Nervous system

• define nervous system

  complex network of nerve cells and fibres that transmit messages from brain and spinal cord to various parts of the body
• define sensation

  perception of changes occurring in and out of body
• define integration

  processing and interpreting sensory information to determine appropriate response
• what are the 2 types of nervous system

  central nervous system

  peripheral nervous system
• what makes up the central nervous system

  brain

  spinal cord
• what makes up the peripheral nervous system

  cranial nerves

  spinal nerves

  autonomic nerves
• what is the function of nervous tissue

  control and coordinate body activity
• describe neurones

  specialised elongated cells transmitting electrical impulse
• describe cell body in motor neurone

  contain nucleus
• describe dendrite in motor neurone

  conduct nerve impulse to body
• describe axon in motor neurone

  conduct impulse away from body
• describe myelin sheath

  coat axon for faster conduction
• describe schwan cells in motor neurone

  produce myelin
• describe neurilemma in motor neurone

  sheath of connective tissue surrounding axon
• describe node of Ranvier in motor neurone

  axon in direct contact with neurilemma, nerve cells up taking oxygen and nutrients
• describe epineurium in motor neurone

  outer connective tissue surrounding whole nerve
• describe neuroglia in motor neurone

  connective tissue between neurones
• describe nerve ending in motor neurone

  at the end of axon transmitting impulse to dendrite of next axon
• describe sodium and potassium during depolarisation

  sodium move in

  potassium move out

  across cell membrane
• define refractory period

  period nerve is unable to respond and cant be reactivated until membrane permeability returns
• what is the recovery time of the refractory period

  few thousandths of a second
• what is the purpose of the refractory time

  ensure nerve impulse travels in 1 direction
• what is the resting state (number)

  -70mV
• what is the (number) of threshold

  -55mV
• what is the (number) for action potential

  +40mV
• what does the effectiveness of the nervous system depend on

  number of nerve impulses per second

  number of neurones activated by stimuli

  type of neurone stimulated
• what are the 2 types of neurone

  excitatory effect

  inhibitory effect
• describe the excitatory effect of neurone

  neurone releases neurotransmitter
• describe the inhibitory effect of neurone

  reduce probability transfer will take place
• what is a synapse

  microscopic gap between neurones
• what is a neuromuscular junction

  gap between neurone and muscle fibre
• what does afferent/ sensory neurones carry impulses

  carry impulse towards brain and spinal cord
• what does efferent/ motor neurones

  carry impulse away form brain and spinal cord to muscles and glands
• describe how to generate an impulse

  alter relationship between negative cell content and positive cell membrane

  changes permeability of cell membrane so sodium and potassium ions are exchanged

  caused by an electrical wave

  all or nothing principle
• define stimuli

  any change inside/ outside body
• define receptors

  specialised cells that detect stimuli
• give an example of sense organs

  eye

  ear

  nose
• describe somatic nervous system

  voluntary nervous system e.g. skeletal muscles
• describe visceral nervous system

  involuntary e.g. smooth muscles
• describe how the CNS developed

  in embryo

  hollow neural tube along dorsal surface

  peripheral fibres grow laterally