Cardiac Flashcards
(30 cards)
What’s the definition of the cardiac cycle?
The events that make up one beat of the heart
How long does the heart take to beat at rest? And what are the two main stages of it beating?
0.8 seconds. Diastole chambers filing with blood (0.5) systole chambers are contracting (0.3)
What is stage 1 and stage 2 and what happens?
Atrial diastole and ventricular diastole. Relax and refill of both atria and ventricles ( blood goes in )
What is stage 3 and 4 and what happens?
Atrial systole and ventricular systole. Contract of both atria and ventricles ( blood goes out )
What are the two valves of the heart and what are they collectively known as?
Tricuspid (3 flaps)
Bicuspid (2 flaps)
Atrioventricular valves
What’s the role of the SA node?
pacemaker.
Encharge if contracting both atria
What is the role of the AV node?
Receives electrical impulse from SA node.
Sits between atria and ventricles
Delays impulse
Causes atria to fully contract
What’s the role of the bundle of his?
A group of specialised fibres located in the septum that separates the two ventricles
Main aspects of the heart conduction system?
The heart is myogenic, meaning it creates its own impulse
The impulse it generates spread throughout the heart causing it to contract
Main aspects of chemoreceptors. What do they do?
Detect chemical changes within the blood:
Rise in CO2
Rise in lactic acid
Decrease in lactic acid
Found in the carotid and aortic arch
Nervous impulses are sent to the ccc in medulla oblongata
Increase in sympathetic nervous stimulation to the SA node
Main aspects of baroreceptors. What is their function?
Detects changes in blood pressure
Contain nerve endings that respond to the stretch of arterial walls (carotid and aortic arch) caused by changes in blood pressure.
Increase in arterial pressure results in a stretch of baroreceptors causing the heart to decrease.
Decrease in arterial pressure results in decrease of receptors and a rise in heart rate.
Main aspects of proprioceptors. What are their role?
Detects muscle movement.
Sensory nerve endings located in muscles tendons joints that provide info regarding movement and body positions.
Info sent to ccc in medulla oblongata- sympathetic and parasympathetic nervous system to increase/decrease
Main aspects of medulla oblongata/CCC.
CCC receives info from receptors
Found in medulla oblongata
What are two nerves that originate in the CCC?
Parasympathetic nerve - slows heart rate down
Sympathetic nerve - speeds heart rate up
What is heart rate?
The amount of times your heart beats per minute
At rest average is - 72 bpm
Pulse is a way to measure your heart rate
How do you work out maximum heart rate?
220-age
Rate at which heart is beating when it’s working it’s hardest to meet your body’s o2 needs - max heart rate.
What is the definition bradycardia?
Resting heart rate lower than 60bpm
Definition of cardiac hypertrophy?
Enlargement of left ventricle as a result of endurance training
Definition of stroke volume?
Amount of blood ejected from left ventricle with each beat.
During exercise it can double (intensity dependant)
What is starlings law of the heart?
If venous return increases stroke volume increases too.
More blood in = more blood out.
Ventricle walls are elastic the more they’re forced to stretch the greater the force of contraction.
Definition of venous return?
Blood returning to the heart through the veins
Definition of ejection fraction?
% of blood pumped out by the heart
Can go from 60%-85% during exercise
Definition of cardiac output?
Amount of blood ejected from heart in 1 minute
Q=HRxSV
At rest it is 5L
What happens as a result of starlings law of the heart?
Stroke volume and ejection fraction increases.
As venous return increases there is greater diastolic filling
