Sue - The Heart Flashcards
Cardiac Output (Q) =
Stroke Volume (SV) x Heart Rate (HR)
The amount of blood pumped out by the ventricle in each contraction
Cardiac Output
The amount of blood pumped out by the left ventricle in each contraction
Stroke Volume
The number of times the heart beats per minute
Heart Rate
During exercise, cardiac output will…
increase until maximum intensity is reached and then it plateau’s
When someone has a lower resting heart rate below 60 beats per minute
Bradycardia
An increase in size and growth of skeletal muscles
Hypertrophy
Why does Stroke volume increase while exercise does up to 40-60 % of maximum effort?
As once the performer reaches this point the ventricles do not have as much to fill up with blood due to an increased HR, causing a plateau
Explain cardiovascular drift?
When there is an increase in heart rate and a decrease in stroke volume due to prolonged exercise in warm conditions
Caused by reduction of fluid in the blood plasma due to increase in sweating so the blood becomes more viscous and so HR decreases > poor hydration
How does the the heart initiate a heart beat?
SAN > Atrial systole (contraction) > AVN > Bundle of His > Bundle branches > Purkinje fibres > Ventricular systole
Starlings Law order?
- Increased VENOUS RETURN (due to veins being squeezed during exercise)
- Leads to a greater diastolic filling so the cardiac muscle is STRETCHED
- More powerful force of contraction
- which increases the EJECTION FRACTION
- Increase in STROKE VOLUME
A stress hormone that is released by the sympathetic nerves and cardiac nerve during exercise
Adrenaline
What effect does Adrenaline have?
It stimulates the SAN which results in an increase in both SPEED and FORCE of contraction, thereby increasing cardiac output. More blood is pumped to the working muscles so they can receive more oxygen for the energy they need.
A nervous system that stimulates the heart to beat faster
Sympathetic
A nervous system that returns the heart to its resting level
Parasympathetic
The part of the nervous system that consists of nerve cells that transmit information to and from the CNS
Peripheral Nervous System (PNS)
The part of the nervous system that consists of the brain and the spinal cord
Central Nervous System (CNS)
Detect an increase in blood CO2
Chemoreceptors
Detect an increase in muscle movement
Proprioreceptors
Detect a change/decrease in blood pressure
Baroreceptors
What do receptors do?
Send impulses to the Medulla Oblongata (brain) which increases the impulses to the SAN via the sympathetic nervous system to increase HR
Causes coronary arteries to become blocked or start to narrow by gradual build-up of fatty deposits
Coronary heart disease
Puts extra strain on arteries and the heart - can increase the risk of a heart attack
High blood pressure
Transports cholesterol in the blood to the tissues and they are linked to an increased risk of heart disease
Known as the ‘bad cholesterol’
LDL - low density lipoproteins
Transports excess cholesterol back to the liver where it is broken down and lowers risk of developing heart disease
Known as the ‘good’ cholesterol
HDL - high density lipoproteins
When the blood supply to part of the brain is cut off causing damage to brain cells so they start to die
Stroke
How can regular exercise reduce the effect on heart disease?
- keeps the heart healthy and more efficient
- lowers LDL and increases HDL
- Can lower blood pressure by up to 5-10mmHg
- aids maintenance of a healthy weight to reduce the risk of stroke by 27%
Name the four chambers of the heart?
Left atrium, Left ventricle, Right atrium, Right ventricle
What are the two types of valve sin the heart and what are there purpose?
Atrio-ventricular valve (AV valve)
Semi-lunar valve
To prevent back-flow of blood
During a game of rugby, describe how the sympathetic pathway controls heart rate during the game?
[4 marks]
- During exercise proprioreceptors detect an increase in muscle movement
- production of carbon dioxide
- stimulates chemoreceptors also
- Impulses sent tot he medulla oblongata and impulses are stimulated through the sympathetic system
- to the SAN
- so HR increases
Explain how the increasing level of carbon dioxide in the blood raises heart rate?
- Detected by chemoreceptors
- impulse sent to the Medulla Oblongata
- through the Sympathetic system
- to the SAN which increases HR
Which vein brings dexoygenated blood into the heart from the body?
Vena Cava
Which artery takes blood towards the lungs from the heart?
Pulmonary artery
Which vein brings oxygenated blood back tot he heart from the lungs?
Pulmonary vein
Which artery carries blood away from the heart at high pressures to the essential areas that require it?
Aorta
How is maximum heart rate calculated?
220 - age
