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A Level PE Miss Rex > The Cardiovascular System > Flashcards

The Cardiovascular System Flashcards

1
Q

Describe the chambers of the heart

A

The heart is divided into two parts by a muscular wall called the septum and each contains two chambers - atrium and ventricle
The atria are smaller than the ventricles as all they do is push the bloody down into the ventricles
The ventricles have thicker walls as they need to contract with greater force in order to push the blood out of the heart
The left side of the heart is larger as it pumps blood all around the body whereas the right side pumps deoxygenated blood to the lungs which are in close proximity to the heart

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2
Q

Describe the blood vessels to the heart

A

The vena cava brings deoxygenated blood back to the right atrium
The pulmonary vein delivers oxygenated blood to the left atrium
The pulmonary artery leaves the right ventricle with deoxygenated blood to go to the lungs
The aorta leaves the left ventricle with oxygenated blood to the rest of the body

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3
Q

Describe the valves of the heart

A

4 main valves in the heart that regulate blood flow by ensuring it moves in one direction. They open up to allow blood through but don’t allow it back
The tricuspid value is located between the right atrium and right ventricle
The bicuspid valve between the left atrium and right ventricle
The semi lunar valve can be found between the right and left ventricles and the pulmonary artery and aorta

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4
Q

What are the different valves in the heart ?

A

The tricuspid valve
The bicuspid valve
The semi lunar valve

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5
Q

Define myogenic

A

The capacity of the heart to generate its own impulses

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6
Q

Define sinoatrial node (SAN or SA node)

A

A small mass of cardiac muscle found in the wall of the right atrium that generates the heart beat. It is more commonly called a pacemaker

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7
Q

Define the atrioventricular node (AVN or AV node)

A

The node replays the impulse between the upper and lower sections of the heart

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8
Q

Define systole

A

When the heart contracts

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9
Q

Define the bundle of His

A

A collection of heart muscle cells that transmit electrical impulses from the AVN via the bundle branches to the ventricles

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10
Q

Define the purkinje fibres

A

Muscle fibres that conduct impulses in the walls of the ventricles

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11
Q

Describe the path of the heart muscle which causes it to contract

A

The electrical impulse starts at the sinoatrial node (SAN)
This impulse then spreads through the heart described as a wave of excitation (similar to a Mexican wave)
From the SAN the 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)
The AVN delays the transmission for 0.1 seconds to enable the atria to fully contract before ventricular systole begins
The impulse then passes down the bundle of His
The bundle of his branch out into smaller bundles called purkinje fibres which spread out throughout the ventricles causing them to contract

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12
Q

Memory tool to remember the path of an electrical impulses throughout the heart

A

S - SAN
A - Atrial systole
A - AVN
B - bundle of his
P - Purkinje fibres
V - ventricular systole

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13
Q

Define the sympathetic nervous system

A

A part of the automatic nervous system that speeds up HR

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14
Q

Define the parasympathetic nervous system

A

A part of the automatic nervous system that decreases heart rate

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15
Q

What are chemoreceptors ?

A

Tiny structures in the arteries that detect changes in blood acidity caused by an increase or decrease in the concentration of carbon dioxide
Chemoreceptors———-> increase in carbon dioxide ————-> increase in heart rate

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16
Q

What are baroreceptors ?

A

Special sensors in tissues and pulmonary vessels that respond to changes in blood pressure to either increase or decrease heart rate
Baroreceptors ———-> Increase in blood pressure ————-> decrease in heart rate

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17
Q

What are proprioceptors ?

A

Sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement
Proprioceptors——-> Increase in muscle movement —————-> Increase in heart rate

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18
Q

What is a hormonal control mechanism for controlling heart rate ?

A

Adrenaline is released by the sympathetic nervous system
It stimulates the SAN which results in an increase of both speed and force of contraction, thereby increasing cardiac output
This results in muscles receiving more blood and oxygen

19
Q

Define stroke volume

A

The volume of blood pumped out by the heart ventricles in each contraction

20
Q

What is venous return ?

A

The volume of blood returning to the heart via the veins. If venous return increases, then stroke volume will also increase

21
Q

What is cardiac output ?

