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
after exercise what factors occur
- temperature decrease
- heartrate decrease
- venous return decrease
- stroke volume decrease
bradycardia
resting heartrate under 60bpm
heart disease - ATHEROSCLEROSIS
- blood vessels going towards the heart start to narrow due to atheroma (fatty deposits)
what causes atherosclerosis?
- high blood pressure
- high cholesterol levels
- lack of exercise
- smoking
heart disease - ANGINA
- when the arteries narrow they are unable to carry oxygen and this causes discomfort (angina)
- if a peice of atheroma breaks off it can cause a blood clott which leads to a heart attack
how to fix atherosclerosis and angina
- exercise helps to keep heart healthy
- more blood can be pumped through - bigger heart
- blood vessels become more flexible - ensures good blood flow
High blood pressure
- high blood pressure put extra strain on the artery walls
- can cause a heart attack, heart failure, kidney disease, stroke or dementia
how to solve high blood pressure?
- regular aerobic exercisecan reduce blood pressure
- lowers systolic and diastolic pressure whihc reduces a heart attack
cholestrol levels - LDL
- low density lipoprotein transports cholestrol in the blood
- doesnt break it down
- “bad”
cholestrol levels - HDL
- high density lipoprotein that transports excess cholestrol back to the liver
- gets broken down
- lower the chance of a heart attack
how to solve bad cholerstrol
regular aerobic exercise decreases LDL and increases HDL which decreases chance of heart attack
strokes
- occurs when blood suplly to the brain is cut off
- can lead to brain injury, disability and death
ischaemic stroke
occurs when a blood clot stops blood supply
haemorrhagic stroke
occurs when a weakened blood vessel supplying to the brain bursts
how to solve stroke
regular exercise lowers blood pressure and maintains healthy weight
what are the two tyoes of curculation?
- pulmonary circulation
- systemic circulstion
arteries/arterioles
- transport oxygnated blood away from the heart
- large middle layer of smooth muscle (allows to vasodilate/vasocontrisct)
cappillaries
- fit one cell thick
- slows down the speed of blood
- allows nutrients to diffuse
veins/venules
- transports deoxyganted blood back to the heart
- pocket valves to prevent backflow
- thin walls which allow venocontrict/venodialte
- thick outlayer which supports valves
blood pressure
- expressed as systolic (highest) / diastolic (lowest)
- average 120mmHg / 80mmHg
- blood pressure = blood glow (cardiac output) X restistance (friction)
blood pressure during endurance training
- increase in cardiac output cause BP to increase
- viscosity increase
what happens to systolic Bp during endurance training?
- increases in line with intensity
- plateau during sub-maximal exercise
- decrease gradually if the intensity is prolonged
- if intensity increases it will continue to with exercise
what happens to diastolic Bp during endurance training?
- changes little during submaximal exercise
- gross muscle activity Bp may fall
- Bp may increase a tiny bit when maximal exercise is reached
pulmonary circulation
deoxygentated blood goes from the heart to thr lungs to get oxygentaded and then back to the heart
systemic circulation oxygenated
oxyganted blood goes from the heart to the body and then deoxyganted blood goes back to the heart
blood pressure
the pressure exerted by the (aterial) blood vessel walls
what happens to blood pressure during isometric/restistance training
- blood vessels are blocked by sustained stactic muscle contractions
- restrict blood flow through aterial and venous which increase vascular resistance
what happens during post exercise recovery?
- systolic Bp decreases temporarily up to 12hrs
- diastolic Bp stays low
hypertension
- prolonged high blood pressure
- high is 140/90
harmful effects of hypertension
- increased workload on heart
- increasing atherosclerosis
- increasing arteriosclerosis
- arterial damage
- congesive heart failure
isometric work
muscle contracts but no movement occurs
increased workload on heart
increased resistance to expel blood
increased atherosclerosis
hardening of the arterial walls
the venous return mechanism
transport of blood from the cappilaries though venules, veins and then either to the supiror or infiror vena cava back to the righ atrium
distribution of cardiac output at rest and during exercise
- vascualar shunt mechanism - redistrobution of blood
- at rest 15-20% supplied to muscles and 80-85% to organs
- 80-85% goes to muscles during exercise however brain is maintained
- blood supply to skin surface decreases
where is the vascomotor control centre?
the medulla oblangata
what does the vasomotor control centre reicve?
messages from chemoreceptors and baroreceptors
what happens to organs during exercise?
the vasomotor control centre decreases the sympathatic stimulations which vasodilates arteries - more blood flow
importance of redistribution of blood
- increased oxygen supply to muslces
- remove waste products
- ensure more blood flow to skin to regulate body temp
- more blood to heart
sympathatic nervous system
- the vasomotor control centre only sends messages via the sympathatic ns
- the arterioles are the blood vessels that are primarly responsable for the vasculr shunt system
- always in the state of slight contraction
venous return mechanisms
- pocket valve - prevent backflow by shutting when heavy, open when new rush
- muscle pump- muscles contract and relax they press on nearby veinsand squeezes blood back to heart
- repiratoty pump - - muscles contract causing pressure change in abdominals and thoracic - press on nearby veins
- smooth muscle - thin layer of muslce that squeezes blood back
- gravity - blood coming from head
- suction pump - fluid runs through vein natrually pulls more fluid
oxyhaemoglobin dissociation
- is when oxygen goes from oxyhaemoglobin to muscles
- during exercise - 3% oxygen goes to plasma, 98% combines with haemoglobin
- carries 4 oxygen molecules
- occurs when partial pressure in the blood is high
- oxygen is stored in myoglobin - higher affinity for oxygen
bohr shift
- as partial pressure of oxygen drops in the tissues - Co2 increased partial pressure - blood becomes acidic
- diffusion gradient becomes bigger - oxygen is realised from haemoglobin quicker
- when body is warmer blood is less viscous
- 3 factors that increase dissociation;
1. increase in blood temp - blood and muscles temp increase, oxygen will dissociate quickly
2. partial pressure co2 increases - dissocate quicker
3. pH - co2 lowers pH in blood, dissociate quicker (bohr shift)
arterio-venous difference (A-VO2)
- the difference between the oxygen content of the arterial blood arriving at the muscle and the venous blood leaving the muscles
- during exercise there is a bigger difference between the volume of oxygen going into the muscles than coming out of the veins compared to at rest - less of a difference
- trained athletes have more myoglobin so they will have a greater difference
