Lecture - CVS (Rajesh Physiol 6)

Question 1

What’s the major function of the vascular system?

Answer 1

Maintaib BP because if we don’t then the cardiac output will go down therefore perfusion down so blood will reduce to the brain and all

Question 2

1. What is blood flow defined as?
2. What’s the overall blood flow in the total ciruclation as an adult?

Answer 2

1. It’s defined as the quantity of blood passing a given point in the circulation in a given period and is normally expressed in ml/min
2. 5000ml/min and that’s the cardiac output

Question 3

What is the formula for blood flow - can you explain why the numerator and denominator are a thing?

Answer 3

F = drop in blood pressure/resistance to flow

So blood enters one end where you have pressure of P1 and leaves through P2. As you flow through, the pressure drops and this delta P is the pressure gradient. The resistance the blood faces is the resitance thing so flow is proportional directly to the pressure gradient and inversely proportional to resistance

Question 4

What are the 4 things that govern blood flow?

Answer 4

1. Pattern of blood flow
   - laminar vs turbulent
2. Resistance of the vessels
   - Poiseuille’s law
3. Series and parallel resistance
4. Pressure difference across circulation

Question 5

1 Factors affecting flow: Pattern of flow

1. What’re the three patterns of blood flow? What does it look like on drawing?
2. Where in the circulaton will the three patterns of blood flow be?
3. Laminar blood flow:
   - what kind of profile is formed and why of the blood? What does it look like in the cross sectional view (both transverse and longitudinal)?
   - sliding motion of one laminar layer over the other is called what?
   - what is shear stress?
   - is it normal to have shear stress?
   - what can high shear stress do? In what situations will you get increased sheat stress?
4. Turbulence blood flow:
   - when the ____ driving the fluid progressively increased - what happens to the flow? So it increases how?
   - does the formula still work?
   - when does the linear flow transition to turbulent flow?
   - what formula do you use to know if the flow is turbulent or laminar?
   - what number in the formula you just said is the ‘cricial value’ - what does this mean?
   - what is Re normally high in?
   - how do you detect the turbulent blood flow?
   - what is an example of something Re is pathologically increased in?

Answer 5

4. The linear relationship formula wouldnt work with turbulence, I think

Question 6

2 Factors affecting flow: resistance of the vessels

1. Is resistance diretly or indirectly proprotional to the flow?
2. Poiseuille’s law tells us the three factors that govern resistance - what are they?
3. What sort of liquid do you use Poiseuille’s law tell us? What is the formula?
4. Why are arterioles and the smallest arteries the main site of resistance to blood flow?

Answer 6

3. SO like, in PHSI191, the law is the formula of resistance (slide 17) inserted into the F = deltaP/R
4. The radius drops heaps and four fold effect on the peripheral resistance

Question 7

3 Factors affecting flow: Series and parallel resistance

1. What variable do these two affect therefore affecting the flow?
2. What is arranged in series in the body?
3. What is arranged in parallel?
4. What does parallel flow in systemic flow guarantee? And allows what?

Answer 7

1. Resistance

Question 8

Pressures governing the blood flow - what is it?

Answer 8

The pressure difference across circulation (arterial vs venous)

Question 9

Aorta and large artery function

1. These vessels reduce the _____ in ____ and _____ generated by the intermittent ejection of the stroke volume
2. This is accomplished by what feature of aorta and large arteries?
3. During systole, energy is stored in the ____ ____ as the elastic elements are stretched. What happens to this energy during diastole?
4. This prevents what between heart beats? Results in more or less what?

Answer 9

-

Question 10

What is pulse pressure in terms of systolic and diastolic pressure?

Answer 10

-

Question 11

Arterial pressure

1. What are the factors determining pulse pressure? So pulse pressure is (systolic - diastolic) but what else is the formula?
2. Draw the two graphs that were on the slide showing how pulse pressure is affected by SV and compliance
3. When arteries harden with aging, what does it reduce so how much does the pulse pressure increase?
4. Does the pulse travel faster than blood? What’s the speed difference?
5. Transmission velocity increases with ______ - what two things can cause this?
6. What is used to estimate human arterial distensibility?

Answer 11

-

Question 12

Factors affecting arterial blood pressure

1. What’s the big first one?
2. Distance along _____ _____
   - what increases with distance
   - what is aortic taper and how does it affect the arterial pressure?
3. What are three other things? Just think - what would affect your arterial blood pressure?
4. On slide 35, there are more things - go read them and what’re the last two in red that I think you should know

Answer 12

2. More stiff as you go along so you get increase arterial pressure and also less diameter and you go down so even more increase pressure since same volume in less space so like, large arteries have hgiher pessure than aorta but it will drop off into the smaller arteries bc resistance increases heaps, I guess.

Question 13

Veins

1. Why do veins appear collapsed in histological slides?
2. Veins also have less _____ _____ and _____ than arteries
3. Veins are highly distensible because they dont have much what? So they’re called ____ vessels and act as blood resorvoirs
4. Because veins have a ____ compliance at normal operating pressures, they can release or store blood in response to what?
5. What’re the 4 determinants of venous pressure?
6. When arteries constrict, what happens? When veins constrict, what happens?
7. What’re varicose veins?

Answer 13

3. not much elastic - so distensible
4. TPR up and increase venous return respectively