The Cardiovascular System Flashcards
(114 cards)
1
Q
What is the cardiovascular system?
A
Its the body’s transport system. It includes the heart and the blood vessels.
2
Q
What are the functions of the cardiovascular system?
A
Carries oxygen + nutrients
Gets rid of carbon dioxide
Regulates body temperature
Protects the body
3
Q
What are the chambers of the heart?
A
It’s divided into two parts by a muscular wall called the septum and each part contains two chambers - an atrium and a ventricle.
4
Q
What do the atria do?
A
They’re smaller than the ventricles as all they do is push the blood down into the ventricles.
They have thinner muscular walls
5
Q
What do the ventricles do?
A
They have much thicker muscular walls as they need to contract with greater force in order to push blood out of the heart.
6
Q
What side of the heart is bigger?
A
The left, as it needs to pump blood all around the body.
Whereas the right pimps deoxygenated blood to the lungs which are in close proximity to the heart.
7
Q
What blood vessels are connected to the heart?
A
The vena cava
Pulmonary vein
Pulmonary artery
Aorta
8
Q
What does the vena cava do?
A
Brings deoxygenated blood back to the right atrium.
There’s the superior (top) and inferior (bottom)
9
Q
What does the pulmonary vein do?
A
From the lungs - Delivers oxygenated blood to the left atrium.
10
Q
What does the pulmonary artery do?
A
Leaves the right ventricle with deoxygenated blood to go to the lungs
11
Q
What does the aorta do?
A
Leaves the left ventricle with oxygenated blood leading to the body.
12
Q
How many valves are in the heart and what are they called?
A
There are 4 main valves
The tricuspid valve
The bicuspid valve
The semi-lunar valves - pulmonary and aortic
13
Q
Where is the tricuspid valve?
A
Between the right atrium and right ventricle.
14
Q
Where is the bicuspid valve?
A
Between the left atrium and left ventricle
15
Q
Where are the semi-lunar valves?
A
Between the right and left ventricles and the pulmonary artery and aorta.
16
Q
What is the cardiac conduction system?
A
A group of specialised cells located in the wall of the heart which send electrical impulses to the cardiac muscle, causing it to contract.
17
Q
What is the Sinoatrial node (SAN)?
A
A small mass of cardiac muscle found in the wall of the right atrium that generates the heartbeat.
Commonly known as the pacemaker.
18
Q
What does myogenic mean?
A
The capacity of the heart to generate its own impulses
19
Q
What is the atrioventricular node (AVN)?
A
Found in the atrioventricular septum.
It relays the impulse between the upper and lower sections of the heart.
20
Q
What is systole?
A
When the heart contracts.
21
Q
What is the bundle of His?
A
A collection of heart muscle cells that transmit electrical impulses from the AVN bias the bundle branches to the ventricles.
22
Q
What are Purkinje fibres?
A
Muscle fibres that conduct impulses in the walls of the ventricles.
23
Q
What’s the order that blood passes through the heart?
A
Vena cava Right atrium Tricuspid valve Right ventricle Pulmonary artery Lungs Pulmonary vein Left atrium Bicuspid valve Left ventricle Aorta Body
24
Q
What does the SAN do?
A
Regulates heart at 60-100 bpm
Generates the heartbeat using electrical impulses
Bachman’s branch carries them to the left atrium
Impulses cause atrial systole.
25
What does the AVN do?
Delays transmission of the cardiac impulse for approximately 0.1 seconds.
This enables the atria to fully contract before ventricular systole begins
Regulates heart at 40-60 bpm.
26
What does the bundle of His do?
The electrical impulse travels through these fibres
Located in the septum, separating the two ventricles
It branches out into two bundle branches called Purkinje fibres.
They go around the ventricles and cause them to contract
Regulates heart at 20-40 bpm
27
What does the conduction system ensure?
It ensures that heart rate increases during exercise to allow working muscles to receive more oxygen.
28
What factors affect the change in rate of the conduction system?
The rate in which cardiac impulses are fired can be controlled by 3 main mechanisms:
Neural control mechanism
Receptors
Hormonal control mechanisms
29
What is the neural control mechanism?
It involves the sympathetic nervous system and the parasympathetic system. The nervous system is made up of two parts: the central nervous system and the peripheral nervous system. These two systems are coordinated by the cardiac control centre located in the medulla oblongata of the brain.
