glomerular filtration Flashcards

1
Q

what are the functions of the kidney

A
regulation of ECF volume and blood pressure 
regulate osmolality 
maintain ion balance
regulate pH
excrete waste
produce hormones
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2
Q

what are the 5 steps in the nephron

A

1 filtration by the glomerulus
2 absorption and secretion by the PCT
3 generation of osmotic gradient by the loop of Henle
4 regulated absorption and secretion by the DCT
5 water uptake in the collecting ducts

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3
Q

what are podocytes

A

cells in the Bowman’s capsule that wrap around the capillaries of the glomerulus
they have long projections which wrap around the capillaries and leave slits between them through which blood is filtered
they have foot processes and secondary processes

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4
Q

describe the triple barrier of the glomerulus

A

endothelial lining of capillaries
basement membrane of the capillaries
foot processes of the podocytes

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5
Q

what size solutes can form the filtrate

A

up to 60 kDa
no cells or large proteins
positively charged molecular are filtered more easily

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6
Q

what is renal blood/ plasma flow

A

total amount of blood/ plasma that traverses the renal artery/vein per unit time

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7
Q

what is approximate RBF

A

1100 ml/min

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8
Q

what is approximate RPF

A

1- haematocrit x RBF = 0.55 x 1100 = 600 ml

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9
Q

what pressures ( starling forces) favour movement into the tubule

A

hydrostatic blood pressue (+55)

oncotic tubule pressure (0)

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10
Q

what forces oppose movement into the tubule

A

hydrostatic pressure of the tubule (-15)

oncotic pressure of the blood ( -30mmHg)

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11
Q

what is the overall pressure of movement into the tubule

A

10 mmhg

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12
Q

what is the GFR

A

rate of filtrate production

125 ml/min

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13
Q

how is myogenic autoregulation mediated

A

stretch receptors in the arteriole

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14
Q

how is pressure in the glomerulus increased

A

dilate the afferent arteriole
or constrict the efferent arteriole
change to blood flow and pressure

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15
Q

how much is renal blood flow

A

20% of CO
1 L/min

renal blood flow is mostly constant over a wide range of BPs so GFR is essentially constant

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16
Q

what is tubuloglomerular feedback

A

a function of the juxtamedullary nephron

flow in the DCT is monitored and high flow information fed back to arterioles

17
Q

what cells monitor filtrate flow in the DCT

A

macula densa cells monitor increase in Na and Ca ions

18
Q

what hormones increase afferent blood flow

A

norepinephrine
epinephrine
angiontensin

19
Q

what hormones decrease renal blood flow

A

atrial naturetic peptide

renal prostaglandins

20
Q

what does angiotensin do

A

causes vasoconstriction which increases blood pressure