kidney

Question 1

what is ultrafiltration

Answer 1

when the fluid part of the blood is filtered from the glomerulus into the renal tubule.

Question 2

what is selective reabsorption

Answer 2

as fluid flows along tubules useful substances are reabsorbed back into the blood in amounts required by the body

Question 3

what is secretion

Answer 3

unwanted substances, are actively secreted in to the tubules

Question 4

what is need for ultrafiltration to take place ( 2 things)

Answer 4

• sufficient pressure, in order to force fluid through filter (3 layers)
• selective barrier, so molecules with an MR > 69,000 are retained in the blood stream, but it allows smaller molecules to pass through.

Question 5

what is the hydrostatic pressure of the blood in glomerulus

Answer 5

7.8 KPa

Question 6

what is the hydrostatic pressure of fluid in capsule

Answer 6

-2.3 KPa

Question 7

what is the osmotic pressure of blood in glomerulus

Answer 7

• 4.2 KPa

Question 8

what is the net filtration pressure

Answer 8

1.3 KPa

Question 9

where is all of the glucose absorbed in the kidney?

Answer 9

the PCT (proximal convoluted tubule)

Question 10

what does the renal artery do?

Answer 10

carries oxygenated blood to the kidney

Question 11

what does the renal vein do

Answer 11

carries deoxygenated blood away from the kidney

Question 12

which is smaller the afferent or efferent arteriole

Answer 12

efferent arteriole

Question 13

why is the efferent arteriole smaller than the afferent arteriole

Answer 13

in order to cause a build up of hydrostatic pressure, in order create pressure in the glomerulus, in order to filter the waste materials.

Question 14

what are podocytes and what is there role/function

Answer 14

• epithelium of the bowman’s capsule
• filter large molecules, to ensure red blood cells, plasma proteins do not enter filtrate.

Question 15

what are the 3 layer of filtration between the glomerulus and bowman’s capsule

Answer 15

• capillary endothelium, contains fenestrations.
• basement membrane, mesh of collagen, that allows molecules with an Mr < 69,000 to pass
• podocytes, epithelium of the bowman’s capsule
  filter large molecules, to ensure red blood cells, plasma proteins do not enter filtrate.

Question 16

what is glomerular filtration rate?

Answer 16

rate at which fluid forms, in the bowman’s capsule, having been squeezed out of the blood plasma, during ultrafiltration.

Question 17

what is absorbed in the PCT (proximal convoluted tubule)

Answer 17

all glucose reabsorbed in PCT + amino acids and vitamins

Question 18

where does ultrafiltration take place

Answer 18

Bowman’s capsule

Question 19

where does selective reabsorption take place

Answer 19

in the PCT (proximal convoluted tubule)

Question 20

what does the PCT contain, in order to maximise SA

Answer 20

• it contains numerous microvilli to create a brush border thus increasing the surface area for transport proteins.
• folding’s in the basal membrane, to increase surface area for reabsorption
• capillaries close to PCT cells, in order to reduce diffusion, osmosis/active transport distance.

Question 21

what is the purpose of the K+, NA+ pump in the PCT

Answer 21

to maintain a steep sodium concentration gradient.

Question 22

summarise how selective reabsorption takes place in the PCT

Answer 22

• NA+, K+ pump, removes NA+ ions from cytoplasm of PCT cells, via active transport.
• NA + ions, cotransporter into cell along with glucose and some amino acids via facilitated diffusion
• glucose conc in the PCT cells increase, and then moves out of cells into capillaries by facilitated diffusion.

Question 23

what has more mitochondria the DCT or PCT

Answer 23

the PCT.

Question 24

what is the DCT

Answer 24

• cells are cuboidal epithelial cells
• small volume of water, are reabsorbed due to transport of NA+/ Cl - ions.
• aldosterone, acts on the DCT, to stimulate increased Na+ reabsorption into the blood.

Question 25

what is the collecting duct

Answer 25

- where ADH acts - creates a steep water concentration gradient between tubules and medulla using the loop of Henle. - determines how much water, is reabsorbed back into the blood stream.

Question 26

what does the loop of Henle act as?

Answer 26

a counter current multiplier.

Question 27

what is ADH

Answer 27

regulates the volume of water that is reabsorbed into the kidney

Question 28

what Aldosterone

Answer 28

Aldosterone is a steroid hormone secreted by adrenal glands. Its main role is to regulate salt and water in the body, thus having an effect on blood pressure

Question 29

what does increasing the length of the loop of Henle do?

Answer 29

the longer the loop of Henle, the greater the solute potential and the lower the water potential is in the medulla, thus meaning, that greater water reabsorption occurs, in the collecting duct, thus meaning a greater concentration of urine (lower volume, (less water in urine))

Question 30

what happens when blood pressure drops

Answer 30

the adrenal gland (zona glomerulosa) causes the release of ADH.

Question 31

what diabetes

Answer 31

inability to control blood glucose levels

Question 32

what is mellitus

Answer 32

a sweet taste - glucose in urine

Question 33

what is insipidus

Answer 33

failure to respond to ADH (ADH, fails to bind to receptors, on collecting duct plasma membrane.