Lecture #36 - Glomerular function

Question 1

The glomerulus isn’t very selective but what is the filtration based on?

Answer 1

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Question 2

Renal blood flow:

1. What percentage of the cardiac output?
2. How many litres per minute?
3. Why have such a high flow?

Answer 2

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Question 3

At which capillary bed is stuff actively secreted?

Answer 3

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Question 4

Renal blood supply pressure profile - what can you say about the pressure of the glomerulus capillaries and efferent arteriole

Answer 4

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Question 5

-Why is renal blood supply regulated?

ALL OF THIS STUFF BELOW (slides 16 to 22) - JUST GET IT SORTED PLZ

1. Intrinsic (autoregulation)
   - what are the two types of intrinsic regulation of blood supply?
   - explain how they work

JGA:
1. So these juxtaglomerular cells are mechanoreceptors and detect BP - what happens if there is a fall in BP? How does that lead to?
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I suggest go look at blackboard - all the tabs with ‘renin’ as keyword. Also, from my current overview: renal blood flow is associated with the pressure in the glomerulus (glomerular hydrostatic pressure) so like i think renal blood flow refers to e.g. how much flowing in and out in the arterioles. And the hydrostatic pressure in the glomerulus is proportional to the GFR —-> these two remain constant at a wide range of mean arterial blood pressures because the renal blood flow is regulated. So if MABP changes, then intrinsic and extrinsic kick in to make sure the glomerular hydrostatic pressure (thus the GFR) remain constant.

The reason glomerular hydrostatic pressure and GFR are proportional (i.e. if pressure decreases, GFR decreases) is because the main driver for filtration is blood pressure in there (60mmHg) since the capsular osmotic pressure is essentially 0 since both the Bowman’s space and glomerulus have isosmotic solution.

The reason there is glomerular osmotic pressure (i.e. fluid wants to move back to glomerulus) but no capsular is because……NaCl is the main contribution of osmolarity and [NaCl] are equal in the primary urine and blood that is why they are isosmotic: albumin dosent count because of its low concentration 100uM and [NaCL] = 145mM. In terms of glomerular osmotic pressure, there is albumin which is relatively higher in glomerulus than that in the capsule because proteins dont filtrate into the capsule, so in this case it is the albumin contributes to the driving force since NaCl concentrations are same.

Answer 5

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Question 6

What is the filtration barrier made of?

What gets through and what doesn’t?

Answer 6

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Question 7

Glomerular filtration is based on what three things?

Answer 7

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Question 8

What are the four forces that contribute to effective filtration pressure? Explain ‘em

What is the main driver for filtration and what opposes?

Answer 8

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Question 9

GFR:

1. Definition?
2. Say three things about it (on slide 34)

Answer 9

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Question 10

What is renal blood flow and what is renal plasma flow?

So how do you link RPF, GRF and efferent arteriole together?

What is the filtration fraction?

Answer 10

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Question 11

Filtered load:

1. Definition?
2. Equation
3. What’s the difference between this and GFR? -

Answer 11

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Question 12

1. How would you measure GFR?

2. What is clearance? i.e………

Answer 12

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