CV System - Regulation of Heart Responses Flashcards
what is the definition of stroke volume SV
The volume of blood that leaves the heart during each contraction
What is the unit for cardiac output
L / Min or Ml / Min
What is the equation of cardiac output
HR X SV
what is the definition of cardiac output
The amount of blood The heart pumps out per minute
what would the difference be between an a trained person and untrained persons resting heart rate
Trained Individuals Resting HR are much lower than untrained individuals
why is a trained person resting heart rate lower than untrained person
cardiac hypertrophy -> heart is bigger -> pumps more blood -> larger SV ->increased size of chambers -> bigger SV -> heart doesn’t have to beat as many times
What is the sympathetic system
A part of the autonomic nervous system that speeds heart rate
What is the Parasympathetic System
A part of the autonomic nervous system that decreases heart rate
What is the medulla oblongata
The most important part of the brain as it regulates processes that keep us alive such as breathing and heart rate
What is the ANS
Autonomic nervous system
What does the ANS do
Determines the rate at which the SAN sends out impulses
How does the sympathetic nervous system increase HR
It releases adrenaline
What does adrenaline increase in the sympathetic nervous system
It increases the strength of ventricular contraction which then increases stroke volume
In the sympathetic nervous system what does noradrenaline do
Aids the spread of electrical impulse throughout the heart, increasing HR
In the sympathetic nervous system what does an increased metabolic rate cause
Increased CO2 and lactic acid, decrease in blood PH (more acidic)
How are the changes of an increased metabolic rate picked up
By the chemoreceptors and they inform the sympathetic system to increase HR to flush out the waste products. This results in an increased cardiac output
What is the parasympathetic nervous system
The nervous system that slows the speed of the heart down which decreases HR
What does the parasympathetic nervous system do to lower the heart rate
Releases Acetylocholine which slows the spread of impulses throughout the heart, this results in a lower heart rate
What are receptors
Part of the nervous system that detects changes in the body.
What do chemoreceptors do
Detect changes in CO2 - an increased concentraton in The blood will stimulate The sympathetic nervous system- which means The heart will beat faster
What do baroreceptors do
Detect changes in blood pressure- Baroreceptors establish set points for blood pressure - an increase or decrease above or below this set point results in The Baroreceptors sending signals to The medulla oblongata
What do proprioceptors do
Increases HR when muscle movement increases
What is adrenaline
A stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise which causes an increase in heart rate
What is ejection fraction
The percentage of blood pumped out by the left ventricle per beat
What is the diastole phase
When the heart relaxes to fill with blood
What does stroke volume depend on
Venous return - The elasticity of cardiac fibres - contractility of cardiac tissue
How does venous return affect stroke volume
If the venous return increases then stroke volume will increase
What is venous return
The volume of blood return to the heart via veins
How does the elasticity of cardiac fibres affect stroke volume
The more the cardiac fibres can stretch, the greater the force of contraction (which also increases ejection fraction - starlings law)
What is starlings law
Increased venous return -> greater diastolic filling of the heart -> cardiac muscle stretched -> more force of contraction -> increased ejection fraction
What is cardiac output
The volume of blood pumped out by the hearts ventricles per minute
How does the contractility of cardiac tissue affect stroke volume
The greater the contractility of cardiac tissue, the greater the force of contraction
How do you calculate cardiac output
Cardiac Output (Q) = Stroke volume (SV) x Heart Rate (HR)
What is cardiac hypertrophy
The thickening of the muscular wall of the heart so it becomes bigger and stronger
What is bradycardia
A decrease in resting heart rate to below 60 beats per minute
How does having a bigger heart affect cardiac output
Enables more blood to be pumped out and as a result the blood doesn’t need to pump as often so resting HR decreases
How do u calculate maximum heart rate
220 - your age
what is cardiovascular drift
Cardiovascular drift occurs after a period of exercise -> HR increase -> stroke volume decreases -> because fluid is lost as sweat -> resulting in a reduced plasma volume -> reduced venous return -> cardiac output increases (no energy needed to cool the body)
