The two nerve cells do not actually touch here for there is a microscopic space between them. The connection between adjacent neurons is called a synapse. A relay neuron connects sensory and motor neurons and is found in the brain or spinal cord (see diagrams 14.1 and 14.2).ĭiagram 14.2 - The relationship between sensory, relay and motor neuronsĬonnections Between Neurons A motor neuron is a nerve cell that transmits impulses from the brain or spinal cord to a muscle or gland. A nerve is a bundle of axons.Ī sensory neuron is a nerve cell that transmits impulses from a sense receptor such as those in the eye or ear to the brain or spinal cord. ![]() The neuron carrying impulses from the spinal cord to the hind leg or tail of a horse, for example, can be several feet long. The cell body of neurons is usually located in the brain or spinal cord while the axon extends the whole distance to the organ that it supplies. This speeds up the rate at which the nerve impulses travel along the nerve (see diagram 14.1). ![]() Many axons have a sheath of fatty material called myelin surrounding them. A typical neuron has a cell body containing a nucleus, one or more branching filaments called dendrites which conduct nerve impulses towards the cell body and one long fibre, an axon, that carries the impulses away from it. Neurons are cells that have been adapted to carry nerve impulses. Nerve impulses can be thought of as being similar to an electric current. These transmit high-speed signals called nerve impulses. Motor function - The third function is the response to the stimuli that causes muscles to contract or glands to secrete.Īll nervous tissue is made up of nerve cells or neurons. The power to integrate, remember and apply experience gives higher animals much of their superiority. The many different impulses from different sources are sorted, synchronised and co-ordinated and the appropriate response initiated. The impulses from these organs are analysed and stored as memory. Integrative function - processing the information received from the sense organs. Inside the body, stretch receptors in the stomach indicate when it is full and chemical receptors in the blood vessels monitor the acidity of the blood. For example the eyes sense changes in light and the ear responds to sound waves. Sensory function - to sense changes (known as stimuli) both outside and within the body. The nervous system has three basic functions:ġ. The first operates via electrical impulses along nerve fibres and the second by releasing special chemicals or hormones into the bloodstream from glands.įunctions of the Nervous System These are the nervous and endocrine systems. Two systems are involved in co-ordination in animals. The adjustment of an animal’s response to changes in the environment and the complex linking of the various processes in the body that this response involves are called co-ordination. Once the prey has been caught and eaten, the digestive system must be activated to digest it. At the same time the respiration rate must increase to supply the oxygen and remove the carbon dioxide produced as a result of this increasedĪctivity. This involves coordinating the contraction of the muscle so the predator can run, there must then be an increased blood supply to the muscles to provide them with oxygen and nutrients. Once a predator has identified suitable prey it has to catch it. The various systems and organs in the body must also be linked so they work together. They must also be able to identify food and escape predators. ![]() They need to be able to sense the temperature of their surroundings, for example, so they can avoid the hot sun. that the autonomic nervous system consists of sympathetic and parasympathetic parts with different functionsĪnimals must be able to sense and respond to the environment in which they live if they are to survive.that the peripheral nervous system consists of cranial and spinal nerves and the autonomic nervous system.the structure and function of the spinal cord.the basic parts of the brain and the function of the cerebral hemispheres, hypothalamus, pituitary, cerebellum and medulla oblongata.that the brain is surrounded by membranes called meninges.that the nervous system can be divided into the central and peripheral nervous systems.that training can develop conditioned reflexes in animals.the nervous pathway known as a reflex with examples.the structure and function of a synapse and neurotransmitter chemicals.the basic structure and functions of a neuron.that the nervous system gathers, sorts and stores information and initiates movement.the role of the nervous system in coordinating an animal’s response to the environment.After completing this section, you should know:
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