Biology Unit 1.5 Revision Notes (Heart)

I hope you find these useful!

Basically, I have divided my notes up into parts of the syllabus, so 1.1, 1.2, 1.3, 1.4 and 1.6 are separate documents, but are all on here.

The part of the syllabus relevant to these notes is on the cover page at the start of the notes.

Sorry for any spelling mistakes or anything :L.

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Heart The gross structure of the human heart and its associated blood vessels in relation to function.
Structure Pressure and volume changes and associated valve movements during the cardiac cycle.
Function Myogenic stimulation of the heart and transmission of a subsequent wave of electrical activity.

Roles of the sinoatrial…

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The valves only open in one way ­ whether they are open or
closed depends on the relative pressure of the heart
If there is higher pressure behind a valve, it is forced open
If there is higher pressure in front of the valve, it is forced

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Cardiac Output

Cardiac output is the volume of blood pumped by the heart per minute (measured in cm3 per
It is calculated with this formula:

Heart rate
o The number of heart beats per minute
o You can measure your heart rate by measuring your pulse
Stroke volume

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Pressure and Volume Graph of the Cardiac Cycle

Positio Explanation

Atrium is contracting ­ blood
A flows into ventricles

Ventricles start to contract ­
ventricular pressure exceeds
B atrial pressure, so
atrioventricular valve close
Pressure is higher in the
C ventricle than in aorta ­ blood is
pushed into…

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Atrium continues to fill with
blood from pulmonary vein;
F atrial pressure exceeds
ventricular pressure, so blood
flows from atrium to ventricle

Changing Heart Rate

Nervous Control:

To speed up heart rate:
o More impulses are sent down the accelerator nerve
o To the SAN
o Which send more impulses…

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The Atheroma as the presence of fatty material within the walls of arteries.
Biological The link between atheroma and the increased risk of aneurysm and thrombosis.
Basis of
Heart Myocardial infarction and its cause in terms of an interruption to the blood flow to heart muscle.
Risk factors associated…

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An atheroma plaque can rupture the
endothelium of an artery, damaging the artery
wall and leaving a rough surface
Platelets and fibrin accumulate at the site of
damage and from a blood clot (a thrombus)
The clot can cause a complete blockage of the
artery or can become dislodged…

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