cv system

what is the cv system made of?

heart, blood and blood vessels

what are the two circuits which blood pump through?

• pulmonary circuit

• systemic circuit

role of pulmonary circuit?

carries deoxygenated blood through the pulmonary artery to the lungs and oxygenated blood through the pulmonary vein back to the heart.

role of the systemic circuit?

carries oxygenated blood through the aorta to the working muscles and deoxygenated blood though the vena cava back to the heart.

what’s the pathway of deoxygenated blood?

vena cava, right atrium, tricuspid valve, right ventricle, pulmonary semi-lunar valve, pulmonary artery, lungs

what’s the pathway of oxygenated blood?

from lungs, pulmonary vein, left atrium, bicuspid valve, left ventricle, aortic semi-lunar valve, aorta, working muscles (body)

what’s the role of the septum?

seperates the right and left sides of the heart.

what are the four chambers in the heart?

right atrium, right ventricle, left atrium, left ventricle

what are the four valves in the heart?

tricuspid, bicuspid, pulmonary semi-lunar, aortic semi-lunar

what are the four blood vessels in the heart?

vena cava, pulmonary artery, pulmonary vein, aorta

what’s the function of the SA node?

generates the electrical impulse, transmits it through the atria walls, causing them to contract.

Where is the SA node located?

Right atrial wall

function of the AV node?

collects the impulse and delays it for 0.1 seconds, allowing the atria to finish contracting. it then transmits the impulse to the bundle of his.

where is the AV node located?

right atrial wall

function of the bundle of his?

splits the impulse in two, ready to be transferred to each ventricle.

where is the bundle of his located?

septum

function of the bundle branches?

transmits the impulse to ventricle walls

where are the bundle branches located?

septum and ventricle walls

function of the purkyn fibres?

transmits the impulse through the ventricle walls causing them to contract.

location of the purkyn fibres?

ventricle walls

what are the two events that make up the cardiac cycle?

diastole, systole

what happens during diastole?

atrial diastole; atria relax and blood enters via the vena cava and pulmonary vein.

ventricular diastole; ventricles relax and blood enters the ventricles from the atria.

what happens during systole?

atrial systole; atria contract and blood is forced into ventricles.

ventricular systole; ventricles contract which forces blood out of the heart into:

1) the aorta to the body

2) the pulmonary artery to the lungs

definition of heart rate?

the number of times the heart beats per minute.

definition of stroke volume?

the volume of blood ejected from the left ventricle per beat.

definition of cardiac output?

the volume of blood ejected from the left ventricle per minute.

how do you calculate cardiac output?

cardiac output = stroke volume x heart rate

what is the effect of submaximal exercise on heart rate?

• anticipatory rise in HR due to adrenaline.

• a rapid increase in HR at the start of exercise to increase blood flow and oxygen delivery.

• a steady-state HR as oxygen supply meets the demand.

• an initial rapid decrease in HR at start of recovery, because working muscles no longer need as much oxygen.

• a more gradual decrease in HR to resting.

what is the effect of maximal exercise on heart rate?

• anticipatory rise in HR prior to exercise due to adrenaline.

• rapid increase in HR at the start of exercise to increase blood flow and oxygen delivery.

• slower increase in HR; no steady state reached - the supply of oxygen will never meet the demand from muscles.

• initial rapid decrease in HR at the start of recovery as the working muscles no longer need as much oxygen.

• more gradual decrease in HR to resting levels

what is the effect of intermittent exercise on HR?

• anticipatory rise in HR prior to exercise due to adrenaline.

• rapid increase in HR at the start of exercise to increase blood flow and oxygen delivery to working muscles.

• rapid decrease in HR as intensity of exercise decreases and there is less demand for blood flow.

• continued fluctuations in HR as demand for oxygen increases and decreases with exercise intensity.

what is the effect of exercise on stroke volume?

• SV increases linearly with exercise intensity, due to increased venous return.

• SV plateaus during sub-max exercise (max SV is reached during sub-max exercise) .

• SV decreases at max exercise because there is less blood in the ventricles at the end of ventricular diastole so less blood is ejected from the ventricles per beat.

what happens to SV during recovery?

• SV remains elevated during recovery to maintain blood flow to working muscles in order to remove lactic acid and Co2.

• it reduces to it’s pre-exercise value gradually.

• a cool down helps to maintain SV.

what is the effect of exercise on cardiac output?

• cardiac output increases linearly with exercise intensity (because Q = HR x SV).

• Q plateaus as exercise intensity continues to rise towards max intensity (because HR increases but SV plateaus and can decrease).

what happens to Q during recovery?

• Q reduces to it’s pre-exercise value gradually.

• because HR decreases quickly, but SV remains elevated during recovery.

• a cool down helps to maintain Q.

how do neural factors regulate heart rate during exercise?

