PE - Cardiovascular System

What side of the heart is oxygenated?

Left side

What side of the heart is deoxygenated?

Right side

Where does the pulmonary vein carry blood to and from?

To the left atrium

From the lungs

Where does the aorta carry blood to and from?

To the body

From the left ventricle

Where does the vena cava carry blood to and from?

To the right atrium

From the body

Where does the pulmonary artery carry blood to and from?

To the lungs

From the right ventricle

Where is the cardiac muscle located?

The left ventricle

What is the septum?

The muscular wall that divides the heart into its left and right sides

What is the apex of the heart?

The blunt, pointed tip of the heart, formed by the left ventricle (bottom of the heart)

What are the 2 main valves in the heart?

Tricuspid valve

Bicuspid valve

Where is the sino-atrial node?

In the top part of the right atrium

What is the role of the sino-atrial node?

Acts as the heart's natural pacemaker, sending electrical impulses to the atria, causing it to contract (atrial systole)

Where is the atrioventricular node located?

in the lower part of the right atrium, near the septum

What is the role of the atrioventricular node?

Acts as the electrical gatekeeper between the atria and ventricles, and delays the electrical impulses from the SA node to allow the heart to fill with blood before it contracts.

What is the role of the purkinje fibres?

To make the ventricles contract

Where is the bundle of his located?

In between the left and right ventricles

What is the role of the bundle of his?

To transmit the electrical impulse from the atrioventricular (AV) node to the ventricles, enabling them to contract

What is the definition of heart rate?

The number of times the heart beats per minute (bpm)

What is the definition of stroke volume?

The amount of blood ejected from the heart per beat (ml)

What is the definition of cardiac output?

The amount of blood ejected from the heart per minute (l/min)

What’s the equation for cardiac output?

Heart rate (HR) x Stroke volume (SV) = Cardiac output (Q)

What’s the definition of cardiac hypertrophy?

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

What is the definition of bradycardia?

A decrease in resting heart rate to below 60bpm

What is venous return?

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

What is Starling’s Law of the heart?

Stroke volume can only increase is venous return increases

What are the stages of Starling’s Law of the heart?

1) Stroke volume increases due to the increased volume of blood filling the ventricles of the heart before contraction

2) This results in an increased number of cardiac fibres

3) This results in increased force of contraction

4) This process synchronizes with venous return

What is diastole?

The period when the ventricles and atria are relaxed, allowing blood to flow into them

What are the stages of diastole?

1) The atria relax, allowing blood to flow into them. The atrioventricular valves are shut at this point which prevents blood flow into the ventricles

2) As the pressure builds in the atria the atriovemtricular valves open and blood flows into the relaxed ventricles. However, it does not flow into the aorta or pulmonary artery die to the semilunar valves

What is systole?

The period when the ventricles and atria are contracting, allowing blood to flow out of the heart

What are the stages of systole?

1) The atria contract, allowing any remaining blood to flow into the ventricles

2) The ventricles contract which raises the blood pressure and forces open the semilunar valves. This allows blood to be forced out of the aorta (to the body) and the pulmonary artery (to the lungs)

What does SAABPV stand for?

Conduction System

S - SAN (sino-atrial node)

A - Atrial systole

A - AVN (atrioventricular node)

B - Bundle of His

P - Purkinje fibres

V - Ventricular systole

What are the stages of the conduction system?

1) The SA node sends an electrical impulse across the atria which stimulates them to contract

2) The impulse arrives at the AV node, where it is delayed, allowing the centricles to fully fill with blood

3) The impulse travels down the bundle of his, located in the septum

4) The impulse travels along the purkinje fibres which branch along the base of the right and left ventricles and cause the ventricles to contract.

What is the role of haemoglobin in the transportation of oxygen?

Haemoglobin carries oxygen to make oxyhaemoglobin. This is transported in the blood to the muscle tissues, where oxygen is released as a result of a high concentration gradient. (high to low)

What is the role of myoglobin in the transportation of oxygen?

Myoglobin stores oxygen within the muscle tissue and does this until the oxygen needs to be used up

What are the 3 health benefits of sport?

1) Prevents heart disease

2) Reduces high cholesterol

3) Prevents a stroke

How does sport prevent heart disease?

Sport improves blood circulation and reduces high blood pressure

How does sport reduce high cholesterol?

Sport reduces weight, which reduces the amount of low density lipoproteins (LDL), e.g. bad cholesterol in the blood. (HDL are the good cholesterol). Exercise increases HDL

How does sport prevent a stroke (caused by the shut-off of oxygen to the brain)?

Sport reduces high blood pressure and promoting weight loss, which in turn promotes blood circulation to the brain.

What is the definition of atherosclerosis?

What occurs when arteries harden and narrow as they become clogged up by fatty deposits

What is the definition of atheroma?

A fatty deposit found in the inner lining of the artery

What is the definition of angina?

Chest pain that occurs when the blood supply through the coronary arteries to the muscle of the heart is restricted

What is the definition of ischaemic stroke?

