14 Homeostasis Flashcards
Describe the process of Ultrafiltration
1 ultrafiltration ;
2 high(er) pressure due to afferent arteriole wider than efferent arteriole ;
3 capillary endothelium has, fenestrations / gaps / holes / pores;
4 small molecules / (named) ions / glucose / amino acids / urea / water, and EITHER leave, blood/ plasma / capillary / glomerulus
OR enter, capsule / filtrate / tubule ;
5 basement membrane forms, (main) filtration / selective, barrier ;
6 (R)MM / Mr, limit of, 68 000 to 70 000 (Da) / 68-70 kDa ;
7 podocytes, form slit pores / support basement membrane ;
Explain the process of osmoregulation
1 hypothalamus / osmoreceptors, detects changes in water potential of blood;
2 (causes) posterior pituitary gland ;
3 (to) release ADH into blood ;
4 ADH binds to receptors;
5 on cell surface membrane of collecting duct (cells) ;
6 stimulates enzyme cascade / phosphorylase enzyme produced ;
7 vesicles, move towards / fuse with, cell surface membrane;
8 (vesicles have) aquaporins ;
9 collecting duct, membranes / cells / walls, more permeable to water ;
10 water moves, down water potential gradient / by osmosis;
11 into, (collecting duct) cells / tissue fluid / blood ;
12 water potential (of blood) returns to set point;
Describe the process of selective reabsorption
1 Na+, actively transported / pumped, out of cells;
2 Na+ enter blood ;
3 Na+ concentration in cells decreases
or
Na+ concentration gradient (between pct lumen and cytoplasm) / described ;
4 Na+ enter cells from, filtrate / lumen ;
5 by facilitated diffusion ;
6 cotransport of, glucose / amino acids;
7 water potential of cells decreases ;
8 water enters cells from (filtrate / lumen) by, osmosis / down the water potential gradient ;
9 glucose /amino acids, leave cells by, (facilitated) diffusion / described ;
10 glucose /amino acids, reabsorbed or move into, tissue fluid/blood
Explain the adaptations of proximal convoluted tubule
1 microvilli for large surface area (for reabsorption) ;
2 (large surface area) for many, cotransporters / carrier proteins ;
3 cotransporter (proteins) to absorb sodium ions with, glucose / amino acids;
4 tight junctions between cells so substances have to pass through the cells / AW;
5 many mitochondria to produce ATP ;
6 (ATP) for the sodium (potassium) pumps
(ATP) to pump / actively transport, sodium ions (into the blood) ;
7 folded basal membrane for many sodium (potassium) pumps;
Explain how a glucose biosensor works
1 blood on, pad / strip, inserted into, biosensor / glucometer;
2 glucose oxidase ;
3 (glucose) → gluconic acid and hydrogen peroxide;
4 (electric) current / flow of electrons / voltage;
5 (current) proportional to glucose, quantity / concentration ;
6 digital / numerical, reading (on screen) ;
Describe how the structure of the bowman’s capsule is adapted to its function
Basement membrane
1 acts as a, filter / filtration barrier ;
2 only, named molecules / ions / molecules less than 68 000-70 000 (R)MM,
can pass through
or
red blood cells / large proteins, cannot pass through ;
Podocyte
3 has, gaps / slits / projections / pores;
4 allows, fluid / water / filtrate, to pass into the, lumen / Bowman’s capsule ;
5 produces, A / basement membrane ;
Describe the principles of cell signalling
1 binding of hormone to cell surface receptor causing conformational change
2 activation of G-protein leading to stimulation of adenyl cyclase
3 ref. to adenylyl cyclase;
4 formation of, cyclic AMP / CAMP ;
5 CAMP acts as a second messenger ;
6 activation of (protein) kinase ;
7 enzyme cascade;
8 amplification of signal ;
9 glycogenolysis / gluconeogenesis / described ;
10 glucose released into blood
Explain what is meant by homeostasis and its importance
1 maintain / keep / regulate, internal, environment / conditions ;
2 within, narrow / set, limits or around, optimum value / set point/ norm ;
3 low (body) temperature and consequence ;
4 high (body) temperature and consequence ;
5 low blood glucose (concentration) and consequence ;
6 high blood glucose concentration and consequence ;
7 low, (blood) water potential / y, and consequence ;
8 high, (blood) water potential / y, and consequence ;
Explain how dipsticks function to test for glucose in a sample of urine
1 (dip stick) has immobilised enzymes;
2 (dip stick) dipped in urine;
3 glucose oxidase and peroxidase ;
4 glucose reacts to give hydrogen peroxide ;
5 (hydrogen peroxide reacts with) colourless substance / chromogen;
6 to give, colour change / coloured substance ;
7 compare with colour chart ;
8 more glucose gives darker colour / colour intensity gives glucose quantity ;
Explain what is meant by negative feedback
1 change in a parameter;
2 detected by receptor ;
3 coordination / described ;
4 (corrective) action taken by effector ;
5 return to, set point / norm / optimum ;
Describe the role of abscisic acid (ABA) in the closure of stomata during times of draught
1 ABA is a stress hormone ;
2 ABA, released / produced / increases, during drought ;
in context of guard cell
3 ABA binds to its receptor on (cell surface) membrane ;
4 stops, Ht /H ions / protons, leaving (guard cell cytoplasm) ;
5 Ca2+ enters ;
6 Ca2+ is a second(ary) messenger ;
(Ca2+/Cl- /K+) channel (proteins) open;
8 Cl- anions, leave ;
9 K+ leave;
10 water potential (in cell) increases ;
11 water leaves by osmosis ;
12 volume of, cell / vacuole, decreases ;
13 cell becomes flaccid closing, stoma / pore ;
Explain the role of insulin in controlling blood glucose concentration
1 (insulin) binds to receptors on, liver / muscle / adipose (cells / tissue / organ) ;
2 GLUT (4) added to membrane of, muscle / adipose, cells
or
(GLUT 4) increases, muscle /adipose, cell, permeability (to glucose);
3 glucokinase phosphorylates glucose in liver cells
or
increased (rate of) diffusion of glucose into liver cells ;
4 more / faster, respiration of glucose ;
5 activates glycogen synthase / causes glycogenesis / causes glycogen synthesis ;
6 causes, lipid / triglyceride / fatty acid, synthesis or
decreases, glycogenolysis / lipolysis / gluconeogenesis ;
7 blood glucose concentration decreases ;
Explain how the stomata opens and closes
1 H+ pumped, out of guard cell / into cell wall of guard cell ; 2 2 inside of cell becomes (relatively) negatively charged ;
3 K+ enters cell by facilitated diffusion ;
4 water potential of cell decreases ;
5 water enters cell by osmosis ;
6 cell, expands / increases in volume / becomes turgid ;
7 stoma opens due to thick inner wall ;
