Lec 5- Neurons and AP's

Question 1

Neuron

Answer 1

A nerve cell specialized to initiate, propagate, and transmit electrical signals, typically consisting of a cell body, dendrites and an axon.

Question 2

Dendrites

Answer 2

Projections from the surface of a neuron’s cell body that carry signals toward the cell body.

Question 3

Axon Hillock

Answer 3

The first portion of a neuronal axon plus the region of the cell body from which the axon leaves; the site of action-potential initiation in most neurons.

Question 4

Axon

Answer 4

A single, elongated tubular extension of a neuron that conducts action potentials away from the cell body; aka nerve fiber.

Question 5

Axon Terminal

Answer 5

The branched endings of neuronal axon, which release a neurotransmitter that influences target cells in close association with the axon terminals.

Question 6

CNS (Central Nervous System)

Answer 6

The brain and spinal cord.

Question 7

PNS (Peripheral Nervous System)

Answer 7

Nerve fibers that carry information between the CNS and other parts of the body.

Question 8

Glial cell

Answer 8

Connective tissue cells of the CNS, which support the neurons both physically and metabolically.
Includes; astrocytes, oligodendrocytes, ependymal cells, and microglia.

Question 9

Sensory/Afferent

Answer 9

Neuron that possesses a sensory receptor at its peripheral ending and carries information to the CNS.

Question 10

Motor/Efferent

Answer 10

Neurons that carries information from the CNS to an effector organ.

Question 11

Interneurons

Answer 11

Neuron that lies entirely within the CNS and is important for integrating peripheral responses to peripheral information as well as for abstract phenomena associated with the “mind”.

Question 12

Action Potential (AP)

Answer 12

A brief, rapid, large change in membrane potential that serves as a long-distance electrical signal in an excitable cell.

Question 13

Depolarization

Answer 13

A reduction in membrane potential from resting potential; movement of the potential from resting toward 0mV.

Question 14

Repolarization

Answer 14

Return of membrane potential to resting potential following a depolarization.

Question 15

Hyperpolarization

Answer 15

An increase in membrane potential from resting potential; potential becomes even more negative that at resting potential.

Question 16

Voltage-gated channels

Answer 16

Channels in the plasma membrane that open or close in response to changes in membrane potential.

Question 17

Threshold

Answer 17

The critical potential that must be reached before an action potential is initiated in an excitable cell.

Question 18

Absolute Refractory Period

Answer 18

When a recently activated patch of membrane is completely refractory (stubborn or unresponsive) to further stimulation.

Question 19

Relative Refractory Period

Answer 19

A second action potential can be produced only by a triggering event considerably stronger than usual.

Question 20

Schwann Cell

Answer 20

Myelin forming cells in the PNS

Question 21

Myelin

Answer 21

An insulative lipid covering that surround myelinated nerve fibers at regular intervals along the axons length.
Cell rolls around the nerve fiber.

Question 22

Oligodendrocytes

Answer 22

Myelin forming cells in the CNS

Question 23

Astrocyte

Answer 23

Glial cells.
Glue of CNS.
Guides for fetal development.
Estab BBB.
Transfer nutrients.
Repair brain injuries.

Question 24

Microglia

Answer 24

Immune defense cells of the CNS, where they remain stationary until activated by an infection or injury.

Question 25

Saltatory conduction

Answer 25

Impulse jumps from node to node, skipping over myelinated sections of the axon.

Question 26

Nerve

Answer 26

Bundles of neurons.

Question 27

Multiple Sclerosis (MS)

Answer 27

Pathophysiologic condition in which nerve fibers in various locations throughout the nervous system lose their myelin.