Blood vessels Gas Exchange

Question 1

What are the three coats/tunicas of the walls of arteries and veins?

Answer 1

1. Tunica Externa
2. Tunica media
3. tunic interna

Question 2

describe tunica externa

Answer 2

outer layer of the wall of blood vessels, composed of connective tissue

Question 3

describe the tunica media

Answer 3

the middle layer of the wall of blood vessels; composed of smooth muscle

Question 4

describe the tunica interna

Answer 4

the internal layer of the wall of blood vessels

Question 5

what are the layers of the tunica interna

Answer 5

1. endothelium
2. glycoproteins and connective tissues to fibres
3. elastin (elastic fibres)

Question 6

describe the distribution of blood within the circulatory system

Answer 6

• majority within the small veins and venules
• next majority within large veins
• then lungs
• systematic arteries
• heart
• capillaries

Question 7

where is the most blood volume

Answer 7

the most of blood volume is in the veinous system

Question 8

describe how veins move blood

Answer 8

veins are able to expand as they accumulate additional amounts of blood (they stretch)

Question 9

what is the average pressure in veins

Answer 9

2mmHg

Question 10

what is the average arterial pressure

Answer 10

100MMHG

Question 11

As venous pressure is too low to return blood to the heart, how do veins return the blood from the lower limbs?

Answer 11

to help veins of the lower limbs return blood to the heart, the veins pass between skeletal muscle groups which provide contractions too help move blood back (SKELETAL MUSCLE PUMP)

Question 12

As venous pressure is too low to return blood to the heart, how do veins return blood from the abdominal and thoracic regions of the body?

Answer 12

The act of breathing and contacting of the diaphragm and pressure in the abdomen from breathing squeezes the veins to help move the blood

Question 13

What ensures the one-way flow of blood back to the heart

Answer 13

venous valves

first demonstrated by William Harvey

Question 14

What drives the blood away from the heart?

Answer 14

-elastic recoil drives the blood away from the heart during diastolic phase when the heart is resting and not providing any pressure

Question 15

how many capillaries are within the body?

Answer 15

over 40 billion capillaries in the body

Question 16

how close are cells to capillaries

Answer 16

any cell in the body is more than 60-80 UM away from a blood capillary

Question 17

describe blood flow to the capillary bed

Answer 17

vasoconstriction decreases the blood flow to the capillary bed, vasodilation increases it

Question 18

what are capillaries made of

Answer 18

the walls of capillaries are composed of just one cell layer : endothelial cells

• they lack smooth muscle and connective tissue

Question 19

what makes material exchange so easy within capillaries

Answer 19

they lack smooth muscle and connective tissue which makes it easier to exchange materials

Question 20

what happens at the arterial end of the capillary

Answer 20

blood pressure forces fluid out of the capillary to the interstitial fluid

Question 21

what happens at the venous end of the capillary

Answer 21

fluid is drawn back into the capillary by osmotic pressure

Question 22

what is the equation used when calculating blood flow

Answer 22

flow= driving forced/resistance

Question 23

what three major factors does resistance depend on

Answer 23

1. radius of the tube/blood vessel
2. viscosity of the blood
3. length of the tube/blood vessel

Question 24

describe how vessel radius effects blood flow

Answer 24

• vessel radius normally regulated by smooth muscle contraction
• smaller radius= less flow

Question 25

describe how blood viscosity effects blood flow

Answer 25

increased viscosity= increased friction= increased resistance= decreased blood flow