Cardiovascular System Flashcards
What is health?
a state of complete physical, mental and social wellbeing
What is fitness?
the ability to cope with the demands of the environment
How is heart disease caused?
build up of fatty deposits- atherosclerosis
arteries cannot deliver oxygen - smaller lumen
causes pain - angina
exercise can stop this
How are strokes caused?
occurs when blood supply to brain is cut off
ischaemic - blood clot stops blood supply
haemorrhagic- weakened blood vessel in brain bursts
exercise can reduce risk
What is cholesteral?
LDL- bad cholesterol linked with heart disease (transport chol to tissues and causes build up)
HDL- good cholesterol linked with reducing risk (transport chol to liver to be broken down)
exercise increases HDL and lowers LDL
What do baroreceptors do?
detect changes in blood pressure- increased blood pressure- sends message to cardiac control centre then to parasympathetic NS to lower heart rate
What do proprioceptors do?
detect an increase in muscle movement and send message to cardiac control centre then to the sympathetic NS to increase heart rate
What do chemoreceptors do?
detect chemical changes- when C02 and lactic acid levels go up send message to cardiac control centre then to sympathetic NS to increase HR
What does myogenic mean?
the heart generates its own impulses
How does an impulse travel through the heart for it to contract?
SA node generates the heartbeat Atrial Systole AV node- delayed Bundle of HIS Purkinje Fibres Ventricular Systole - contraction
How are factors affecting heart rate detected?
the receptors send a message to the medulla (cardiac control centre) in the brain which sends a message to the parasympathetic or sympathetic NS to in/decrease heart rate
What is the hormonal control mechanism?
the release of adrenalin which stimulates the SAN which increases cardiac output
this is known as anticipatory rise
What are the neural control mechanisms?
the sympathetic (adrenalin) and parasympathetic (vagus nerve) nervous system in increasing and decreasing the heart rate
chemoreceptors
baroreceptors
proprioceptors
What is stroke volume?
volume of blood pumped out of the heart in each contraction
Trained vs untrained person
trained person will have a higher stroke volume
untrained person will be a lot lower
What can affect the stroke volume of a person?
venous return- more blood returning = higher sv
elasticity of cardiac fibres- more elastic means a larger contraction can occur
How can exercise affect the heart?
bradycardia- lower resting heart rate (greater HR range)
hypertrophy- thickening of muscle wall so more blood can be pumped out
a trained athlete will have a greater HR range
What is the equation for cardiac output?
cardiac output = stroke volume x heart rate
How can a trained and untrained person have the same cardiac output?
different sized hearts/hypertrophy –trained bigger
different stroke volumes – trained bigger;
different heart rates – untrained higher;
=product of sv x hr will be the same
at maximal exercise if they are the same age- trained will be higher
What does Starling’s Law say?
during exercise: increased venous return greater diastolic filling cardiac muscles stretch bigger force of contraction bigger ejection fraction
What is ejection fraction?
% of blood pumped out by left ventricle per beat
What is cardiovascular drift?
the progressive decrease in stroke volume and blood pressure while heart rate is rising
How does cardiovascular drift occur?
occurs during steady state exercise lasting 60 mins in warm environments
fluid is lost as sweat so blood volume decreases
venous return decreases
decreases stroke volume (starlings law)
What is venous return?
the return of blood to the vena cava - 70% of blood is left in the veins at rest so this can be returned to the heart when needed
the suction pressure of the heart draws up blood
