Fluid Electrolyte Homeostasis Flashcards

1
Q

what does sodium transport facilitate

A

reabsorption of nutrients, water and ions

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2
Q

how much filtrate is absorbed in the proximal convoluted tubule

A

65%

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3
Q

how much filtrate absorbed in the ascending loop of henle

A

25%

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4
Q

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

A

in the distal convoluted tubule

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5
Q

which hormone inserts aquaporins into the distal convoluted tubule

A

adh / vasopressin

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6
Q

which hormone inserts sodium channels into the distal convoluted tubule

A

aldosterone

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7
Q

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

A

small volume of concentrated urine

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8
Q

what does ANP do to the distal convoluted tubule

A

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

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9
Q

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

A

overall homeostatic regulation of blood volume and pressure

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10
Q

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

A

the changes in systemic blood pressure

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11
Q

what is the glomerular filtrate rate defined as

A

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

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12
Q

what influences the GFR

A
  • glomerular hydrostatic pressure
  • capsular hydrostatic pressure
  • glomerular osmotic pressure
  • systemic blood pressure
  • renin angiotensin aldosterone system
  • disease
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13
Q

what do the kidneys measure GFR as a proxy for

A

the systemic blood pressure

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14
Q

what generates the glomerular hydrostatic pressure

A

the fact that blood is arriving faster than it can leave

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15
Q

what is the osmotic potential determined by

A

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

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16
Q

list what is absorbed in the PCT

A
  • 65% sodium and water
  • 100% glucose and amino acids
  • 50% waste, urea
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17
Q

what is absorbed in the descending loop of henle

A

water

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18
Q

what is absorbed in the thick ascending limb

A

25% sodium and potassium and chlorine

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19
Q

where in the kidneys can water be absorbed

A
  • PCT
  • descending loop of henle
  • DCT
  • collecting duct
20
Q

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

A

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

21
Q

what does the juxtaglomerular apparatus do

A

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

22
Q

describe the location of the juxtaglomerular apparatus

A

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

23
Q

what does the macula densa do

A

detects the sodium concentration

24
Q

what do the juxtaglomerular cells do

A

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

25
Q

what are juxtaglomerular cells

A

modified smooth muscle cells

26
Q

describe how blood pressure affects sodium filtrate concentration

A

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

27
Q

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

A
  • no issues sensed in the macula densa
  • no signals sent to JG cells
  • diameter of afferent greater than efferent
28
Q

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

A
  • 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
29
Q

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

A

tubuloglomerular feedback

30
Q

describe the state of the JG apparatus when blood pressure decreases

A
  • 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
31
Q

describe the series of events in the RAAS system

A
  • 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
32
Q

list all the actions of angiotensin II

A

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

33
Q

how does RAAS ultimately restore blood volume

A

via increased fluid and salt retention

34
Q

what happens in the kidneys when there is raised blood pressure

A

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

35
Q

chronic kidney disease reduced GFR. what does this cause

A
  • inadequate removal of fluid and waste products of metabolism
  • inappropriate activation of RAAS
36
Q

what can cause chronic kidney disease

A
  • hypertension
  • diabetes
  • high cholesterol
  • kidney infections
  • glomerulonephritis
  • polycystic kidney disease
  • kidney stones
  • long term use of NSAIDS
37
Q

what are kidney stones

A

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

38
Q

what are the symptoms of chronic kidney disease

A
  • hypertension
  • nausea
  • oedema
  • blood or proteins in the urine
  • aneamia
  • weak or painful bones
39
Q

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

A

ankles, hands, feet and lungs

40
Q

how can hypertension be regulated

A
  • diet and weight loss
  • combination of anti hypertensive treatments
  • diuretics
  • ace inhibitor/angiotensin receptor blocker
  • aldosterone agonists
41
Q

what is furosemide an example of

A

a diuretic drug

42
Q

what does furosemide target

A

NKCC2

43
Q

what does NKCC3 regulate

A

the sodium reabsorption on the apical membrane in the kidneys

44
Q

how much kidney function is there in stage five kidney failure

A

15%

45
Q

what is dialysis

A

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

46
Q

what are the two types of dialysis

A

haemodialysis
peritoneal dialysis

47
Q

what is the renal blood flow rate

A

1.2 litres a minute