applied anatomy & physiology - cardiovascular system

Question 1

what does heart rate, stroke volume and cardiac output mean?

Answer 1

HR - the number of times the heart beats in 1 minute
SV - the amount of blood that is pumped out of the heart per beat
Q - the volume of blood ejected from the heart per minute

Question 2

what are the short term effects of HR, SV, Q?

Answer 2

HR - increases (70bpm to max HR [200-age])
SV - increases (70ml to 170ml)
Q - increases (5L to 25L)

Question 3

what are the long term effects/adaptations of HR, SV, Q?

Answer 3

HR
-resting HR decreases (bradycardia - lower than 60) due to cardiac hypertrophy
-working HR decreases due to increased stroke volume
-recovery HR increases due to increased vascularisation, venous return mechanism
SV
-increases due to increased venous return, myocardium stretch, force mechanism
Q
-increases due to hypertrophy, contraction force, aerobic respiration efficiency

Question 4

what are the different intensities of exercise?

Answer 4

sub maximal - represents aerobic work, below an athletes maximal output, normally anywhere between 40-60% of intensity
maximal - between 90-100% intensity

Question 5

what is the conduction system and the process?

Answer 5

The heart is myogenic - it generates/controls its own electrical impulse (cardiac impulse)
-cardiac impulse initiated from the SA node (pacemaker) in the right atrium
-impulse passes through the right and lef walls of the AV node (wave of excitation)
-causing both atria to contract - atrial systole
-AV node conducts impulse down through the septum to the apex of the heart (to the bundle of HIS)
-impulse travels up and aorund the ventricles walls via purkinje fibres
-causing both ventricles to contract - ventricular systole
-cycle continues. SA node initiates the next cardiac impulse

Question 6

what does systole and dystole mean?

Answer 6

systole - contracts and empties
dystole - relaxes and fills

Question 7

what is the process for the regulation of heart rate?

Answer 7

The rate at which the impulse are fired is dependent on 3 mechanisms:
receptors: chemoreceptors/baroreceptors/proprioceptors
-the sensory organs pick up the stimuli by these receptors regarding carbon dioxide, oxygen, pH, blood pressure, movement
The info is relayed to the CCC (located in the medulla oblongata) via sensory nerves
Sensory nerves then stimulate one of the motor nerves (sympathetic and parasympathetic nervous system) based on required response
Then along the accelerator/vagus nerve

Question 8

what is sympathetic and parasympathetic stimulation?
what does the accelerator and vagus nerve do?

Answer 8

sympathetic - results in the accelerator nerve increasing the rate at which the SA node fires cardiac impulses (at the same time parasympathetic stimulation decreases)
parasympathetic - results in the vagus nerve decreasing the HR

accelerator = increase HR
vagus = decrease HR

Question 9

what does each receptor respond to ?

Answer 9

proprioceptors - detect increased muscle contractions/movements
increase HR then
chemoreceptors - detect increased CO2
it then increases HR
baroreceptors - detect increased blood pressure
it then decreases HR
-then heart rate decreases through parasympathetic nervous system

Question 10

what are the cause of atherosclerosis?

Answer 10

high blood pressure
high levels of cholesterol
lack of exercise
smoking

Question 11

what is coronary heart disease (CHD)?

Answer 11

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
-this process is called atherosclerosis
-the fatty deposits are called atheroma
narrow arteries=unable to deliver oxygen to heart = pain and discomfort
-this is called angina
atheroma break off in the coronary arteries = blood clots
-results in blockage forming and cuts off oxygen blood to heart = heart attack

Question 12

how do you prevent CHD?

