Lecture 6: basic physiology of nerve cells Flashcards
(43 cards)
What can affect the presynaptic neuron?
Stimuli on the dendrites and cell body (the soma)
What area generates the action potential?
The axon hillock
What response do dendrites and the cell body (soma) make when affected by stimuli?
Graded responses that alter membrane potential (depolarise or hyperpolarise)
At what point is an action potential generated?
If the hillock reaches threshold
What potential does excitatory neurons produce?
Excitatory post-synaptic potentials
What potential does inhibitory neurons produce?
Inhibitory post-synaptic potentials
What type of response can action potentials have?
All or nothing response
What are the thin, ribbon-like cells that commonly wrap around axons called?
Schwann cells
What is the effect of the layers of myelin that make a shwann cell called?
Myelination
What are the gaps between Schwann cells where the axon membrane touches the extracellular fluid called?
Nodes of Ranvier
How fast does an AP travel down a myelinated axon?
Approx. 150m/s
How fast does an AP travel down an unmyelinated axon?
0.5 to 10 m/s
The wider the axon, the ____ the AP
Faster
What type of neuron are Aalpha?
Motor neurons/proprioceptors, muscle spindles, golgi, tendon, organs
What type of neuron are Abeta?
touch, mechanical touch/pressure
What type of neuron are Adelta?
Pain (fast) temp
What type of neuron are C?
Pain (slow) temp, itch
What happens if myelination breaks down?
Signals no longer work in concert, results in multiple sclerosis
What are the two main types of cell-cell propagation?
Electrical synapse, chemical synapse
Why do electrical synapses act directly and quickly?
Gap junctions allow AP to continue from one cell to the next
What is a limitation of electrical synapses?
Does not allow much variation in the post-synaptic response
What molecules are released into the synaptic cleft in chemical synapses?
Neurotransmitters
What triggers AP on the postsynaptic neuron after a chemical synapse?
Binding of neurotransmitters to the post synaptic membrane (can also rebind to trigger more)
What is the first step of voltage-activated Ca2+ channels when an action potential arrives at the synaptic terminal?
Depolarisation opens the voltage-activated Ca2+ channels