Lecture #39 - plasma volume and sodium homeostasis

Question 1

What is the fast and slow system - like, what do they respond to?

Answer 1

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Question 2

What are three examples of water and salt losses? What about water and salt gains

Explain the changes in volume, osmolarity and circulating volume. Why would you want to control volume? Because like, osmolarity important else cell size and functions change (e.g. RBCs)

Answer 2

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Question 3

By what mechanism do we correct problems with circulating volume/BP? i.e. what is the slow system

Answer 3

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Question 4

So the changes to ECF (plasma) volume are sensed by body at 3 different sites:

What are they and where are the receptors found?

Answer 4

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Question 5

High pressure baroreceptors

• sense what?
• where are the two places they’re found?
• signals to what?
• what are the two effects they do?

Low pressure baroreceptors

• sense what?
• 3 places where they’re found
• signals to where?
• if high volume, what do atria release and what effect does it have?

Intra-renal sensors:
-two kinds - what are they and what do each sense and what effect?

Answer 5

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Question 6

Integration:

• Information about the circulating volume from all 3 sensory systems is integrated to regulate ____ ____ of ____ (and ____)
• When circulating volume and renal flow are sensed to be high - mechanisms adjust to enhance ____ _____ (mostly via _____) - what happens to water and thus volume (i.e. BP)?
• When circulating volume and renal flow are low, mechanisms activated to ____ ___ (control mainly by ____) - what happens to water and volume (i.e. BP)

Answer 6

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Question 7

Mechanisms for ECF volume regulation - five of them, name them

Answer 7

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Question 8

ANP (atrial natriuretic peptide) by high-pressure baroreceptors - if increased volume:

1. _____ secrete ANP in response to increased volume
   - ______ senses extra vol and gives signal that……
2. What are its 3 effects? What will all these effects essentially lead to?
3. From the flow chart (back page):
   - what actually stimulates the cardiac atria to secrete ANP?
   - what happens to plasma ANP?
   - what happens to aldosterone?
   - what happens to kidneys? (arterioles and tubules)
   - so what is the end result?

Answer 8

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Question 9

Renal sympathetic nerves and ADH by volume sensors - if low volume:

1. What are its three effects?
2. What is the overal effect? (Na excretion and water and volume)
3. What other hormone is related to this and what does it do?

Answer 9

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Question 10

You know that diagram on slide 31 - memorise that

Answer 10

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Question 11

Renin-Angiotensin system (RAS) when BP low:

1. Renin - what is it and where is it secreted?
2. Cleaves what and where is this made?
3. How is angiotensin 1 converted then?
4. What is the active form of angiotensin?
5. What are the three effects of angiotensin?
6. Slide 36 says 5 effects

Flow chart slide 39:

• decrease effective circulating volume so you stimulate through what two things to increase renin?
• what does renin do?
• where is angiotensin 1 converted to angiotensin 2?
• WHAT HAPPENS TO HYPOTHALAMUS WITH ANGIOTENSIN? (2)
• what happens to renal gland?
• what do aldosterone and angiotensin do to kidney?

Answer 11

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Question 12

What are the three stimuli for renin release from JGA when ECF volume is low?

Answer 12

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Question 13

Aldosterone

1. What kind of hormone?
2. Secreted from where?
3. What stimulates it?
4. What does it act on and what does it do?
5. Aldosterone’s effect on:
   - Na+
   - Cl-
   - K+
   - Acid (NhH4)

Answer 13

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