Venous return and starlings law

Question 1

what can you remember about the structure of veins and how it relates to their function?

Answer 1

• carry blood towards the heart
• mostly carry deoxygenated blood (not pulmonary)
• no stretch - very thin layer of smooth muscle
• thin-walled large lumen have valves to prevent backflow

Question 2

Venous Return:

Answer 2

venous return is the return of blood to the right side of the heart via the vena cava

Question 3

during exercise, the ___ of ___ returning to the heart (_____) ____.

Answer 3

during exercise, the AMOUNT of BLOOD returning to the heart (VENOUS RETURN) INCREASES.

Question 4

under normal circumstances:

venous return ____ stroke volume (i.e when goes in comes out)

Answer 4

venous return = stroke volume

Question 5

the 6 venous return mechanisms:

Answer 5

1. the skeletal muscle pump
2. the respiratory pump
3. pocket valves or valves
4. smooth muscle in the walls of veins
5. gravity
6. the suction pump action of the heart

Question 6

the skeletal pump:

Answer 6

when muscles contract and relax they change shape.

this change in shape means muscles press on nearby veins causing a pumping effect and squeeze the blood towards the heart

Question 7

the respiratory pump:

Answer 7

when muscles contract and relax during breathing in and out, pressure changes occur in the thoracic (chest) and abdominals (stomach) cavities.

these changes in pressure compress nearby veins and assist blood return to the heart

Question 8

pocket valves:

Answer 8

blood in the veins only flows in one direction

this is because one blood has passed the valves, they close preventing backflow

Question 9

gravity:

Answer 9

gravity helps the blood return to the heart from the upper body

Question 10

smooth muscle:

Answer 10

a very thin layer of smooth muscle in the walls of the veins. this helps squeeze blood back towards the heart

Question 11

Blood pressure:

Answer 11

the force exerted by the blood against the blood vessels

Question 12

Systolic pressure:

Answer 12

the pressure in the arteries when the ventricles are contracting

Question 13

Diastolic pressure:

Answer 13

the pressure in the arteries when the ventricles are relaxing

Question 14

blood pressure = _____ * ______

Answer 14

blood pressure = blood flow * resistance

Question 15

impact of blood pressure on venous return:

Answer 15

when systolic blood pressure increases, there’s an increase in venous return, systolic pressure decreases, decrease in venous return