Chapter 4 - Nervous System

Question 1

Parts of the neuron

7

Answer 1

Cell body / soma
Dendrites
Axon hillock
Axon
   -myelin sheath
      -oligodendrocytes / Schwann cells
Nodes of Ranvier
Nerve terminal
Synapse

Question 2

What is a nerve?

What are 3 types of nerves based on the info they carry?

Answer 2

Nerve = many neurons bundled together

Sensory
Motor
Mixed

Question 3

What is a ganglia?

Answer 3

Cell bodies of the same type clustered together.

Question 4

What are tracts? Where are they found (general)?

Answer 4

Tracts are when axons are bundled together in the CNS

They only carry one type of information (unlike nerves)

Cell bodies of neurons IN THE SAME TRACT are grouped into nuclei.

Question 5

What is an astrocyte?

Answer 5

Cell that nourishes the neuron and forms the BLODD-BRAIN BARRIER (which controls transmission of dilutes from he bloodstream to the nervous tissue)

Question 6

What are ependymal cells?

Answer 6

These cells line the ventricles of the brain and produce cerebrospinal fluid (physical support for the brain, and shock absorber)

Question 7

What are microglia ?

Answer 7

Phagocytic cells that break down waste products and pathogens in the CNS

Question 8

What are oligodendrocytes and Schwann cells?

Answer 8

Oligo - CNS
Schwann - PNS

Produce myelin around axons

Question 9

What is the threshold value of an action potential?

Answer 9

-55 mV to -40 mV

Question 10

What is temporal summation?

What is spatial summation?

Answer 10

Summation is the additive effect of multiple inhibitory/excitatory signals.

Temporal: multiple signals are within a short period of time

Spatial: additive effects are based on the number and location of the signals.

Question 11

What are the main functions of the nervous system?

Answer 11

Govern involuntary behavior
Govern voluntary behavior
Maintain homeostasis

Question 12

What is a sensory neuron?

What does it do?

Answer 12

–> AFFERENT neuron

Transmit sensory info rom receptors to the spinal cord and brain

Question 13

What is a motor neuron?

What does it do?

Answer 13

–> EFFERENT neuron

Transmits motor info from the brain and spinal cord to muscles and glands.

Question 14

What is an interneuron?

Answer 14

Between other neurons
Located mostly in brain and spinal cord
Most numerous
Often linked to REFLEXIVE behavior

Question 15

What is a supraspinal circuit?

Answer 15

When the sensory info is processed at the level of the brain / brainstem.

Differs from reflexes, which only require processing at the level of the spinal cord.

Question 16

White matter & grey matter

In the brain vs in spinal cord

Answer 16

White - axons in myelin sheaths
Grey - cell bodies a and dendrites

White matter lies DEEPER in the brain.
White matter lies on the OUTSIDE in the spinal cord.

Question 17

4 divisions of the spinal cord:

Answer 17

Cervical
Thoracic
Lumbar
Sacral

Question 18

What is the dorsal root ganglia?

Answer 18

Sensory neurons bring in info from the periphery and enter the BACK of the spine - the cell bodies are found on the DORSAL ROOT GANGLIA.

Question 19

Where do motor neurons exit the spine?

Answer 19

Ventral part of the spinal cord

Question 20

The PNS (peripheral) has how many cranial and spinal nerves?

Answer 20

12 pairs of cranial nerves

31 pairs of spinal nerves

Question 21

Two subdivisions of the PNS:

Answer 21

Somatic nervous system
Autonomic nervous system

(Voluntary/involuntary)

Question 22

What does the somatic nervous system consist of?

Answer 22

Sensory and motor neurons

Distributes throughout skin, joints, and muscles.

Question 23

What does the autonomic nervous system consist of?

Answer 23

Regulates 
   Heartbeat 
   Respiration
   Digestion 
   Temperature control
   Glandular secretions 

Manages involuntary muscles (ie internal organs and glands)

Regulates body temp via SWEATING or PILOERECTION.

Question 24

Diff between somatic and autonomic:

Answer 24

In peripheral component:

Somatic: motor neuron goes directly from spinal cord to muscle

Autonomic: two neurons work in series - preganglionic and postganglionic. Preganglionic soma is in CNS (spine), axon goes to a ganglion in the PNS where it synapses on the cell body of the postganglionic neuron, which then affects the muscle.

Question 25

What is a neuron?

Answer 25

A cell capable of transmitting electrical impulses and translating electrical impulses into chemical signals.

Question 26

Two subdivisions of the Autonomic nervous system:

Answer 26

Sympathetic
Parasympathetic

(These are antagonistic)

Question 27

Parasympathetic NS - what it does:

7

Answer 27

Constricts pupils 
Stimulates saliva
Constricts bronchi*
Slows heartbeat*
Stimulates peristalsis & secretion*
Stimulates bile release*
Contracts bladder*

*innervated by cranial nerve X (vagus)

Question 28

What does the sympathetic NS do?

9

Answer 28

Dilates pupils 
Inhibits salivation
Dilates bronchi
Accelerates heartbeat
Stimulates sweating/piloerection
Stimulates glucose prod + release
Secretion of adrenaline + noradrenaline
Inhibits bladder contraction
Stimulates orgasm

Question 29

Neurotransmitters in sympathetic versus parasympathetic responses:

Answer 29

Parasympathetic:
Acetylcholine (in both pre and post ganglionic neurons)

Sympathetic:
Acetylcholine in preganglionic
NOREPINEPHRINE in postganglionic

Question 30

Monosynaptic reflex arc:

One example

Answer 30

Has a single synapse
(Between sensory neuron, and motor neuron)

Example: knee-jerk reflex

Question 31

Polysynaptic reflex arc:

One example

Answer 31

AT LEAST one inter neuron between sensory neuron and motor neuron.

Ie withdrawal reflex (stepping on a nail, withdrawing the foot - requires balance from the other foot, inter neurons provide connection from sensory info to the motor neuron in the other leg)

Question 32

What system controls all of the GLANDS in the body (except sweat glands)?

Answer 32

The parasympathetic nervous system