1.1: The Cardiovascular System Flashcards
1
Q
What is the cardiovascular system?
A
- the body’s transport systems
- it includes the heart and the blood vessels.
- during exercise, an efficient cardiovascular system is extremely important as the heart works to pump blood through the various blood vessels to deliver oxygen to the working muscles and gather waste products
- it’s also responsible for transporting heat (a by-product of exercise) to the skin so a performer can cool down
2
Q
What are the chambers of the heart?
A
- the heart is divided into two parts by a muscular wall called the septum and each part co rains two chambers - an atrium or a ventricle
- right atrium
- left atrium
- right ventricle
- left ventricle
3
Q
What are atria?
A
- are smaller than the ventricles as they push the blood down into the ventricles. This doesn’t require much force so they have thinner muscular walls.
4
Q
What are ventricles?
A
- the ventricles have much thicker muscular walls as they need to contract with greater force in order to push blood out of the heart.
5
Q
What are the blood vessels?
A
- vena cava: brings deoxygenated blood back to the right atrium
- pulmonary vein: delivers oxygenated blood to the left atrium
- pulmonary artery: the pulmonary artery leaves the right ventricle with deoxygenated blood
- aorta: leaves the left ventricle with oxygenated blood.
6
Q
What are the valves in the heart?
A
- four main valves in the heart that regulate blood flow by ensuring it moves in only one direction. They open to allow blood to pass through and then close to prevent back flow.
- tricuspid valve: located between the RA and RV
- bicuspid valve: located between the LA and LV
- *
7
Q
Key term - myogenic:
A
- the capacity of the heart to generate its own impulses
8
Q
Key term - sinoatrial node (SAN or SA node):
A
- a small mass of cardiac muscle found in the wall of the right atrium that generates the heartbeat. - It is more commonly called the pacemaker
9
Q
Key term - atrioventricular node (AVN or AV node):
A
- this node relays the impulse between the upper and lower sections of the heart.
10
Q
Key term - systole:
A
- when the heart contracts
11
Q
Key term - bundle of his:
A
- a collection of heart muscle cells that transmit electrical impulses from the AVN via the bundle branches to the ventricles.
12
Q
Key term - purkinje fibres:
A
- muscle fibres that conduct impulses in the walls of the ventricles.
13
Q
What is the Cardiac conduction system:
A
- the cardiac conduction system is a group of specialised cells located in the wall of the heart which send electrical impulses to the cardiac muscle, causing it to contract.
- when the heart beats, the blood needs to flow through it in a controlled manner, in through the atria and out through the ventricles.
14
Q
Cardiac conduction system:
A
- heart muscle is described as being myogenic as the brat starts in the heart muscle itself with an electrical signal in the sinoatrial node (SAN).
- this electrical impulse then spreads through the heart in east us often described as a wave of excitation.
- from the SAN the electrical impulse spreads through the walls of the atria, causing them to contract and forcing blood into the ventricles.
- the impulse then passes through the atrioventricular node (AVN) found in the atrioventricular septum. The AVN delays the transmission of the cardiac impulse for approximately 0.1 seconds to enable the atria to fill contract before ventricular systole begins.
- the electrical impulse then passes down through some specialised fibres which form the bundle of His. This is located in the septum separating the two ventricles.
- the bundle of His branches out to two bundle branches and then moves into smaller bundle called purkinje fibres which spear throughout the ventricles causing them to contract.
15
Q
Cardiac conduction system - method:
A
- SAN
- atrial systole
- AVN
- bundle of His
- purkinje systole
- ventricular systole
16
Q
What is the Autonomic nervous system (ANS)?
A
- involves the sympathetic and parasympathetic nervous system.
- the nervous system is made up of two parts;
- the central nervous system (CNS) - consists of the brain and spinal cord
- the peripheral nervous system - consists of nerve cells that transmit information to and from the CNS.
17
Q
Key term - sympathetic system:
A
- a part of the autonomic nervous system that speeds up heart rate.
18
Q
Key term - parasympathetic system:
A
- a part of the autonomic nervous system that decreases heart rate.
19
Q
What is the Cardiac Control Centre (CCC)?
