6.2 blood system

Question 1

what does blood comprise of? fill in

• ???
• RBC
• WBC
• platelets
• ions
• ???

Answer 1

plasma, plasma proteins

Question 2

the left side of the heart pumps [ox/deox] blood to ______

Answer 2

oxygenated, the body

Question 3

the right side of the heart pumps [ox/deox] blood to _______

Answer 3

deoxygenated, lungs

Question 4

which type of blood vessel transports blood at high pressure from the heart ventricles to body tissues and lungs?

Answer 4

arteries

Question 5

what are the structural features of arteries? (4)

Answer 5

1. narrow lumen
   
   • maintain high b.p.
2. thick wall w outer layer of collagen
   
   • withstand high pressure needed to pump blood to e rest of e body
3. inner layer of smooth muscle
   
   • for contraction/dilation to alter diameter of lumen and thus control local b.p.
4. elastic fibres
   
   • allow artery walls to stretch + recoil
   • maintains pressure + helps pump the blood

Question 6

what are the structural features of capillaries? (3)

Answer 6

1. 1-cell thick endothelium w permeable basement membrane only
   
   • quick exchange of materials
2. narrow
   
   • penetrate all parts of tissues to deliver blood close to the cells
3. large total cross-sectional area (of capillary bed)
   
   • slow blood flow allows time for exchange

Question 7

what are sinusodial capillaries?

Answer 7

capillaries w open spaces between cells

Question 8

what are capillaries with pores called?

Answer 8

fenestrated capillaries

Question 9

capillaries that limit permeability of large molecules are usually ___________capillaries

Answer 9

continuous

Question 10

veins function to…

Answer 10

collect blood from the tissues and transport it at low pressure to the atria of the heart

Question 11

what are the structural features of veins?

Answer 11

1. very wide lumen
   
   • maximise blood flow
2. thin wall containing less muscle and elastic fibres
   
   • as pressure is low
3. valves
   
   • prevent backflow of blood

Question 12

why would backflow of blood occur in veins?

Answer 12

venous pressure it too low to readily pump blood back to the heart against gravity

Question 13

what assists blood flow in veins? (short)

Answer 13

skeletal muscular activity

Question 14

identify the blood vessels

Answer 14

-

Question 15

what moves into tissues from the bloodstream?

Answer 15

• O2
• nutrients
• hormones

Question 16

what moves out of the tissues from the bloodstream?

Answer 16

• CO2
• nitrogenous waste
• hormones

Question 17

William Harvey discovered that…

Answer 17

the heart pumped blood around the body

Question 18

what are the advantages of double circulation? (2 short)

Answer 18

• ensures ox and deox blood do not mix
• lower b.p. in pulmonary circuit to facilitate gaseous exchange at the lungs
• higher b.p. for systemic circuit to pump blood throughout body

Question 19

label a diagram of a heart

Answer 19

-

Question 20

label a dissected heart

Answer 20

-

Question 21

the heart beat is initiated by the…

Answer 21

sinoatrial node

Question 22

what is the sinoatrial (SA) node and its function?

Answer 22

a group of specialised muscle cells which generate electric impulses to control the rate and timing at which cardiac muscle cell contract

Question 23

the SA node acts as a __________

Answer 23

pacemaker

Question 24

how does the SA node control the heartbeat?

Answer 24

they spontaneously produce an electrical impulse

Question 25

why is there a delay between the 'lub' and 'dub' heart sounds?

Answer 25

- SA node spontaneously produces an electrical impulse - impulse is first propagated through the wall of the atrias, causing atria to contract - AV node is stimulated by impulses and sends a signal across to the septum via Bundle of His and then Purkinje fibres - causes ventricular contraction - sequence of events allows delay between atrial and ventricular contraction - thus delay between 'lub' and 'dub' heart sounds

Question 26

why is a delay between atrial and ventricular contraction necessary?

Answer 26

to allow time for the ventricles to fill w blood

Question 27

what is the basal heart rate?

Answer 27

the heart rate when a person is at rest

Question 28

what determines the basal heart rate?

Answer 28

sinoatrial node

Question 29

what is a trigger that can cause changes in heart rate?

Answer 29

changes to conc of CO2 (changes in blood pH)

Question 30

the transmission of _________ and the release of _____ can cause changes in heart rate

Answer 30

nerves impulses, hormones

Question 31

what does 'autonomic' in autonomic nervous system (ANS) mean?

