Lab Final Exam Unit 2 Flashcards
What are the two divisions of the Nervous system. Give their organs and functions.
- Central Nervous System - brain and spinal cord - controls body function
- Peripheral Nervous System - nerves and ganglia - communicates with the CNS from or to rest of the body.
Define Resting Membrane Potential. What is the resting membrane potential of a typical neuron?
The voltage (charge) differences across the cell membrane when the cell is at rest. -70mV
Define absolute refractory period.
the delay that happens after the first action potential has begun, before the second can be triggered; the time requred for the Na+ channel gates to reset to their resting positions (about 1-2 msec.)
Define relative refractory period.
follows the absolute refractory period. During this time some, but not all, Na+ channel gates have reset to their original positions and some K+ channels are still open.
What happens during depolarization?
Na+ enters the cell
What happens during repolarization?
K+ exits the cell
What type of channel does Na+ use to enter the cell? What causes it to open? close?
voltage gated na+ channel
opens at the threshold of -55mV; closes at +30mV due to an inactivation gate that inactivates the channel.
What type of channel does K+ use to exit the cell? What causes it to open?
voltage gated K+ channel
Slowly begins to open at the threshold of -55mV
What causes hyperpolarization?
the slow closing of the K+ channels.
How does the cell return to normal gradient after an action potential?
Na+/K+ pump returns cell to its normal gradient of K+ inside and Na+ outside
what is an example of a Voltage-gated Na Channel antagonists?
lidocaine
What speeds up the conduction of action potentials?
- larger axons
- schwann cells insulate
- knodes of ranvier
How do Knodes of Ranvier assist AP’s?
they are loaded with voltage gated channels to add extra support. AP’s jump from knode to knode causing saltatory conduction.
What neurotransmitter is released from the axon terminal in the motor end plate?
ACh - acetyl choline
Where is a somatic motor neuron cell body found in the spinal cord?
ventral horn
Which structural types of neurons may be sensory?
bipolar, unipolar
Which structural types of neurons may be motor?
multipolar
how are graded potential different from action potentials?
GRADED:
- decremental (get weaker over distance
- variable amplitudej (can be + or -)
- used for integration
- can happen in cell bodies or dendrites
- use ligand gated channels
- can sum
What ion has the greatest effect on the RMP? why?
K+ because it has more channels
What is the “blind spot”?
an area where a persons view is obstructed.
Where exactly is the blind spot?
entry of the optic nerve on the retina. (optic disc)
What is it about the anatomy of the eye that causes there to be a blind spot?
there are no photoreceptors in the optic disk.
Describe the pupillary eye reflex. Why is it considered consensual?
reflex that controls the diameter of the pupil in response to the intensity of light that falls on the retinal ganglion cells of the eye. it is considered consensual because what happens to one eye creates a response in both.
Loss of lens elasticity of the eye results in what? (usually occurs with age)
presbyopia