A

Antibody A substance carried in the blood that helps destroy germs.

Aorta The largest artery in the body. It carries oxygen-rich blood away from the heart and towards other parts of the body.

Appendix A small tube attached to the large intestine. The appendix is thought to play a part in the body’s defence system against germs.

Artery A blood vessel that carries blood away from the heart. Most arteries carry oxygen-rich blood to other parts of the body. The pulmonary artery, which runs from the heart to the lungs, carries oxygen-poor blood.

B

Backbone The column of bones, called vertebrae, that runs the length of the back. It supports the body and protects the spinal cord. The backbone is also known as the spine or vertebral column.

Bacterium (plural: bacteria) A tiny organism made of just one cell. Some bacteria invade living things and cause diseases, but most types are harmless.

Ball-and-socket joint A type of joint that allows bones to move in any direction. The round end of the bone sits in the joint like a ball in a cup. The hips and shoulders are both examples of ball-and-socket joints.

Bile A thick, greenish fluid that helps break down fat in food. Bile is produced by the liver and is stored in the gall bladder.

Bladder The organ that collects and stores urine after it leaves the kidneys.

Blood A fluid that carries oxygen and nutrients to the body’s cells and removes their wastes. It contains several different types of cells: red blood cells, white blood cells and platelets. Pumped by the heart, blood travels through a network of blood vessels to all parts of the body and then back to the heart.

Bone marrow The jelly-like substance in the middle of bones. Red bone marrow makes new blood cells. Yellow bone marrow stores fat and minerals.

Bones Hard, strong parts that fit together to make the body’s basic framework: the skeleton. Bone is made of living cells, surrounded by hard minerals. Bones support the body’s weight and give it shape, protect its internal organs, and work together with the muscles to make the body move.

Brain The large organ inside the skull that controls our feeling, thinking, moving and breathing. The brain and spinal cord are linked to the rest of the body by cable-like nerves, which carry messages in both directions. The brain, spinal cord and nerves make up the nervous system.

Brain stem The part of the brain that links it to the spinal cord.

Bronchus The airway that connects each lung to the trachea (windpipe). Inside the lungs, the bronchi divide into smaller bronchi.

C

Canines The four pointed teeth near the front of the mouth, used to grip food.

Capillary The smallest type of blood vessel. The walls of capillaries are so thin that oxygen and other nutrients can seep through them into the body’s cells.

Carbohydrates Types of nutrients that include starch, found in bread, pasta, potatoes and rice, and energy-rich sugars such as glucose.

Carbon dioxide A waste gas produced by cells as they release energy from glucose. It is carried in the bloodstream to the lungs, where it is breathed out.

Cartilage A strong, flexible tissue that covers and cushions the ends of bones. Some body parts, such as the outer ear, are shaped by cartilage.

Cell The basic “building block” of the body. There are over 200 kinds, such as blood cells, nerve cells and muscle cells. They vary in size and shape, but nearly all are far too small to see without a powerful microscope. At the heart of the cell is the nucleus, which controls the rest of the cell. Coiled up inside the nucleus are strands of a substance called DNA.

Cochlea A tiny, coiled tube in the inner ear. It contains a fluid that ripples as sound vibrations pass through it. "Hairs" detect the movement and send signals to the brain.

Colon The main part of the large intestine. Here, water is taken into the blood from watery, undigested food. The remaining waste (faeces, or poo) is pushed towards the rectum.

Cornea The transparent dome at the very front of the eye. The cornea does most of the work of focusing light on the retina at the back of the eye.

D

Dentine A hard, yellowish, bone-like material inside teeth.

Dermis The lower layer of skin. It contains blood vessels, nerve endings and hair roots.

Diaphragm The sheet of muscle beneath the lungs that helps breathing.

Digestion The process of taking in food and breaking it down into nutrients that can be absorbed into the blood and used by the body. The mouth, oesophagus, stomach and intestines make up the digestive system.

DNA (Deoxyribonucleic acid) A chemical in the nucleus of each cell that can copy itself, and carries the instructions (genes) needed to build and run a cell. The DNA molecule looks like a twisted ladder, with two strands linked by “rungs”.

E

Ear bones Three tiny bones in the middle ear, also known as the ossicles. They are: the malleus (hammer), attached to the eardrum, the stapes (stirrup), attached to the inner ear and the incus (anvil), which connects the two.

Eardrum A thin piece of skin stretched tight between the middle and outer ear. When sounds hit the eardrum it vibrates, transmitting sound waves to the ear bones.

Ears Organs that detect sound, positioned on either side of the head. Ears collect sounds from the air, and change them into nerve signals, which are sent to the brain. They also help the body to balance.

