Nervous System

• The nervous system is a complex network of nerve cells & its function is to receive information from the environment and then coordinate the body to respond accordingly.
• Neurons= specialised cells of the nervous system responsible for transmitting electrical and chemical messages across the nervous system.
• Neurons typically consist of dendrites: receive nerve impulses from other neurons towards the cell body.
• Neurons typically consist of cell bodies: the life centre of the cell (contains the nucleus & mitochondria etc).
• Neurons typically consist of axons: they carry the impulses away from the cell body towards the end.
• Some neurons are covered in myelin sheath which insulates the axon to speed up neural transmission.
• Sensory neuron- afferent (PNS to CNS)
• Sensory neurons- carry messages from sense receptors (skin, eyes etc) to the CNS, so it can be responded to. The message is perceived as sensations in the brain (touch, taste etc). Sometimes the info is dealt with by the spinal cord.
• Relay neurons- relay messages between sensory neurons and other motor neurons, once it has been interpreted & an appropriate response selected.
• Relay neurons- found only in the CNS, are small in length (less than a mm) & are not myelinated.
• Motor neurons- connect the CNS to effectors (muscles & glands) to bring about the response.
• Motor neurons- when stimulated it releases neurotransmitters which bind to the gland or muscle & signal for it to be activated in response to the sensory information it received from the sensory neurons.
• Motor neurons- efferent (CNS to PNS)
• The whole nervous system is controlled by the brain.