heart Flashcards
what are the internal structures of the heart ?
- left & right ventricles
- left & right atria
- AV valves
- Semilunar valves
what are the AV valves ?
- tricuspid valve (right)
- bicuspid valve (left)
what are the semilunar valves ?
- pulmonary valve (right)
- aortic valve (left)
what are the external blood vessels of the heart ?
- vena cava
- pulmonary artery
- pulmonary veins
- aorta
what does the cardiovascular system refer to ?
heart
blood
blood vessels
what are the 2 circuits of the heart ?
pulmonary circuit
systemic circuit
what is the pulmonary circuit ?
circulation of blood through the pulmonary artery to the lungs and pulmonary vein back to the heart
what is the systemic circuit ?
circulation of blood through the aorta to the body and vena cava back to the heart
what is the coronary circulation composed of ?
coronary arteries
coronary veins
what is the dual action pump ?
2 heart sides/ pumps
why does the left side of the heart/cardiac muscle thicker ?
so it can forcefully contract to circulate oxygenated blood through the systemic system to the muscles and organs
what do the atrioventricular valves consist of ?
bicuspid
tricuspid
what do the atrioventricular and semilunar valves do ?
prevent backflow of blood
what does the right side of the heart circulate ?
deoxygenated blood
where does deoxygenated blood enter the heart ?
vena cava
what is oxygenated blood ?
blood saturated with oxygen and nutrients such as glucose
what is deoxygenated blood ?
blood depleted of oxygen saturated with carbon dioxide and waste products
describe the pathway of blood
body
vena cava
right atrium
tricuspid valve
right ventricle
semilunar valve
pulmonary artery
lungs
pulmonary vein
left atrium
bicuspid/mitral valve
left ventricle
semilunar valve
aorta
back to body
what does myogenic ?
the capacity of the heart to generate its own electrical impulse which causes the cardiac muscle to contract
what is the conduction system ?
a set of structures in the cardiac muscle that create and transmit an electrical impulse, forcing the atria and ventricles to contract
what are the steps in the conduction system ?
- SA node - initiates cardiac impulse
- Passes over both atria walls
- Causes atria to contract
- Impulse recieved by AV node
- Impulse conducted down bundle of his / purkinje fibres
- impulse travels up perkinje fibres
- causes ventricles to contract (ventricular systole)
- diastole (heart fills with blood)
what is the SA node ?
generates electrical impulses, causing atria walls to contract
what is the SA node known as ?
the pacemaker, determines heart rate
what is the AV node ?
collects the impulse and delays it by 0.1 seconds to allow the atria to finish contracting
what is the bundle of his ?
located in the septum, splitting the impulse into 2, ready to be distributed to ventricles
what are bundle branches ?
carry impulses to the base of each ventricle
what are Purkinje fibres ?
distribute the impulses through the ventricle walls, causing them to contract
what is diastole ?
the relaxation phase of the cardiac muscle where chambers fill with blood
what is systole ?
conduction + CONTRACTION phase of cardiac muscle where blood is ejected into the aorta and pulmonary artery
what is the cardiac cycle ?
events of one heart beat
how long does a complete cardiac cycle take ?
0.8 seconds
what are the 2 phases of the cardic cyle ?
systole
diastole
how long does diastole take ?
0.5 seconds
what happens during diastole ?
- relaxation of atria and ventricles means lower pressure in heart
- blood fills atria increasing atrial pressure above ventricle pressure
- blood is forced past AV valves so blood moves into ventricles (70 % of blood)
how long does systole take ?
0.3 seconds
what are the 2 contraction phases of systole ?
- atrial
- ventricular
what happens during atrial systole ?
both atria contract forcing the remaining 30% blood past AV valves into both ventricles
- aortic and pulmonary valves are closed
what ha[[ens during ventricular systole ?
- both ventricles contract forcing blood up past aortic and pulmonary valves
- diastole phase begins cycle again
- aortic and pulmonary valves close
what is stroke volume ? (SV)
the amount of blood ejected from the heart ventricles per beat
what is the typical resting volume of stoke volume ?
65- 70 ml
what is heart rate
the number of heart beats per minute
what is the typical resting heart rate (HR) ?
72 bpm
what is cardiac output (Q) ?
the volume of blood ejected from the heart ventricles in 1 minute
when calculating what units do we always use for cardiac output ?
L/Min
how do you calculate cardiac output ?
SV X HR
what is the trained individual SV ?
80/85 ml
what is the trained individual HR ?
60 bpm (or less)
what is the trained individual Q ?
5 Lmin
what is bradycardia ?
a resting HR below 60 bpm
how do you calculate maximum HR ?
subtract age from 220
what indicates high aerobic fitness ?
low resting hr
fast hr recovery after exercise
how low a heart rate could elite trained athletes have ?
40/60 bpm
what does hypertrophy do ?
increase SV due to increase in size and strength to heart muscle wall
what is our max heart rate ?
the highest heart rate value one can achieve in an all out effort to the point of exhaustion
a HR plateau is reached during a constant rate of what ?
sub maximal work
how is a HR plateau achieved ?
by aerobic work where 02 supply is equal to the demand from muscles
what does a HR plateau represent ?
the optimal hr for meeting the circulatory demands at the rate of work
the lower the steady state hr for any level of work, the what ?
more efficient the heart
when we start to exercise, what happens to the demand of oxygen we need for our muscles ?
it increases rapidly
how is hr proportional to the intensity of exercise ?
it increases as intensity increases until we reach HR max
what is the stroke volume response during exercise ?