Answer 12

the heart is a muscle - exercise helps it stay in shape
regular exercise keeps heart healthy and more efficient. it can pump more blood around the body as exercise makes the heart bigger and stronger means increase in SV
regular exercuse maintains flexibility of blood vessels ensures good blood flows, normal blood pressure, low cholesterol levels

Question 13

how does the body regulate the HR?
In terms of adrenaline

Answer 13

Adrenaline is released form the adrenaline glands in response to feeling nervous + stressed.
The hormone is transported to heart via bloodstream
It then travels to right atrium through vena cava.
Then stimulates SA node as it passes into right atrium
It results in an increase in HR

Simultaneously, the senosry nerves, chemoreceptors + proprioceptors react to a stimuli and send a nerve signals to the CCC (cardiac control centre)
The CCC is in the medulla olongata
This then sends a signal down the sympathetic system via the accelerator nerve to the SA node
Therefore increase in HR

Question 14

what does high density lipoproteins (HDL) do?

Answer 14

transport cholesterol away to be broken down in the liver which reduces the risk of coronary heart disease
also known as ‘good cholesterol’

Question 15

what does low denisty lipoproteins (LDL) do ?

Answer 15

transport cholesterol in the blood which can build up (called plaque) then increases the risk of coronary heart diesease
also known as ‘bad cholesterol’

Question 16

where to LDL and HDL come form?

Answer 16

LDL comes from animal products
-travels in blood
-builds up plaque
HDL come from exercise and healthy diet
-take away LDL/cholesterol to liver and breaks down

Question 17

how can you reduce levels of bad cholesterol (LDL) and increase HDL?

Answer 17

exercise
vegetarian diet/healthy diet
quit smoking
medication

Question 18

what happens during the cardiovascular drift?

Answer 18

an increase in HR during prolonged endurance-based exercise, despite working at constant intensity
an increase in HR occurs due to effects of dehydration
when exercising for long periods of time or in warm temps, an increase loss of fluids through sweat, expiration and muscle contraction occurs
-reults in decrease in blood plasma and a subsequent thickening of blood
the decrease in blood plasma results in decrease in venous return (the volume of blood returning to the heart) and therefore decrease in SV (volume of blood ejected from the left ventricle per beat)

Question 19

As time moves on what happens to the SV, HR , Q?
(arbituary unit against time)

Answer 19

cardiac output increase overtime during exercise
SV decreases because at maximal intenisty the heart doesn’t have enough time to fill as the HR has to increase to allow more blood around the body
SV best at sub maximal intensity as it has time to fill

Question 20

what is blood pressure?

Answer 20

The force exerted by the blood against the blood vessel wall.
This pressure comes from the heart as it pumps around the body.

Question 21

Effects of high blood pressure and how can it be prevented?

Answer 21

High blood pressure puts extra strain on the arteries and heart.
If left untreated, there’s an increase chance of heart attack, heart failure, kidney disease, stroke or dementia

Regular aerobic exercise can reduce blood pressure
-it lowers both systolic and diastolic pressure by up to 5-10mmHg which reduces risk of a heart attack by up to 20%

Question 22

what is a stroke?
how to reduce risk of stroke?

Answer 22

The brain needs a constant supply of oxygenated blood and nutrients to to maintain its function.
The energy to work all the time is provided by oxygen delivered to the brain in the blood.
A stroke occurs when blood supply to the brain is cut off - causes damage to brain cells and start to die
-leads to brain injury, disability or death

regular exercise can help lower your blood pressure and maintain a healthy weight, which can reduce your risk of stroke by 27%

Question 23

what are 2 types of strokes?

Answer 23

ISCHAEMIC STROKES: most common form, occurs when blood clot stops blood supply
HAEMORRHAGIC STROKES: occurs when a weakened blood vessel supplying the brain burst

Question 24

what is venous return?

Answer 24

The return of blood to the right side of the heart via the vena cava up to 70% of the total volume of blood is contained in the veins at rest, means large volume of blood can be returned to the heart when needed

Question 25

how is venous return linked to straling’s law?

Answer 25

During exercise, amount of blood returning to the heart increases
This means that if more blood is being pumped back to the heart, then more blood has to be pumped out - stroke volume increases (this is starling’s law)

Question 26

how do the 3 main mechanisms help venous return?

