Nervous Tissue Chapter 14

Front 1

Two subdivisions of the Nervous System

Back 1

Central nervous system (CNS)
Peripheral nervous system (PNS)

Front 2

Central nervous system (CNS)
consists of

Back 2

 brain and spinal cord

Front 3

Peripheral nervous system (PNS) consists of

Back 3

 cranial nerves, spinal nerves, and ganglia

Front 4

CNS and PNS perform three general functions:

Back 4

1. Collecting Information
2. Processing and evaluating information
3. Responding to information

Front 5

Two functional divisions of the NS

Back 5

Sensory NS
Motor NS

Front 6

SNS Subdivided into two systems:

Back 6

1. Somatic sensory – touch, pain, pressure, vibration and proprioception
2. Autonomic sensory – impulses from viscera
Motor Nervous

Front 7

Somatic sensory
(Sensory NS)

Back 7

touch, pain, pressure, vibration and proprioception

Front 8

Visceral sensory
(Sensory NS)

Back 8

impulses from viscera

Front 9

Sensory NS(afferent)--sensory info from_____ receptors to_____ .

Back 9

PNS, CNS

Front 10

Motor NS(efferent)--sends impulses from _____ to _____ .

Back 10

CNS, effectors

Front 11

Somatic motor (voluntary)
(Motor NS)

Back 11

causes contraction of skeletal muscles

Front 12

Autonomic motor (involuntary)
(Motor NS)

Back 12

regulates smooth and cardiac muscle and glands

Front 13

Two distinct types of cells w/in NS:

Back 13

Neurons
Glial cells

Front 14

electrically excitable cells
o initiate, transmit and receive nerve impulses

Back 14

Neurons

Front 15

non-excitable cells
o support and protect neurons

Back 15

Glial cells

Front 16

Cell that is the structural and functional unit of NS

Back 16

Neurons (nerve cells)

Front 17

Cell that conducts nerve impulses from one part of body to another part

Back 17

Neurons (nerve cells)

Front 18

3 Features of Neurons:

Back 18

1. High metabolic rate
2. Extreme longevity
3. nonmitotic

Front 19

Three main structural regions of a neuron:

Back 19

cell body
dendrites
axon

Front 20

Neuron cell body

Back 20

o Contains typical organelles
o Nucleus, mitochondria, free ribosomes and rough ER (Nissl bodies)

Front 21

Dendrites

Back 21

o Short processes from cell body
o receive nerve impulses
o Carry to cell body

Front 22

Axon

Back 22

o Single, long process from cell body
o Connects to cell body at axon hillock .
o transmit nerve impulses to other cells

Front 23

Structures Associated with Axons:

Back 23

1. Axon collaterals
2. Telodendria
3.Synaptic knobs

Front 24

side branches of main axon

Back 24

Axon collaterals

Front 25

fine terminal extensions at the ends of axon and collaterals

Back 25

Telodendria

Front 26

expanded regions at tip of telodendria

Back 26

Synaptic knobs

Front 27

Structural Classification of Neurons

Back 27

Classified according to number of processes from cell body
Unipolar
bipolar
multipolar

Front 28

single short process that branches like a T

Back 28

Unipolar neuron

Front 29

two processes, one dendrite and one axon

Back 29

Bipolar neuron

Front 30

many dendrites and a single axon
o most common of all neurons

Back 30

multipolar neuron

Front 31

Functional Classification of Neurons:

Back 31

1. Sensory (afferent) – sensory receptors to CNS
2. Motor (efferent) – impulses from CNS to muscles or glands
3. Interneurons– facilitate communication between sensory and motor neurons

Front 32

Sometimes referred to as Neuroglia

Back 32

Glial cells

Front 33

Glial cell found..

Back 33

both CNS and PNS

Front 34

Glial cells are smaller than neurons and capable of...

Back 34

mitosis

Front 35

Physically protect and nourish neurons

Back 35

Glial cells

Front 36

These cells are more numerous than neurons...

Back 36

Glail cells

Front 37

_________more likely to be derived from glial cells than neurons

Back 37

Brain tumors

Front 38

Glial Cells of CNS

Back 38

Astrocytes
Ependymal
Microglial
Oligodenrocytes

Front 39

Most abundant glial cells in CNS?

Back 39

Astrocytes

Front 40

Functions of Astrocytes

Back 40

Functions include:
1. Help to form the Blood-brain-barrier (BBB)
2. Regulate tissue fluid composition
3. Form a structural network
4. repair damaged neurons
5. Assist development of fetal neurons

Front 41

Ependymal Cells

Back 41

Ciliated cuboidal epithelial cells
 line ventricals of brain and central canal of spinal cord
 produce cerebral spinal fluid (CSF) and form the chrid plexus .

