The Cardivascular System (P1) Flashcards
What is the Arterio-Venous Difference?
The difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles.
When is their a high arterio venous difference and when is their a low difference ? And why?
There is a high difference during exercise because more oxygen is needed from the blood for muscle contractions. There is a low difference during rest because as not much oxygen is required by the muscles.
How does a high difference in the Arterial-Venous Difference affect gaseous exchange?
This affects gaseous exchange at the alveoli as more oxygen is taken in and more carbon dioxide is removed.
How is oxygen transported? As a percentage.
97% is transported with haemoglobin in oxyhemoglobin.
3% with blood plasma
What is haemoglobin and myoglobin?
An iron containing pigment found in the red blood cells.
Myoglobin is the ‘muscle haemoglobin’. An iron containing muscle pigment in slow twitch muscle fibres which has a higher affinity for oxygen than haemoglobin.
.When partial pressure (concentration) of oxygen is high e.g in the lungs how many molecules of oxygen can a haemoglobin molecule carry?
.When partial pressure is low e.g in muscle tissue what happens to oxygen molecules?
. What is this called ?
.4 molecules
. Oxygen is released from oxyhaemoglobin
. Oxyhaemoglobin association/dissociation curve
Where does the oxygen go when it dissociates from haemoglobin?
Myoglobin takes oxygen away from haemoglobin into the muscle cell and stores it until it is needed by the mitochondria for aerobic respiration and energy production.
Who has large amounts of myoglobin and mitochondria and why?
Endurance athletes as a result of training.
What is the oxyhaemoglobin dissociation curve?
It helps us to understand how haemoglobin in our blood transports and releases oxygen. The curve shows the relationship between oxygen and haemoglobin.
What is a Bohr Shift?
During exercise, the s-shaped curve shifts to the right because when muscles require more oxygen, the dissociation of haemoglobin in blood capillaries to the muscle tissue occurs more readily.
What are the four reasons why a Bohr shift occurs?
- Increase in blood and muscle temperature during exercise
- Decrease in the partial pressure of oxygen- muscles use more oxygen to provide energy
- Increase in the partial pressure of carbon dioxide- muscles produce more carbon dioxide as a by-product.
- Lower pH- The increase in lactic acid/increased co2 in muscles/blood acidity
What is the vascular shunt mechanism?
The redirecting of blood to the areas that most need it. During exercise the skeletal muscles require more oxygen so more blood needs to be redirected to them.
What may occur if a performer eats less than an hour before exercise?
A full gut would result in more blood being being directed to the stomach instead of the working muscles .
What is the cardiovascular system?
The body’s transport system.
In the heart, what does the dual action pump do?
Pumps blood to two destination. Heart and lungs.
What does the right side of the heart do?
Pumps deoxygenated blood towards the lungs.
What does the left side of the heart do?
Pumps oxygenated blood towards the body.
What is the name of the mucular wall that seperates the two chambers?
The septum.
Each half contains two chambers which are called….
which are bigger?
Atrium and ventricles. Ventricles are bigger
What does the atria do?
Atria push blood down into the ventricles which does not require much force so they have thinner muscular walls.
What do ventricles do?
They have thicker muscular walls so they need to contact with more muscular force to push blood out of the heart.
What do the superior/inferior vena cava do?
Carry deoxygenated blood from the body to the right atrium.
What does the pulmonary vein do?
Carries oxygenated bloodfrom the lungs to the left atrium.
What does the aorta do?
Carries oxygenated blood from the left ventricle to the whole body.
What seperates atria from the ventricles?
2 AV (atrioventricular) valves
What is the main role of the valve?
To prevent backflow.
What are the two names of the valves of the heart?
Tricuspid and bicuspid.
What side if the tricuspid valve?
Right
What side is the bicuspid valve?
Left
What is the journey of the red blood cell in order?
Vana cava, right atrium, tricuspid valve, right ventricle, pulmonary artery, lungs, pulmonary vein, left atrium, bicuspid valve, left ventricle and aorta.
What is a cardiac impulse?
An electrical impulse responsible for strimulating the heart to contract (systole).
What does myogenic mean?
The capacity of the heart to generate its own impulses.
What is the order of the cardiac conduction system?
SA Node Atrial systole AV Node Bundle of his Bundle his branches Purkinje fibres Ventricular systole
What is the SA node?
It generates the heart rate. Also called a pacemaker.
What is atrial systole?
An elctrical impulse through the walls of the atrial causing them to contract.
What is AV node?
This node relays the impulse between ther upper and lower sections of the heart.
What is the bundle of his?
A collection of heartt muscle cells that transmit electrical impulses from the AV node via the bundle branches.
What is the purkinje fibres?
Muscle fibres that conduct impulses in the walls of the ventricles.
What does CCC stand for?
Cardiac Control Centre
Where is the CCC found?
Medulla Oblongata (brain)
What do chemoreceptors detect? Where are the found?
Detects changes in blood acidity caused by an increase or decrease in the levels of carbon dioxide. Carotid arteries and aorta.
What will happen if there is an increase in the levels of carbon dioxide in the blood?