Embryo An unborn baby in its first eight weeks inside the womb. During this period, all of the main body parts and organs, such as the brain, heart, eyes, ears and toes form.

Enamel The hard white coating on the outside of teeth. Enamel is the hardest substance in the body.

Epidermis The upper layer of the skin. It constantly renews itself as dead cells are worn away.

Epiglottis A flap of cartilage attached to the top of the larynx in the throat. It stops food from entering the trachea (windpipe) during swallowing.

Eyes Two round organs at the front of the head. They detect light and convert it to nerve signals which are sent to the brain.

F

Faeces Solid food waste that cannot be digested. This is mostly vegetable and fruit fibre and harmless bacteria.

Fats Types of nutrients found in meat, fish, dairy products, nuts and some fruit and vegetables. They are also known as lipids.

Fertilization The coming together of a sperm and an egg. A fertilized egg is ready to grow into a baby.

Fibre The part of fruit and vegetables that the body cannot digest.

Foetus An unborn baby after its eighth week in the womb until it is born.

G

Genes A set of instructions that tell the body how to grow and maintain itself. Genes are contained within DNA.

Germs The microscopic bacteria, viruses, fungi and protozoa that can cause disease. They are also called pathogens.

Gland An organ that produces a substance needed by the body, such as tears or saliva.

Glucose The main source of energy for the body. It is released from carbohydrates in food during digestion and stored in the liver in the form of glycogen.

Gum The pink tissue that forms a tight seal around the teeth.

H

Hair A thread-like strand growing from the skin. Hair consists mainly of dead cells packed with tough, waterproof keratin. Living cells at the bottom of the hair root make the hair grow.

Heart A large organ in the chest that pumps blood around the body.

Hinge joints A type of joint that allows bones to move like opening and closing a door. The elbow is a type of hinge joint.

Hormones Chemical messengers carried in the bloodstream. They control body activities such as growth and reproduction.

I

Incisors The thin, sharp teeth at the front of the mouth. During chewing, they come together like scissors to cut up food.

Infectious disease A disease caused by germs entering and multiplying inside the body. Some infectious diseases, including cold, flu and measles, can be passed on from person to person.

Intestines The continuous tube linking the stomach to the rectum. It is divided into the small intestine and the large intestine.

Iris The coloured part of the eye. It is a ring of muscle that controls the amount of light that enters the eye by changing the size of the pupil.

JK

Joint The place where two or more bones meet. Joints allow the skeleton to move.

Kidneys A pair of organs that take out wastes, excess water and salts from the blood to make urine.

L

Larynx The small organ, also known as the voice box, that enables us to make sounds. It sits at the top of the trachea (windpipe), where it contains the vocal cords.

Ligament A strap that holds two bones together at a joint.

Liver A large organ that takes in nutrients from the small intestine. The liver also removes poisonous substances from the blood.

Lungs The two spongy organs in the chest, through which oxygen enters the bloodstream.

M

Minerals Chemicals that are needed by the body. For example, calcium, needed for healthy teeth and bones, is found in milk, cheese and vegetables.

Molars The wide teeth at the back of the mouth, used to crush and chew food.

Muscles Tissues made up of long cells that are able to contract (shorten) in order to create movement. Skeletal muscles are attached to bones and work together to move body parts, such as the arms or legs, in different directions. The walls of body organs also contain muscle tissue. For example, muscle in the walls of the heart enables it to pump blood.

N

Nail A hard, flat plate, made of keratin, that protects the ends of toes and fingers.

Nasal cavity The large space behind the nose, divided into two passageways, each connecting one nostril to the throat.

Nerve A bundle of cells, called neurons, that relays signals between the brain (or spinal cord) and the body.

Nervous system The network made up of the brain, spinal cord and nerves.

Neuron An individual nerve cell.

Nutrients Substances in food, including carbohydrates, proteins, fats, vitamins and minerals, that humans and other living things need to live and stay in good health.

O

Oesophagus The tube through which food passes from the mouth to the stomach.

Organ A structure that does a particular job in the body. The brain, stomach, heart and skin are all examples of organs.

Ovaries Two female reproductive organs that produce eggs, or ova.

Oxygen A gas that is needed by the body's cells to release energy from food.

P

Pelvis A bowl-shaped ring of bones consisting of two hip bones joined to the bottom of the backbone.

Placenta An organ that develops in the uterus (womb) during pregnancy. It provides the foetus with nourishment and oxygen via the umbilical cord.

Platelets Tiny fragments of cells found in the blood. When a blood vessel is damaged, they collect at the wound, stick together and help form a clot. This prevents blood loss or infection by invading bacteria.

