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Higher Human Biology (Revised 2021) > Unit 2: Physiology & Health - Key Area 5/6: The Structure and Function of Arteries, Capillaries and Veins/The Structure and Function of the Heart > Flashcards

Unit 2: Physiology & Health - Key Area 5/6: The Structure and Function of Arteries, Capillaries and Veins/The Structure and Function of the Heart Flashcards

1
Q

Where is the pathway of blood circulation in the heart?

A

Blood leaves the heart in arteries, then flows through capillaries before returning to the heart in veins.

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2
Q

In what condition is blood when it leaves the heart?

A

When blood leaves the heart it is under high pressure (having been pumped out of the heart).

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3
Q

What happens to blood pressure when it flows away from the heart and through the circulatory system?

A

As the blood flows away from the heart and through the circulatory system there is a decrease in blood pressure.

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4
Q

Where do arteries carry blood to?

A

Away from the heart, to the rest of the body.

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5
Q

What is the structure of an artery like?

A

Endothelium lines the central lumen and is surrounded by layers of tissue. Arteries have an outer layer of tissue containing elastic fibres and a middle layer containing smooth muscle with more elastic fibres.

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6
Q

What do the elastic fibres in arteries mean for the artery and what are they needed for?

A

The elastic fibres mean that arteries have elastic walls which can stretch and recoil to accommodate the surge of blood after each contraction of the heart.

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7
Q

What can the smooth muscle in arteries do and what does this cause?

A

The smooth muscle can contract causing vasoconstriction or relax causing vasodilation to control blood flow.

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8
Q

How do the the central lumen of arteries compare to that of veins and why is this?

A

Arteries have a narrower central lumen than veins due to the thicker layer of muscle in arteries.

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9
Q

What do arteries divide into?

A

Arteries divide into arterioles.

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10
Q

Do arteries contain valves?

A

No.

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11
Q

What do capillaries allow to happen?

A

Capillaries allow exchange of substances with diffusion through their very thin walls.

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12
Q

What do veins do?

A

Veins carry blood back to the heart.

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13
Q

What is the structure of a vein like?

A

Veins have an outer layer of tissue containing elastic fibres and a much thinner muscular wall than arteries. Their central lumen is wider than in arteries. Veins contain valves that prevent the backflow of blood.

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14
Q

What are the smaller vessels that come together to form veins called?

A

Venules

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15
Q

Where is the lumen in an artery and vein?

A

The very centre of the artery and vein.

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16
Q

Where is the endothelium in an artery and vein?

A

The endothelium is the layer that surrounds the central lumen in an artery and vein.

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17
Q

Where is the muscle tissue in an artery and vein?

A

The muscle tissue is the middle layer of the artery and vein that surrounds the endothelium and is in between the connective tissue and endothelium.

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18
Q

Where is the connective tissue in an artery and vein?

A

The connective tissue is the outer layer of a vein and artery.

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19
Q

What do valves in veins do?

A

Prevent the back flow of blood.

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20
Q

What is one of the major structural differences between veins and arteries?

A

Veins contain valves but arteries do not.

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21
Q

Why do arteries not need valves but veins do?

A

The blood flow is under so much pressure leaving the heart that it can only flow in one direction only. Whereas in veins the blood is under very low pressure, so to prevent the back flow of blood valves are needed in veins.

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22
Q

What is the difference in blood arriving at the arteriole end of a capillary bed compared to the blood in the capillaries?

A

Blood arriving at the arteriole end of a capillary bed is at a higher pressure than blood in the capillaries.

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23
Q

As the blood is at a higher pressure at the arteriole end of the capillary bed what happens to the blood?

A

The blood is forced into the narrow capillaries, it undergoes pressure filtration.

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24
Q

What happens when blood undergoes pressure filtration?

A

Much of the plasma (liquid part of the blood) is squeezed out through the thin walls - this liquid is called tissue fluid.