Answer 26

The pressure of the blood in the large veins is very low, which makes it difficult to return blood to the heart
Large lumen of veins offer little resistance to blood flow - active mechanisms are needed to help venous return:

1)THE SKELETAL MUSCLE PUMP - when muscles contract and relax they change shape. This change means that the muscles press on the nearby veins and cause a pumping effect adn squeeze the blood towards the heart
2)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
3)POCKET VALVES - its important that blood in the view only flows in 1 direction - presence of valves ensures that happens. Because once the blood has passed through the valves, they close to prevent back flow

Question 27

what are the other factors that aid venous return?

Answer 27

A very thin layer of smooth muscle in the walls of the veins
-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

Question 28

what happens to the mechanisms in venous return during exercise?

Answer 28

It is important to maintain venous return to ensure the skeletal muscles are receiving enough oxygen to meet the demands of the activity.
Valves and the smooth muscle found in veins are sufficient enough to maintain venous return - but not the same during exercise:
-demand for oxygen is greater and the heart is beating faster, so vascular system needs to help out
-the skeletal muscle pump and respiratory pump are needed to ensure venous return is maintained

During exercise, it is possible due to our skeletal muscle are constantly contracting and our breathing is elevated

Question 29

what happens to the mechanisms immediately after exercise?

Answer 29

we still maintain these mechanisms
performing active cool down to keep skeletal muscle pump adn respiratory pump working
- therefore, preventing blood pooling (blood collecting in the veins)

Question 30

what is starling’s law?
And what happens when venous return increases?

Answer 30

“The heart can only pump out what it receives”
1. increased venous return causes ….
2. greater diastolic filling of the heart which causes ….
3. the cardiac muscle to be stretched which causes ….
4. greater contraction force which causes ….
5. an increased ejection fraction and therefore increased stroke volume.

Question 31

Greater explaination of venous return?

Answer 31

70% of blood is in veins at rest - thats why SV increases during exercise
-SV is the amount of blood pumped out of the heart per beat
-Venous return is the blood returning to the heart via the vena cava
-The elasticity of the myocardium fibres in the left ventricle will determine the degrees of stretch of cardiac tissue during diastole
-The more the cardiac fibres can stretch the greater the force of the contraction
-The greater the force of the contraction, the greater the ejection fraction
-Ejection fraction; the percentage of blood pumped out by the heart per beat

Greater the elasticity, the greater the stretch = greater of contraction

Question 32

What are the factors that affect stroke volume?

Answer 32

venous return mechanisms
myocardium stretch and recoil
hydration levels of the blood/viscosity
cardaic muscle tone

Question 33

what is the percentage of blood at organs and muscles during rest and exercise?

Answer 33

At rest 80% to organs and 20% to muscles
During exercise 20% to organs and 80% to muscles

Question 34

how is the redistribution of blood different during rest and during exercise?

Answer 34

-DURING EXERCISE:
the arteries around muscles widen as the muscles need more oxygen so it combine with glucose for energy. But the less vital organ experience the arteries narrowing as they don’t need as much oxygen
-DURING REST:
it is the opposite
the vital organ has widened arteries but muscles have narrowing arteries

Question 35

how does redistribution of blood occur during exercise?

Answer 35

-blood flow controlled by VCC (vasomotor control centre)
-medulla oblongata
-chemical changes detected by receptors during exercise
-VCC stimulated through sympathetic nervous system
-blood flow redistributed via vasocontriction and vasodilation
-pre-capillary sphincter also aid distribution

Question 36

what does vasoconstriction and vasodilation result from?

Answer 36

vasocontriction = from increased stimulation of the sympathetic nervous system
vasodilation = from decreased stimulation of the sympathetic nervous system

Question 37

How does the body control the increased distribution of blood to the working muscles during exercise?