- SV increases linearly with increasing work but only up to intensities if 40%-60% max work
what happens to SV after 40%-60% max work ?
SV values plateau and may even fall while HR continues to increase
when are maximal SV volumes reached ?
during submaximal work
SV increased from 70ml (average) at east to max values of what during exercise ?
120/140 ml per beat during exercise
what is the reserve ESV used during exercise for ?
to allow SV to increase
what is ESV
end systole volume
what is EDV ?
end diastole volume
what is the equation relating ESV EDV and SV
EDV - ESV = SV
what are the submaximal values for HR, SV, Q ?
HR - 120-150
SV - 120/140 ml
Q - 15-20 l
what is the cardiac output (Q) response during exercise ?
if SV x HR = Q, Q also increased directly in line with exercise intensity
the resting values if 5 l min go to what for cardiac output during exercise ?
5 L min to 20 L min
for elite endurance athletes what can their cardiac output reach during exercise ?
40 l min
why does Q initially increase during exercise ?
due to increase in HR and SV
when exercise intensity exceeds 40%-60% of max work rate any further increases in Q is due to what ?
HR rather than SV
why does SV as HR increases ?
there is less time for diastole and for blood to fill
what is starlings law ?
SV is dependent on venus return - venus return increased in exercise so stroke volume and cardiac output increases so more blood can return to the heart
what happens at rest ( starlings law and sv )
less blood returns to the heart
sv is lower (70ml)
explains what happens during exercise to sv (starlings law)
more blood reigned to the heart (increases VR)
causes a greater EDV - stretches and enlarges ventricle walls
greater stretch and recoil increased the force of ventricular contraction (systole)
increases ventricular contractility almost emptying all the EDV and increasing SV
stroke volume at rest normal
65/70 ml
stroke volume at rest value trained
80/85 ml
stroke volume sub max value / normal
80/100 ml
stroke volume sub max values trained
160/200ml
stroke volume max value normal
100/120 ml
stroke volume trained value max
160/200 ml
heart rate resting value - trained
70/72 bpm
heart rate resting value trained
<60 bpm
heart rate sub max value
up to 100/130 bpm
cardiac output rest - trained and normal
5 L min
cardiac output sub max value
10/15 Lmin
cardiac output max value
20/40 Lmin
what happens to heart rate and cardiac output prior to exercise
anticipatory rise
increase slightly in heart rate
how does an anticipatory rise occur
- adrenalin is released and directly stimulates the SA node to increase heart rate
what happens at the start of exercise to heart rate and cardiac output
it increases rapidly
why does cardiac output and heart rate increase rapidly as exercise starts
1- neural system stimulates medulla oblongata
2- proprioreceptors detect motion
3- chemoreceptors detect change in pH levels and oxygen increase and carbon dioxide decrease
4- baroreceptors detect initial increase in blood pressure
5- increased release of adrenaline
what happens at sub maximal work to heart rate and cardiac output
it plateaus
heart rate at 150bpm
cardiac output at 15 /20 Lmin
what happens to cardiac output and heart rate at maximal values
continued increase but slower to maximal values
heart rate at 180 bpm
cardiac output at 40 Lmin
why does heart rate and cardiac output plateau at sun maximal work
- temperature increases and VR
- maintained BCP stimulation
- maintained release of adrenaline and supply of oxygen to meet the sub maximal demand by the muscles
why do heart rate and cardiac output values continue to increase at maximal work
- increase in bcp stimulation
- increase in adrenaline
- increase in temperature /vr
- increased oxygen demand from maximal work intensity
what happens to heart rate and cardiac output during recovery
- rapid decrease as exercise stops
why is there a rapid decrease in cardiac output and heart rate as exercise stops
- due to a decrease in all factors
- causes heart rate/cardiac output to decrease
- decrease in bcp stimulation to medulla
- decrease adrenaline
- decrease vr/temperature
what happens to heart rate and cardiac output later in recover
there’s a slower decrease in heart rate and cardiac output towards resting values
this takes longer in maximal intensity work
why is there a slower decrease in heart rate/ cardiac output at immediate recovery
- to repay oxygen debt (epoc)
- elevated heart rate/q needed to remove lactic acid and carbon dioxide and to replenish oxygen, atp and pc stores
where is the regulation of heart rate / cardiac control center/ autonomic nervous system located in the brain
medulla oblongata
what are the 3 neural receptors of the brain
- baro receptors
- proprioreceptors
- chemoreceptors
baroreceptors
- stretch receptors
- increase blood pressure
- lungs
proprioreceptors
involved in motor movement
chemoreceptors
- detect changes in oxygen levels, carbon dioxide and pH
what is part of the intrinsic system
- venous return
- temperature
(thermoreceptors)
what is part of the intrinsic system
- venous return
- temperature
(thermoreceptors)
hormonal system
adrenaline
involved in anticipatory rise
what does adrenaline do
directly stimulate the sa node to increase heart rate
how can recovery happen with help of the para-sympathetic nervous system
- vagus nerve stimulated the sa node to decrease heart rate and stroke volume
- decreasing cardiac output
how can the sympathetic nervous system increase cardiac output
the cardiac nerve stimulates the sa node to increase heart rate and stroke volume
