Fluid Electrolyte Homeostasis

Question 1

what does sodium transport facilitate

Answer 1

reabsorption of nutrients, water and ions

Question 2

how much filtrate is absorbed in the proximal convoluted tubule

Answer 2

65%

Question 3

how much filtrate absorbed in the ascending loop of henle

Answer 3

25%

Question 4

where in the kidneys is sodium transported regulated depending on the body’s requirements

Answer 4

in the distal convoluted tubule

Question 5

which hormone inserts aquaporins into the distal convoluted tubule

Answer 5

adh / vasopressin

Question 6

which hormone inserts sodium channels into the distal convoluted tubule

Answer 6

aldosterone

Question 7

what kind of urine is produced from the actions of aldosterone and adh

Answer 7

small volume of concentrated urine

Question 8

what does ANP do to the distal convoluted tubule

Answer 8

blocks the actions of adh and aldosterone to encourage fluid excretion and the production of a large volume of dilute urine

Question 9

what is the importance of the hormonal regulation of filtrate composition in the DCT

Answer 9

overall homeostatic regulation of blood volume and pressure

Question 10

what effects the levels of adh aldosterone and anp in the DCT

Answer 10

the changes in systemic blood pressure

Question 11

what is the glomerular filtrate rate defined as

Answer 11

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

Question 12

what influences the GFR

Answer 12

• glomerular hydrostatic pressure
• capsular hydrostatic pressure
• glomerular osmotic pressure
• systemic blood pressure
• renin angiotensin aldosterone system
• disease

Question 13

what do the kidneys measure GFR as a proxy for

Answer 13

the systemic blood pressure

Question 14

what generates the glomerular hydrostatic pressure

Answer 14

the fact that blood is arriving faster than it can leave

Question 15

what is the osmotic potential determined by

Answer 15

the proteins staying in the blood that hold onto some of the fluid

Question 16

list what is absorbed in the PCT

Answer 16

• 65% sodium and water
• 100% glucose and amino acids
• 50% waste, urea

Question 17

what is absorbed in the descending loop of henle

Answer 17

water

Question 18

what is absorbed in the thick ascending limb

Answer 18

25% sodium and potassium and chlorine

Question 19

where in the kidneys can water be absorbed

Answer 19

• PCT
• descending loop of henle
• DCT
• collecting duct

Question 20

why is the concentration of sodium in the filtrate higher if the blood pressure is higher

Answer 20

because the hydrostatic pressure is greater meaning the filtrate flows much faster and there is less time for the sodium to move out

Question 21

what does the juxtaglomerular apparatus do

Answer 21

it connects the distal convoluted tubule with the glomerulus, and measures and responds to changes in the sodium concentration of the filtrate

Question 22

describe the location of the juxtaglomerular apparatus

Answer 22

it is next to the glomerulus, and is surrounding the afferent arteriole. connects glomerulus to DCT

Question 23

what does the macula densa do

Answer 23

detects the sodium concentration

Question 24

what do the juxtaglomerular cells do

Answer 24

they adjust the diameter of the afferent arteriole depending on sodium concentration being detected by the macula densa

Question 25

what are juxtaglomerular cells

Answer 25

modified smooth muscle cells

Question 26

describe how blood pressure affects sodium filtrate concentration

Answer 26

blood pressure affects glomerular hydrostatic pressure which affects glomerular filtrate rate which affects the sodium filtrate concentration

Question 27

describe the state of the juxaglomerular apparatus when blood pressure is homeostatic

Answer 27

- no issues sensed in the macula densa - no signals sent to JG cells - diameter of afferent greater than efferent

Question 28

describe the state of the JG apparatus when the blood pressure is elevated

Answer 28

- increased blood pressure - increased hydrostatic pressure - increased sodium concentration in the filtrate - macula densa take up the sodium and water will follow due to osmosis - the cells swell and release adenosine from basolateral membrane - adenosine acts on JG cells to make them constrict and reduce the diameter of the afferent arteriole to reduce the hydrostatic pressure

Question 29

what is the name of the feedback system in the JG apparatus to regulate the blood pressure

Answer 29

tubuloglomerular feedback

Question 30

describe the state of the JG apparatus when blood pressure decreases

Answer 30

- decreased BP - decreased glomerular hydrostatic pressure - decreased glomerular filtrate rate - decreased sodium filtrate concentration - macula densa senses this, water and sodium drawn out of macula densa making it shrivel - release of prostaglandins from macula densa - act on JG cells to dilate the diameter of the afferent arteriole and will also release renin to activate RAAS - blood pressure restored

Question 31

describe the series of events in the RAAS system

Answer 31

- angiotensinogen released into circulation - renin converts angiotensinogen into angiotensin I - angiotensinogen convert ing enzyme converts angiotensin I into angiotensin II - angiotensin II potent vasoconstrictor and will rapidly increase blood pressure

Question 32

list all the actions of angiotensin II

Answer 32

binds to target receptors on the following: - arterioles for constriction - hypothalamus to stimulate thirst - pituitary gland to release ADH - adrenal cortex to release aldosterone

Question 33

how does RAAS ultimately restore blood volume

Answer 33

via increased fluid and salt retention

Question 34

what happens in the kidneys when there is raised blood pressure

Answer 34

baroreceptors detect this and stimulate the release of ANP to counteract the actions of adh and aldosterone and increase water and salt excretion

Question 35

chronic kidney disease reduced GFR. what does this cause

Answer 35

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

Question 36

what can cause chronic kidney disease

Answer 36

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

Question 37

what are kidney stones

Answer 37

waste products of metabolism that start to crystallise, some can be passed without notice but some can be very painful

Question 38

what are the symptoms of chronic kidney disease

Answer 38

- hypertension - nausea - oedema - blood or proteins in the urine - aneamia - weak or painful bones

Question 39

where is oedema likely to occur in cases of chronic kidney disease

Answer 39

ankles, hands, feet and lungs

Question 40

how can hypertension be regulated

Answer 40

- diet and weight loss - combination of anti hypertensive treatments - diuretics - ace inhibitor/angiotensin receptor blocker - aldosterone agonists

Question 41

what is furosemide an example of

Answer 41

a diuretic drug

Question 42

what does furosemide target

Answer 42

NKCC2

Question 43

what does NKCC3 regulate

Answer 43

the sodium reabsorption on the apical membrane in the kidneys

Question 44

how much kidney function is there in stage five kidney failure

Answer 44

15%

Question 45

what is dialysis

Answer 45

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

Question 46

what are the two types of dialysis

Answer 46

haemodialysis peritoneal dialysis

Question 47

what is the renal blood flow rate

Answer 47

1.2 litres a minute