24.3 the nervous system and neurones Flashcards
neurones (nerve cells)
- specialised cells adapted to rapidly carrying nerve impulses from one part of the body to another
- they are the key cells that make up the nervous system
nerve impulses
- electrochemical changes
nervous system has 2 major divisions
- central nervous system (CNS)
- peripheral nervous system (PNS)
CNS is made up of
brain and spinal chord
PNS is made up of
pairs of nerves that originate from either the brain or the spinal chord
PNS is divided into:
1) sensory neurones
2) motor neurones
what do sensory neurones do
carry nerve impulses from receptors towards the CNS
what do motor neurones do
carry nerve impulses away from the CNS to effectors
motor nervous system is subdivided into:
- the voluntary nervous system
- the automatic nervouse system
what does the voluntary nervous system do
- carries nerve impulses to body muscles and is under voluntary (conscious) control
what does the automatic nervous system do
- carries nerve impulses to glands, smooth muscle and cardiac muscle and is not under voluntary control (involuntary)
what is the the spinal chord
- a column of nervous tissue that runs along the back and lies inside the vertebral column for protection
structure of neurones - it is made up of:
- cell body
- dendrons
- axon
- myelin sheath
- Schwann cells
- nodes of Ranvier
what is a cell body
- contains nucleus
- contains large amounts of ER; associated with the produced of protiens and neurotransmitters
what are dendrons
- are small extensions of the cell body
- they subdivide into smaller branched fibres called dendrites; carry nerve impulses towards the cell body