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25
What is the only difference between plasma and tissue fluid?
The only difference between plasma and tissue fluid is that plasma contains plasma proteins whereas tissue fluid does not.
26
Why does plasma contain plasma proteins but tissue fluid doesn’t?
The protein is too large to be filtered through the capillary walls.
27
What role does tissue fluid have?
Tissue fluid supplies respiring cells with glucose oxygen and other substances. Carbon dioxide and other metabolic waste diffuse out of the cells and into the tissue fluid to be excreted.
28
What happens to most of the tissue fluid?
It returns to the blood.
29
What happens to tissue fluid which does not return to the blood?
The fluid that does not return to the blood (excess tissue fluid) is absorbed by small lymphatic vessels and the fluid is now referred to as lymph.
30
What do the lymphatic vessels do with lymph?
The lymphatic vessels return the lymph to the circulatory system.
31
What is the inner lining of blood vessels called?
The endothelium.
32
Why do arteries need more elastic fibres than veins?
Arteries constrict and dilate more than veins, to accumulate surges of high blood pressure.
33
Describe vasoconstriction?
The artery wall contracts to make the size of the lumen smaller so less blood can flow through so blood pressure increases.
34
Describe vasodilation?
The artery muscle increases in size so that the size of the lumen increases and more blood can flow through.
35
What is the heart?
A muscular pump consisting of 4 chambers and various associated blood vessels.
36
Through what vein does deoxygenated blood arrive at the heart?
The vena cava.
37
Where does deoxygenated blood that has arrived at the heart from the vena cava go ?
The deoxygenated blood that has arrived at the heart through the vena cava moves into the right atrium and down into the right ventricle.
38
How does deoxygenated blood that is in the right ventricle get pumped out and where does this go?
When the heart contracts blood is pushed into the pulmonary artery which carries it to the lungs to be oxygenated.
39
Where does oxygenated blood from the lungs go and how is it then pumped out into the body?
From the lungs, oxygenated blood arrives at the heart in the pulmonary vein, passes into the left atrium, down into the left ventricle and is the pushed into the aorta (where it will travel round the body) when the heart contracts.
40
Where does blood from the vena cava go and what type of blood is this?
The blood that enters the vena cava is deoxygenated and will enter the right atrium.
41
Where does blood from the pulmonary vein go and what type of blood is this?
Blood that enters the pulmonary vein is oxygenated and will enter the left atrium.
42
On a diagram what side is the pulmonary vein on?
The far right hand side.
43
On a diagram what side is the pulmonary artery on?
On a diagram the pulmonary artery is left hand side of the middle of the heart.
44
On a diagram what side is the vena cava on?
The far left hand side.
45
On a diagram what side is the aorta on?
On a diagram the aorta is on the right hand side of the middle of the heart.
46
Where does blood from the pulmonary artery go and what type of blood is this?
The pulmonary artery takes deoxygenated blood to the lungs to be oxidised.
47
Where does blood from the aorta go and what type of blood is this?
Blood from the aorta is oxygenated and is pumped around the body.
48
Why is the left ventricle much thicker than the right ventricle?
The left side of the heart has to pump blood all the way around the body but the right side of the heart has to pump blood to the lungs only.
49
What does AV stand for in AV valves?
Atrioventricular
50
What does SL stand for in SL valves?
Semilunar
51
Where is the right atrioventricular (AV) valve?
Between the right atrium and right ventricle.
52
Where is the right semilunar (SL) valve?
Between the right ventricle and pulmonary artery.
53
Where is the left atrioventricular (AV) valve?
Between the left atrium and the left ventricle.
54
Where is the left semilunar (SL) valve?
Between the left ventricle and the aorta.
55
Why does the heart contain valves?
The heart contains valves to prevent the back flow of blood. Therefore the blood can only travel in one direction.
56
How much blood does the left and right ventricle pump?
The left and right ventricle pump the same volume of blood through the aorta and pulmonary artery.
57
What is the definition of heart beat?
The number of heart beats in one minute.
58
What is the definition of stroke volume?
The volume of blood pumped out by each ventricle during each contraction.
59
What is the definition of cardiac output?
The volume of blood pumped through each ventricle per minute.
60
What is the equation for cardiac output?
CO = HR x SV
61
What does the cardiac cycle refer to?
The cardiac cycle refers to the pattern of contraction and relaxation of the heart during one complete heartbeat.
62
What is contraction of the heart known as?
Systole
63
What is relaxation of the heart known as?
Diastole
64
What happens in diastole of the heart?
