Cardiovascular system Flashcards
(102 cards)
1
Q
What does myogenic mean?
A
The ability of the heart to generate its own electrical impulses.
2
Q
What is the Sinoatrial Node?
A
A small mass of cardiac tissue found in the wall of the right atrium that generates the heart beat, by sending out electrical impulses.
3
Q
What is the Atrioventricular Node?
A
This node relays the impulse between the upper and lower chambers of the heart.
It delays the impulse here for 0.1s to enable the atria to fully contract before ventricular systole begins.
4
Q
What is the Bundle of His?
A
A collection of heart muscle cells that transmit electrical impulses from the AV node via the bundle branches to the ventricles.
5
Q
What are the Purkinje fibres?
A
Muscle fibres that conduct impulses in the walls of the ventricles.
6
Q
What is systole?
A
The heart’s contraction phase where blood is forced out the chambers.
7
Q
What is diastole?
A
The heart’s relaxation phase where the chambers fill with blood.
8
Q
What is cardiac output?
A
The volume of blood pumped out of the ventricles per minute.
9
Q
What is heart rate?
A
The number of times the heart beats per minute.
On average it’s 72bpm.
10
Q
What is stroke volume?
A
The volume of blood pumped out of the ventricles per contraction.
On average, 70ml at rest.
11
Q
What is the sympathetic nervous system?
A
A part of the autonomous nervous system that increases heart rate.
12
Q
What is the parasympathetic nervous system?
A
A part of the autonomic nervous system that decreases heart rate.
13
Q
What is cardiac hypertrophy?
A
The thickening of the muscular wall of the heart so it becomes bigger and stronger, it can also mean a larger ventricular cavity.
14
Q
What is bradycardia?
A
A decrease in resting heart rate below 60bpm.
15
Q
What is the medulla oblongata?
A
The part of the brain that regulates processes that keep us alive such as breathing and heart rate.
16
Q
What is myocardium?
A
The muscular wall of the heart.
17
Q
What is the septum?
A
The thick muscular wall that separates the left and right side of the heart.
18
Q
What are chemoreceptors?
A
Tiny structures in the carotid arteries and aortic arch that detect changes in blood acidity caused by an increase or decrease in carbon dioxide concentration.
19
Q
What are baroreceptors?
A
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.
20
Q
What are proprioceptors?
A
Sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement.
21
Q
What is adrenaline?
A
A stress hormone released by the sympathetic nerves and cardiac nerve during exercise.
22
Q
What does adrenaline do?
A
It increases heart rate by stimulating the Sinoatrial node.
23
Q
What is venous return?
A
The return of blood to the right side of the heart via the vena cava.
24
Q
What is ejection fraction?
A
The percentage of blood pumped out of the left ventricle per beat.
25
What is blood pressure?
The force exerted by the blood against the blood vessel wall.
Blood flow x resistance.
26
What is systolic pressure?
The pressure in the arteries when the ventricles are contracting.
27
What is diastolic pressure?
The pressure in the arteries when the ventricles are relaxing.
(Resistance to blood flow)
28
Why are the atria and ventricles different sizes?
The atria are smaller as they only push the blood down into the ventricles.
This requires little force so the walls are thinner.
The ventricles have thick muscular walls as they need to contract with force to push the blood out of the heart.
29
Why is the left side of the heart bigger than the right?
It needs to pump blood all around the body whereas the right side pumps blood to lungs, which are in close proximity.
30
What are the valves of the heart?
The tricuspid valve is located between the right atrium and the right ventricle.
The bicuspid valve is between the left atrium and left ventricle.
The semi-lunar valves are found between the right and left ventricles and the pulmonary artery and aorta.
31
What are valves?
They regulate blood flow by ensuring it moves in only one direction.
They open to allow blood through and then close to prevent backflow.
32
How does the cardiac conduction system work?
The SA node initiates the electrical impulse.
The signal spreads through the heart as a wave of excitation.
It spreads through the walls of the atria, causing them to contract, and forcing blood into the ventricles.
The impulse passes through the AV node.
The impulse is delayed for 0.1 seconds to allow the atria to fully contract before ventricular systole.
The impulse passes through the Bundle of His.
This branches into two bundle branches then into smaller bundles called purkinje fibres.
These spread throughout the walls of the ventricles, causing them to contract.
33
What is pulmonary circulation?
Deoxygenated blood from the heart via the pulmonary artery to the lungs, and oxygenated blood back to the heart via the pulmonary vein.
34
What is sytemic circulation?
Oxygenated blood to the body via the aorta, and then the return of deoxygenated blood back to the heart via the vena cava.
35
What is the function of the cardiovascular system?