The chemoreceptors will detect the increase in co2 in the blood. The CCC will stimulate the sympathetic nervous system to send sympathetic nerve impulses to the SA node and then the heart will beat faster.
What will happen with a decrease in the levels of carbon dioxide?
The chemoreceptors will detect the decrease in co2 in the blood.The CCC will stimulate the parasympathetic nervous system to send parasympathetic nerve impulses to the SA node which will decrease heart rate.
What do the baroreceptors detect and where are they found?
They respond to changes in blood pressure to either increase or decrease heart rate. Found in the aorta, heart and pulmonary vessels.
What happens if there is an increase in blood pressure?
Baroreceptors detect the increase and the CCC will stimulate the parasympathetic nervous system to send parasympathetic impulses to the SA node which will decrease heart rate.
What happens if there is an decrease in blood pressure?
Baroreceptors detect a decrease and the CCC will stimulate the sympathetic nervous system to send sympathetic impulses to the SA node which will increase heart rate.
What are proprioceptors?
sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement.
What happens when an increase in movement is detected?
The proprioceptors send a signal to the CCC which stimulates the sympathetic nervous system to send sympathetic impulses to the SA node which will increase heart rate.
What happens when an decrease in movement is detected?
The proprioceptors send a signal to the CCC which stimulates the parasympathetic nervous system to send parasympathetic impulses to the SA node which will decrease heart rate.
What type of control are chemoreceptors, baroreceptors and proprioceptors?
Neural control
What is released before and during exercise?
Adrenaline
What is adrenaline?
A stress hormone released by the sympathetic nervous system during exercise.
What does adrenaline stimulate?
Adrenaline stimulates the SA node which increases speed and force of the heart contaction, thereby increasing cardiac output.
What does adrenaline stimulation result in?
More blood/oxygen pumped to the working muscles.
What is stroke volume?
The volume of blood pumped out of the heart ventricles each contraction.
What is heart rate?
The number of times your heart beats per minute
What is cardiac output?
Volume of blood pumped out of the heart ventricles per minute.
What is the average resting value for stroke volume?
70ml
What is cardiac hypertrophy?
The thickening of the muscular wall of the heart so it becomes bigger and stronger.
What three things does stroke volume depend on?
- Venous return
- elasticity of cardiac fibres
- Contractibility of cardiac fibres
How does venous return increase stroke volume?
The volume of blood returning to the heart via the veins. If venous return increases, then stroke volume increases.
How does the elasticity of cardiac fibres affect stroke volume?
The greater the stretch in the diastole phase, the greater the force of contraction. A greater force of contraction can increase ejection fraction.
What is the ejection fraction?
Percentage of blood pumped out of the left ventricle per beat.
How does the contractibility of cardiac fibres affect stroke volume?
The greater the contractibility the greater the force of contraction. This increases stroke volume and ejection fraction.
When does stroke volume plateau? and why?
Stroke volume plateaus between 40-60% of maximal effort. Increased heart rate approaching maximal effort results in a shorter diastolic phase- the ventricles don’t have time to fill up as much so pump as much out.
What is the average resting value for heart rate?
72 bpm
How does aerobic fitness affect maximum and resting heart rates?
Aerobic athletes tend to have lower resting heart rates and higher maximum heart rates.
What is bradycardia?
A decrease in resting heart rate below 60 bpm
What does cardiac hypertrophy mean for heart rate?
Greater force of contraction (contractibility). This means more oxygen to muscles as less is needed for heart contractions.
What is the equation for cardiac output?
Q= SV X HEART RATE
What is the average resting value for cardiac output?
Q= 70ml x 72bpm
= 5.04 litres
When will cardiac output plateau?
Once maximum intensity has been reached.
What are the six stages of heart rate during maximal and sub maximal exercise?
- Anticipatory rise
- Sharp rise
- Heart rate continues to rise
- Steady state
- Rapid decline
- Slower recovery
What is the single largest death in the western world?
Coronary heart disease
What is coronary heart disease?
Where the coronary arteries that supply the heart muscle with oxygenated blood become block/narrow by gradual build ups of fatty deposits. (Atheroma’s)
What happens if an atheroma (fatty deposit) breaks off?
Can cause blood clots and therefore a blockage.
What is atherosclerosis?
Progressive narrowing of arterial walls caused by fatty deposits, restricting blood flow and increasing blood pressure and the formation of blood clots.
What are the five major lifestyle choices that cause CHD?
. Inactive lifestyle . High blood pressure . Smoking . Obesity . High levels of cholesterol
What are the blood vessel diseases and two main heart related diseases?
Blood vessels: atherosclerosis
Heart: Angina, heart attack
What are the two forms of cholesterol?
HDL (high density lipoproteins)
LDL (Low density lipoproteins)
What do HDL’s do?
Transports excess cholesterol in the blood to the liver where it is broken down. The ‘good’ cholesterol as it lowers the risk of heart disease.
What do LDL’s do?
Transports excess cholesterol in the blood to tissues. The ‘bad’ cholesterol as it increases the risk of heart disease.
What is a stoke?
A stoke occurs when the blood supply to the brain is cut off.
what are the two types of stroke?