Answer 31

involuntary

Question 32

what are the two main pathways in the autonomic nervous system

Answer 32

parasympathetic and sympathetic

Question 33

what is the part of the brain that sends nerve impulses to cause changes in the heart rate?

Answer 33

medulla oblongata

Question 34

the two nerves that are help regulate the heart rate are...

Answer 34

parasympathetic nerve and sympathetic nerve

Question 35

the parasympathetic and sympathetic nerves release... (1 word)

Answer 35

neurotransmitters

Question 36

what neurotransmitter does the parasympathetic nerve release?

Answer 36

acetylcholine

Question 37

the sympathetic nerves releases the neurotransmitter __________

Answer 37

noradrenaline

Question 38

nerve impulses are sent down the _____________ pathway via the ________ nerve to cause a decrease in heart rate

Answer 38

parasympathetic, vagus nerve

Question 39

what nerve does the sympathetic pathway use to send nerve impulses?

Answer 39

cardiac sympathetic nerve

Question 40

parasympathetic and sympathetic pathways represent ______________ (relationship) control of the autonomic nervous system

Answer 40

antagonistic

Question 41

recap: what are hormones?

Answer 41

chemical messengers released into the bloodstream that act specifically on distant target sites

Question 42

what hormone is released to increase heart rate?

Answer 42

adrenaline

Question 43

what is another name for adrenaline?

Answer 43

epinephrine

Question 44

from where is adrenaline released?

Answer 44

from the adrenal glands

Question 45

how does adrenaline affect the heart during fight-or-flight response? (1, short)

Answer 45

- incr heart rate by incr force of contraction in preparation for vigorous physical activity

Question 46

what happens to the heart during a fight-or-flight response? (5)

Answer 46

1. nerve response - the medulla oblongata sends nerve impulses down the sympathetic pathway via cardiac sympathetic nerve - nerve releases neurotransmitter noradrenaline - causes SA node to speed up heart rate + incr force of contraction 2. hormone response - adrenaline is released by adrenal glands - causes SA node to incr heart rate - this incr the transport of O2 and glucose for vigorous physical activity

Question 47

what does systole mean? hint: *s*ustain

Answer 47

contraction

Question 48

what does diastole mean? hint: *d*ilate

Answer 48

relaxation

Question 49

briefly name the events of the cardiac cycle

Answer 49

atrial systole -> ventricular systole/atrial diastole -> ventricular diastole

Question 50

what happens during ventricular systole/atrial diastole? (6)

Answer 50

1. ventricular systole: - ventricles contract, incr b.p. within - this forces AV valves to close -> prevent backflow of blood -> 'lub' - forces semilunar valves in pulmonary artery and aorta to open - blood flows to the lungs + rest of e body respectively 2. atrial diastole: - atria relax - atria is refilled by ox and deox blood from pulmonary veins and vena cava respectively

Question 51

what happens during ventricular diastole? (4)

Answer 51

- ventricles relax -> reduces pressure within - semilunar valves close -> prevent backflow of blood into ventricles -> 'dub' - when pressure in ventricles drops to a lvl lower than atrial pressure, AV valves open - blood passes passively into ventricles

Question 52

what happens during atrial systole? (3)

Answer 52

- atria contracts - remaining blood is pumped into ventricles - ventricles filled w blood

Question 53

what causes the 'lub' sound?

Answer 53

closing of AV valves

Question 54

what causes the 'dub' sound?

Answer 54

closing of semilunar valves

Question 55

what is the hardening and narrowing of the arteries due to cholesterol deposits called?

Answer 55

atherosclerosis

Question 56

how can atherosclerosis lead to a heart attack? (6)

Answer 56

1. atheromas develop in arteries -> significantly reduce diameter of e lumen 2. restricted blood flow -> incr pressure -> damage to arterial wall fr shear stress 3. damaged region is repaired w fibrous tissue -> significantly reduces elasticity of vessel wall 4. smooth lining of artery is progressively degraded -> atherosclerotic plaques form 5. if plaque ruptures -> blood clotting triggered -> forms a thrombus 6. thrombus occludes coronary artery -> O2 and glucose cannot be transported to heart muscle cells -> heart attack