Bio 318 Exam 1 Neurophysiology PP
What happened to the amount of neurotransmitter release when you switched from the control extracellular fluid to extracellular fluid with no Ca2+?
Decreased
What happened to the amount of neurotransmitter release when you switched from the extracellular fluid with no Ca2+ to the extracellular fluid with low Ca2+?
Increased
When the stimulus intensity is increased, what changes: the number of synaptic vesicles released or the amount of neurotransmitter per vesicle?
Increasing stimulus intensity results in a greater number of synaptic vesicles being released.
How did neurotransmitter release in the Mg2+ extracellular fluid compare to that in the control extracellular fluid?
Less than
How does Mg2+ block the effect of extracellular calcium on neurotransmitter release?
Magnesium acts as an antagonist to calcium in the nervous system.
Discuss the relative permeability of the membrane to Na+ and K+ in a resting neuron.
Membrane permeability of a resting neuron to K+ is four to five times greater than for Na+.
Explain why increasing extracellular K+ causes the membrane potential to change to a less negative value.
Resting membrane potential is negative because the negative charge inside the cell is greater than the positive charge outside the cell. Increasing extracellular K+ increases the positive charge outside the cell. This decreases the difference between the inside and outside of the cell.
Discuss how a change in Na+ or K+ conductance would affect the resting membrane potential.
A change in K+ conductance would have a greater effect on resting membrane potential than a change in Na+ conductance because the membrane is more permeable to K+.
Explain why a change in extracellular Na+ did not alter the membrane potential in the resting neuron.
A change in extracellular Na+ results in little change to resting membrane potential because the plasma membrane of a neuron is only slightly permeable to Na+ because it contains relatively few Na+ leakage channels. This inhibits net diffusion of Na+ into or out of the cell.
CSF:
choroid plexus in lateral ventricles interventricular foramen 3rd ventricle cerebral aqueduct 4th ventricle "russian holes" subarachnoid space villi blood sinus
what are the receptor and effector of the stimulus leading to the patellar reflex?
receptor: patellar stretches effector: quad. muscle contracts
Explain why increasing extracellular K+ reduces the net diffusion of K+ out of the neuron through the K+ leak channels.
There is usually more K⁺ inside the cell relative to the extracellular environment. Increasing extracellular K⁺ reduces the concentration gradient, thus reducing net diffusion of K⁺.