The most common type of stroke and occur when a blood clot stops the blood supply to the brain

What is the definition of haemorrhagic stroke?

What occurs when a weakened blood vessel supplying the brain bursts

What are the 2 main fitness benefits of sport?

• Higher cardiac output

• Improved components of fitnes

How does sport cause higher cardiac output?

The heart becomes stronger (from cardiac hypertrophy) and more efficient, therefore the heart is able to pump more blood per beat (increased stroke volume), meaning it needs to beat less to deliver oxygen, resulting in a lower resting heart rate. This in turn leads to an increased cardiac output (HR x SV = Q)

What are the 3 neural factors of the regulation of the heart?

The cardiac control centre (in the medulla oblongata) is informed by:

• Baroreceptors - respond to blood pressure

• Proprioceptors - respond to muscle activity/movement

• Chemoreceptors - respond to increased levels of CO2 in the blood

How does the cardiac control centre increase heart rate?

1. Detects a change from one of the 3 receptors

2. Sends electrical impulses through the sympathetic nervous system to the SA node

3. SA node follows the conduction system causing the heart to contract more frequently

How does the cardiac control centre decrease heart rate?

1. Detects a change from one of the 3 receptors

2. Sends electrical impulses through the parasympathetic nervous system to the SA node

3. SA node follows the conduction system causing the heart to contract less frequently

What are the 2 hormonal factors of the regulation of the heart?

Heart rate can be controlled by two hormones:

• Adrenaline - increases heart rate by stimulating the adrenergic receptors and the SA node

• Noradrenaline - released during stressful situations in order to increase the heart rate and prepare the body to deal with the situation

What are the intrinsic factors of the regulation of the heart?

Intrinsic factors such as the core temperature of the body, control the heart rate:

• When the core temperature is too high, the heart rate increses in order to increase the blood flow to the skin where heat can be lost

In what process does hte body respond to exercise by altering the distribution of blood flow around the body?

Vascular shunt mechanism

What is vascular shunting controlled by?

Vasomotor control centre

How is the blood supply increased to the working muscles using the vascular shunt mechanism?

1) Chemoreceptors detect an increase in CO2 levels

2) Electrical impulses are sent to the vascular control centre in the medulla oblongata

3) Impulses are sent to the muscles where the sympathetic nervous system stimulation is decreased

4) The arteries and precapillary sphincters therefore vasodilate

5) There is therefore increased blood flow and cardiac output to the capillaries of the working muscles

How is the blood supply decreased to the non-essential organs using the vascular shunt mechanism?

1) Chemoreceptors detect an increase in CO2 levels

2) Electrical impulses are sent to the vascular control centre in the medulla oblongata

3) Impulses are sent to the muscles where the parasympathetic nervous system stimulation is increased

4) The arteries and precapillary sphincters therefore vasoconstrict

5) There is therefore decreased blood flow and cardiac output to the capillaries of the non-essential organs

What are the 5 mechanisms of venous return?

1. The skeletal muscle pump

2. The respiratory pump

3. Valves

4. Smooth muscle

5. Gravity

How does the skeletal muscle pump increase venous return?

Blood vessels are squeezed as the muscles around them contract. This forces blood against gravity.

How does the respiratory muscle pump increase venous return?

The pressure gradient between the thoraic and abdominal cavities forces blood through the veins

How do the valves increase venous return?

Ensure blood doesn’t flow backwards in the veins, where it is under low pressure

How does the smooth muscle increase venous return?

Able to constrict

How does gravity increase venous return?

Aids the venous return of blood from areas above the heart

Why does the oxyhaemoglobin dissasociation curve move to the right (Bohr shift)?

The affinity (attraction to) of haemoglobin for oxygen is reduced as the partial pressure of oxygen decreases.

Why does the affinity of haemoglobin for oxygen reduce?

When we exercise, the reduction of blood pH (due to increased CO2 and lactic acid levels) and increased temperature reduces the affinity, allowing O2 to be released to the muscles more readily when we exercise.

What is partial pressure?

The pressure exerted by a single gas

What is cardiovascular drift?

When heart rate increases to meet the demand for oxygen at the working muscles, stroke volume and arterial blood pressure decrease. Cardiac output is maintained or slightly increases to provide more blood to the working muscles and to help you cool down. Blood loses water due to sweat and therefore becomes viscous

Why does cardiovascular drift occur?

As a result of reduced volume of plasma in the blood, therefore reducing venous return and stroke volume. This is then comprensated for by an increase in heart rate, which tries to cool down the body as a result of body fluid lost.

What is atrio-venous difference (A-VO2 Diff)?

The difference in the levels of oxygen between the arterial and venous blood

Why is there a small A-VO2 Diff at rest?

Due to the relatively low amount of oxygen being used by the muscles

Why si there a larger A-VO2 Diff during exercise?

As the muscles undergo exercise, they consume a much higher amount of oxygen, meaning that there is an increase in the amount of oxygen in the capillaries surrounding the muscle and less in the vein. This reduced amount of oxygen in the veins, in combination with the amount of oxygen in the arteries staying constant results in a larger A-VO2 Diff