Disease Defences 6.2

Question 1

From where to where do arteries convey the blood at high pressure?

Answer 1

from the ventricles to the tissues of the body

Question 2

What do arteries have in their walls?

Answer 2

• muscle cells
• elastic fibers

Question 3

What do muscle cells and elastic fibers assist?

Answer 3

maintaining blood pressure btw pump cycles

Question 4

Where do blood flow in the finest stage?

Answer 4

trough tissues of the capillary

Question 5

What do capillaries do?

Answer 5

allow exchange of materials btw cells in the tissue and the blood

Question 6

What do veins do?

Answer 6

• collect blood at low pressure from the tissues of the body
• returns it to the atria of the heart

Question 7

What prevents backflow in veins?

Answer 7

Valves

Question 8

What type is the lung’s circulation?

Answer 8

separate

Question 9

Where is the heartbeat initiated?

Answer 9

in the sinoatrial node

Question 10

What does the sinoatrial node act as?

Answer 10

pacemaker

Question 11

How does the sinoatrial node send its signal?

Answer 11

through the walls of the atria -> walls of the ventricles

Question 12

How can the heart rate be reduced of increased?

Answer 12

through two nerves in the medulla of the brain

Question 13

What chemical increases heart rate?

Answer 13

Epinephrine

Question 14

Who discovered circulation?

Answer 14

William Harvey

Question 15

During the cardiac cycle…

Answer 15

pressure changes occur from the left atrium, left ventricle and aorta

Question 16

What is transported through the blood?

Answer 16

• oxygen
• nutrients
• antibodies
• hormons
• heat
• carbon dioxide
• urea

Question 17

Plasma

Answer 17

Dissolves or carries all other components of blood, nutrients, wastes

Question 18

Erythrocytes

Answer 18

Transport oxygen in haemoglobin molecules

Question 19

Leucocytes

Answer 19

Phagocytes - “eat up” pathogen and dead cells
Lymphocytes - B-cells and T-cells for the immune response

Question 20

Platelets

Answer 20

clotting of blood following damage to cells or erythrocytes

Question 21

arteries

Answer 21

• carry high pressure blood
• away from the heart -> tissue that need it

Question 22

capillaries

Answer 22

• very small
• blood moves slowly under low pressure for the exchange of substances.

Question 23

veins

Answer 23

• low pressure blood
• back to the heart
• valves that allow the blood to flow in the correct direction

Question 24

structure of arteries

Answer 24

• small lumen
• high blood pressure

Question 25

adaptations of arteries

Answer 25

- muscle contraction-> high blood pressure - elastic fiber stretch - thick muscular wall and fibrous outer layer

Question 26

structure of capillaries

Answer 26

- smallest blood vessels - adapted to the exchange of substances to and from the blood

Question 27

adaptations of capillaries

Answer 27

- basement membrane permeable - wall is one cell thick - contains pores

Question 28

structure of veins

Answer 28

- large lumen - low pressure

Question 29

adaptations of veins

Answer 29

- less muscle - walls are thinner - less elastic - valves required to prevent back-flow of blood

Question 30

double circulation

Answer 30

-deoxygenated blood -> right atrium ->right ventricle to the lungs - where CO2 is offloaded and O2 is picked up - it is now oxygenated blood, -> left atrium ->left ventricle of the body - O2 is used and CO2 is collected as a waste product - now its deoxygenated blood -> right atrium

Question 31

what is the beating of the heart due to?

Answer 31

myogenic muscle contraction

Question 32

what is the characteristic of muscle contraction in the heart?

Answer 32

it's not controlled externally

Question 33

what is the region of myocytes called?

Answer 33

sinoatrial node

Question 34

what is the OTHER region of myocytes called?

Answer 34

atrioventricular node

Question 35

myogenic initiation

Answer 35

the heart does not stop beating

Question 36

cardiac muscle is

Answer 36

indefatigable

Question 37

when exercising

Answer 37

- more co2 is present in the blood - it is detected by the chemoreceptors in the brain's medulla oblongada - speeding the heart rate

Question 38

when CO2 levels fall

Answer 38

the nerve (vagus) reduces heart rate

Question 39

adrenaline

Answer 39

epinephrine

Question 40

the cardiac cycle

Answer 40

DIASTOLE - atria and ventricles relaxed - blood flows into heart from veins - AV valves open - SL valves closed ATRIAL SYSTOLE - atria contract and ventricles relaxed - blood pushed into ventricles - AV valves open - SL valves closed VENTRICULAR SYSTOLE - atria relaxed and ventricles contract - blood pushed into arteries - AV valves closed - SL valves open

Question 41

Atherosclerosis

Answer 41

degenerative disease - areas of the artery wall become damaged

Question 42

What happens in atherosclerosis?

Answer 42

- macrophages release growth factors, encouraging growth of fibrous tissue - cholesterol builds up in damaged areas -> plaques and arteries lose their elasticity - as the build up grows the lumen narrows restricting blood flow - if blood clotting is triggered the blood cloths are known as CORONARY THROMBOSIS

Question 43

risk factors of coronary heart disease

Answer 43

Genetic Age Sex Smoking Diet Exercise Obesity Stress