To deliver oxygen to the working muscles.
| To remove waste products.
36
What is the pathway of blood?
Aorta - body - inferior/superior vena cava - right atrium - tricuspid valve - right ventricle - semi-lunar valve - pulmonary artery - lungs - pulmonary vein - left atrium - bicuspid valve - left ventricle - semi-lunar valve.
37
What is the cardiac control centre?
The part of the brain which controls the heart and respiratory rate.
It is found in the medulla oblongata.
38
What is the nervous system made up of?
The central nervous system, which consists of the brain and spinal cord.
The peripheral nervous system, which consists of nerve cells that transmit information to and from the CNS.
39
How does the neural control mechanism work?
When chemoreceptors, proprioceptors and baroreceptors stimulate the sympathetic nervous system, heart rate increases.
When they stimulate the parasympathetic system, heart rate decreases.
40
What is the hormonal control mechanism?
The release of adrenaline during exercise stimulates the SAN, which increases the speed and force of contraction, and therefore cardiac output.
This means more blood is pumped to the working muscles and recieve more oxygen.
41
What is the equation for cardiac output?
Heart rate x stroke volume.
42
What factors affect stroke volume?
Venous return
| Elasticity of cardiac fibres.
43
How does venous return affect stroke volume?
This is the volume of blood returning to the right side of the heart via the vena cava.
If this increases, stroke volume also increases (Starling's law).
44
How does elasticity of cardiac fibres affect stroke volume?
This is concerned with the degree of stretch of cardiac tissue during diastole.
The more stretch, the greater the force of contraction.
Greater force of contraction can increase ejection fraction - Starling's Law.
45
What is Starling's law?
Increased venous return - greater diastolic filling of the heart - cardiac muscle stretched - greater force of contraction - increased ejection fraction.
46
What is maximum heart rate?
220 - age.
| Heart rate will increase in direct proportion to exercise intensity until the maximum heart rate.
47
What is the heart rate in an untrained performer vs trained?
Trained: has a lower resting and a higher maximum heart rate.
Their heart rate range is higher.
48
What does heart rate do in maximal and sub-maximal exercise?
Both:
Anticipatory rise
Sharp rise mainly due to anaerobic work.
(Maximal only) Heart rate continues to rise due to maximal workloads stressing the anaerobic systems.
(Submaximal only) Steady state as the athlete is able to meet the oxygen demand with the oxygen supply.
Both: Rapid decline in heart rate as soon as exercise stops.
Slower recovery as body systems return to resting levels.
Heart rate needs to remain elevated to rid the body of waste products.
49
What are stroke volume, heart rate and cardiac output values?
During exercise, in untrained person: 120ml x 202bpm = 24.24L
Trained person: 170ml x 202 = 34.34L.
At rest, untrained person: 70ml x 72 = 5.04L
Trained person: 84ml x 60 = 5.04L.
50
How does stroke volume respond to exercise?
Stroke volume increases as exercise intensity increases.
But only up to 40-60% of maximum effort.
After this, stroke volume plateaus.
The ventricles do not have as much time to fill with blood, so can not pump as much out.
51
What is heart disease?
It occurs when the coronary arteries become blocked or start to narrow by build-up of fatty deposits (athereroma).
This is called atheroscolerosis.
52
What causes heart disease?
High blood pressure
High cholesterol levels
Lack of exercise
Smoking
53
What effect does heart disease have on the body?
As the coronary arteries narrow they are unable to deliver enough oxygen to the heart, causing pain and discomfort - angina.
If a piece of artheroma breaks off in the coronary arteries it can cause a blood clot which forms a blockage.
This can cut off oxygenated blood supply to the heart muscle, resulting in a heart attack.
54
How can heart disease be prevented?
Exercise keeps the heart healthy and more efficient.
It can pump more blood around the body as exercise causes hypertrophy, resulting in increased stroke volume.
Regular exercise also maintains the flexibility of blood vessels, ensuring good blood flow, normal blood pressure and low cholesterol levels.
55
What is high blood pressure?
Blood pressure is the force exerted by the blood against the blood vessel wall.
High blood pressure puts extra strain on the arteries and heart.
Considered to be > 140/90 mmHg, while normal bp is between 90/60 and 120/80.
56
What effect does high blood pressure have on the body?
It puts increased strain on the arteries and heart.
| Left untreated, it increases the risk of heart attack, heart failure, kidney disease, stroke or dementia.
57
How is high blood pressure prevented?
Regular aerobic exercise.
It lowers both systolic and diastolic pressure by up to 5-10 mmHg.
This reduces the risk of a heart attack by up to 20%.
58
What are Low Density Lipoproteins?