Front 42

Small, motile cells(cleanup)
 Wander through CNS
 exhibit Phagocytic activity
 remove cellular debris from dead or dying cells

Back 42

Microglial Cells

Front 43

 Associated with CNS axons only
 Wrap themselves around axons
 Produce myelin .
 Form myelin sheath .
 insulator of electrical activity

Back 43

Ogliodendrocytes

Front 44

Two types of glial cells in the PNS:

Back 44

Satellite Cells
Neurolemmocytes or Schwann Cells

Front 45

Neurolemmocytes or Schwann Cells

Back 45

o Associated w/ PNS axons
o Same function as Ogliodendrocytes.
 Wrap around axons Produce myelin
 Form myelin sheath .

Front 46

Satellite Cells

Back 46

o Flattened cells
o Found around cell bodies in ganglia
 Separate cell bodies
 Regulate exchange of nutrients and wastes.

Front 47

Rapid conduction of electrical charge along plasma membrane

Back 47

Nerve Impulse or action potential

Front 48

Myelin consists mainly of

Back 48

Lipids

Front 49

Outer membrane of Myelin Sheath called

Back 49

Neurilemma

Front 50

Sheath forms when cell wraps around axon

Back 50

Cytoplasm and nucleus squeezed to periphery
 Overlapping layers of membrane form sheath

Front 51

can myelinate multiple axons

Back 51

Ogliodendrocyte

Front 52

can myelinate one axon

Back 52

Neurolemmacyte

Front 53

Gaps in the myelin sheath are called

Back 53

Neurofibril or Nodes of Ranvier

Front 54

The region that contains organelles such as the nucleus and Nissl bodies is the

Back 54

Cell Body

Front 55

Saltatory Conduction

Back 55

“jumping” from node to node

Front 56

Only place where action potential can occur

Back 56

Neurofibril or Nodes of Ranvier

Front 57

System that is more vulnerable to damage

Back 57

PNS

Front 58

Which is faster?
Myelinated or Unmyelinated Axon

Back 58

Myelinated

Front 59

3 factors involved in Axon repair:

Back 59

Amount of Damage.
– Secretion of growth factors by neurolemmocyte
– distance between site of damaged axon and effector organ

Front 60

Axon Regeneration:
Greater distance, (more of less) possibility of repair

Back 60

less

Front 61

Which System (CNS or PNS) has a greater chance of Axon Regeneration?

Back 61

PNS

Front 62

Why is Axon Regeneration limited in the CNS?

Back 62

Ogliodendrocytes do not secrete growth factor
• Actively inhibit growth

Front 63

Nerve = bundle of

Back 63

Axons

Front 64

Nerve Structure:
Individual myelinated axon wrapped in___________

Back 64

Endoneurium

Front 65

Nerve Structure:
Groups of axons bundled into_____ .
• Surrounded by_____

Back 65

Fascicles
Perineurium

Front 66

Nerve Structure:
Fascicles bundled together by__________

Back 66

Epineurium

Front 67

Junction between neuron and another neuron or an effector_____

Back 67

Synapse

Front 68

Nerve impulse transmitted to next cell by way of__________

Back 68

Synapse

Front 69

Synapse consists of:

Back 69

Presynaptic Neuron
Postsynaptic neuron
Synaptic Cleft

Front 70

Presynaptic Neuron

Back 70

Transmit impulse

Front 71

Postsynaptic neuron

Back 71

Receive impulse

Front 72

Synaptic Cleft

Back 72

Between Presynaptic Neuron and Postsynaptic neuron

Front 73

Three common types of Synapses:

Back 73

Axodendric
Axosomatic
Axoanonic

Front 74

Axodendric Synapse

Back 74

Presynaptic Axon to postsynaptic dendrite

Front 75

Synaptic Communication:
Sequence of events

Back 75

Impulse reaches Synaptic knob.
– Causes increase in ca++ in knob
– Ca++ causes Synaptic vesicles to fuse w/membrane and release NT
– NT bind receptors on postsyn. cell
• Synaptic delay – time it takes NT to bind

Front 76

Synaptic delay

Back 76

– time it takes Neurotransmitter to bind

Front 77

Neuronal Pools or Neuronal Pathways

Back 77

complex groupings of interneurons in CNS

Front 78

4 types of Neuronal Pools

Back 78

Converging circuit
Diverging circuit
Reverberating Circuit
Parallel-after-discharge

Front 79

Converging circuit

Back 79

many neurons to one neuron
• Receives input from several neurons

Front 80

Diverging circuit

Back 80

one neuron to many neurons
• One pool to multiple pools

Front 81

Reverberating Circuit

Back 81

use feedback to produce repeated, cyclical stimulation of circuit
• Continues until inhibitory stimuli or synaptic fatigue

Front 82

Parallel-after-discharge Circuit

Back 82

several neurons or pools process same info at one time
• Single presynaptic neuron stimulates different groups of neurons
– Each neuron passes impulse to common postsynaptic cell
Higher thought process