Lesson 4 - Blood circulation

Question 1

meaning arteries

Answer 1

vessels that carry blood away from the heart towards the cells of the body

Question 2

meaning veins

Answer 2

vessels that carry blood towards the heart from the cells of the body

Question 3

meaning capillaries

Answer 3

small vessels that spread throughout the tissues of the body and deliver blood to individual cells. The capillary network links the arterioles and the venules

Question 4

meaning lumen

Answer 4

the central space inside the blood vessel

Question 5

meaning arterioles

Answer 5

small branches of the arterial system, furthest from the heart

Question 6

meaning peripheral arteries

Answer 6

arteries further away from the heart but before the arterioles

Question 7

meaning venules

Answer 7

small branches of the venous system, furthest from the heart

Question 8

meaning inferior vena cava

Answer 8

the vein that carries the returning blood from the lower parts of the body to the heart

Question 9

meaning superior vena cava

Answer 9

the vein that carries the returning blood from the upper parts of the body to the heart

Question 10

meaning semilunar valves

Answer 10

half moon-shaped one-way valves found at frequent intervals throughout the venous system to prevent the backflow of blood

Question 11

all arteries carry oxygenated blood, except for:

Answer 11

• pulmonary artery
• umbilical artery

Question 12

function of pulmonary artery

Answer 12

carries deoxygenated blood from the heart to the lungs

Question 13

function umbilical artery

Answer 13

during pregnancy, it carries deoxygenated blood from the fetus to the placenta

Question 14

describe the structure of the arteries

Answer 14

• external layer of tough tissue
• small lumen
• contain middle layer of elastic fibres and smooth muscle
• contain smooth lining

Question 15

function of elastic fibres in arteries

Answer 15

elastic fibres stretch to accommodate great volumes of water pushing through under high pressure, without bursting

Question 16

how do the elastic fibres in arteries help to push blood through

Answer 16

the elastic fibres stretch and relax during each surge, to squeeze the blood and move it along in a continuous flow

Question 17

how do the peripheral arteries control the amount of blood that flows into an organ

Answer 17

the muscle fibres of the vessel walls of the peripheral arteries contract and relax to change the size of the lumen. This controls the blood flow as a smaller lumen means it so harder for blood to get through

Question 18

what happens to the size of the elastic fibres layer of the artery the further away from the heart

Answer 18

decreases

Question 19

what happens to the size of the collagen fibres layer of the artery the further away from the heart

Answer 19

decreases

Question 20

what happens to the size of the lumen of the artery the further away from the heart

Answer 20

decreases

Question 21

state some adaptations the capillaries have for more efficient exchange

Answer 21

• no cell is far from a capillary
• as capillary of lumen is very small, blood travels slowly, so more opportunity for diffusion to occur
• ## no walls (one cell thick), so small diffusion distance

Question 22

all veins carry deoxygenated blood, except for:

Answer 22

• pulmonary vein
• umbilical vein

Question 23

function pulmonary vein

Answer 23

carries oxygenated blood from lungs back to the heart to be circulated around the body

Question 24

function umbilical vein

Answer 24

during pregnancy, carries oxygenated blood from the placenta into the fetus

Question 25

describe the structure of veins

Answer 25

- smooth inner surface - thin layer of smooth muscle with few elastic fibres - large lumen - outer tough layer consisting of collagen fibres

Question 26

which 2 veins carry the returning blood to the heart

Answer 26

inferior vena cava & superior vena cava

Question 27

which 2 ways is deoxygenated blood carried back to the heart under low pressure

Answer 27

- semilunar valves throughout the venous system prevent backflow of blood, making sure blood only moves towards the heart - when muscles contract during physical activity, the veins in between the muscles gets squeezed, so blood is move up the veins.

Question 28

which vessel carries blood at the highest pressure

Answer 28

arteries

Question 29

which vessel carries blood at the lowest pressure

Answer 29

veins

Question 30

which vessel carries blood has the highest surface area

Answer 30

capillaries

Question 31

which vessels carries blood has the lowest surface area

Answer 31

arteries & veins

Question 32

which vessel has the highest velocity

Answer 32

arteries

Question 33

which vessel has the lowest velocity

Answer 33

capillaries