Control Of Blood Water Potentail

Question 1

Whta is osmoregution

Answer 1

Control of blood water potential bias homeostatic mechanisms

Question 2

where does osmoregulation kidney

Answer 2

nephrons

Question 3

describe the nephron structure

Answer 3

long tubules surrounded by capillaries

renal capsule with glomerulus - at the start of the nephron: cup shaped, surrounds glomerulus
proximal convoluted tubule - series of loops surrounded by capillaries walls, walls made up of epithelial cells with microvilli
loop of Henle - hairpin loop extends from cortex into medulla
distal convoluted tubule - similar to PCT but fewer capillaries
collecting ducts -DCT from several nephrons empty into collecting duct

Question 4

function of the nephron

Answer 4

filter the blood to remove waste and selectively reabsorb useful substances back into the blood

Question 5

what does urine contain

Answer 5

water
dissolved slats
urea
other small substances

Question 6

what does urine not contain

Answer 6

protein and bloods = protein are too large to be filtered out of the blood
glucose = all glucose is absorbed at selective reabsorption in the PCT

Question 7

how does filtering and reabsorption occur

Answer 7

stage 1: ultrafiltration
- occurs due high hydrostatic pressure, water and small molecules are forced out of the glomerulus capillaries into the renal capsule

stage2: selective reabsorption
- occurs in the proximal convoluted tubule
- 85% filtrate gets reabsorbed into blood

stage 3&4: the loop of Henle
- maintains a sodium ion gradient so water can be reabsorbed by the blood

stage 5&6
- water moves out of the distal convoluted tubule and collecting duct to return back to the blood
- the collecting duct then carries the remaining liquid(urine) to the ureter

Question 8

what is ultrafiltration.

Answer 8

• blood enter kidney via the renal artery at high pressure
• renal artery divides into the afferent arteriole, then the glomerulus = cause high hydrostatic pressure of the blood
• water and smaller molecules such eg glucose and mineral ions are forced out of the glomerulus down a pressure gradient into the bowman’s capsule
• pressure gradient aided by the efferent article leaving the glomerulus being narrower than the afferent arteriole
• proteins left behind in blood as they are too large

Question 9

describe selective reabsorption

Answer 9

• glucose re absorbed by co transport from epithelial cells of the proximal convoluted tube to blood capillaries
• carried out by active transporting Na+ ions creating low Na+ conc in epithelial cells
• Na+ moved from the PCT lumen by facilitated diffusion, which also brings in glucose

Question 10

adaptions of proximal convoluted tubule

Answer 10

microvilli - large SA for reabsorption
lots of mitochondria - provide ATP for active transport

Question 11

how is sodium ion gradient maintained by the loop of Henle

Answer 11

• mitochondria in the walls of the cells provide energy to actively transport sodium ions out of the ascending limb out of the loop of henle
• accumalauition of Na+ outside of the nephron in the medulla lower wp
• water diffuses out by osmosis into the interstitial space and then the blood capillaries, water reabsorbed into the blood
• at the base of the ascending limb some Na + are transported out by diffusion

Question 12

reabsorption of water at the DCT and collecting duct

Answer 12

• water moves out the DCT and collecting duct by osmosis
• collect duct runs parallel to loop of Henle so ion conc increases as you moe down into medulla

Question 13

Process of osmoregulation