• baroreceptors detect an increased blood pressure.

• chemoreceptors detect an increase in Co2 and a decrease in O2 and PH of blood.

• proprioceptors detect an increase in movement.

• receptors send the information to CCC (cardiac control centre) which is controlled by the autonomic nervous system.

• this activates the sympathetic NS which then stimulates the accelerator nerve to increase firing rate of the SA node to increase HR.

how do hormonal factors regulate HR during exercise?

• adrenaline is secreted by the adrenal glands which stimulates the sympathetic nervous system.

• this increases the firing rate of the SA node to increase HR.

how do intrinsic factors regulate HR during exercise?

• increased temperature, increases the speed of nerve transmission in the heart which stimulates the SA node and increases HR.

• increased venous return means increased volume of blood returning to the right side of the heart. this causes an increased stretch of the atrial and ventricular walls.

• this increase HR and SV.

how do neural factors regulate HR during recovery?

• baroreceptors detect decreased blood pressure.

• chemoreceptors detect decreased Co2 and increased O2 and PH of blood.

• proprioceptors detect decreased movement.

• receptors send info to CCC which uses the parasympathetic nervous system via the vagus nerve to decrease firing rate of SA node, causing HR to decrease.

how do hormonal factors regulate HR during recovery?

• less adrenaline is secreted from the adrenal glands.

• which stimulates the parasympathetic nervous system.

• causing a decrease in the firing rate of the SA node, causing HR to decrease.

how do intrinsic factors regulate HR during recovery?

• decreased temperature (causes decreased speed of nerve transmission) and decreased venous return (decreased volume of blood returning to the right side of the heart)

• causes the SA node to decrease HR

• less blood forced down into ventricles

• so decreased stretch of ventricle walls, so decreased force of contraction

• this decreases SV and Q

definition of the vascular shunt mechanism?

the redistribution of cardiac output during exercise.

process of redistribution of Q during exercise?

• start of exercise is detected by chemoreceptors, baroreceptors and proprioceptors.

• receptors send this information to the vasomotor control centre (VCC) in the brain.

• the VCC uses the SNS to increase or decrease stimulation to arterioles and pre-capillary sphincters.

• at working muscles:

  1) decreased sympathetic stimulation leading to;

• vasodilation of arterioles, opening of pre capillary sphincters to increase blood flow to working muscles.

• at the non-essential organs;

  1) increased sympathetic stimulation leading to;

• vasoconstriction of the arterioles, closing of the pre-capillary sphincters to decrease blood flow to the non-essential organs.

process of redistribution of Q during recovery?

• end of exercise is detected by receptors in the body;

• chemoreceptors detect decrease in Co2 or increase in O2.

• baroreceptors detect a decrease in blood pressure.

• proprioceptors detect a decrease in muscle activity.

• these receptors send the info to the VCC in the brain.

• the VCC uses the sympathetic nervous system to;

  at the working muscles:

• increased stimulation leads to, vasoconstriction of arterioles and closing of pre-capillary sphincters to decrease blood flow to the working muscles (20%)

  at the non-essential organs:

• decreased stimulation leads to, vasodilation of the arterioles and opening of the pre-capillary sphincters to increase blood flow to the non-essential organs (80%)

describe the 5 mechanisms of venous return during exercise

• smooth muscle in the veins contract to help squeeze blood back towards the heart

• gravity helps the blood return to the heart

• the skeletal muscle pump is where skeletal muscles contract which compress nearby veins, forcing blood back to the heart

• pocket valves in the veins prevent the back flow of blood

• the respiratory pump is where the pressure change (between the thoracic cavity and abdominal cavity) compresses the nearby veins and helps squeeze blood back to the heart

describe the maintenance of venous return during recovery

• an active recovery maintains the skeletal and respiratory pumps and maintains venous return

• without an active recovery, blood can pool in the legs causing causing VR and SV to decrease

• pocket valves are thought to help VR after exercise by keeping the blood flowing in one direction

give the heart rate values for a trained and untrained athlete at rest, sub-max and maximal exercise

untrained at rest - 70bpm

trained at rest - 50bpm

untrained at sub-max - 100bpm

trained at sub-max - 120bpm

untrained at max - 220 - age bpm

trained at max - 220 - age bpm

give the stroke volume values for a trained and untrained athlete at rest, sub-max and maximal exercise

untrained rest - 70ml

trained rest - 100ml

untrained sub-max - 100ml

trained sub-max - 200ml

untrained max - 100ml

untrained max - 200ml

give the cardiac output values for an untrained and trained athlete at rest, sub-max and maximal exercise

untrained rest - 5L/min

trained rest - 5L/min

untrained sub-max - 10L/min

trained sub-max - 24L/min

untrained max - 20L/min

trained max - 40L/min