Anatomy dictionary

Using this dictionary

This dictionary gives a brief overview of some body organs and systems.

• First point tells you what it does and how it works
• Second point tells you about things that can make it stronger or weaker
• Third point tells you how it is affected by medicines or other drugs

Brain

• The brain is the centre of the nervous system and controls all other organ systems in the body through electrical impulses or chemicals
• Affected by diseases such as epilepsy and mental illnesses (eg depression, schizophrenia). Damaged by impact (injury), lack of blood supply, chemicals in the blood (eg alcohol). Exercise helps keep a good blood supply to the brain and can improve depression
• Some medicines alter messages being sent within, and to and from the brain (eg pain messages). Medicines can help to control seizures, relieve anxiety and depression, make you sleep

Central nervous system (CNS)

• CNS is made up of the brain and spinal cord. Operates using electrical impulses or chemicals so all parts of the body can communicate
• Damaged by injury and infection. Damage can result in paralysis if messages from the brain can't pass along spinal cord
• Drugs such as alcohol and opioids can depress (slow) CNS so that the heart, breathing, or movements may slow or stop altogether. Some medicines act by stimulating or depressing the CNS or reducing pain messages

Heart

• The heart is a muscle that contracts regularly to pump blood around the body
• Regular exercise makes the heart strong. Damaged or weakened by smoking, lack of physical activity, fatty and/or salty foods. Blockages that stop blood reaching it can cause a heart attack. Affected by cardiovascular diseases such as high BP, problems with rhythm (arrhythmia), diabetes
• Medicines can help the heart by
• Evening out the heartbeat (antiarrhythmics)
• Thinning the blood (antiplatelets, warfarin)
• Opening up or relaxing blood vessels and lowering BP (antihypertensives)
• Removing excess fluid (diuretics)
• Lowering fat (lipids) in the blood 
• Dissolving blood clots or stopping blood clots forming (thrombolytics)

Blood — circulatory/cardiovascular system (CVS)

• CVS is made up of the heart and blood vessels (arteries, veins and capillaries)
• Good blood supply to all parts of the body needed for good health — blood provides nutrients and oxygen, removes waste. Damaged by smoking (kills small capillaries and blocks arteries), diabetes (damages walls of blood vessels), too much fatty food (blocks arteries)
• See Heart for how medicines affect the blood system

Lungs — respiratory system

• Lungs put oxygen into the blood so it is circulated around the body
• Badly damaged by smoke, dust, infections (eg pneumonia), especially during childhood. Affected by conditions such as asthma and COPD. Lungs are kept healthy with exercise, good hygiene, not smoking, keeping out of dust and fire smoke
• Medicines help treat lung infections (eg antibiotics), control asthma, help breathing

Stomach

• The stomach is the main organ in the digestive system. It begins breakdown (digestion) of food by churning it with enzymes and acid
• Damaged by infections that cause ulcers, too much acid, too much alcohol, some medicines
• Medicines treat infections and help stop the stomach producing too much acid (eg proton pump inhibitors). Some medicines (eg NSAIDs) must be taken with food so they don't damage stomach lining

Digestive system

• Digestive system breaks down food, provides nutrition for the body, removes waste. Includes mouth, oesphegus, stomach, intestines, rectum
• Doesn't work well if not enough fibre (eg fruit, vegetables, grains) in food eaten or if person eats too much. Bowel cancer is associated with obesity
• Medicines can help reduce acid in the stomach, and relieve nausea (antiemetics), constipation (laxatives), diarrhoea

Kidneys — urinary system

• Kidneys help remove waste from the blood and regulate the body
• Affected by repeated urinary tract infections, skin infections, high BP, diabetes, too much alcohol (grog), old age
• Can be badly damaged by taking too much of some medicines. Other medicines help damaged kidneys function better and remove waste from the body

Liver

• The liver cleans the blood and helps with digestion
• Badly damaged by too much alcohol (grog), infections (eg hepatitis), too much of some medicines (eg paracetamol)
• Medicines can help treat infections and improve functioning

Pancreas

• Pancreas makes hormones (eg insulin) and enzymes that help to break down food in the small intestine
• Damaged by too much alcohol, gallstones, infections (eg mumps). If pancreas can’t make enough insulin to break down sugar — person will develop diabetes
• Medicines can help increase the amount of insulin made by the pancreas to help control diabetes, and replace enzymes that break down food

Thyroid

• The thyroid is one of the largest glands in the body. Produces hormones that regulate metabolism and affect the growth and functioning of many other systems in the body
• Wrong amounts of thyroid hormones can make people very unwell
• Medicine (eg thyroxine) can help to control amount of thyroid hormone in the body

Reproductive system

• In women — vagina, uterus, ovaries. In men — testes, penis
• Damaged by infections, especially STIs. Problems for women include having trouble getting pregnant, bleeding, cancer
• Medicines can prevent pregnancy (eg the Pill), help to control bleeding and ovulation, and treat infection. Some medicines can harm production of sperm, others can harm an unborn baby

Musculoskeletal system

• Musculoskeletal system gives us shape, lets us move by contracting the muscles to pull the bones
• Affected by injuries that break bones or tear muscles, bone infections, arthritis, osteoporosis. Physical activity and good nutrition when young build strong bones and muscles
• Some medicines can help build bones, others can damage them. Medicines can help to relieve pain associated with arthritis and inflammation, and treat infections

Skin

• The skin is the largest body organ. It helps regulate temperature, protects the body from germs and fluid loss, and stores water, fat and vitamin D. It allows us to feel sensations
• Damaged by injuries (especially burns), too much sun, smoking. Affected by dermatitis, eczema, allergies, infections
• Medicines can treat infections, reduce inflammation and allergies (eg cortisone creams)

Ears

• The inner and outer ear let us hear by sensing movements in the air and converting them to signals that are sent to the brain. The inner ear also helps us to balance
• Structure of ear can be badly damaged by meningitis, chest and ear infections (especially when young) resulting in poor hearing, learning, language development
• Medicines can help treat meningitis, ear and respiratory infections

Eyes

• Eyes allow us to see by detecting light and converting it into a picture (image) in our brain
• Affected by allergies, infections, glaucoma. Badly damaged by too much sun (especially midday sun), diabetes, smoking, infections such as trachoma. Important to protect eyes by keeping them clean, out of bright light, eating good food, having regular eye checks
• Medicines can help treat eye infections, glaucoma, allergies

Nose

• The nose lets us smell and taste, cleans and warms the air we breathe in
• Allergies and infections can irritate lining of the nose causing swelling and blockages, make the nose run
• Medicines can treat allergies, or open a blocked nose (eg nasal sprays)