Physiology: Short Term Responses to Exercise Flashcards
Define heart rate
The number of times the heart beats per minute
Define stroke volume
The amount of blood pumped out of the left ventricle per beat
Define cardiac output
The amount of blood pumped out of the left ventricle per minute
Outline the relationship between heart rate, stroke volume and cardiac output
Cardiac output = stroke volume x heart rate
What is the cardiac output of a performer with a heart rate of 70bpm and a stroke volume of 70mls
4,900mls/min
How is maximum heart rate calculated?
220 - age (+ or - 10)
What does cardiac hypertrophy mean?
The heart gets bigger and stronger
Who would have a lower resting heart rate - a healthy active individual or a sedentary individual? Why?
An active individual, as they have a higher stroke volume
What is known as the heart’s pacemaker?
The SAN
Outline the first process in the conduction of the heart and explain what it causes.
The SAN sends out an electrical impulse - causing the atria to contract and forcing blood into the ventricles
Outline the role of the AVN in the conduction of the heart.
The AVN sends out a second nerve impulse
In the conduction of the heart, where does the second nerve impulse get sent and what does it cause.
The second nerve impulse is sent down the bundle of His, causing a delay of 0.1 seconds.
What happens to the atria in the diastolic phase?
It passively fills with blood.
What happens to the ventricle in the diastolic phase?
It passively fills with blood
What happens to the atria in the systolic phase?
It squeezes, forcing blood into the ventricles
What happens the ventricles in the systolic phase?
They contract, forcing blood out of the heart
Does the heart relax or contract in the diastolic phase?
Relax
Does the heart relax or contract in the systolic phase?
Contract
Define the term venous return
The return of blood to the heart
How many mechanisms are there or venous return?
3
Name the mechanisms of venous return
Muscle Pump
Respiratory Pump
One-way Valves
Explain the muscle pump
Where the muscles contract, squeezing the veins and forcing blood to the heart
Explain one-way valves
In the veins and prevent the back flow of blood
Explain the respiratory pump
The chest size increases, which squeezes the veins and forces blood back to the heart
Describe the 6 steps of Starling’s Law
During exercise, there is a greater venous return
Therefore, a greater amount of blood fills the heart
Therefore, there is a greater stretch of the walls of the heart
Therefore, their is a greater force of contraction
Therefore, there is a greater stroke volume
Therefore, their is greater amount of O2 to the working muscles
What are the benefits of Starling’s Law?
A greater amount of O2 is delivered to the working muscles, so the performer can use aerobic respiration at higher intensities for longer
What is the role of a chemoreceptor?
To detect changes in blood acidity levels.
What is the role of a proprioceptor?
To detect muscular contractions
What is the role of a baroreceptor?
To detect a change in blood pressure
What is the role of a thermoreceptor?
To detect changes in body temperature
In order to change heart rate, where do receptors send impulses to?
The cardiac control centre in the medulla
The cardiac control centre in the medulla
Sympathetic
To increase heart rate, which pathway does the medulla send nerve impulses down?
Acceleratory
To decrease heart rate, what kind of nerve impulses does the medulla send?
Parasympathetic
To decrease heart rate, which pathway does the medulla send nerve impulses down?
Inhibitory
What is the redistribution of blood also known as?
Vascular shunting
In order to redistribute blood, where do receptors send a nerve impulse to?
Vaso-motor control centre in the medulla
To cause vaso-dilation or vaso-constriction, where does the vaso-motor control centre send impulses to?
The pre-capillary sphincters
What does vaso dilation mean?
The blood vessels become bigger
What does vaso constriction mean?
The blood vessels become smaller
What happens to blood flow to the digestive system during exercise?
It decreases
What happens to blood flow to the brain during exercise?
It stays the same
What happens to blood flow to the skin during exercise?
It increases
What happens to blood flow to the heart during exercise?
It increases