Ischaemic and haemorrhagic
What is an ischaemic stoke?
the most common form where a blood clot stops blood supply to the brain.
what is an haemorrhagic stoke?
Occurs when a weakened blood vessel supplying the heart bursts.
How can regular physical activity impact cholesterol levels?
Decreases LDL’s and increases HDL’s
When does cardiovascular drift occur?
After 10 minutes of prolonged/same intensity exercise in a warm environment.
What is cardiovascular drift?
A progressive decrease in stoke volume and arterial blood pressure with a progressive rise in heart rate.
A portion of the lost fluid from sweat comes from plasma volume. What does a decrease in plasma volume result in?
It will decrease venous return and therefore stoke volume.
Why does heart rate increase during cardiovascular drift?
To compensate and maintain cardiac output to create more energy to cool the body down.
How can cardiovascular drift be minimised?
Maintain high fluid before and during exercise.
What is the vascular system made up of?
Made up of blood vessels that carry blood around the body.
What do blood vessels do?
Delivers oxygen and takes away waste products.
How does the vascular system help the body during exercise?
Together with the heart and lungs, blood vessels ensure muscles have enough oxygen to cope with the increased demand for energy during exercise.
What are the two types of blood circulation?
Pulmonary and systemic
What is pulmonary circulation?
Deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart.
What is systemic circulation?
Oxygenated blood to the body from the heart and then the return of deoxygenated blood from the body to the heart.
What is the definition of blood pressure?
Force exerted by the blood against the blood vessel wall.
What is the equation of blood pressure?
Blood flow X resistance
high blood pressure over a long period of time can lead to…
obesity
What is systolic pressure?
The pressure in the arteries when the ventricles are contracting.
What is diastolic pressure?
The pressure in the arteries when the ventricles are relaxing.
Where is blood pressure measured and what is a typical value?
Brachial artery (upper arm) 120/80 mmHG( millimetres of mercury)
Why is blood pressure different in different parts of the body?
Depends on the distance of blood vessels away from the heart.
What is venous return?
The return of blood to the right side of the heart via the vena cava.
What percentage of the total volume of blood remains in the veins at rest (pocket valves)?
Up to 70%
What is starling’s law?
If more blood is pumped back to the heart (venous return), then more blood has to be pumped out so stroke volume increases.
What are the three main mechanisms that increase venous return? *=at rest
- The skeletal muscle pump
- the respiratory pump
- pocket valves*
What other factors increase venous return? *=at rest
. Thin layer of smooth muscle in the veins*
. Gravity*
. The suction pump action of the heart*
What is and what does the skeletal muscle pump do for venous return?
Muscular contraction causes a pumping effect and squeezes the blood towards the heart.
What is and what does the respiratory pump do for venous return?
When muscles contact and relax when respiring, presssure changes occur in the thoracic cavity (chest) and the abdominal cavities (stomach) which compresses veins and increases venous return.
What are and what do pocket valves do for venous return?
Ensures blood in the veins only flow in one direction. Once blood has passed through there is no back flow.
How does the smooth muscle in the walls of veins increase venous return?
Helps squeeze the blood back to the heart.
How does gravity increase venous return?
Helps blood return to the heart from the upper body.
What happens to venous return (VR) during exercise?
Skeletal muscle and respiratory pumps are needed to ensure VR is maintained and muscle demand for oxygen is met.
Why is a cool down needed for venous return?
To keep pumps working to prevent blood pooling in the veins (pocket valves) and to prevent dizziness.
What is the pressure gradient concerning venous return?
The mean systemic pressure minus the right atrial pressure all divided by venous vascular resistance.
What happens to performance when there is a low venous return?
There is a decrease in stoke volume and cardiac output which decreases oxygen supply to the working muscles reducing their ability to contact aerobically.
what % of cardiac output is supplied to our muscles and body organs at rest?
15-20% to muscles
80-85% to body organs
what % of cardiac output is supplied to our muscles and body organs during exercise?
80-85% to muscles
15-20% to body organs
How does the vascular shunt mechanism work during rest?
Receptors detect an decrease in intensity.The VMCC uses sympathetic stimulation resulting in Skeletal muscle arterioles and precapillary sphincters vasoconstricting, decreasing blood flows to the muscles. The VMMC uses parasympathetic stimulation to cause organ arterioles and precapillary sphincters to vasodilate, increasing blood flow to body organs.
How does the vascular shunt mechanism work during exercise?
Receptors detect an increase in intensity.The VMCC uses parasympathetic stimulation resulting in Skeletal muscle arterioles and precapillary sphincters vasodilating, increasing blood flow to the muscles. The VMMC uses sympathetic stimulation to cause organ arterioles and precapillary sphincters to vasoconstrict, decreasing blood flow to body organs.
What is the VMCC and where is it?
Vasomotor control centre. In the medulla oblongata (the brain)
what stimulates the VMCC?
Proprioceptors, baroreceptors and chemoreceptors
Why is the redistribution of blood important?
. increases the supply of oxygen to the working muscles
. Removes waste products from muscles
. Ensures more blood goes to the skin during exercise helping to regulate body temperature.
. Directs more blood to the heart
