Chapter 13: Neural Tissue Flashcards
1
Q
what are the two communication systems in neural tissue?
A
nervous system and endocrine system
2
Q
What does the nervous system do? How does it accomplish this?
A
coordinate all body systems
-accomplished by the transmission of signals
(body parts to the central nervous system)
(central nervous system to the body parts.)
3
Q
what kind of signaling does the nervous system use?
A
electrochemical signaling
4
Q
the endocrine system is a (slower/faster) scale than the nervous system. What chemicals in the bloodstream does it use?
A
slower; hormones
5
Q
what is in the general make up of the nervous system?
A
Connective tissues
Blood vessels
Neurons
Neuroglia
6
Q
what are the two divisions of the nervous system? What makes up each?
A
Central nervous system (CNS)
-brain and spinal cord
Peripheral nervous system (PNS)
-cranial and spinal nerves
7
Q
describe the CNS (5 things)
A
- Brain and spinal cord
- Covered by meninges
- Starts as a hollow tube
- Bathed in cerebrospinal fluid
- Integration center
8
Q
describe the PNS (3 things)
A
- consists of cranial and spinal nerves that contain both sensory and motor fibers
- connects CNS to muscles, glands & all sensory receptors
- Brings info to and from the CNS
9
Q
What are the two divisions of the peripheral nervous system? what are they responsible for?
A
Afferent Division = sensory
Efferent Division = motor
10
Q
the efferent division can be broken down into two divisions. What are they?
A
Somatic Division (conscious) Autonomic Division (unconscious)
11
Q
What are 5 general functions of the nervous system?
A
Receptors-detect stimuli Sensory-afferent PNS Integrative-CNS Motor-efferent PNS Effector-muscle/gland
12
Q
describe neurons
A
structural & functional units
Excitable
Amitotic
13
Q
describe neuroglial
A
accessory cells
act like connective tissue
14
Q
what are the three major structures of a neuron?
A
soma dendrite axon
15
Q
what is the soma?
A
cell body (mononucelate)
16
Q
what does the soma consist of? describe *4 things
A
Nissl Bodies: ribosomes clusters; give gray color
Axon Hillock: connects soma to axon
Perikaryon: region around the nucleus
Neurofibrils: cytoskeleton that extend into dentrites/axons; gives shape
17
Q
what do dendrites do?
A
respond to neurotransmitters
18
Q
are dendrites myelinated?
A
no
19
Q
do dendrites conduct impulses away or towards the cell body?
A
towards
20
Q
how many axons are there per cell?
A
1
21
Q
do axons conduct impulses away or towards the cell body?
A
away
22
Q
axons can give off what?
A
collaterals
23
Q
many axons are wrapped in a what?
describe what this is
A
Myelin Sheath: glial cells wrapped around the axon
24
Q
what is located at the end of an axon?
A
synaptic terminals
25
axons produce what?
neurotransmitters
26
slide 15
does the axon or neurotransmitter contact muscle fibers, glands, and/or other neurons?
27
what is another name for axonal transport?
| what is this?
Axoplasmic flow
| Movement of cellular materials (not signals) through the axon
28
What are the two types of axonal transport?
| describe them
Anterograde
-away from soma; neurotransmitters, organelles, nutrients
Retrograde
-toward soma; degraded materials to be recycled & extracellular substances
29
What is the axoplasma?
cytoplasm of axon
30
what does the axoplasma consist of?
```
Few organelles
Cytoskeletal proteins
-Form cytoskeleton
-Maintain shape
-Generate axonal transport
```
31
what is the axolemma?
plasma membrane of an axon
32
what does the axolemma consist of?
| describe them briefly
Collaterals: side branches
Telodendria: terminal extensions
Synaptic terminal: contains synaptic vesicles; where neuron contacts postsynaptic cell
33
The structural classification of neurons is based on the number and morphology of_________
dendrites
34
what are the four structural classifications of neurons?
Anaxonic
Bipolar
Unipolar
Multipolar
35
describe anaxonic structure
-Small neurons
-Axons can not be distinguished from dendrites
(CNS, especially interneurons that coordinate special senses)
36
describe bipolar structure
Several small dendrites converge onto one
Dendrite & axon separated by soma
Unmyelinated
(Sensory neurons of special sensory organs)
37
describe unipolar structure
```
Also know as pseudo-unipolar
Several small dendrites converge onto one large one
Dendrite & axon continuous
Usually myelinated
(Majority of sensory neurons in PNS)
```
38
describe multipolar structure
```
Many dendrites extend from soma
Long axon
Myelinated
Majority of motor neurons in PNS
Spinal interneurons in CNS
```
39
afferent neurons have ______ function
sensory
40
describe afferent neurons
| cell body location, where impulses are carried to, etc
Cell body usually are outside CNS
Have receptor ends on dendrites or are associated with receptor cells in sense organs
Carry impulses from peripheral body parts to brain or spinal cord
41
afferent neurons have three receptors. What are they?
exteroceptor
Proprioceptors
Interoceptors:
42
What are Exteroceptors responsible for?
touch, light, temperature, pressure, chemicals
43
what do proprioceptors do?
monitor muscle and skeleton position
44
what do interoceptors do?
monitor internal systems (digestion, respiration, urinary, etc.)
45
describe interneurons
```
Only in CNS
Classified based on effects
-Excitatory
-Inhibitory
Most abundant
-Link 2 or more neurons
```
46
efferent neurons have ____ function
motor
47
for efferent neurons where are the cell bodies normally located? where do they carry impulses?
