Cardiovascular system Flashcards
What is the order of the heart?
superior vena cava - RIGHT ATRIUM - Tricuspid valve - RIGHT VENTRICLE - pulmonary valve - PULMONARY ARTERY - lungs - LEFT ATRIUM - mitral valve - LEFT VENTRICLE - aortic valve - AORTA - body
What is diastole?
ventricle/atriums relax, filling with blood
What is systole?
ventricle/atriums contracting, realising blood
What does myogenic mean?
the heart beats itself, it creates its own signal
How is a heartrate created?
- sino-artial node (SAN) creates an electrical impulse
- causes atrial systole (contract)
- atriaventricular node (AVN) holds impulse for 0.1s - all blood fills ventricles
- impulse goes into the bundle of His and then goes into the purkinje fibres
- causes ventricular systole
stroke volume
- volume of blood pumped out of the ventricles in each contraction (average 70ml)
- stroke volume increases proportionally to work intensity and then plateus when sub-maximal exercise has been reached
- stroke volume increases due to increased venous return and starlings law
cardiac output
the volume of blood pumped out by the hearts ventricles per minute
venous return
volume of blood returning to the right atrium via the veins, the greater the venous return the greater the stroke volume
the elasticity of cardiac fibres
the degree of stretch of cardiac tissue during the diastole phase of cardiac cycle, greater the stretch greater the force
What is starlings law?
increased venous return means more blood enters the ventricles during the diastolic phase which causes more stretch and then they contract more forcefully (an elastic band)
ejection fraction equation
- ejection fraction = stroke volume / diastolic volume
- average is 60% but goes to 85% during exercise
the contractility of cardiac tissue (myocardium)
increased contractility allows greater force which increase the stroke volume
maximal heartrate
220-age=max heartrate
anticipatory rise
prior to exercise heartrate increases due to the hormone adrenaline being realised
cardiac hypertrophy
when regular aerobic exercise causes te cardiac muscles to get bigger and stronger
steadystate exercise
when the oxygen demands are met by the oxygen supply
cardiovascular drift
- occurs during prolonged exercise (10 mins in a warm enviroment)
- due to sweating (portion of plasma)
- this reduces venous return and stroke volume
- to minimise you need a high fluid consumption
stroke volume in a trained athlete
- resing stroke volume - 80-110ml
- submaximal exercise - 160-200ml
- maximal exercise - 160-200ml
stroke volume in an untrained person
- resting stroke volume - 60-80ml
- submaximal exercise -100-120ml
- maximal exercise - 100-120ml
cardiac output on a trained athlete
- resting - 5L/min
- submaximal exercise - 15-20L/min
- maximal exercise - 30-40L/min
cardiac output in an untrained person
- resting - 5L/min
- submaximal exercise - 10-15L/min
- maximal exercise - 20-30L/min
what controls the cardiac control centre?
autonomic nervous system
conduction system
controls the cardiac cycle
what determins the rate at which cardiac impulses are fired?
- neural control
- hormonal control
- intrinsic control
proprioceptors
- detect an increase in muslce movement
- located in muslce tendons and joints
chemoreceptors
- detect increase in lactic acid and carbon dioxide levels
- located in medulla oblongata
baroreceptors
- detects an increase in blood pressure
- located in blood vessels
intial factors that effect our heart rate
- temperature increase
- decrease in blood viscosity
- venous return