A

The volume of blood pumped out by the heart ventricles per minute

22
Q

What is cardiac hypertrophy ?

A

The thickening of the muscular wall of the heart so it becomes bigger and stronger

23
Q

What is cardiovascular drift ?

A

During steady exercise our heart rate will slowly climb. Cardiovascular drift is a progressive decrease in stroke volume and blood pressure, together with a progressive rise in heart rate. It occurs during prolonged exercise (after 10 minutes) despite the intensity of the exercise staying the same. This occurs as when we sweat, a portion of this lost fluid comes from the plasma volume. This reduce in plasma volume reduces venous return. Heart rate increases in order to compensate for the lost venous return

24
Q

What is blood pressure ?

A

The force exerted by the blood against the blood vessel wall

25
Q

What is venous return ?

A

The return of blood to the right side of the heart via the vena cava

26
Q

What different mechanisms help for venous return ?

A

The skeletal muscle pump
The respiratory pump
Pocket valves
A very thin layer of smooth muscle in the walls of the veins helps squeeze blood back to the heart
The suction pump action of the heart

27
Q

What is the skeletal muscle pump ?

A

When muscles contract and relax they change shape. This change in shape means that the muscle press on nearby veins and cause a pumping effect and squeeze the blood back towards the heart

28
Q

What is the respiratory pump ?

A

When muscles contract and relax during breathing in and breathing out. The lungs push on nearby veins and assist blood back to the heart

29
Q

What are pocket valves ?

A

Force blood in one direction to prevent the back flow of blood

30
Q

What is the Bohr shift ?

A

During exercise, the S shaped diagram shifts to the right because when muscles require more oxygen, the dissociation of oxygen from haemoglobin in the blood capillaries to the muscle tissue occurs more readily

31
Q

What factors are responsible for the increase in the dissociation of oxygen from haemoglobin which results in more oxygen being available for the working muscles ?

A

Increase in blood temperature
Partial pressure of carbon dioxide increases
pH

32
Q

How does an increase in blood temperature result in more blood being available for working muscles

A

When blood and muscle temperature increases during exercise, oxygen will dissociate from haemoglobin more readily

33
Q

How does partial pressure of carbon dioxide increase result in more oxygen being available for working muscles ?

A

As the level of blood carbon dioxide rises during exercise, oxygen will dissociate faster from haemoglobin

34
Q

How does pH result in more blood being available for working muscles ?

A

More carbon dioxide will lower the pH in the blood. A drop in blood pH will cause oxygen to dissociate from haemoglobin more quickly

35
Q

What is vascular shunting ?

A

The redistribution of blood to more active areas of the body

36
Q

What is vasodilation ?

A

The widening of blood vessels to increase the flow of blood back to the capillaries

37
Q

What is vasoconstriction ?

A

The narrowing of the blood vessels to reduce blood flow into the capillaries

38
Q

Where is the tricuspid valve located ?

A

Between the right atrium and the right ventricle

39
Q

Where is the bicuspid valve located ?

A

Between the left atrium and the left ventricle

40
Q

Where is the semi-lunar valve located ?

A

Between the right and left ventricles and the pulmonary valve and aorta

41
Q

What is starlings law ?

A

Starling’s Law states that the greater venous return, the greater stroke volume is. As venous return increases the walls of the ventricles are stretched further. Results in a more powerful contraction. Increases the amount of blood pumped around the body during exercise

42
Q

What 3 factors can effect the Bohr shift ?

A

Increase in blood temperature - When blood and muscle temperature increases during exercise, oxygen will dissociate from haemoglobin more readily
Partial pressure of carbon dioxide - As the levels of blood carbon dioxide rises during exercise, oxygen will dissociate faster from haemoglobin
pH - more carbon dioxide will lower the pH levels in the blood. A drop in pH will cause oxygen to dissociate from haemoglobin more quickly

43
Q

What is A-V02 diff ?

A

A-V02 diff is the difference between the arterial blood arriving at the muscles and the venous blood leaving the muscles. It measures how much oxygen the muscles take from the blood. During exercise the muscles will require more blood and therefore there will be a higher A-V02 diff. Trained performance also have a higher A-V02 diff as their muscles are more efficient at taking oxygen

A Level PE Miss Rex (11 decks)

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