homeostasis

Question 1

what is homeostasis and what does it affect

Answer 1

maintenance of contant stable internal environment despite external changes within restricted limits
controls ph, bgl , temperature
too high bgl- wp reduced cells shrivel and die
too low- no respiration

Question 2

negative and positive feedback

Answer 2

neg- restores to norm

pos- further increases deviation eg contractions in childbirth

Question 3

when does bgl rise and fall

Answer 3

rises after eating , falls after excericse

Question 4

role of pancreas

Answer 4

endocrine tissue that has islets of langerhans. a cells secrete glucagon and b cells secrete insulin

Question 5

in the liver
1glycogenesis
2glycogenolysis
3gluconeogenesis

Answer 5

1 glucose to glyogen - when bgl too high
2 glycogen to glucose - when bgl low
3 make glucose from non carb sources - when bgl low

Question 6

if bgl too high

Answer 6

insulin secreted, binds to receptors on liver and muscle cells
changes tertiary structure of glucose channel proteins so more glucose into cell via facilitated d
incr absorption of glucose to cells
insulin activates enzymes to do more gylogenesis
incr rate of respiration
incr conversion of glucose to fat

Question 7

if bgl too low

Answer 7

glucagon secreted binds to specific protein receptors on liver cells which causes glyogenolysis and gluconeogenesis to happen to incr amount of glucose in blood
also decr rate of resp in cells

Question 8

what is the role of adrenaline

Answer 8

if bgl too low, secreted by adrenal glands,binds to receptors on liver cells
activates glycogenolysis and activates glucagon secretion
reduces insulin and glycogenesis

Question 9

2nd messenger model

Answer 9

adrenaline and glucagon bind to transmembrane protein receptors, changes the shape and activates adenylyl cyclase which converts atp to camp.
camp binds to protein kinase a to do glycogenolysis

Question 10

diabetes type 1 vs type 2

Answer 10

type 1- immune system attacks b cells, bgl stays high, stops synthesis of insulin, treat w insulin injections and eat less carbs

type 2 - cant make enough insulin, bgl high, contol w excercise and good diet

Question 11

why does wp fluctuate

Answer 11

incr - diet, resp

decr- sweat, urination , breathing

Question 12

making the glomerular filtrate

Answer 12

diameter of afferent arteriole bigger than efferent so buildup of hydrostatic pressure in glomerulus
water glucose and minerals squeezed out capillary to form gf
blood cells and proteins cant get through into renal capsule as too big since wall of glomerulus is 1 cell thick

Question 13

what is the movement of gf resisted by

Answer 13

capillary endothelial cells
connective tissue,
low wp of glomerulus

Question 14

adaptation of glomerulus

Answer 14

renal capsule inner layer has podocytes which let filtrate pass through easier

Question 15

reabsorption of glucose and water by pct

Answer 15

na + actively transported out cells lining the pct into the blood capilaries so na+ conc in pct low
na+ diffuse down conc grad from lumen of pct into epithelial cells via faciliated diffusion. they take glucose w them (co transport)
now the glucose and na+ and wateer into pct they diffuse into blood and are reabsorbed

Question 16

adaptations of pct

Answer 16

microvilli -large sa to reabsorb h20 and glucose
lots of mitochondria for active trans of na+
infoldings of basal membrane to incr sa

Question 17

maintaining na+ grad in medulla by loop of henle

Answer 17

loh produces na+ to allow water to be absorbed by collecting duct
na+ actively transported out ascending limb , impermeable to water, so wp lowered in surrounding medulla
in descending, water moves out via osmosis and na+ moves in.
at lowest point, lowest wp of filtrate

Question 18

countercurrent system

Answer 18

between the filtrate in the collecting duct and the fluid in the medulla. although diff in wp are low, grad is maintained along whole length of collecting duct

Question 19

reabsorption of water by dct and collecting duct

Answer 19

cells lining dct have microvilli and mitochondria for active transport
these help h20 and salt levels in filtrate to adjust to help control ph and water level of blood
permeability of dct wall adjusted depends on how much water needs to be absorbed

Question 20

how does adh deal w low wp

Answer 20

osmoreceptors in hypothalamus detect fall in wp as they shrink via osmosis
so hypothalamus makes adh which goes to pituatry gland and secreted by kideny
receptors on dct and collecting duct bind w adh , which actives phosphorylase
this causes vesicles in cell to fuse w cell surface membrane and plasma membranes w aqua porins let out. membrane becomes more permeable to h20.
also incr permeability of collecting duct to urea which lowers wp of fluid around duct so more water leaves cs via osmosis down grad and enters blood