AQA 8461 · Topic 2 · Organisation
The heart, heart disease and how your body is organised
Poke the diagram, sort the terms and test yourself. Each lesson is short, and you can check your understanding as you go.
You will be able to
- Explain how cells, tissues, organs and organ systems fit together
- Label the heart and trace blood through it
- Link the structure of arteries, veins and capillaries to their jobs
- Describe what blood is made of
- Explain coronary heart disease and evaluate its treatments
- Tell correlation from causation when looking at risk factors
Other topics
Prototype. Content is written to match the AQA specification but always check against your own notes and the official specification.
Lesson 1
Levels of organisation
Living things are built in layers. Each layer is made of the one below it, and the heart is a good example of that.
- CellBasic building block, e.g. a cardiac muscle cell
- TissueA group of similar cells working together, e.g. cardiac muscle
- OrganA group of different tissues working together, e.g. the heart
- Organ systemA group of organs working together, e.g. the circulatory system
- OrganismAll the organ systems together: you
The heart is an organ made of several tissues: muscle tissue that contracts to pump blood, connective tissue, and epithelial tissue lining the chambers. With the blood vessels and the blood it forms part of the circulatory system.
Try it: which level is it?
Pick a level for each item. A wrong answer is greyed out so you can try again.
Lesson 2
The heart
The heart is a muscular organ that pumps blood. It is really two pumps in one: the right side sends blood to the lungs, and the left side sends it around the body.
Blood passes through the heart twice on every full trip around the body. The right side pumps deoxygenated blood to the lungs. The left side pumps oxygenated blood to everything else. Going back to the heart after the lungs lets the blood be pumped out again at high pressure.
Explore the heart
Drawn as if you are facing the person: their right side is on your left. The thicker the outline, the thicker the muscle wall.
A group of cells in the right atrium controls the natural resting heart rate. If it goes wrong, doctors can fit an artificial pacemaker to correct an irregular heartbeat.
Arteries carry blood away from the heart, veins carry it towards the heart. It is not about oxygen. The pulmonary artery carries deoxygenated blood and the pulmonary vein carries oxygenated blood.
Follow the blood
Blood has just come back from the body. Tap the stages in order, starting with the vena cava.
Lesson 3
Blood vessels and blood
Three types of vessel carry the blood, and each one is built for its job.
Compare the vessels
Try it: which vessel?
rate = volume ÷ time (for example cm³ per minute)
What is in blood?
Lesson 4
Coronary heart disease
The heart muscle needs its own supply of oxygen, delivered by the coronary arteries. When these narrow, the heart is in trouble.
Layers of fatty material build up inside the coronary arteries. The lumen narrows, so less blood and less oxygen reach the heart muscle. A complete blockage causes a heart attack.
Try it: block an artery
Treatments
Know what each does and one advantage and one disadvantage. Exams love "evaluate".
If the heart cannot cope, a donor heart can be transplanted, or an artificial heart can keep someone alive while they wait for a donor. Faulty valves can be replaced with biological valves (from animals or human donors) or mechanical valves.
Lesson 5
Health and risk factors
Coronary heart disease is a non-communicable disease. Where does it come from, and how do scientists know?
Health
The state of physical and mental wellbeing, not only the absence of disease.
Communicable disease
Caused by pathogens and can be passed from person to person (e.g. measles).
Non-communicable disease
Not caused by pathogens and not passed on (e.g. coronary heart disease, most cancers, type 2 diabetes).
Risk factors
A risk factor is something linked to an increased chance of getting a disease. Some directly cause it, others are only linked.
- Smoking: cardiovascular disease, lung disease, lung cancer
- Obesity: cardiovascular disease, type 2 diabetes
- Alcohol: liver disease, brain damage
- Poor diet / lack of exercise: obesity, cardiovascular disease
- Carcinogens and ionising radiation: cancers
Diseases can affect each other. Physical ill health can lead to mental ill health. Some viruses living in cells can trigger cancers. Immune reactions to pathogens can trigger allergies such as asthma.
Non-communicable diseases cost individuals (lost income, quality of life) and health services (treatment, long-term care) and are important at local, national and global levels.
Try it: correlation or cause?
A correlation means two things happen together. It does not prove one causes the other. A causal link needs a mechanism or strong evidence.
Lesson 6