Specialised cells
Cells which are adapted to carry out a specific function in the body
Epithelial cells
Cells that cover the internal and external surfaces of organs
Cell membrane
The membrane which forms the boundary between the cytoplasm of a cell and the medium surrounding it and controls the movement of substances into and out of the cell.
Mitochondria
Organelle(s) within cells that produce ATP, used as a store of chemical energy. Often called the cell's powerhouse
Radiation
The emission of heat, light or other electromagnetic waves.
Receptors
Protein molecules attached to cells that only bind to specific molecules with a particular structure
Diffusion
The spreading out of the particles of a gas or any substance in solution down a concentration gradient
Pancreas
An endocrine gland which produces insulin
Vesicle
Small sac that stores or transports substances inside a cell
Membrane
A thin, flexible sheet-like structure that acts as a lining or a boundary in an organism.
Insulin
A hormone produced by the pancreas. It allows cells in the body to take in and store glucose.
Osmosis
The movement of water through a partially permeable membrane down a concentration gradient from a dilute solution (where there is a high concentration of water) to a concentrated solution (where there is a relatively low concentration of water).
Gland
A group of cells which produce and secrete a particular substance. Many glands pass their secretions into a tube or duct, whereas endocrine glands secrete hormones directly into the blood.
Nerve
A bundle of neurones - it may be all sensory neurones, all motor neurones or a mixture of both
Sperm
The male sex cell or gamete. The full name is spermatazoan, abbreviated to sperm cell or sperm.
Cell structure and transport
Humans are multi cellular organisms. That means they are made up of billions of individual cells. These cells are not all the same. There are many different cell types that are specialised to perform the range of functions needed in a complex organism.
Different types of cells
As new cells grow and replicate, they become specialised to do particular jobs. Nerve cells that carry electrical signals, muscle cells which generate force and pancreas cells making insulin are just a few examples. Amazingly, all of these cells have grown from just one single fertilised egg cell.
Ciliated epithelium
Many types of cancer, including those of the stomach, lung, skin and bowel, start off in epithelial cells. These cells line your organs and tissues and are exposed to environmental influences which, over time, can cause cancer to arise. For example smoking and lung cancer, ultraviolet radiation and skin cancer.
Sperm cell
Nerve cell
How molecules move in and out of cells
Substances can cross the cell membrane by diffusion, osmosis and active transport. Use the animation to see how each of them works.
Question 2
The body contains specialised cells which are arranged into tissues and organs. Specialised cells have specialised structures.
Click on the structures that are likely to be seen in these different cells.