Premolars The flat, broad teeth between the canines and the larger molars. Premolars are used for grinding food.

Proteins A group of nutrients obtained from food and needed by the body. Foods rich in protein include meat, poultry, fish, beans and nuts.

Puberty The period when a child’s body develops so that it is able to reproduce. This usually takes place between the ages of 11–14 in girls and 13–16 in boys.

Pulp The soft tissue at the centre of teeth. It contains nerves and blood vessels.

Pulse The beat felt in the arteries as blood is pushed through them. Each beat is caused by the heart squeezing and relaxing once. The number of pulses felt per minute is called the pulse rate. You can feel your pulse by placing your fingers on the inside of your wrist, where an artery passes just under the skin.

Pupil An opening in the iris, through which light enters the eye. The pupil varies in size to control the amount of light reaching the retina. It shrinks in bright light and grows larger in dim light.

R

Rectum The last part of the large intestine, in which faeces (poo) are stored before they are passed out of the body when you go to the toilet.

Respiration Breathing, the process that takes oxygen into the body and gets rid of waste carbon dioxide. Breathing in draws air into the lungs, where oxygen passes into the bloodstream and is carried to every cell in the body. Meanwhile, the bloodstream transports carbon dioxide in the opposite direction, from the cells to the lungs, where it is breathed out. Breathing out also enables us to speak.

Retina The layer that lines the inside of the back of the eye and is sensitive to light.

S

Saliva A slippery liquid that makes food moist and easier to swallow.

Senses The means by which the body can detect what is happening in the outside world. There are five main senses: sight, hearing, taste, smell and touch.

Skin The outer covering of the human body. Tough, waterproof and germ-proof, skin protects the body’s insides. It also filters the sun’s harmful rays and enables the brain to detect touch and pain.

Skull A strong, bony structure that supports and protects the brain, and shapes the head and face.

Small intestine A long tube linking the stomach to the large intestine, or colon. Here nutrients are taken into the bloodstream.

Sperm Tiny, tadpole-like male sex cells. They each have a compact "head" and a long, beating flagellum ("tail").

Spinal cord A column of nerves that runs from the brain down the back, protected by the backbone.

Stomach The organ where digestion begins. Its muscular walls churn food into a creamy paste.

Sweat Watery fluid produced by sweat glands and released through pores (tiny holes) in the skin. Sweat helps the body to cool down. When it evaporates (turns from a liquid into a gas), it takes some of the body’s heat with it.

T

Taste buds Clusters of taste-detecting cells on top of the tongue. Five tastes—sweet, sour, salty, bitter and umami (meaty)—can be detected.

Tears A salty liquid that keeps the eyes moist and clean. Tears are made in glands above the eyes and drain from the eye into the nose.

Tendon A tough cord that attaches a muscle to a bone. Bones are moved when muscles pull on tendons.

Tissue Groups of cells that are similar to one another. They make up the organs, muscles, bones and other parts of the body.

Tongue A muscular organ partly attached to skull bones. The tongue tastes food, and helps to move it around the mouth. It also helps us to form words during speech.

Tonsils Tissue at the back of the mouth at the entrance to the throat. The tonsils help to trap and kill germs.

Trachea The airway connecting the lungs to the larynx (voice box). Air flows through it to and from the mouth and nose.

U

Umbilical cord A cord containing blood vessels that connects a foetus to the placenta during pregnancy. The foetus receives food and oxygen through it.

Ureters The tubes through which urine passes from the kidneys to the bladder.

Urethra The tube through which urine passes from the bladder out of the body.

Urine A mixture of water, salts and waste substances, produced in the kidneys. It is stored in the bladder before being expelled from the body when you pee.

Uterus Also known as the womb, an organ in a woman’s body in which a baby develops during pregnancy.

V

Vaccination A treatment that prevents disease by injecting the body with a harmless version of a germ, which the body learns to recognize. If the body later encounters the actual germ, it will then destroy it before it can cause harm.

Vein A blood vessel that carries blood towards the heart. Most veins carry blood low in oxygen from the body's cells to the heart. The pulmonary veins, which run from the lungs to the heart, carry blood that has just been enriched with oxygen.

Vertebrae The 26 separate bones that fit together as a column to make the backbone. Discs of cartilage cushion them so that the backbone can bend.

Vitamins Essential nutrients that are needed in small amounts to make the body work properly and stay healthy. For example, vitamin A, found in leafy green vegetables and carrots, is important to eyesight and skin. Eggs and fish are rich in vitamin D, which is needed for strong bones.

X

X-ray A technique that uses radiation to produce an image of the inside of the body. X-rays can, for example, reveal a broken bone, or show if the lungs are infected.

Consultant: Kristina Routh