the conc gradient is high and then active transport lowering water potential of the tissue surounding the tube
what is the hypothalamus
region of the brain which acts as a control centre of the involuntry nervous system
what is an osmoreceptors
cells within the hypothalmus that detects changes in blood water potential
what is a pituitary gland
endocrine gland situated at the base of the brain
anterior (front ) and posterior ( back)
what is ADH
hormone produced by hypothalmus and secreted by posterior pituitary gland
what happens when blood water potential is too high
detected by the osmoreceptor in the hypothalmus
posterior lobe of pituitary gland releases less ADH
walls of collecting duct and distal convoluted tube become less permibale
more urine is less concentrated
water potential gradient decreases
what happens when blood water potential is too low
cells shrivel and this is detected by the osmoreceptors in hypothalmus
posterior lobe of pituotary gland releases ADH
ADH reaches collecting duct via blood making it more permiable to H2O
less urine and is more concentrated
describe the action of ADH
binds to protiens on the surface of the cell
leading to the activation of the enzyme phosphorylase casuing vesicles containing aquaporins to fuse with cell surface membrane
increasing its permeability to water