Sympathetic nervous impulses are sent to the SAN and there is a decrease in parasympathetic never impulses so that the heart rate increases
30
What is the sympathetic nervous system?
A part of the autonomic nervous system that speeds up heart rate
31
What is the parasympathetic system?
A part of the autonomic nervous system that decrease heart rate.
32
What is the medulla oblongata?
It regulates processes that keep us alive such as breathing and heart rate.
33
What is the types of receptors involved with conduction system?
Chemoreceptors
Baroreceptors
Proprioceptors
34
What are chemoreceptors?
Tiny structures in the carotid arteries and aortic arch that detect a change in blood acidity cause by an increase or decrease in the concentration of carbon dioxide.
35
What do chemoreceptors do during exercise and how?
Detect an increase in carbon dioxide.
An increased concentration of carbon dioxide in the blood will have the effect of stimulating the sympathetic nervous system, which means the heart will beat faster.
36
What are baroreceptors?
Special sensors in tissues in the aortic arch, carotid sinus, heart and pulmonary vessels that respond to changes in blood pressure to either increase or decrease heart rate.
37
What do baroreceptors do during exercise and how?
At the start of exercise the baroreceptor set point increases, which is important as the body doesn’t want heart rate to slow down as this would negatively affect performance, as less oxygen would be delivered to the working muscles.
38
What do baroreceptors do?
They establish a set point for blood pressure.
An increase/decrease above/below this point results in baroreceptors sending signals to the medulla in the brain.
An increase in arterial pressure causes an increase in the stretch of the baroreceptor sensors and results in a decrease in heart rate.
39
What are proprioceptors?
Sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement.
40
What do proprioceptors do during exercise and how?
At the start of exercise, they detect an increase in muscle movement.
These receptors then send an impulse to the medulla, which sends an impulse through the sympathetic nervous system to the SAN to increase the heart rate.
When the parasympathetic system stimulates the SAN, heart rate decreases.
41
What’s the hormonal control mechanism?
Hormones can also have an effect on heart rate.
The release of adrenaline during exercise is known as hormonal control.
42
What is adrenaline?
A stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise which causes an increase in heart rate.
43
How does adrenaline effect heart rate?
Its stimulates the SAN (pacemaker) which results in an increase in both the speed and force of contraction, thereby increasing cardiac output.
This results in more blood being pumped to the working muscles so they can receive more oxygen for the energy they need.
44
What is stroke volume?
The volume of blood pumped out by the heart ventricles in each contraction.
Average resting stroke volume is approximately 70ml.
45
What does stroke volume depend on?
Venous return.
The elasticity of cardiac fibres.
The contractility of cardiac tissue (myocardium).
46
What is venous return?
This is the volume of blood returning to the heart via the veins.
47
What is meant by the elasticity of cardiac fibres?
This is concerned with the degree of stretch of cardiac tissue during the diastole phase of the cardiac cycle.
48
What is Starling’s law?
The more the cardiac fibres can stretch, the greater the force of contraction will be.
A greater force of contraction can increase the ejection fraction.
This is called starlings law.
49
What is the diastole phase?
When the heart relaxes to fill with blood.
50
What is the ejection fraction?
The percentage of blood pumped out by the left ventricle per beat.
51
How does the contractility of cardiac tissue affect stroke volume.
The greater the contractility of cardiac tissue, the greater the force of contraction. This results in an increase in stroke volume.
It is also highlighted by an increase in the ejection fraction.
52
What happens to stroke volume if venous return increases?
If venous return increases, then stroke volume will also increase.
(If more blood enters the heart, then more goes out).
53
What is heart rate?
The number of times the heart beats per minute.
54
What is cardiac output?
The volume of blood pumped out by the heart ventricles per minute.
55
What’s the equation of cardiac output?
Cardiac output (Q) = Stroke volume (SV) x Heart rate (HR).
56
What’s the heart rate range in response to exercise?
Heart rate increases with exercise but how much it increases is dependant on the intensity of the exercise.
Heart rate will increase in direct proportion to exercise intensity - the higher the intensity, the higher the heart rate.
Heart rate does eventually reach a maximum.
57
How do you calculate maximum heart rate?
Subtract your age from 220.
58
Why does a trained performer have a greater heart rate range?
Because their resting heart rate is lower and their maximum heart rate increases.
59
What’s cardiac hypertrophy?
The thickening of the muscular wall of the heart so it becomes bigger and stronger; also can mean a larger ventricular cavity.