A
- co-ordinates the CNS and peripheral nervous system and is located in the medulla oblongata - the most important part of the brain as it regulates processes that keep us alive such as breathing and heart rate.
- sympathetic nervous impulses are sent to the SAN and there is a decrease in parasympathetic nerve impulses so that heart rate increases.
- the cardiac control centre (CCC) is stimulated by chemoreceptors, baroreceptors and proprioceptors.
20
Q
What are chemoreceptors?
A
- tiny structures in the carotid arteries and the aortic arch and they sense chemical changes.
- during exercise, chemoreceptors detect an increase in carbon dioxide. The role of blood CO2 is important in controlling HR. An increased conc. of CO2 in the blood will have the effect of stimulating the sympathetic nervous system, which means the heart will beat faster.
21
Q
What are baroreceptors?
A
- they contain nerve endings that respond to the stretching of the arterial wall caused by changes in blood pressure, they establish a set point for bp. When the set point changes, signals are sent to the medulla.
- an increase in arterial pressure causes an increase in the stretch of the baroreceptor sensors and results in a decrease in heart rate.
- a decrease in arterial pressure causes a decrease in the stretch of the baroreceptor sensors and results in an increase in heart rate.
- at the start of exercise, the baroreceptor set point increases, which is important as the body does not want the heart rate to slow down as this would negatively affect performance, as less oxygen would be delivered to the working muscles.
22
Q
What are proprioceptors?
A
- sensory nerve endings located in muscles, tendons and joints that provide information about movement and body position.
- at the start of exercise, they detect an increase in muscle movement. These receptors then send an impulse to the medulla, which then sends an impulse through the sympathetic nervous system to the SAN to increase heart rate.
- when the parasympathetic nerve simulates the SAN, heart rate decreases.
23
Q
What is adrenaline?
A
- a stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise. It stimulates the SAN 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
24
Q
What is stroke volume?
A
- ‘the volume of blood pumped out by the heart ventricles in each contraction’
- during exercise, the need to transport more oxygen to the working muscles means the heart has to work harder.
25
Q
Factors that stroke volume depends on:
A
- venous return: this is the volume of blood returning to the heart via the veins. If VR increases, then stroke volume will also increase.
- the elasticity of cardiac fibres: this is concerned with the degree of stretch of cardiac tissue during the diastole phase (when the heart relaxes to fill with blood) of the cardiac cycle. 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 - the percentage of blood pumped out by the left ventricle per beat. This is Starling’s Law.
- the contractility of cardiac tissue: the greater the contractility of cardiac tissue, the greater the force of contraction. This results in an increase in stroke volume.
26
Q
Starling’s Law - simplified:
A
- increased venous return
- greater diastolic filling of the heart
- cardiac muscle stretched
- more force of contraction
- increased ejection fraction
27
Q
What is heart rate (HR)?
A
- the number of times the heart beats per minute.
- on average, the resting heart rate is approximately 72 beats per minute.
28
Q
What is cardiac output?
A
- ‘the volume of blood pumped out by the heart ventricles per minute’.
- cardiac output (Q) = stroke volume (SV) x heart rate (HR)
29
Q
Cardiac hypertrophy:
A
- the thickening of the muscular wall of the heart so it becomes bigger and stronger; also can mean a larger ventricular cavity.
- this will have an important effect on stroke volume, heart rage and therefore cardiac output.
- a bigger, stronger heart will allow blood to be pumped out per beat - this leads to a reduction in heart rate as it doesn’t have to best as often.
30
Q
Bradycardia?
A
- a decrease in resting heart rate to below 60 bpm.
- oxygen delivery to the muscles improves as there is less oxygen needed for contractions of the heart.
31
Q
What are the impacts of physical activity and sport on the health of the individual?
A
- heart disease
- high blood pressure
- cholesterol levels
- strokes
32
Q
Heart disease:
A
- coronary heart disease 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 (atheroma). High blood pressure, lack of exercise, high levels of cholesterol and smoking can all cause atherosclerosis.
- as the arteries become narrow they are unable to deliver enough oxygen to heart and pain and discomfort occurs - angina.
- if a fatty deposit breaks off in the coronary artery it can cause a blood clot which results in a blockage forming - this can cut off the supply of oxygenated blood to the heart muscle resulting in a heart attack.
