The Human Heart Flashcards
The Cardiac Cycle 1/5
Cardiac muscle is relaxed (distole) the blood drains into the LA from the lungs along the PV
The Cardiac Cycle 2/5
Raising of the blood pressure in the LA forces the left AV valve to open
The Cardiac Cycle 3/5
Contraction (left atrial systole) of the left atrial muscle forces more blood through the valve
The Cardiac Cycle 4/5
As soon as the left atriole systole is over the left ventricular muscles start to contract (left ventricular systole)
The Cardiac Cycle 5/5
this forces the left AV valve closed and open the SL in the mouth of the aorta. Blood then leaves the LV along the aorta
What are the purkyne fibres
special muscle fibres that don’t contract but conduct electrical impulses
What are purkyne fibres responsible for
carrying the impulses from the atria to the ventricles
What is the vagus nerve
Decreases heart rate
What is the sympathetic cardiac nerves
Increase heart rate and force contraction
What does a ECG measure
measures the electrical activity of the heart
What does the P wave
Caused by the depolarisation of the atria, which results in atrial contraction (systole)
What does QRS wave measure
Caused by the depolarisation of the ventricles, which results in ventricular contraction
This is the largest wave because the ventricles have the largest muscle mass
What does the T wave
Caused by the repolarisation of the ventricles, which results in ventricular relaxation (diastole)
What is the cardiac output equation
Cardiac O = stoke volume x Heart rate
What does the cardiac output equation measure
Volume of the blood pumped out of the heart in 1 min
What is Tachycardia
When the heart beats too fast it is tachycardic
Explain the difference the thickness of the wall of the right atrium and the wall of the right ventricle
the the right ventricle has mare cardiac muscle to deal with the volume and pressure of the blood
the right atrium pumps blood to the right ventricle
the right ventricle pumps blood to the lungs
Explain why a blood clot in an artery leading to the brain could cause a stroke
reduced blood flow which resulst in less oxygen reaching the brain
reulsting in no areboic respiration= no atp which produces lactic acid
Bradycardia
When the heart beats too slow it is bradycardic
Ectopic heartbeat
This condition is caused by an early heartbeat followed by a pause
When do valves open
when the pressure is greater BEHIND them
When do valves close?
When the pressure is greater in FRONT
Remember valves stop the backflow of blood
Why do the AV valves open?
if you have a higher pressure in the atria compared to the ventricles that’ll cause the AV open
Why do the AV vavles close?
If you have higher pressure in the ventricles compared to the atrria
Why do the SLV open
when the pressure in the ventricles is much higher than the aorta
Why do the SLV close
when the pressure is higher in the arteris (aorta) compared to in the ventricles
Explain how a blood clot can cause a heart attack
. prevents oxygen reaching the heart cells
- This prevetns areboic respiration
- (cardiac) muscle { unable to contract / dies
Explain what is meant by the term myogenic
idea that stimulation generated from within (muscle)
idea that this results in depolarisation
Explain how an electrocardiogram (ECG) can be used to calculate a person’s heart rate
it shows electrical activity of the heart
-Identify one heart beat
-count the number of { these / peaks / eq } in a {set time /
stated time}
=obtain heart rate e.g. beats divided by
time ;
describe the pressure changes that take place
in the left ventricle during each stage of this cardiac cycle
-Pressure increases during atrial styole and ventricukar dystole
-Pressures increases during ventricular systole
and then pressure decrease
During this cardiac cycle, the changes in pressure that occur in the left atrium and
in the left ventricle are different.
pressure changes are smaller in the atrium than ventricle
- The atrium has less cardiac muscle than the ventricle
- The atrium does not have to push the blood as far as the ventricle has to
- the increase in pressure happens inthe atrium before the ventricle
