1.5 Venous return

Question 1

what is venous return

Answer 1

flow of blood back to the heart, via the veins and specifically the vena cava

more blood is ejected from the heart (stroke vol)

Question 2

why are venous return mechanisms needed in the body

Answer 2

low pressure of the blood in the veins

in order to help venous return

Question 3

Venous Return Mechanisms:

describe the role of the skeletal muscle pump

Answer 3

muscles contracting and relaxing are constantly changing shape

results in muscles pressing on nearby veins

causes a pumping action which pushes b. back towards the heart

Question 4

describe the role of the respiratory pump

Answer 4

breathing in and out causes contractions in many muscles & the diaphragm

causes a constant change in pressure of the thoracic (chest) cavity

compressing the veins & causing venous return

Question 5

describe the role of pocket valves

Answer 5

veins are full of pocket valves

as blood passes through these valves they close in order to prevent the back flow of blood

Question 6

what other factors aid in venous return

Answer 6

1. smooth muscle
2. gravity
3. suction pump of the heart

Question 7

describe the role of smooth muscle

Answer 7

1. lines the walls of the veins & makes it easier for b. to travel through the veins without disturbance

Question 8

describe the role of gravity

Answer 8

2. veins above the heart will be assisted by gravity - makes it easier for b.f back to the heart

Question 9

describe the role of the suction muscle pump

Answer 9

3. as the heart relaxes and refills the low pressure generates a ‘suction’ action - makes it easier to take in b. from the veins

Question 10

definition of blood, systolic & diastolic pressure

Answer 10

B.P = pressure of the b. in the circulatory system

S.B.P = pressure of the b. against the wall of the arteries as the heart contracts

D.B.P = pressure of the b. in the heart as it relaxes & refills