Nervous system pt.3
Which of the following cause a postsynaptic transmission to stop?
-Diffusion of the neurotransmitter into the nearby extra-cellular fluid -Reuptake of the neurotransmitter by endocytosis -Degradation of the neurotransmitter in the synaptic cleft
relative refractory period
A new action potential is possible but only with a stronger than normal stimulus
Chemical Classes of Neurotransmitters
Acetylcholine, amines, amino acids, neuropeptides
Synapses
Area of communication where signals are transmitted between the two neurons that are communicating
Why is myelin important?
Assist in the regeneration of damaged fibers, speeds up signal conduction in the nerve fiber, it insulates the nerve fiber
involved in elevation of mood and the control of voluntary movement
Dopamine
True or false: receptors that bind the neurotransmitter at the postsynaptic cell membrane are voltage-gated.
False
Most common inhibitory neurotransmitter in the brain
GABA
In an action potential, which event directly follows repolarization?
Hyperpolarization of the membrane
Dopamine
Involved in elevation of mood and control of voluntary movement
Serotonin
Involved in sleepiness, alertness, thermoregulation, and mood
Acetylcholine
Located at the neuromuscular junctions; excites skeletal muscle, inhibits cardiac muscle
Why does depolarization occur?
More sodium ions diffuse into the cell, creating a positive charge.
absolute refractory period
No stimuli or any strength will generate a new action potential
ligand-gated channels
Respond to chemical stimuli
mechanically-gated channels
Respond to mechanical vibration, pressure, touch, and stretching stimuli
Norepinephrine
Sympathetic nervous system; dreaming, walking, and mood; excites cardiac muscle; can excite or inhibit smooth muscle and glands depending on location
The resting membrane potential is negative due to which of the following?
There are more negatively charged particles on the inside of the membrane than on the outside.
True or false: after the passage of the action potential, the sodium-potassium pump re-establishes the resting membrane potential.
True
True or false: if the postsynaptic membrane potential reaches threshold level, an action will be produced.
True
True or false: the area between the presynaptic nerve cell and the postsynaptic muscle cell is termed the synaptic cleft.
True
True or false: the sodium-potassium pump is involved in establishing the resting membrane potential.
True
excites skeletal muscle and inhibits cardiac muscle
acetylcholine
leak channels
alternate between open and closed randomly
When voltage-gated sodium channels are open, sodium flows _____________ the neuron making the inside of the cell more _______________.
into; positive
Which of the following will lower the speed of propagation of an action potential?
low temperature
GABA
most common inhibitory neurotransmitter
During the absolute refractory period which of the following is true?
no stimulus of any strength will trigger a new action potential
Involved in dreaming, waking, and mood. It also excites cardiac muscle
norepinephrine
Voltage-gated channels
respond to a direct changes in the membrane potential
involved in sleepiness, alertness, thermoregulation and mood
serotonin
Normally, sodium and potassium leakage channels differ because ___________________.
sodium ions diffuse through leakage channels into the cell, but potassium ions diffuse through leakage channels out of the cell
A synapse is:
space between adjacent neurons through which an impulse is transmitted
Which of the following factors will increase the speed of propagation?
temperature, myelination, axon diameter