60
What’s the effect of cardiac hypertrophy?
It will effect stroke volume, heart rate and therefore cardiac output.
A bigger, stronger heart will enable more blood to be pumped out per beat (i.e. stroke volume).
The end of diastolic volume of the ventricle increases. If the ventricle can contract with more force and thus push out more blood, the heart does not have to beat as often, so resting heart rate will decrease.
This is known as bradycardia.
61
What is bradycardia?
It’s a decrease in resting heart rate to below 60 beats per minute.
62
What happens when bradycardia occurs?
Oxygen delivery to the muscles improves as there is less oxygen needed fro contractions of the heart.
63
What happens to cardiac output in response to exercise?
During exercise there is a large increase in cardiac output due to an increase in heart rate and an increase in stroke volume.
It will increase and the intensity of exercise increases until maximum intensity is reached and then it plateaus.
64
What happens to stroke volume in response to exercise?
It increases as exercise intensity increases.
| This is only the case up to 40-60% of maximum effort. Once a performer reaches this point, it plateaus.
65
Why does stroke volume plateau when exercising?
The increased heart rate near maximum effort results in a shorter diastolic phase. Quite simply, the ventricles do not have as much time to fill up with blood, so they cannot pump as much out.
66
What is heart disease commonly known as?
Coronary heart disease or CHD.
| Its the leading cause of deaths both in the UK and around the world.
67
What is CHD?
It occurs when your coronary arteries, which supply the heart muscle with oxygenated blood, become blocked or start to narrow by a gradual build-up of fatty deposits called atheroma.
68
What is atherosclerosis?
Occurs when arteries harden and narrow as they become clogged up by fatty deposits.
69
What causes atherosclerosis?
High blood pressure, high levels of cholesterol, lack of exercise and smoking
70
What is atheroma?
A fatty deposit found in the inner lining of an artery.
71
What is angina?
Chest pain that occurs when the blood supply through the coronary arteries to the muscles of the heart is restricted.
72
What can cause a blood clot?
If a piece of fatty deposit (atheroma) breaks off in the coronary artery
73
What can a blood clot do?
Create a blockage.
| This can cut of the supply of oxygenated blood to the heart muscle resulting in a heart attack.
74
What is blood pressure?
Force exerted by the blood against the blood vessel wall.
75
Where does the pressure come from? (Blood pressure)
The heart as it pumps the blood around the body
76
What does high blood pressure do?
Puts extra strain on the arteries and heart and if left untreated increases the risk of heart attack, heart failure, kidney disease, stroke or dementia.
77
What can exercise do to blood pressure?
Regular aerobic exercise can reduce blood pressure.
It lowers both systolic and diastolic pressure by up to 10-15 mmHg which reduces the risk of a heart attack by up to 20%.
78
What are the two types of cholesterol?
Low density lipoproteins (LDL)
High density lipoproteins (HDL)
79
What is LDL?
Transport cholesterol in the blood to the tissue and are classed as ‘bad’ cholesterol since they are linked to an increased risk of heart disease
80
What is HDL?
Transport excess cholesterol in the blood back to the liver where it is broken down.
These are classed as ‘good’ cholesterol since they lower the risk of developing heart disease.
81
What can exercise do to cholesterol?
Regular physical activity can lower bad LDL cholesterol levels.
Also significantly increase good HDL cholesterol levels.
82
What is a stroke?
Occurs when the blood supply to the brain is cut off.
83
What can a stroke do?
Causes damage to the brain cells so they start to die. This can lead to brain injury, disability and sometimes death.
84
What are the two types of stroke?
Ischaemic strokes - most common and occur when a blood blot stops the blood supply.
Haemorrhagic stroke - occurs when a weakened blood vessel supplying the brain bursts
85
How can exercise help reduce strokes?
Lowers blood pressure and helps maintain healthy weight, which reduces risk by 27%
86
What is steady state?
Where the athlete is able to meet the oxygen demand with the oxygen supply.
87
What is cardiovascular drift?
Progressive decrease in stroke volume and arterial blood pressure, together with a progressive rise in heart rate.
88
When does cardiovascular drift occur?
During prolonged exercise (after 10 minutes) in a warm environment, despite the intensity of the exercise remaining the same.
89
Why does cardiovascular drift occur?
When we sweat, a portion of this lost fluid comes from plasma volume. This decrease in plasma volume will reduce venous return and stroke volume.
