Lecture #11: Nervous system Flashcards
Which occur during repolarization?
- Na+ gates shut
- K+ goes out
- Inside becomes more negative
What ion enters the pre-synaptic cell that causes neurotransmitter to be released into the synaptic gap?
Calcium (Ca+2)
Nervous system
Stimulus –> Sensory receptor — (synapse) —> Sensory neuron (affrent neuron)— (synapse) —> interneuron —-> (synapse)—> motor neuron (efferent neuron) —-> (synapse) —-> Effector —-> Response
Neuron
nerve cell
Dendrites
receive incoming information
Axon hilic
nerve impulse starts here
Support cells
also called Gliel cells
- has gaps (mylin sheath)
Terminal buttons
output to another cell
Axon in resting state
Na+ gates (channel) closed but voltage sensitive
K+ gates (channel) closed but voltage sensitive
- takes longer to respond than Na+ gates
What is the resting state potential in milivolts?
-70 milivolts
What is the charge inside and outside of axon during resting state?
inside = negative (lots of K+)
- concentration gradient inside cell
- electrical gradient inside cell
outside = positive (lots of Na+)
Sodium potassium pump
requieres 1 ATP to pump 3 sodium (Na+) to the outside and 2 inside
- maintains the resting state
Action potential
A brief reversal of charge (from negative to positive inside cell) at one point across the axon (cell) membrane
Nerve impulse
the re-creation of an action potential to the end of the axon
Process of action potential
- Resting state
- when depolarization reaches a threshold (-55 mv), Na+ gates begin to open, Na+ comes in, more depolarization (positive feedback loop)
- Repolarization: K+ gates open (Na+ gates close)
- potassium floods out (concentration + electrical gradient out) - Hyperpolarization (let out - then gates shut)
