Cardio - Vascular Function Flashcards Preview

Physiology 2130 > Cardio - Vascular Function > Flashcards

Flashcards in Cardio - Vascular Function Deck (29):
1

What is the pressure and resistance of the aorta and large arteries?

Blood pressure is high (110mmHg) and resistance is low
-average pressure change from aorta to large arteries is relatively the same

2

When does blood pressure begin to drop and why?

When blood reaches the small arteries is where we encounter resistance

3

Where is the greatest resistance?

In the arterioles
-accounts for ~1/2 the total resistance in the entire systemic circulation

4

What is the pressure in the arterioles?

55mmHg

5

What is the blood pressure of blood going from arterioles to capillaries?

40mmHg

6

What is the blood pressure within the capillaries?

20mmHg

7

What is the blood pressure when blood goes from capillaries to venules?

10-15mmHg

8

What is the blood pressure when blood finally reaches the right atrium?

Pressure is almost 0
-encounters small but significant amount of resistance

9

What drives the blood through the vessels?

Pressure change through the system

10

What causes the blood to flow through circulation?

Drop in pressure from high (aorta) to low (veins)

11

What is blood flow effected by?

Pressure change (or pressure gradient) between 2 points and resistance in the circulatory system

12

Simplified, what is the resistance effected by?

Radius of the vessel
-smaller the radius the greater the resistance
-values normally don't change much

13

What is the equation for blood flow?

(P1-P2) x r^4
-therefore small changes in the radius will have a large effect on blood flow

14

What does flow into vessels have to equal?

Flow out of vessels
-division of quantities can be different but the overall output has to be the same

15

What happens to the pressure gradient if one vessel radius is reduced?

The vessels before and after the reduced radius vessel will increase output and therefore increase the blood flow

16

Which change in blood flow is better?

Change in radius diameter is better for us than a change in pressure

17

What pressure and volume characteristics contribute to circulation?

structural properties

18

What is blood velocity?

Is the speed at which the blood is moving through a particular blood vessel (cm/sec)

19

What is blood flow?

The volume of blood moving through a set of vessels (L/min)

20

What is the blood flow a rest?

5ml/min
-same throughout the systemic system

21

Why is mean blood velocity higher in aorta then vena cava but blood flow stays the same?

Because the vena cava has a slightly larger diameter
-inorder to have the same blood flow, blood has to move faster through the narrow vessels (aorta)
-therefore velocity is higher in the aorta than the vena cava

22

What happens when you keep dividing into more vessels?

The velocity decreases

23

Why is velocity so low in capillaries ?

Since there is so many of them, the same amount of blood is spread out further to maximize diffusion
-as they start to reunite with the venues velocity starts to increase but not as high as the aorta because the diameter of the vena cava is bigger

24

What are the 3 layers of arteries and veins?

1. Outer layer (tunica externa)- fibrous connective tissue
2. Mid layer (tunica media)- Smooth muscle and elastic tissue
3. Inner layer (tunica interna)- Endothelial cells

25

What are capillaries only made up of endothelial cells?

To permit the diffusion of substances into and out of the blood

26

What does the function of a vessel/artery depend on?

The content of each of the 3 tissues

27

What are the blood characteristics like in the aorta and large arteries?

high 120mmHg and pulsatile
high blood velocity

28

What is the structure like of the aorta and large arteries like?

Large diameters
Lots of elastic tissue
Relatively thin walls which can be easily distended = low resistance to blood flow
-average blood pressure doesn't drop much

29

What is the purpose of the aorta and large arteries?

"shock absorbers" when he heart ejects blood into these vessels (up to 70ml) so the arteries can absorb the amount of blood being pumped out

Distributes blood