Kidney Tubular Function

Question 1

what does sodium transport facilitate?

Answer 1

reabsorption of nutrients, water and ions

Question 2

how much is reabsorbed in the PCT?

Answer 2

65%

Question 3

how much is absorbed in the ascending loop of Henle?

Answer 3

25%

Question 4

how much is reabsorbed in the DCT?

Answer 4

up to 8%

Question 5

how much sodium is reabsorbed?

Answer 5

98%

Question 6

what does ADH do in the DCT?

Answer 6

targets the epithelium in the DCT and tells it to insert aquaporins

Question 7

what is the overall function of ADH inserting aquaporins in the DCT?

Answer 7

to maintain homeostasis of the internal fluid compartment

Question 8

what signals the release of the hormones in the DCT?

Answer 8

changes in blood pressure (decreased for ADH and aldosterone and increase for ANP)

Question 9

if ADH inserts aquaporins the what does aldosterone insert in the DCT?

Answer 9

sodium channels

Question 10

collectively what do ADH and aldosterone action result in in the DCT?

Answer 10

fluid reabsorption producing a small volume of concentrated urine which increases homeostatic regulation of blood pressure and volume

Question 11

what is the action of ANP in the DCT?

Answer 11

fluid excretion which leads to large volume of dilute urine and then decreased homeostatic regulation of blood volume and pressure

Question 12

what hormones does a decrease in blood pressure release?

Answer 12

ADH and aldosterone

Question 13

what hormones does an increase in blood pressure release?

Answer 13

ANP

Question 14

what is glomeruluar filtration rate?

Answer 14

the rate at which blood is filtered through the glomerulus into the Bowman’s capsule

Question 15

what is GFR influenced by?

Answer 15

glomerular hydrostatic pressure, capsular hydrostatic pressure, glomerular osmotic pressure, systemic blood pressure, renin-angiotensin-aldosterone system and disease

Question 16

if the GFR is greater what does it mean for sodium?

Answer 16

there is less time to reabsorb it in the glomerulus so there is a higher concentration of it in the DCT

Question 17

what is reabsorbed in the PCT?

Answer 17

65% Na and water, 100% glucose and amino acids, 50% waste (urea)

Question 18

what is reabsorbed in descending loop of Henle?

Answer 18

water

Question 19

what is reabsorbed in the ascending loop of Henle?

Answer 19

25% Na (+ K and Cl)

Question 20

what is reabsorbed in the DCT?

Answer 20

<8% Na and water

Question 21

what does the juxta-glomerular apparatus do?

Answer 21

connects the DCT with the glomerulus and measures and responds to changes in Na+ concentration of the filtrate

Question 22

what is reabsorbed in the collecting tubules?

Answer 22

water

Question 23

what does excretion equal?

Answer 23

(filtration - reabsorption) + secretion

Question 24

what does the macula densa do?

Answer 24

detects concentration of sodium in the filtrate

Question 25

what do the juxtaglomerular cells do?

Answer 25

adjust the diameter of the afferent arteriole when it receives signals from the macula densa

Question 26

what are the modified smooth muscle cells?

Answer 26

mesangial cells and supporting cells

Question 27

what needs to happen for juxtaglomerular cells to be effected?

Answer 27

the macula densa must release adenosine

Question 28

what is the sequence of events if glomerular hydrostatic pressure is increased?

Answer 28

increased BP - increased glomerular hydrostatic pressure - increased GFR - increased sodium filtrate conc. - macula densa released adenosine - juxtaglomerular cells swell which constricts afferent arteriole and decreased hydrostatic pressure

Question 29

what does tubuloglomerular feedback regulate?

Answer 29

systemic blood pressure

Question 30

what happens when the macula densa shrivels?

Answer 30

they release prostaglandins

Question 31

why would the macula densa shrivel?

Answer 31

decreased sodium concentration in filtrate

Question 32

what happens when the macula densa swells?

Answer 32

release adenosine

Question 33

what makes the macula densa swell?

Answer 33

increased sodium filtrate concentration

Question 34

what is the sequence of events if the glomerular hydrostatic BP is decreased?

Answer 34

decreased BP - decreased glomerular hydrostatic pressure - decreased GFR - decreased sodium conc. in filtrate - macula densa release prostaglandins - juxtaglomerular cells maintain the afferent arteriole diameter but secretes renin to activate renin-angiotensin system

Question 35

how does the renin-angiotensinogen restore blood pressure?

Answer 35

via angiotensin 2

Question 36

describe the process in which renin-angiotensinogen restores blood pressure

Answer 36

1 - angiotensinogen released into circulation, 2 - renin converts angiotensinogen into angiotensin 1, 3 - angiotensinogen converting enzyme converts angiotensin 1 into 2, 4 - angiotensin 2 is a potent vasoconstrictor and rapidly increases blood pressure

Question 37

where is angiotensin released from?

Answer 37

the liver

Question 38

where does angiotensin 2 bind to target receptors on and for what?

Answer 38

arterioles for constriction, hypothalamus for thirst, pituitary gland for release of ADH, adrenal medulla for release of aldosterone

Question 39

how does angiotensin 2 restore blood volume?

Answer 39

via increased fluid and salt retention

Question 40

where is the ANP released from?

Answer 40

from epithelial cells in the lining of the atrium of the heart which have baroreceptors to know when to release the peptide

Question 41

summarise what happens when there is high concentration of sodium and it is detected by the juxtaglomerular apparatus?

Answer 41

release aldosterone - vasoconstriction - tubuloglomerular feedback

Question 42

what does tubuloglomerular feedback ensure?

Answer 42

that the capillaries do not get damaged

Question 43

summarise what happens when there is a low concentration of sodium and it is detected by the juxtaglomerular apparatus?

Answer 43

release of prostaglandins - renin release - activation of RAAS

Question 44

summarise the actions of ANP

Answer 44

it counteracts ADH and renin to remoe excess fluid and lower blood pressure

Question 45

what happens to GFR as kidney disease worsens?

Answer 45

it decreases

Question 46

how does kidney disease affect the CVS?

Answer 46

GFR is decreased which activates RAAS system which increases BP

Question 47

what are the consequences of chronic kidney disease?

Answer 47

inadequate removal of fluid and waste products of metabolism, inappropriate activation of RAAS

Question 48

what are the causes of chronic kidney disease?

Answer 48

hypertension, diabetes, high cholesterol, kidney infections, glomerulonephritis, polycystic kidney disease, kidney stones, long-term use of NSAIDs

Question 49

what two causes of kidney disease can be related to oral bacteria

Answer 49

kidney infections and glomerulonephritis

Question 50

when do kidney stones develop?

Answer 50

when waste starts to crystallise which blocks kidney function

Question 51

what are the symptoms of chronic kidney disease?

Answer 51

hypertension, nausea, oedema in hands., ankles feet or lungs, blood/protein in urine, anaemia and weak/painful bones

Question 52

how is hypertension regulated?

Answer 52

diet/weight loss, combination of anti-hypertensive treatments, diuretics, ACE inhibitors/angiotensin receptor blockers, aldosterone agonists

Question 53

how do ACE inhibitors/angiotensin receptor blockers work?

Answer 53

prevent conversion of angiotensin 1 to angiotensin 2

Question 54

what is kidney failure?

Answer 54

stage 5 kidney disease, end stage renal disease with less than 15% kidney function, dialysis and/or kidney transplant required

Question 55

what is dialysis

Answer 55

artificial removal of waste, solutes, water and toxins from blood

Question 56

what are the 2 types of dialysis?

Answer 56

haemodialysis, peritoneal dialysis