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Semester 4 > case 7 - introduction to the kidney > Flashcards

case 7 - introduction to the kidney Flashcards

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1
Q

what is the function of the kidney via the maintenance of the extracellular fluid volume

A

via sodium and water

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2
Q

what is the endocrine secretion function of the kidney

A

renin-angiotensin system
erythropoeitin
vitamin D - calcium regulation

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3
Q

what are the different parts of the nephron

A

renal corpuscle
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule

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4
Q

what does the renal corpuscle do

A

produces filtrate

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5
Q

what does the loop of henle do

A

further reabsorption of water (descending limb)
And both sodium and chloride ions (ascending limb)

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6
Q

what does the distant convoluted tubule do

A

secretion of ions, acids, drugs and toxins
variable reabsorption of water, sodium ions and calcium

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7
Q

what does the collecting duct do

A

variable reabsorption of water and reabsorption or secretion of hydrogen and bicarbonate ions

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8
Q

what does the papillary duct do

A

delivery of urine to minor calyx

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9
Q

what are the different parts of the collecting system

A

collecting duct
papillary duct

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10
Q

where does filtration happen

A

in the nephron

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11
Q

where does selective reabsorption happen

A

in the proximal convoluted tubule

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12
Q

where does secretion happen

A

in the collecting duct

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13
Q

what surrounds the nephron

A

the vasa recta

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14
Q

what happens in the vasa recta

A

this is where the substances that are reabsorbed from the tubular fluid and that we need to retain, re-enter the blood supply and then drain into the vein to eventually come back and leave via the hillum into the renal vein to then be returned to the general circulation

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15
Q

what is normal cardiac output

A

5 litres per minute

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16
Q

how much of the cardiac output do the kidneys recieve

A

20% - 1L per minute

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17
Q

what is the equation for glomerular filtration rate

A

GFR = Kf × [PGC - (PBC + p(pie)GC)]

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18
Q

what is Kf

A

filtration coefficient

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19
Q

what is PGC

A

glomerular capillary hydrostatic pressure
- favours filtration

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20
Q

what is pie(GC)

A

glomerular capillary oncotic pressure
- opposed filtration

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21
Q

what is PBC

A

Bowman’s capsule hydrostatic pressure
- opposes filtration

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22
Q

what should oncotic pressure be

A

0

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23
Q

where does blood enter the glomerulus through

A

the afferent arteriole and then enters the glomerular capillary network

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24
Q

where does filtration occur

A

in the ball of capillary

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25
Q

what is part of the filtration barrier

A

podocytes are part of the filtration barrier - stops larger molecules from leaving the blood and entering the tubular fluid

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26
Q

what is the cut off point at which the physical barrier prevents filtration

A

approximately the size of albumin

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27
Q

what is the charge in the membrane

A

it has negative charge - there is also a charge barrier

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28
Q

do the GFR in notes in the introduction to kidney example!!!

A
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29
Q

the next few flashcards are explaining the mechanism of autoregulation

A
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30
Q

what happens as blood pressure in the renal artery increases

A

there is a corresponding increase in the resistance to flow of the afferent arteriole.

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31
Q

what happens to the afferent arteriole when this happens

A

it begins to constrict as renal artery pressure goes up

32
Q

what happens to the efferent arteriole leading out of the glomerulus

A

it does not change

33
Q

what does this mean and what is the result

A

therefore, the resistance to the outflow stays constant as renal arterial pressure increases as afferent pressure goes up.

the result of this is in response to the increase in resistance as the pressure goes up, the glomerular capillary pressure within the glomerular capillaries remains constant and as a result, over the normal pressure range, renal blood flow remains constant and glomerular filtration rate remains constant

34
Q

therefore, what is it that helps maintain a constant blood flow and a constant GFR

A

the afferent arteriole contracting and relaxing

35
Q

what is the myogenic tone autoregulation mechanism

A

vascular smooth muscle responds by vasoconstricting

36
Q

what is the tubuloglomerular feedback autoregulation mechanism

A

distal tubular flow regulates vasocontriction by monitoring what goes through it

37
Q

what lecture for explanation of diagram in notes

A

GO TO NOTES THIS IS IMPORTANT

38
Q

what is the concept of renal clearance measurement of GFR equation

A

Ux V
(over)
Px

39
Q

what is Ux

A

urinary concentration of x

40
Q

what is V

A

urine volume per unit of time

41
Q

what is Px

A

plasma concentration of x

42
Q

what is the equation for renal clearance

A

‘Volume of plasma which is cleared of substance x per unit time’

