Biology AS AQA Unit 1 The Heart and Heart Disease

Made these notes for my year 12 summer exam to revise and read over. There are spelling mistakes in most of my files but due to the busy exam schedule I had no time to correct them (sorry).

Most files have more information than what is needed but I feel it helps you feel more confident walking into the exam if you have a greater knowledge background and may help when having to apply knowledge to questions. Good luck :)

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  • Created by: Chelcie
  • Created on: 02-09-13 12:39
Preview of Biology AS AQA Unit 1 The Heart and Heart Disease

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The Heart and Heart Disease
Mammals need a double circulatory system for the heart to increase the blood pressure before it is
distributed to the rest of the body.
ATRIUM
It is a thin walled and elastic and stretches as it collects blood.
Pumps blood to the ventricles and therefore has a thin muscular wall.
VENTRICLE
Thicker muscle wall as has to pump
blood to lungs or rest of body.
LEFT ATRIOVENTRICULAR
(BISCUSPID) VALVES
RIGHT ATRIOVENTRICULAR
(TRICUSPID) VALVES
PULMONARY VESSELS
Vessels connecting the heart and the
lungs
AORTA
Connected to the left ventricle and
carries oxygenated blood to all parts
of the body except the lungs
VENA CAVA
Connected to the right atrium and
brings deoxygenated blood from the
tissues
PULMONARY ARTERY
Connected to the right ventricle and carries deoxygenated blood to the lungs
PULMONARY VEIN
Connected to the left atrium and brings oxygenated blood back from the lungs
SUPPLING THE HEART MUSCLE WITH OXYGEN
CORONARY ARTERIES branch off the aorta and supply the heart with oxygen.

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DIASTOLE (Relaxation)
Blood returns to the atria of the heart through the pulmonary vein and the vena cava.
The atria fill; pressure rises pushing open the atrioventricular valves and allowing blood to
pass through to the ventricles.
The muscular walls of atria and ventricles are both relaxed.
This causes the pressure to be lower in the aorta and the pulmonary artery, so the semi
lunar valves in the aorta and the pulmonary artery closes.…read more

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HOW IS THE CARDIAC CYCLE CONTROLLED?
Muscle is MYOGENIC (contraction is initiated within the muscle itself) rather than neurogenic
(nervous impulse from the outside causing the contraction)
1. A wave of electrical activity is INITIATED from the sinoatrial node (SAN) (the pacemaker)
across both Atria causing them to contract.
2. A layer of non-conductive tissue (the atrioventricular septum) prevents the wave
crossing to the ventricles.
3. The wave of electrical activity then passes through the atrioventricular node (AVN) which
lies between the atria.
4.…read more

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CHD
CHD affects the coronary arteries which supply the heart muscle with glucose and oxygen that is
required for respiration.
ATHEROMA
Atheroma is a fatty deposit that forms WITHIN THE WALL of an artery.
It begins as fatty streaks of accumulated white blood cells that have taken up low-density
lipoproteins (LDLs)
The streaks enlarge to form an atheromatous plaque.
Atheromatous plaques are made up of deposits of cholesterol, fibres and dead muscle cells.…read more

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Aneurysms frequently burst forming a haemorrhage and therefore loss of blood to the region
served by that artery.
A brain aneurysm is known as a cerebrovascular accident (CVA) or a stroke.
MYOCARDIAL INFARCTION
Heart attack
Blockage in the coronary artery causing the heart to stop beating as the blood supply is cut off.
RISK FACTORS ASSOCIATED WITH CHD
SMOKING
Carbon monoxide: combines easily but irreversibly with haemoglobin forming
carboxyhaemoglobin. This reduces the capacity of oxygen that can be carried by the blood.…read more

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