Lecture - CVS (Rajesh Physiol 8 Microcirculation)

Question 1

Microcirucaltion:

1. What two things happen in the microcirucaltion?
2. The microcirculation of each organ is specifcially _____ to meet its own special needs
3. The design of microcirucaltion - within a organ, arteries branch seeral times before they from ______, the arterioles in turn branch more into what?
4. So blood enters thr capillary through what and leave through what?
5. DO the caps have the capability to constrict?
6. Arterioles can termnate into what two things?
7. What can metaarterioles directly connect to as well?
8. What’s the primary function of caps?
9. How is this function acheived? (two things that can let the cap residence time be 0.5-2s)
10. Are all the capillaries open in an organ? What’s an example of something that does open up more caps?

Answer 1

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Question 2

Capillary structure

1. Does the strucutre of caps vary between organs?
2. Does the thin wall of endothelial cells have SM?
3. Covered by b____ m______
4. How long and wide are they?
5. Are the cells attached tightly to each other? If not then what do they have between them? What does this allow?
6. What else do the endothelial cells contain that allows transport of larger things from inside the lumen to outside?
7. Since caps dont have SM, what so they have that allows contraction or dilation of them?
8. Even though 7, the true cap is devoid of SM and is inacapble of active constriction.
9. Is the pressure of 25-34mmHg high for caps?
10. Despite having a thin walll (endothelium), the caps can withstand high pressures without bursting. Why’s this?

Answer 2

9. Yes considering their size

Question 3

Law of Laplace

1. What does this law describe the relationship between? What’s the formula? What does each variable stand for and what does it mean?
2. Why is the wall tension (tendency for the vessel wall to _____0 is much lower in capillary, why?
3. So what essentially protecs the caps to withstaqnd high pressure?

Answer 3

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Question 4

3 classes of caps:

What are each type and

• permeability of each
• located where?
• what’s the note about the continuous caps and brain?
• what special feature of each? (like holes but where?)
• what capillary allows proteins to be filtered through?

Also, what’s the thing that prevents the proteins being filtered through the caps?

Answer 4

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Question 5

There are two major functions of capilarries - what are they and what’re the mechanisms?

Answer 5

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Question 6

Solute exchange: diffusion through conc grads for nutrition and hornome delivery

1. What establishes diffusion at capillary?
2. What sort of subtances (including what two important gases) easily diffuse through endothelial cells?
3. How do ions and polar molecules pass through? (the ones that are poorly soluble)
4. Are proteins usually allowed to diffuse through the water filled channels? (what is an exception of this?)
5. Transcapillary diffusion gradient is because of what? Explain this
6. What percentage of nutrient or drug transport is by diffusion?

Answer 6

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Question 7

Factors affecting diffusion across capillaries

1. Type of ______
   - what’re all the 6 types of transport
   - how do these types of molcues get across (like which routes): large non lipid-soluble or proteins, lipid soluble (O2/CO2), small non lipid-soluble (eg glucose, salts, water)
2. Molecule ______
   - what’s the relationship between the permeability and size?
3. _____ demand
   - how is this a factor? Explain it in 3 steps
4. Recruitment of _____
   - having more capillaries will do two things, what are they?

Answer 7

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Question 8

1st main function of caps: fluid exchange for regulation of plasma & interstitial fluid volumes through pressure gradients across walls and it obeys Starling’s principles

1. Starling’s principle of fluid exchange: cap blood flow is affected by ____ _____ _____ pressure (colloid osmotic pressure) as well as ______ pressure
2. What’re the 4 pressures that determine the filtration rate?
3. What’s the filtration pressure like on the arterial side and the venous side? So do you recover all the volume you lose into the interstitium?

Fluid exchange at capillary:

1. Water is driven across the capillary wall by the sum of what two pressues of the blood and interstitial fluid
2. What is the colloid osmotic pressure of the blood (____ pressure) generated by? (What’re they dissolved in?)
3. What forces tends to move water out of the cap? (filtration)
4. What forces tends to draw water in?
5. Normally, is the filtration or the reabs greater? What role does the lymph have to do here?
6. So which end of the cap tends to filter and which one absorbs?
7. What will these clinical conditons do to the balance between the cap pressure and oncotic pressure
   - inflammatory response
   - haemorrhage/shock
   - heart failure
   - hepatic failure
8. There’s always a marginally higher outward force than inward - what picks up this excess fluid from the interstitium?
9. How does odema result?
10. In what conditions can you see odema?
11. Fluid transfer across the cap wall in the opposite direction is also important medically - what two conditons?

Answer 8

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