Heart rate increases to compensate and maintain a higher cardiac output in an attempt to create more energy to cool the body down.
90
How do you minimise cardiovascular drift?
Maintain high fluid consumption before and during exercise
91
What is the vascular system?
Made up of blood vessels that carry blood through the body.
92
What does the vascular system do?
The blood vessels deliver oxygen and nutrients to the body tissues and take away waste products such as carbon dioxide.
Together with the heart and lungs, the blood vessels ensure that muscles have an adequate supply of oxygen during exercise in order to cope with the increased demand for energy.
93
What are the types of circulation?
Pulmonary - deoxygenated blood from the heart to lung. Oxygenated back to the heart.
Systemic - oxygenated blood to body from heart. Deoxygenated return from body to heart.
94
What’s the order of the blood vessels around the body?
Heart = arteries - arterioles - capillaries - venules - veins = heart
95
What are the characteristics of the blood vessels?
Veins = thinner muscle/elastic tissue layers. Lower pressure, valves, and a wider lumen.
Arteries = highest pressure, more elastic layer to cope with fluctuations in pressure, smaller lumen and a smooth inner layer.
Capillaries = wide enough for 1 red blood cell. This slows down blood flow and allows for diffusion of nutrients
96
What is blood pressure?
Force exerted by the blood against the blood vessel wall
97
What is the equation for blood pressure?
Blood flow x resistance
98
What is systolic pressure?
The pressure in the arteries when the ventricles are contracting
99
What is diastolic pressure?
Pressure in the arteries when the ventricles are relaxing
100
What is venous return?
The return of blood to the right side of the heart via the vena cava.
101
What is the venous return at rest?
Up to 70% of the total volume of blood is contained in the veins at rest. This means that a large amount of blood can be returned to the heart when needed.
102
What happens to the venous return during exercise?
The amount of blood returning to the heart (venous return) increases.
103
What is Starlings Law?
If more blood is being pumped back to the heart, then more blood has to be pumped out, so stroke volume will increase.
104
Why are there venous return mechanisms?
The pressure of the blood in the large veins is very low and this makes it difficult to return blood to the heart. In addition, the large lumen of the vein offers little resistance to blood flow.
This means that active mechanisms are needed to help venous return.
105
What are the venous return mechanisms?
The skeletal muscle pump
The respiratory pump
Pocket valves
A very thin layer of smooth muscle in the walls of the veins. This helps squeeze blood back towards the heart.
Gravity helps the blood return to the heart from the upper body.
The suction pump action of the heart.
106
What is the skeletal muscle pump?
When muscles contract and relax they change shape. This change in shape means that the muscles press on the nearby veins and cause a pumping effect and squeeze the blood towards the heart.
107
What is the respiratory pump?
When muscles contract and relax during breathing in and breathing out, pressure changes occur in the thoracic (chest) and abdominal (stomach) cavities. These changes in pressure compress the nearby veins and assist blood return to the heart.
108
What are pocket valves?
It is important that blood in the veins only flows in one direction. The presence of valves ensures that this happens. This is because once the blood has passed through the valves, they close to prevent the blood flowing back.
109
Why is it important to maintain venous return during exercise?
To ensure the skeletal muscles are receiving enough oxygen to meet the demands of the activity.
110
How to the mechanisms work during exercise?
At rest, valves and the smooth muscle found in veins are sufficient enough to maintain venous return. However, this is not the case during exercise.
The demand for oxygen is greater and the heart is beating faster, so the vascular system has to help out too. Now the skeletal muscle pump and the respiratory pump are needed to ensure venous return is maintained.
111
How do we maintain the mechanisms?
During exercise, this is possible because our skeletal muscles are constantly contracting and our breathing is elevated.
Immediately after exercise, we still need to maintain these mechanisms. Performing an active cool-down will keep skeletal muscle pump and respiratory pump working, therefore preventing blood pooling.
112
What is the impact of blood pressure on venous return?
When systolic blood pressure increases, there is also an increase in venous return, and when systolic pressure decreases, there is a decrease in venous return.
113
What is the impact of a pressure gradient between the right atrium and the vena cava on venous return?
Venous return is determined by a pressure gradient.
114
What is the pressure gradient?
The pressure gradient is the mean systemic pressure minus the right atrial pressure, and resistance is the total peripheral vascular resistance.
