- nervous system controls activities
- sense organs help organisms to (a) adjust rapidly to any changes in environment and (b) enable various parts of the body to coordinate with each other quickly
- central nervous system (brain + spinal chord)
- peripheral nervous system (cranial nerves from brain + spinal nerves from spinal chord + sense organs)
- sense organs receive stimuli -> sense organs = receptors
- sense organs produce electrical messages called nerve impulses
- nerve impulses are transmitted by the central nervous system by nerves
- HOW NERVES PROCESS INFORMATION
- information is gathered by receptors
- information gathered is converted into electrical signals (nerve impulses)
- nerve impulses are transmitted bu peripheral nerves to central nervous system
- brain interprets pattern of nerve impulses
- brain initiates nerve impulses that are transmitted to effectors
- effectors carry out action
- NERVOUS TISSUE
- sensory neurones -> transmit nerve impulses from sense organs (receptors) to central nervous system
- motor neurones -> transmit nerve impulses from central nervous system to effectors
- relay neurones -> transmit nerve impulses from sensory neurones to motor neurones (found WITHIN the central nervous system)
- MOTOR NEURONE
- dendron -> nerve fibres that transmit nerve impulses towards the cell body. the end of the dendron is called a dendrite and the dendrites receive nerve impulses from other neurones.
- cell body -> contains nucleus and cytoplasm. irregular in shape.
- axon -> nerve fibres that transmit nerve impulses away from cell body. usually long.
- myelin sheath -> layer of fatty substances coating the axon. insulates the axon.
- neurilemma -> thin membrane surrounding the myelin sheath
- node of Ranvier -> regions where myelin sheath is absent. allows nerve impulses to jump from node to node, speeding up the transmission of nerve impulses.
- dendrites of axon -> transmit nerve impulses from motor neurone to effector.
- motor end plate ->junction between dendrite and muscle fibres.
- SENSORY NEURONE
- circular cell body
- only one long dendron and one short axon
- Synapse is a junction between two neurones or a junction between a neurone and an effector
mar 23 2013 ∞
aug 14 2013 +
aug 14 2013 +