5.3-nerves (why is this hard) Flashcards
where is the cell body of a motor neurone found?
spinal cord or brain
what is a Dendron?
long projection that carries impulse towards a cell body
where are the cell bodies of sensory neurones found?
dorsal root ganglia, just outside the spinal cord
what produces myelin?
Schwann cells
what is salutatory conduction?
when the nerve impulses jump from node to node
what is the function of myelin?
speeds up nerve impulses
insulates neurone
why are not all nerves myelinated?
not necessary: short neurones, thick axons
where’s the myelin in non myelinated neurones and why?
neurones not individually wrapped but still associated with myelin, because it helps keep nerve alive and is involved in regeneration.
what is a fibroblast?
specialised tissue found in pacinian corpuscles
what is the axon hillock?
where the action potential will propagate from
what is an action potential?
a brief reversal of the potential across the membrane of the neurone.
what type of neurone has dendrites?
motor
relay
what type of neurone has a Dendron?
sensory
what are the channels like in a neurone at resting potential?
Na+/K+ pump going
Na+ channels closed
some K+ channels open
what are the channels like in a neurone when the stimulus is detected?
Na+ channels open
Na+/K+ pump still going
K+ channels closed
what are the channels like in a neurone during depolarisation?
Na+ channels open
voltage gated Na+ channels open
Na+/K+ pump still going
why is transmission of action potentials along the axon slower in the absence of saltatory conduction?
no nodes of ranvier
shorter local currents
whole axon needs to be depolarised
what is a pacinian corpuscle?
pressure sensor found in the skin
what is a transducer?
cell that converts one form of energy to another
which sensory receptors detect a change in light intensity?
rods and cones in retina
which sensory receptors detect a change in pressure on skin?
pacinian corpuscles
which sensory receptors detect movement?
hair cells in inner ear
which sensory receptors detect change in muscle length?
muscle spindles in skeletal muscle
which sensory receptors detect chemicals in the air?
olfactory cells in epithelium lining fo nose