Answer 37

(oxygen has lower partial pressure (concentration) at alititude/during exercise, But carbon dioxide has high partial pressure during exercise)
-Using the vascular shunt mechanism
-Receptors: Chemoreceptors detec increases in blood acidity / increase in partial pressure of CO2 / decrease in pH / decrease in partial pressure of O2, Propriocepetors detect increase in muscle movement/contraction, Baroreceptors detect increase in blood pressure
-Infomation sent to the vasomotor control system (VCC) in the medulla oblongata
-The VCC uses the sympathetic nervous system to ….
-decrease nerve impulses or sympathetic stimulation to the arterioles or pre-capillary sphincters (PCS) leading to the muscles
-which causes vasodilation of arterioles leading to the muscles
-and then vasodilates the pre-capillary sphincters (PCS) leading to the muscles

-But increases nerve impulses or sympathetic stimulation to the arterioles or pre-capillary sphincters (PCS) leading to the organs
-causes vasocontriction of arterioles leading to the organs
-which causes the vasoconstriction of the pre-capillary sphincters (PCS) leading to the organs

Question 38

where does the oxygen go during exercise?

Answer 38

oxygen diffuses into the capillaries supplying the skeletal muscles
-3% dissolves into plasma, 97% combines with haemoglobin to form oxyhaemoglobin
-when fully saturated, haemoglobin will carry 4 oxygen molecules
This occurs when the partial pressure of oxygen in the blood is high
(e.g.in the alveolar capillaries of the lung)

Question 39

Transportation of oxygen:
what happens at the tissues in terms of oxygen pressure?

Answer 39

oxygen is released from oxyhaemoglobin due to the lower pressure of oxygen that exist there
this is referred to as oxyhaemoglobin dissociation

Question 40

Transportation of oxygen:
whats happens in the muscles, in terms of how oxygen is stored?

Answer 40

oxygen stored by myoglobin because it has a higher affinity for oxygen and then will store the oxygen for the mitrochondria until it needs to be used by the muscles
the mitrchondria are the centres in the muscles where aerobic respiration takes place

Question 41

what is the bohr shift ?
(during exercise)

Answer 41

The graph shows x-axis=partial pressure of oxygen and y-axis=% of saturation (with S-shape line)
During exercise, the S-shaped curve shifts to the right because when muscles require more oxygen, the dissociation of oxygen from haemoglobin in capillaries to muscle tissue occurs more readily.
In the tissues, there’s a low partial pressure of oxygen and high partial pressure of carbon dioxide, so haemoglobin unloads at this point.
This means even more oxygen is available to the tissue

Question 42

3 factors responsible for increase in dissociation of oxygen from haemoglobin which results in more oxygen being available for use in working muscles:

Answer 42

increase blood temperature
partial pressure of CO2 increases
pH level decreases as acidity levels increases

-all cause more oxygen to be released by haemoglobin at muscle tissue faster

Question 43

1)what does partial pressure mean?
2)what does affinity of oxygen mean?

Answer 43

1) concentration
2) likes oxygen

Question 44

1) what does dissociation mean?
2) what does association mean?

Answer 44

1) moves away
2) moves towards

Question 45

During exercise, why does the dissociation curve shift to the right?

Answer 45

Muscles require more oxygen.
The dissociation of oxygen from haemoglobin in blood capillaries to the myoglobin the muscle tissue to the association of the mitrochondria in the muscle cells as it has the highest affinity of oxygen (out of haemoglobin, myoglobin, mitrochondria).
This happens due to the blood temperature increasing (which is an exothermic reaction), the partial pressure of CO2 increases, the acidity level rises from pH level lowering.
This then more oxygen is released to muscle tissue by haemoglobin

Question 46

What is Arterio-venous difference?
(A-VO2 diff)

Answer 46

Difference between the oxygen content of the arterial blood arriving at the muscle and the venous blood leaving the muscles.

Question 47

What happen arterio-venous difference at rest and during exercise?

Answer 47

At rest: A-VO2 diff is low as not much oxygen is required by the muscles
During exercise: much more oxygen is needed from the blood for the muscles so the A-VO2 diff 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 A-VO2 diff as trained performers can extract a greater amount of oxygen from the blood