nervous system - histo lec Flashcards
1
Q
receive stimuli from the environment or from different organs of the body
transmit impulses to the brain and spinal cord
A
Nervous tissues
2
Q
Properties of Nervous Tissues:
A
- Irritability
- react to various stimuli - Conductivity
- transmit impulses
3
Q
A. Anatomical Division
A
CNS – brain and spinal cord
PNS – Peripheral Nervous System
- nerves outside the CNS and their associated ganglia
4
Q
B. Functional Division
A
Sensory component – transmits signal ( electrical impulses) to the CNS
Motor component – transmits impulses from the CNS to various structures of the body
1. somatic
2. autonomic
5
Q
C. Consists of two types of cells
A
Nerve cells (neurons) – conduct electrical impulses glial (neuroglial cells – support, nurture, and protect the neurons
6
Q
2 elements of nervous tissue:
- structural and functional units
- receive and transmit impulses
A
- Neurons
7
Q
2 elements of nervous tissue:
- glial cells - specialized type of connective tissue - non neuronal cells of the CNS and PNS
A
- Neuroglia
8
Q
Nucleus – “owl-eye nucleus”
-abundant in ?
A
euchromatin
9
Q
cytoplasmic organelles in neurons
A
Cytoplasmic organelles a. Nissl bodies - polysomes and RER most abundant in motor neuron b. Golgi complex and mitochondria c. melanin- containing granules d. Lipofuscin- containing granules e. lipid droplets
10
Q
- polysomes and RER most abundant in motor neuron
A
Cytoplasmic organelles
a. Nissl bodies
11
Q
- cytoskeletal filaments of neuron
A
a. neurofilaments
b. microtubules
c. actin filaments
12
Q
receive stimuli from sensory cells, axons or other neurons
A
dendrites
13
Q
and convert these signals into action potentials that are transmitted toward the soma
A
dendrites
14
Q
presence of arborized terminals
A
dendrites
15
Q
spines on the surface
A
dendrites
16
Q
cytoplasm lacks Golgi complex
A
dendrites
17
Q
- conducts impulses away from the soma to the axon terminals
A
AXONS
18
Q
- up to 100 cm length
A
AXONS
19
Q
- originates at the axon hillock
A
AXONS
20
Q
- with axon collateral
A
AXONS
21
Q
- axoplasm with SER, RER, mitochondria
A
AXONS
22
Q
- Initial segments for site if various excitatory and inhibitory stimuli
A
AXONS
23
Q
- terminates into axon terminals
A
AXONS
24
Q
- membrane is called axolemma
A
AXONS
25
- many dendrites and one axon
| ex. neurons in the CNS
1. Multipolar neuron
26
- one axon and one dendrite
| ex. neurons in the retina of the eye and neurons in the nasal cavity
2. Bipolar neuron
27
- one process extending from the cell body that divides into an
axon and dendrite
ex. Spinal and cranial ganglia
3. Unipolar neurons (pseudounipolar)
28
>Protect and support neurons
>Do not conduct impulses or form impulses or form synapses
>Cell Division
>Revealed only in histologic sections by special gold and silver stains
neuroglial cells
29
Are the largest of the neuroglial cells
astrocytes
30
“perivascular feet” that surround blood vessels and pia matter
astrocytes
31
glial cell
| Supply energy for metabolism
astrocytes
32
Forms a protective sealed barrier between the pia mater and the nervous tissue of the brain and spinal cord
astrocytes
33
Scavenge ions or debris from neuronal activity
astrocytes
34
glial cell
| Structural support
astrocytes
35
Form scar tissues after injury to CNS
| (e.g cerebral infarct)
astrocytes
36
Two types of Astrocytes
gray matter
branched processes envelop blood vessels, neurons and synaptic areas
Blood-brain barrier
With GFAP
Protoplasmic
37
Two types of Astrocytes
white matter
Long slender processes
fibrous
38
protects the CNS from fluctuating levels of electrolytes,hormones, and tissue metabolites
circulating in the blood vessels
The blood–brain barrier
39
Live symbiotically with neurons in the CNS
| Located both in gray and white matter
Oligodendrocytes
40
Produces myelin that insulates and protects axons
Oligodendrocytes
41
increases the speed of transmission of the action potential down the axon.
Myelin sheath:
42
decreases the metabolic needs of the neuron by reducing the total amount of ion exchange that happens during an action potential.
Myelin sheath:
43
Flat cells, few mitochondria and GA
| From neural crest cells
Schwann Cells
44
For regeneration of nerve fiber
Schwann Cells
45
Protect and insulate neuron in PNS
Schwann Cells
46
- phagocytic
- remove bacteria and cell debris from the CNS
- distributed in GM and WM
- secrete cytokines
3. Microglia
47
line the neural tube and ventricles of the brain and spinal cord
Ependymal cells
48
transport and circulation of the CSF
Ependymal cells
49
no basal lamina
Ependymal cells
50
low columnar/cuboidal GLIAL CELL
Ependymal cells
51
Contribute to formation of choroid plexus
Ependymal cells
52
Functional apposition where signals are transmitted from one neuron to another or from neuron to other type of cell (e.g. muscle)
synapse
53
- enclosed by myelin sheath
- prevents loss of nerve impulse
- circular constrictions (Nodes of Ranvier)
- internodal segments or Schwann segments
Myelinated nerve fibers
54
- naked axons
- devoid of myelin sheath
- neurolemma
Unmyelinated nerve fibers
55
classification of peripheral nerves as to function
Sensory – contain afferent fibers (to the CNS)
Motor – contain efferent fibers (from the CNS)
Mixed – contain both afferent and efferent fibers
56
Are encapsulated aggregations of neuronal cell bodies (soma) outside the CNS
GANGLIA
57
Two types of ganglia
Autonomic ganglia
| Craniospinal ganglia
58
mostly myelinated nerve fibers, some unmyellinated and glial cells
White matter –
59
– mostly neuronal cell bodies, unmyelinated
| fibers, and neuroglial cells
Gray matter
60
Degeneration of distal axonal segment
| (anterograde changes)
“Wallerian degeneration”
61
2. Regeneration of proximal axonal segment
(retrograde changes)
