Chapter 11: Nervous System

Question 1

What 3 things does the nervous system do?

Answer 1

1. Sensory input: protects environment
2. Integration: processes input
3. Motor output: respond

Question 2

What does the CNS consist of?

Answer 2

Brain and spinal cord

Integrative and control centers

Question 3

What does the PNS consist of?

Answer 3

Cranial nerves and spinal nerves

Communication between CNS and rest of the body

Question 4

What does the sensory division consist of?

Answer 4

Somatic and visceral sensory nerve fibers

Transmits info to the CNS

Question 5

What does the motor division consist of?

Answer 5

Motor nerve fibers

Transmits info away from the cns

Question 6

What does the somatic nervous system consist of?

Answer 6

Somatic motor (voluntary)
Conducts impulses from CNS to skeletal muscles

Question 7

What does the ANS consist of?

Answer 7

Visceral motor (involuntary)
Conducts impulses from CNS to cardiac and smooth muscles and glands

Question 8

What are the 2 principal cell types in the nervous system?

Answer 8

1. Neuroglia (glial cells): supporting cells

2. Neurons: excitable cells that transmit information

Question 9

Why is the nervous system fragile?

Answer 9

There is no connective tissue so it is held together by cells

Question 10

What are astrocytes?

Answer 10

CNS
The most abundant, versatile, and branched glial cells.
Cling to neurons, synaptic endings, and capillaries.
Support and brace neurons.
Help determine capillary permeability.
Regulate environment of the neurons and presence of neurotransmitters.
Holds the CNS together by wrapping around other structures that are present in the nervous system.

Question 11

What are microglia?

Answer 11

CNS.
Small cells with thorny processes.
Migrate toward injured neurons.
Phagocytize microorganisms and neuronal debris.
Rough equivalent of macrophage.

Question 12

What are ependymal cells?

Answer 12

CNS.
Line the central cavities of the brain and spinal column.
Separate CNS interstitial fluid from cerebrospinal fluid.
Produce CSF at choroid plexuses.
Sometimes connected by tight junctions; sometimes have cilia.
Play a key role in synthesis of cerebral spinal fluid and reabsorption in the spinal cord.

Question 13

What are oligodendrocytes?

Answer 13

CNS
Branched cells.
Processes wrap around multiple axons in CNS, forming insulating myelin sheaths.
Multiple sclerosis (demylination in the CNS).
Produce myelin.
This makes communication faster and serve as a means of protection against physical injury and the scaffolding in the repair of axons.

Question 14

What are satellite cells?

Answer 14

PNS.
Equivalent of astrocytes.
Surround neuron cell bodies in the PNS.
Regulate conditions present in the soma.

Question 15

What are Schwann cells?

Answer 15

PNS.
Equivalent to oligodendrocytes and do almost everything they do.
Very small cells.
Surround peripheral nerve fibers and form myelin sheaths.
Vital to regeneration of damaged peripheral nerve fibers.

Question 16

What are the special characteristics of neurons?

Answer 16

Long-lived (100+ years)
Amitotic
High metabolic rate
Plasma membrane functions in electrical signaling and cell-to-cell interactions during development

Question 17

What is the difference between the structural class of a multipolar and unipolar neuron?

Answer 17

Multipolar: many processes extend from cell body and all are dendrites except for one axon.
Unipolar: one process extends from the cell body and forms central and peripheral processes, which make up an axon

Question 18

What neuron type is the most abundant and has a common structure?

Answer 18

Multipolar

Question 19

What type of neuron is the 1st order neuron in all sensory pathways?

Answer 19

Unipolar

Question 20

What type of neuron are the 2nd and 3rd order neurons in all sensory pathways?

Answer 20

Multipolar

Question 21

What are the function and properties of dendrites?

Answer 21

Receive info.
Found on 2nd order neuron.
Increase surface area –> increase # of synapses.

Question 22

What is the function of the soma?

Answer 22

Receives and transmits info

Question 23

What is the function of the axon?

Answer 23

Outgoing info

Question 24

What are the parts of the axon?

Answer 24

1. Axon hillock: generate new AP
2. Axon branches
3. Terminal or bouton
4. Myelin
5. Nodes of Ranvier

Question 25

What are Nodes of Ranvier and where are they found?

Answer 25

Gap between myelin that is only found on myelinated axons

Question 26

How is myelin distributed on an axon?

Answer 26

Found in intervals | Myelin - no myelin - myelin - no myelin

Question 27

What does white matter consist of and what occurs in it?

Answer 27

``` Myelinated fibers (axons). Sensory pathways travel through myelinated white matter ```

Question 28

What does gray matter consist of and what occurs in it?

Answer 28

Dendrites and somas (unmyelinated). | Communication between neurons in the sensory and motor pathways.

Question 29

How do myelin sheaths work in the PNS?

Answer 29

Myelin sheath will wrap around an axon in one location - can be multiple wrappings, but only one location.

Question 30

How do myelin sheaths work in the CNS?

Answer 30

Oligodendrocytes are big cells: one soma with many branches that reach out to multiple different axons simultaneously. One oligodendrocyte can wrap around multiple different axons, or the same axon in multiple locations. Can have 50 different wrappings per cell. Wrappings are independent of each other. Nucleus does not have to be associated with the wrappings themselves.

Question 31

How do neurons function?

Answer 31

Neurons are highly irritable (excitable) and respond to adequate stimulus by generating an AP, which is always the same regardless of stimulus.

Question 32

What are the principles of electricity?

Answer 32

1. More positive charges outside cell than inside cell. 2. Energy is required to separate opposite charges across a membrane. 3. If opposite charges are separated, the system has potential energy. 4. Energy is liberated when the charges move toward one another.

Question 33

What is voltage?

Answer 33

Measure of potential energy difference. | Average voltage in neurons: -70 mV

Question 34

What is potential difference?

Answer 34

Voltage measured between 2 points.

Question 35

What is resistance (R)?

Answer 35

Hindrance to charge flow (provided by plasma membrane) | Resist change

Question 36

What are insulators?

Answer 36

Substances with high electrical resistance (Myelin) | Perfect resistor

Question 37

What are conductors?

Answer 37

Substance with low electrical resistance (water with electrolytes) Allow/part of change. Integral proteins: facilitate movement of ions across membrane