Peripheral Nervous System Flashcards
What are signals for the PNS?
Hormones
Nerves
Muscles
What do action potentials require?
Excitable cells and voltage gated ion channels
What do voltage gated ion channels give rise to? Are they graded or all or nothing?
Positive feedback loop
All or nothing
The strength of an impulse is altered by what?
Number and frequency of action potentials
Most voltage gated ion channels use which ion?
Sodium
When are voltage gated ion channels calcium gated?Are they faster or slower than sodium?
Some smooth muscle
Cardiac cells
Endocrine cells
much slower
Calcium is a second messenger. What does this mean?
It can link with an action potential with intracellular signalling
What is the absolute refractory period? What is the state of the ion channels?
Interval where a secondary action potential cannot be initiated, no matter the stimulation size
All channels inactivated
How many gates are involved in sodium gated ion channels? How many states?
2 gates, therefore 3 states
What are the 3 stages of sodium based action potentials?
Deactivated - low membrane potential, closed
Activated - open
Inactivated - closed for refractory period
What is the relative refractory period?
Second action potential is inhibited but not impossible
Some sodium ion channels inactivated,
Increased K+ conductance
What is a nerve fibre?
Part of a neuron
What is the cell body of a neutron?
Perikaryon
Soma
What are dendrites?
Receiving antenna of a neuron
What are microfilaments and microtubules?
Protein networks which provide transport and structure for neurons