Nerves Flashcards
What is the CNS?
The Central Nervous System- the nerves running along your spine and through your brain
What is the PNS?
The Peripheral Nervous System- the nerves that connect to all other parts of the body (not spine/brain)
What is a nerve?
A bundle of neurons (nerve cells)
What does a transducer do?
NB: Verb = to transduce
It converts energy from one form to another
Example of a transducer?
A sensory receptor
What is the pathway of impulses in the nervous system?
Stimulus (e.g. a change in light intensity)
Receptor (e.g. rod and cone cells in retina)
Sensory Neurone
CNS
Motor neurone
Effector (e.g. muscles in iris)
Response (e.g. size of pupil changes)
Label a sensory neurone
DRAW/REVISE a diagram!!!
Dendrite Dendron Cell body Nucleus Axon Direction of impulse from dendrite → axon
Label a motor neurone
DRAW/REVISE a diagram!!!
Dendrites Cell body Nodes of Ranvier Myelin Sheath Axon Synaptic knobs
Details about the dendron of a sensory and motor neurone?
A sensory neurone has a long dendron
A motor neurone doesn’t have a dendron
What is a an electrical impulse?
A rapid and fleeting change in charge across the membrane
What does the myelin sheath do to a neurone?
It insulates the axon and prevents short circuits with other axons - increases speed of impulse
A weak stimulus means
A low frequency of impulses
A strong stimulus means
A high frequency of impulses + more than one neurone fires at the same time
What is a synapse?
A connection between neurones
What is the gap between neurones called and what is the size of it?
Synaptic cleft
Size: approx. 20nm
How does information cross the gap between neurones?
The info crosses as a chemical signal because electrical impulses cannot cross the synaptic cleft
What is a synaptic knob?
The swollen end of the axon
What does a synaptic know contain?
Many vesicles that contain neurotransmitter chemicals
Many mitochondria
What do the mitochondria do in a synaptic knob?
Release energy via aerobic respiration to make neurotransmitter chemicals
How does info transmit across synapses?
- There are many vesicles in the first neurone, which are full of the neurotransmitter chemical
- When an impulses sweeps down the cell membrane of the presynaptic neurone, the change in charge causes the release of the neurotransmitter
- The neurotransmitter molecules DIFFUSE across the cleft and bind to the membrane of the postsynaptic neurone
- This causes an electrical impulses to start in the 2nd neurone
What is a presynaptic and postsynaptic neurone?
Presynaptic neurone = first neurone in a synapse transmission
Postsynaptic neurone = second neurone in a synapse transmission