43
Q

what is the gold standard ideal marker of GFR

A

insulin

44
Q

what is also used clinically as a marker for GFR

A

creatinine; used clinically but affected by diet, gender, age, ethnicity

45
Q

what is the filtered load of salt in the nephron

A

around 1.5 kg per day although we only use 9g of salt per day

46
Q

what does plasma Na+ determine

A

extracellular fluid volumes
arterial blood pressure

47
Q

what is the transporter responsible for the majority of sodium reabsorption

A

NHE-3

48
Q

where does the bulk of reabsorption occur

A

proximal tubule
67% Na+ reabsorbed

49
Q

where does fine tuning reabsorption occur

A

distal and collecting duct
8% Na+ reabsorbed

50
Q

where does the rest of Na+ get reabsorbed

A

Loop of Henle

51
Q

through what does the reabsorption of sodium in the proximal tubule occur

A

through the exchange of the sodium hydrogen exchanger and it is NHE-3.

52
Q

what is the official name of NHE-3

A

SLC9A3

53
Q

what does this exchanger do

A

it takes up a sodium ions and moves it down its concentration gradient into the cell and exchanges it for a hydrogen ion, taking it out of the cell into the tubular fluid.

54
Q

what is this then linked to

A

the movement of chloride coming into the cell through a chloride anion exchanger

55
Q

what happens to the sodium that has been reabsorbed

A

it has been pumped out by the NaK ATPase

56
Q

what is the other transporter on the basolateral side of the membrane

A

the sodium hydrogen exchanger; NHE-1 (SCL9A1)

57
Q

what is this exchanger involved in

A

the regulation of cell volume, not in the regulation of sodium

58
Q

what happens in the late distal/collecting duct

A

fine turning

59
Q

under what control does this happen

A

under hormonal control

60
Q

how and where is aldosterone released from

A

aldosterone from the adrenal cortex is released as a result of the stimulation by angiotensin II

61
Q

what does this aldosterone do

A

makes ENaC channels be produced and inserted into the membrane and stimulates these channels to open

62
Q

what happens at the same time

A

aldosterone allows K+ channels to be open and allows this K+ to be lost and added to the filtrate

63
Q

what is the glucose transport solute carrier family

A

SLC5

64
Q

what are the two transporters in this category and what do they do

A

SGLT1 - transports 1 glucose: 2 Na
SGLT2 - transports 1 glucose: 1 Na

65
Q

what does the GLUT family transporters do

A

facilitated diffusion

66
Q

what are the two GLUT family exchangers that we are concerned with

A

GLUT 1 and GLUT 2

67
Q

what are low-affinity, high-capacity (early proximal) transporters

A

SGLT2 and GLUT2

68
Q

what are high-affinity, low-capacity (late proximal) transporters

A

SGLT1 and GLUT1

69
Q

what is the fasting glucose excretion rate and the GFR

A

Fasting glucose ~ 5 mmol/L and GFR = 125 mL/min

70
Q

therefore what is the filtered glucose

A

Filtered glucose = 5 x 0.125 = 0.63 mmol/min

71
Q

what is the transport maximum

A

Transport maximum (Tm) ~ 1.25 mmol/min

72
Q

what is the plasma glucose and what does this value mean

A

Plasma glucose ~ 10 mmol/L - this is the value when Tm is exceeded and cannot reabsorb all the glucose

73
Q

what happens if Tm is exceeded

A

you see glucose in the urine

74
Q

what is splay

A

splay reflects the fact that the transport properties of each individual nephron are slightly different. so the maximum that each individual nephron can reabsorb is not exactly the same

splay is uraemic toxins and therefore means loss of glucose in the urine

75
Q

what happens in the cortex

A

there is gluconeogenesis - 20% of glucose production

76
Q

what happens in the medulla

A

there is glycolysis

glucose is broken down into pyruvate

Semester 4 (80 decks)

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