A&p Chpt 12 -Nerve Tissue (Part 2)

Front 1

Why do neurons rarely form tumors?

Back 1

Mature neurons have little or no capacity for mitosis and seldom form tumors

Front 2

Cell type that gives rise to most common type of brain tumor?

Back 2

Astrocyte: Astrocytomas grow rapidly, malignantly, and seldom mestatizes.

Front 3

Why is it difficult to treat brain tumors?

Back 3

Blood-brain barrier prevents chemotherapy

Front 4

Function of Myelin?

Back 4

Insulation around a nerve fiber

Front 5

Constituents of myelin?

Back 5

Proteins and lipids

Front 6

Significance of Axon Hillock?

Back 6

area where the signal begins (trigger zone)

Front 7

Node of Ranvier

Back 7

gap between segments

Where signals are propogated
faster

Front 8

Can Scwann Cells wrap around more than one axon?

Back 8

Yes, they can wrap around more than one axon

Front 9

Multiple Sclerosis

Back 9

Chronic Demyelinating disease of CNS

Autoimmune

CNS plaques are formed

optic nerve is no longer myelinated

Symptoms: visual inpairment, speech problems

Front 10

In Multiple Sclerosis, _____ and ____ of the CNS are replaced by hardened plaques.

(Characterized by remission and relapse)

Back 10

In Multiple Sclerosis, Oligodendrocytes and Myelin of the CNS are replaced by hardened plaques.

Characterized by remission and relapse

Front 11

Axon Diamter vs Conduction Velocity?

Back 11

Ranked from Slowest to Fastest

(Small myelinated, small unmyelinated, Large myelinated)

Larger the Fiber, faster the signal

Front 12

Degeneration and Regeneration process

Back 12

Degeneration- axon and myelinated sheath degenerate, (Soma swells), cell dies

Regeneration: tube guides axonal sprout back to its original destination, schwann cells produce cell adhesions and growth factors to guide axon back to its original position

Front 13

3 Processes that contribute to the Resting Membrane Potential in nerves and what is the value (mV)?

Back 13

1. Ions Diffusing

2. Selectively Permable Plasma Membrane

3. Electrical attraction of Cations and Anions

-70mV

Front 14

At RMP in nerves the concentration of K+ in the cell is (higher or lower) than outside the cell?

Back 14

At RMP in nerves the concentration of K+ in the cell is (higher or lower) than outside the cell?

Front 15

Which is more permeable: Na+ or K+?

Back 15

K+ is more permeable in the plasma membrane

Front 16

K+ or Na+ has a greater influence on the RMP?

Back 16

K+

Front 17

Sodium/Potassium pump only contribute ____ mV because of the requirement of a lot of ATP

Back 17

Sodium/Potassium pump only contribute 3mV because of the requirement of a lot of ATP

Front 18

Action Potential is produced by _________ in the plasma membrane.

Back 18

Action Potential is produced by Voltage regulated gates in the plasma membrane.

Front 19

Trigger Zone referes to?

Back 19

Where action potential takes place at the voltage regulated gates.

Front 20

Local Potential

Back 20

Disturbances in the membrane potential when a neuron is stimulated.

1. Ligand/mechnically gated
2. Hyperpolarize
3. Graded Response
4. Reversible
5. Short Distance

Front 21

5 Characteristics of Action Potential

Back 21

1. Voltage Gated
2. Depolarization
3. All or none response
4. Irreversible
5. Occurs in great distance

Front 22

Threshold of Action Potential

Back 22

The critical Voltage that local potentials need to open the "Voltage-regulated" gate.

Voltage needed to open the Voltage-gate

Front 23

How concentrations and length of axons effect voltage Channels

Back 23

More Voltage-gated channels, greater length of axon

Front 24

Depolarization

Back 24

Voltage becomes more positive because Na+ comes in.

Decreases potential across the cell membrane

Front 25

Hyperpolarization

Back 25

RMP becomes lower or more negative than the original -70mV

Front 26

During the Absolute Refractory Period, what cannot occur?

Back 26

Another Action Potential

Front 27

Relative Refractory Period occurs during ______

Back 27

Relative Refractory Period occurs during HyperPolarization

Need a strong stimulus for another action potential to occur

Front 28

Absolute Refractory Period occurs durring a _____

Back 28

Absolute Refractory Period occurs durring a spike

Front 29

What occurs during Saltatory Conduction and how does it affect velocity?

Back 29

Nerve Signals are jumping from node to node and myelinated fibers transmit signals faster