Health and Social Care Unit 4 LO5

Components of the nervous system

The nervous system receives, transmits and responds to information from the external environment and from the body’s internal environment, through a collection of nerve cells.

• Central nervous system - The central nervous system is the control centre for the body; it consists of the brain and spinal cord. The spinal cord connects the brain, by long lines of individual nerve cells, to every area in the body.
• Spinal cord - It transmits information to and from the brain through structures called nerves.
• Autonomic system - Controls and regulates processes such as heart rate and gut movements (peristalsis). These actions are automatic - unconsciously controlled.
• Sensory and motor neurones (somatic nervous system) - Sensory nerves transmit information from the : senses - the eyes, ears, etc. - to the brain. Motor nerves transmit information to the muscles from the brain.
• Peripheral nervous system - All the nerves outside the central nervous i system make up the peripheral nervous system. It relays information from the brain and spinal cord to the rest of the body, and the reverse information from the body to the brain and spinal cord. Peripheral nerves include autonomic, sensory and motor nerves.

The structure and function of the brain

• Cerebral cortex - The cerebral cortex is the wrinkly, outermost layer of the brain, responsible for thinking and processing sensory information from the body. There are four lobes, each responsible for processing different types of information. It is made of tightly packed neurons.

• Cerebellum - Positioned at the back of the skull, the cerebellum coordinates and regulates muscle activity. It is also involved in the control of muscles to maintain balance.

• Frontal lobes - The frontal lobes carry out higher-level mental processes such as thinking, decision-making and planning.

• Corpus callosum - The corpus callosum is a bridge of nerve tissue that connects the two halves of the brain and enables communication between the two.

• Hypothalamus - The hypothalamus is responsible for the maintenance of body temperature. It also regulates appetite and thirst, letting us know when we need to eat or have fluids.

• Medulla - The medulla automatically carries out and regulates life-sustaining functions such as breathing, swallowing and heart rate.

• Meninges - The meninges are three layers of membranes surrounding the brain and the spinal cord. They provide a barrier from the rest of the body and act as protection from infection.

The structure and function of a neuron

• Neuron - Neurons are specialised nerve cells that transmit electrical impulses (information) i from one part of the body to another.
• Axon - Axons are the long thread-like part of a nerve cell, along which impulses are conducted away from the cell body to other cells. There is only one per neuron.
• Dendron (dendrite) - Dendrons are short, branched structures on the neuron that receive electrical impulses and carry them towards the cell body. There can be as many as 1000 per neuron.
• Myelin sheath - The myelin sheath is a fatty white substance that surrounds the axon. It forms a protective, insulating layer and…