Cell body usually are inside CNS
| Carry impulses from the brain or spinal cord to peripheral body parts
48
what is the difference between somatic and autonomic efferent neurons?
somatic controls skeletal muscle and autonomic controls smooth muscles/glands
49
what are the 2 neuroglial cells in the PNS?
Satellite and Schwann
50
what are the 4 neuroglial cells in the CNS?
Astrocytes
Oligodendrocytes
Ependymal cells
Microglia
51
describe astrocytes
the largest and most common neuroglial cell it is star shaped
52
what are the functions of astrocytes ?
```
Structure and repair
Metabolism
Regulate ions and nutrition
Guide neurons to targets
Form blood-brain barrier
```
53
Oligodendrocytes are like ______ but smaller
| What are there 2 functions?
Like astrocytes but smaller
Functions:
Form myelin in CNS
Sequester debris
54
describe microglia and their functions
```
Smallest & least common
Derived from myeloid cells
Functions:
Help support neurons
Phagocytosis
Increase in number during injury or disease
```
55
describe ependymal and their functions
```
Columnar/cuboidal
Microvilli on luminal surface
Joined by gap junctions
Functions:
Help produce cerebrospinal fluid (CSF)
Form porous layer
Monitor CSF composition
```
56
describe satellite cells
Associated with soma
Assist with exchange of nutrients
Isolates neuron from extraneous stimuli
57
what do schwann cells do and what are their functions?
```
Produce myelin in PNS
Encloses axons of longer peripheral nerves
Functions:
Support neurons
Prevent contact
Myelinate large PNS axons
```
58
compare and contrast myelinated and unmyelinated axons
Myelinated
-appear white
-CNS; Oligodendrocytes myelinate part of several axons
-PNS; Schwann cell myelinates part of one axon
Unmyelinated
-appear gray
-Many axons associate with a single Schwann cell
(Note: rarely are PNS axons without ANY covering)
CNS; no glial cells
59
what is the myelin?
plasma membrane of Schwann cell wrapped around axon
60
what is the Neurilemma?
part of Schwann cell that contains cytoplasm
61
gaps in the myelin sheath are called what?
nodes of Ranvier
62
the myelination process starts at week______ and ends at year ______-______
14; 2-3
63
what is the function of myelin?
increase rate of action potential and isolate axons
64
describe regeneration of nerve fibers
:)
| slides 40-44
65
how is the repair in the CNS different than the repair in the PNS?
More limited
Degeneration occurs after injury
Oligodendrocytes do not proliferate
Proximal end sprouts but has no tube to follow
Astrocytes produce scar tissue and chemicals blocking regrowth
66
what is irritability?
ability to respond to stimuli
67
what is excitability ?
ability to transmit an impulse
68
what is an action potential?
an electrical impulse changing the permeability of a membrane
69
what is a nerve impulse?
action potential moving down an axon
70
impulses travel faster when....
axon is myelinated
| larger diameter
71
Synapses are a site of communication between ...
Sensory structure and neuron
Neuron & effector
2 neurons
Any two cells with gap junctions
72
what are the two types of synapses?
electrical and chemical
73
describe an electrical synapse and give an example
Gap junctions cause the exchange of charged ions between two cells
Ex. Intercalated disks in cardiac muscle
74
describe a chemical synapse and give an example
Chemicals are release by one cell and travel to another
Ex. Neuro-muscular junction
Ex. Neuron-neuron contact
75
______ house neurotransmitter
Synaptic vesicles
76
chemical synapses only exist in the ________
presynaptic cell
77
chemical synapses release neurotransmitter into the....
synaptic cleft
78
Receptors on ____________ register the neurotransmitter
post-synaptic membrane
79
true or false: chemical synapses communicate in only 1 direction
true
| only axons have synaptic vesicles
80
what are the steps that occur at a chemical synapse?
slides 51-52
81
neuronal pools receive impulses from ________. These impulses are carried away on______
```
afferent fibers (input)
efferent fibers (output)
```
82
what are the five types of neuronal pools?
```
Convergence
Divergence
Serial processing
Parallel processing
Reverberation
```
83
serial processing is....
one neuron to another in series
84
describe Divergence
- When impulse leaves a pool, it may spread into several output fibers
- Allows impulse to be amplified
85
describe Convergence
- Single nerve in pool may receive impulses from 2 or more incoming fibers
- If lead to same nerve; they are said to converge
- Allows summation of impulses from different sources
86
parallel processing....
processes information from several neurons at once
87
In Reverberation...
positive feedback continues activity of circuit
88
One neuron may receive either ________ & _______ stimuli from multiple neurons. The net effect of all this input results in a _________. If this charge is positive enough it will result in an _______.
excitatory, inhibitory, net charge, action potential
89
The point where an action potential can be produced is known as the what?
threshold
90
If a neuron is excited, but still below threshold.......
no impulse, but nerve is more excitable to next impulse. The nerve is said to be facilitated
91
this whole system of facilitation allows for the (multiple/singular) source/s to manage the nervous system
multiple (slide 60)
92
What three structures are found in the CNS? briefly describe what they are
Nuclei: collection of neuron cell bodies
Center: collection of neuron cell bodies working together
Tracts: bundles of axons
93
What two structures are found in the PNS? briefly describe what they are
Ganglia: collection of neuron cell bodies
Nerves: bundles of axons
