The membrane which forms the boundary between the cytoplasm of a cell and the medium surrounding it. It is selectively permeable to ions and organic molecules and controls the movemennt of substances in and out of cells.
The system of hormones (endocrines) that bring about chemical coordination of the body
Made up of many cells
Protein molecules attached to cells that only bind to specific molecules with a particular structure
A single celled organism carries out all the functions of life within its plasma cell membrane. However once organisms become multicellular they need to coordinate what happens in all of their different cells.
As multicellular organisms get bigger and bigger, cells differentiate and form tissues and organs which carry out specific functions. It is important that the different body systems work together. Animals have the biggest problem because they need to move around to find food and mates. A nervous system gives them a coordination system that works fast.
The human body is made up of around 10 billion cells which all have to work together to keep you alive. People need to move about, avoid danger, find food, water and mates, control their body temperature and coordinate the activities of all the main body systems (for example the digestive system and circulatory system). This coordination is brought about by the nervous system and the endocrine system. The nervous system provides rapid coordination using electrical impulses which travel around the body fast – from about 1-120 metres per second.
In humans the nervous system is made up of the following parts:
Click on the diagram to reveal the labels.
A nerve is a bundle of neurones. Sensory nerves contain only sensory neurones, motor nerves contain only motor neurones and mixed nerves carry both.
The way the nervous system works to control the responses of your body can be summed up as:
receptor → sensory neurone → coordinator (CNS) → motor neurone → effector
How the nervous system works to coordinate a conscious response to a stimulus.
a) Which type of neurone carries impulses from the CNS to the muscles and glands of the body?
b) Which two structures make up the human central nervous system?
c) Summarise the way that the nervous system coordinates and controls your body