LDL transport cholesterol in the blood by the tissues and are classed as bad cholesterol as they are linked to increased risk of heart disease.
59
What are High Density Lipoproteins?
HDL transport excess cholesterol in the blood back to the liver where it is broken down.
It's 'good' cholesterol as it lowers the risk of heart disease.
60
What effect does cholesterol have on the body?
High cholesterol levels can increase the risk of heart disease and strokes, as it can build up in the arteries and block them.
61
What are strokes?
It occurs when the blood supply to part of the brain is cut off.
This causes damage to the brain cells so they start to die.
This can lead to brain injury, disability and sometimes death.
62
What are ischaemic strokes?
Most common, occur when a blood clot stops the blood supply.
63
What are haemorrhagic strokes?
Occur when a weakened blood vessel supplying blood to the brain bursts.
High blood pressure often weakens blood vessels.
64
How can strokes be prevented?
Regular exercise can help lower blood pressure and help maintain a healthy weight.
These can reduce the risk of a stroke by 27%.
65
What is cardiovascular drift?
A progressive decrease in stroke volume and arterial blood pressure, and a progressive rise in heart rate.
It occurs during prolonged exercise after 10 minutes, in a warm environment, despite the intensity of exercise remaining the same.
66
What is steady state?
When the athlete is able to meet the oxygen demand with the oxygen supply.
67
Why does cardiovascular drift occur?
When we sweat, a portion of the lost fluid comes from the plasma volume.
This decrease in plasma volume means the blood becomes more viscous and will reduce venous return and stroke volume.
Heart rate increases to compensate and maintain a higher cardiac output, to create more energy to cool the body down.
68
How can cardiovascular drift be minimised?
Maintaining high fluid consumption before and during exercise.
69
What does the vascular system consist of?
Heart - arteries - arterioles - capillaries - venules - veins - heart.
70
What are the characteristics of veins?
```
Carry mainly deoxygenated blood back to the heart.
Have valves.
Thin muscle and elastic tissue layers.
Wider lumen.
Carry blood at low pressure.
```
71
What are the characteristics of arteries?
Carry mainly oxygenated blood away from the heart.
Thicker muscle and elastic tissue (to cope with pressure fluctuations).
Blood flows under high pressure.
Smaller lumen.
Smooth inner layer.
72
What are the charateristics of capillaries?
One cell thick, only wide enough to allow one red blood cell through at a time.
Slow down blood flow.
Allow the exchange of nutrients and oxygen with the tissues to take place by diffusion.
73
What are blood pressure readings?
BP is measured at the brachial artery in the upper arm.
At rest, is typically 120/80 millimetres of mercury (mmHg).
It is mainly dependent on the distance of the blood vessel from the heart.
74
How is venous return affected by exercise?
At rest, up to 70% of the total volume of blood is contained in the veins.
This means that a large amount of blood can be returned to the heart when needed.
During exercise, venous return increases, which increases stroke volume.
75
Why are there venous return mechanisms?
The pressure of the blood in the large veins is very low which makes it difficult to return blood to the heart.
The large lumen of the vein offers little resistance to blood flow.
76
What are the venous return mechanisms?
The skeletal muscle pump
The respiratory pump
Pocket valves
77
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, squeezing blood towards the heart.
78
What is the respiratory pump?
When muscles contract and relax during breathing in and out, pressure changes occur in the thoracic and abdominal cavities.
These changes compress the nearby veins and assist in blood return to the heart.
79
What are pocket valves?
Valves ensure blood only flows in the veins in one direction.
Once the blood has passed through the valves, they close to prevent the blood flowing back.
80
What factors aid in venous return?
A very thin layer of smooth muscle in the walls of the veins helps squeeze the blood back towards the heart.
Gravity helps the blood return to the heart from the upper body.
The suction pump action of the heart.
81
How does blood pressure impact venous return?
When systolic pressure increases, venous return increases.
| When systolic pressure decreases, venous return decreases.
82
What is plasma?
The fluid part of blood (mainly water) that surrounds blood cells and transports them and proteins.
83
What is haemoglobin?
An iron-containing pigment found in red blood cells, which combines with oxygen to form oxyhaemoglobin.
When fully saturated, haemoglobin will carry 4 oxygen molecules.
84
What is myoglobin?
An iron-containing muscle pigment in slow-twitch muscle fibres that has a higher affinity for oxygen than haemoglobin.
It stores the oxygen in the muscle fibres which can be used quickly when exercise begins.
85
How is oxygen transported?
During exercise, when oxygen diffuses into the capillaries, 3% dissolves into the plasma and 97% forms oxyhaemoglobin.
This occurs when the partial pressure of oxygen in the blood is high.
