THE NERVOUS SYSTEM Flashcards
(32 cards)
Define stimulus
Detectable change in internal or external environment of an organism that produces a response
What 2 systems is the nervous system made of
Central nervous system
Peripheral nervous system
What 2 systems makes up peripheral nervous system
Somatic nervous system
Autonomic nervous system
What 2 things does autonomic nervous system have
Sympathetic
Parasympathetic
What neurotransmitter does sympathetic system have
Noradrenaline
What neurotransmitter does parasympathetic system have
Acetylcholine
Steps of nervous system
Stimulus - receptor - sensory neurone - relay neurone in CNS - motor neurone - effector - response
What are the 2 types of nerve net
Ganglion cells
Sensory cells
What do ganglion cells do
Provide connections in several directions
What are the 3 neurones
Sensory
Relay
Motor
What does sensory neurone do
Carry impulse from sense receptors to the CNS
What does motor neurone do
Carries impulse from CNS to effector
What does relay neurone do
Receive impulse from sensory neurone / relay neurone and carries it to motor neurone
What does cell body do
Release neurotransmitter
What does axon do
Send impulse away from cell body
What does myelin sheath do
Speed up nerve impulse transmission at nodes of ranveir with its insulating layer of lipids
What does Dendron do
Send impulse to cell body
Describe resting potential
- sodium podium pump, pumps 3Na+ out and 2K+ inside by active transport
- sodium ion channels close to prevent from reentry of NA+ ions
- potassium ion channels open to allow ions to leave by facilitated diffusion
- per in at negative ions stay inside cell so membrane is polarised at -70mV
What is the charge in resting potential
-70mV
What happens during depolarisation action potential
- sodium ion channels open, ions move in by F.D
- high concentration of Na+ ions therefore reaches threshold potential of -55mV
- more voltage gated sodium ion channels open, big Na+ influx
- causes a positive charge inside cell of +40mV
What happens during repolorisation of action potential
- sodium potassium pump reopens = 3Na+ out, 2K+ in
- sodium channels close at +40mV
- voltage gated potassium channels open at +40mV, K+ out by F.D
What happens during hyperpolorisation at action potential
- potential difference inside cell is lower than -70mV ( resting potential )
Define absolute refractory period
Period during when no new action potential may be initiated
What is the all or nothing law
When nerve impulse either initiated or not and its always the same size
