abdomen

1 the front part of the body below the chest and above the pelvis. It contains the stomach and several other organs, including the intestines and the liver. noun [count]

2 the back part of the three parts into which the body of insects or some other arthropods is divided. The other parts are the head and the thorax. noun [count]

In a test called amniocentesis, a fine needle is passed through the abdomen of a pregnant woman into the amnion.

Grasshoppers and other insects have breathing holes along the sides of their abdomen.

absorb

1 to absorb liquid into a living cell through its cell membranes, for example by osmosis. noun [uncount]

2 to take in nutrients through the walls of the intestines into the blood

Root hairs absorb water containing plant nutrients.

Special lymph cells in the small intestine absorb fats.

anus

the opening at the end of the alimentary canal through which solid waste passes out of the body. noun [count]

Undigested food is passed out through the anus as faeces.

bladder

the part inside the body like a bag where urine collects before being passed out of the body through the urethra.

noun [count]

The ureter takes urine from the kidneys to the bladder.

blood

the red liquid that is pumped around the body from the heart. Blood carries oxygen, hormones, and nutrients to the various parts of the body, and also helps to get rid of waste products. It consists of plasma which contains red blood cells and white blood cells, and platelets. noun [uncount]

Oxygen is carried in the blood.

brain

1 the organ inside the skull in vertebrates that controls physical and nervous activity and intelligence. noun [count]

2 the place in the bodies of some invertebrates that is the main centre of nerve tissue. noun [count]

The illness had affected his brain.

The ‘brains’ of some invertebrates are no more than a network of nerve fibres.

breathe

to take air into the lungs through the nose or mouth and let it out again.

verb [intransitive/transitive]

We begin the exercise by breathing deeply (=breathing large amounts of air).

bronchial tube

one of the tubes in the chest through which air goes into the lungs.

noun [count]

In a mammal each lung is linked to the trachea by a bronchial tube.

bronchus

one of the two main tubes coming from the trachea that carry air into the lungs. It has many smaller tubes called bronchioles connected to it. (plural bronchi) noun [count]

carbon dioxide

the gas that is produced when humans and other animals breathe out and when fossil fuels are burned. It is used by plants in the process of photosynthesis. Carbon dioxide is a greenhouse gas. Chemical formula: CO2 noun [uncount]

Carbon dioxide dissolves in rainwater to form weak carbonic acid.

cell

the smallest unit from which all living things are made. All cells have a cell membrane, and plant cells also have a cellulose cell wall. A cell also has a nucleus that contains the organism’s genetic information, cytoplasm, and very small parts called organelles.

noun [count]

The brains of mammals contain millions of brain cells.

cell membrane

the outer layer surrounding the cytoplasm of all cells. The cell membrane controls which substances go in and out of the cell. noun [count]

New viruses burst out through the cell membrane, destroying the cell.

cellular

relating to the cells of living things. adjective

Oxygen is used up by cellular respiration.

cellulose

a substance that forms the walls of plant cells and plant fibres. It is insoluble in water, and is used to make plastics, explosives, paper, fabrics, and other products. noun [uncount]

Cows have micro organisms in their stomachs to help them digest cellulose.

cell wall

a strong layer that surrounds each cell in organisms other than animals, protecting them and giving them shape. In most plants, the cell wall is made of cellulose, and in fungi it is made of chitin.

noun [count]

Chlorella is a plant-like protist with a cellulose cell wall and a chloroplast.

chloroplast

the part of the cells of plants where photosynthesis takes place. It is shaped like a very small bag and it contains chlorophyll.

noun [count]

Each cell of Spirogyra has a spiral-shaped chloroplast.

chromosome

a structure that looks like a very small piece of string and that exists, usually as one of a pair, in the nucleus of all living cells. Chromosomes contain the genetic information that says whether a person, animal etc. is male or female and what characteristics they get from their parents. noun [count]

During cell division each chromosome makes an exact copy of itself.

circulatory

relating to the movement of blood around the body. adjective

Smoking can lead to circulatory problems.

cytoplasm

the substance inside the cells of living things, apart from the nucleus. It contains several different chemicals and structures. noun [uncount]

Many chemical reactions take place in the cytoplasm.

digest

to break down food in the alimentary canal into soluble substances that the body can absorb. verb [transitive]

Pepsin works in the stomach to digest protein.

digestion

the process by which food is broken down by the body into simple soluble substances that the body can absorb and then use for growth and as fuel for energy. noun [uncount]

Enzymes speed up the process of digestion.

digestive

relating to digestion. adjective

The digestive system is a tube running from the mouth to the anus.

duodenum

the first section of the small intestine, just below the stomach. noun [count]

The bile duct carries bile from the gall bladder to the duodenum.

enzyme

a protein produced by all organisms that behaves as a catalyst (=a substance that speeds up chemical reactions but does not itself change.) noun [count]

Each enzyme does a particular job, e.g. sucrase breaks down sucrose.

epithelial

relating to the epithelium. adjective

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