At the tissues, oxygen is released from oxyhaemoglobin due to the lower pressure of oxygen there - oxyhaemoglobin dissociation.
In the muscle, the myoglobin stores the oxygen for the mitochondria until used by the muscles.
86
How do baroreceptors work?
They contain nerve endings that respond to the stretching of the arterial wall caused by changes in blood pressure.
An increase above or decrease below the set point for blood pressure send signals to the medulla.
An increase in arterial pressure causes an increase in the stretch of the baroreceptor sensors and decreases heart rate, and vice versa.
87
How do baroreceptors change during exercise?
At the start of exercise, the baroreceptor set point increases, so heart rate does not slow down and negatively affect performance.
88
How does pressure gradient between the right atrium and the vena cava impact venous return?
Venous return is determined by pressure gradient.
Venous pressure - right atrial pressure divided by venous vascular resistance.
The blood pressure in both the right atrium and the peripheral veins is normally very low, so that the pressure driving venous return from the peripheral veins to the heart is also relatively low.
Small changes of blood pressure in the right atrium or peripheral veins can largely change the pressure gradient, and significantly affect venous return.
89
What is the oxyhaemoglobin dissociation curve?
The partial pressure of oxygen in the lungs is higher, haemoglobin is almost completely saturated with oxygen.
In the tissues, the partial pressure is lower, so haemoglobin gives up some of its oxygen to the tissues - up to 23%.
90
What is the Bohr shift?
During exercise, the curve shifts to the right because when the muscles require more oxygen, the dissociation of oxygen from haemoglobin in the blood capillaries to the muscle tissue occurs more readily.
91
Which factors are responsible for the Bohr shift?
Increase in blood temperature - when blood and muscle temperature increase during exercise, oxygen dissociates from haemoglobin more readily.
Partial pressure of carbon dioxide increases, causing oxygen to dissociate faster.
pH - more carbon dioxide will lower the pH in blood, causing oxygen to dissociate quicker.
92
What is the vascular shunt mechanism?
The redistibution of blood flow to areas where it is most needed /cardiac output.
During exercise, the skeletal muscles need more oxygen.
93
What is vasodilation?
The widening of blood vessels to increase the flow of blood into the capillaries.
94
What is vasoconstriction?
The narrowing of the blood vessels to reduce blood flow to the capillaries.
95
Why is redistribution of blood important?
Used to increase the supply of oxygen to the working muscles.
Remove waste products from the muscles, such as carbon dioxide and lactic acid.
Ensure more blood goes to the skin during exercise to regulate body temperature and get rid of heat through radiation, evaporation and sweating.
Directs more blood to the heart as it is a muscle and requires extra oxygen during exercise.
96
What are the measurements of cardiac output to places during vigorous exercise and rest?
Skeletal muscle: 80-85% vs 15-20%.
| Vital organs: 15-20%, mainly the brain vs 80-85%.
97
Why is it important to not eat before competition?
Sports performers should not eat less than an hour before a competition as a full gut would result in more blood being directed to the stomach instead of the working muscles.
This would have a negative effect on performance as less oxygen is being made available.
Blood flow to the brain must remain constant to ensure brain function.
98
How does redistribution of blood flow occur?
The vasomotor centre, in the medulla oblongata of the brain, controls blood flow and pressure.
When chemoreceptors detect chemical changes, they stimulate the vasomotor centre, which redistributes blood through vasodilation and vasoconstriction.
During exercise, vasodilation will occur in the arterioles supplying the working muscles, increasing blood flow and oxygen supply.
99
How does redistribution of blood occur by the sympathetic nerves?
When stimulation of the sympathetic nerves located in the blood vessel walls increases, vasoconstriction occurs and blood flow reduces so it can be redistributed to the other parts of the body such as the muscles.
When stimulation by the sympathetic nerves decreases, vasodilation occurs and increases blood flow to that part.
100
What are pre-capillary sphincters?
They are tiny rings of muscle located at the opening of capillaries.
When they contract, blood flow is restricted though the capillary and when they relax, blood flow is increased.
During exercise, the capillary networks supplying skeletal muscle will have relaxed pre-capillary sphincters to increase blood flow and therefore saturate the tissues with oxygen.
101
What is arterio-venous difference?
A-VO2 difference.
The difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles.
102
How does A-VO2 difference change during exercise?
At rest, it is low as not much oxygen is required by the muscles.
But during exercise, more oxygen is needed from the blood for the muscles so the difference is high.
This increase will affect gaseous exchange at the alveoli so more oxygen is taken in and more carbon dioxide is removed.
Training also increases the arterio-venous difference as trained performers can extract greater amounts of oxygen from the blood.