Both the atria and ventricles are relaxed. Blood returning to the atria flows into the ventricles. The AV valves are open and the SL valves are closed due to the higher pressure in the arteries.
65
What happens in atrial systole?
The atria contract and ventricles relax. The remainder of the blood in the atrium is transferred through the open AV valves to the ventricles. The SL valves are shut/closed.
66
What happens in ventricular systole?
The ventricles contract and the atria relax. This closes the AV valves and pumps the blood out through the open SL valves to the aorta and on to the body,and to the pulmonary artery and then onto the lungs.
67
What are responsible for the sounds heard with a stethoscope?
The opening and closing of the AV and SL valves are responsible for the heart sounds heard with a stethoscope.
68
What does the heart have that initiates each heartbeat?
A pacemaker.
69
What is the pacemaker in the heart and where is it located?
The pacemaker is the sino - atrial node (SAN) and is located in the upper wall of the right atrium.
70
How does the SAN work and what is this the basic principle of?
It starts electrical impulses which sets the rate at which the cardiac muscle cells contract. This is the principle that allows doctors to give the heart an electric shock to start in emergencies.
71
How does the SAN cause the heart to contract And what does this cause to happen?
The impulse from the SAN then spreads through the atria causing them to contract. This causes atrial systole.
72
What happens after the impulse from the SAN cause atrial systole and what does this cause?
The impulse then travels to the atrioventricular node (AVN) which passes it through a bundle of conducting fibres down the central wall of the heart and the up through the walls of the ventricles. This causes the ventricles to contract at the same time (ventricular systole).
73
During diastole what is happening to the AV and SL valves?
The AV valves are open and the SL valves are closed.
74
During atrial systole what is happening to the AV and SL valves?
The AV valves are open and the SL valves are closed.
75
During ventricular systole what is happening to the AV and SL valves?
The AV valves are closed and the SL valves are open.
76
The electrical impulses of the heart generate what and what does this mean can be done?
The electrical impulses of the heart generate currents that can be detected electrodiagram (ECG).
77
What does start/p wave of an ECG show?
Wave of excitation spreading over the atria from the SAN.
78
What does the middle/QRS complex of an ECG show?
Shows the wave of excitation passing through the ventricles.
79
What does the end/T wave of an ECG show?
The electrical recovery of the ventricles towards the end of ventricular systole.
80
What can an ECG show?
An ECG can show any problems with the heart’s rhythm, and the conduction of the heart beat through the hear, which may be affected by underlying heart diseases such as atrial flutter, ventricular fibrillation or ventricular tachycardia.
81
What does the medulla regulate and how does it do it?
The medulla regulates the rate of the SAN through the antagonistic action of the autonomic nervous system (ANS).
82
What two divisions is the autonomic nervous system made up of?
The sympathetic and parasympathetic division.
83
What do the sympathetic nerves release and what does this cause to happen?
The sympathetic nerves release noradrenaline which accelerate/increase the heart rate.
84
What do the parasympathetic nerves release and what does this cause to happen?
The parasympathetic nerves release acetylcholine which slow/decrease the heart rate.
85
What does contraction of the ventricles (ventricular systole) initially cause to happen?
Blood pressure to increase.
86
What does blood need to be to travel round the body and for pressure filtration?
The blood needs to be under pressure.
87
As the blood relaxes (diastole) what happens to blood pressure?
It decreases.
88
How does a blood pressure machine work?
In the measure of blood pressure an inflatable cuff first stops blood flow in the arm. The cuff then gradually deflates and the blood starts to flow again. The blood flow is detected by a pulse and this is referred to as systolic pressure. The blood eventually flows freely and is no longer detected as a pulse when diastolic pressure is reached.
89
When does blood pressure change in the aorta?
During the cardiac cycle.
90
What machine is used to measure blood pressure?
A sphygmomanometer.
91
What is the typical blood pressure reading for a young adult?
120/80 (120 over 80).
92
What is blood pressure measured in?
mmHg.
93
If a blood pressure reading was 120/80 what does this show?
During contraction of the ventricles blood pressure is 120mmHg. This is systolic pressure. During ventricular relaxation it drops to 80mmHg. This is diastolic pressure.
94
What is high blood pressure called?
Hypertension
95
What is hypertension a major risk factor for?
Many diseases including coronary heart disease.
96
What does ECG stand for?
Electrodiagram
97
What part of the brain regulates the rate of the SAN?
The medulla

Higher Human Biology (Revised 2021) (21 decks)

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