Module 5 Nervous tissue Part 2 Flashcards
To process and coordinate:
o sensory data from inside and outside of
body
Brain and spinal cord
To process and coordinate:
motor commands: control activities of
peripheral organs ex: skeletal muscles,
glands,etc
Brain and spinal cord
To process and coordinate:
higher functions of brain: intelligence,
memory, learning, emotion
Brain and spinal cord
Major region of CNS
- Cerebrum
- Cerebellum
- Spinal cord
Covered by 3 layers of connective tissue
Meninges
with very small amount of collagen
or fibrous tissue which make them delicate
and damaged easily due to injuries in the
cranial and vertebral bones that protects
them
Meninges
made by
regions of the nervous
system containing
groupings of myelinated
axons, composed of
capillaries, neuroglia,
nerve fibers
White matter
mainly
comprised of groups of
neuron cell bodies,
dendrites & synapses
(connections between
neurons)
Gray mater
membranes made up of connective
tissues that brain tissues from cranial bone
Meninges
3 layers of meninges
- Dura
- Arachnoid
- Pia matter
Composed of dense fibroelastic connective tissue
that continue to the periosteum of the cranial
bone
Dura matter
- All internal surface of dura mater and external or
spinal cord is surrounded by simple squamous
epithelium that originated from mesenchyme
Dura matter
- Subdural space separate dura mater from the
arachnoid
Dura matter
connective tissue sheet in contact with
dura mater and collagen and fibroblast arranged
loosely , with collagen and fibroblast
Arachnoid
Connective tissue in the …………..has no capillaries
to supply nutrients but it has larger blood vessels
Arachnoid
sponge-like cavity filled with
CSF, surrounds the trabeculae. It serve as cushion
that protect CNS from trauma
Subarachnoid
a CSF filled projection covered by
endothelial cells, serve as site for absorption of CSF into the blood
Arachnoid villi
Composed of flattened cells closely lined
in the surface of CNS tissue
Pia matter
It does not directly connect with the
nerve cells or fibers
Pia matter
Completely enveloped the Cerebral
arteries and veins travel in the
subarachnoid space
Pia matter
composed of capillary endothelial cells,
protects neuron and glia from toxins,
infectious agents and other substances
Blood brain barrier
– Composed of highly vascularized tissue with
prominent folds and villi projecting into 4
large ventricles of the brain
Choroid plexus
– Function is to remove water from blood and
release it as CSF
Choroid plexus
largest part of human brain
Cerebrum or cortex
associated w/ higher brain function: thought and action
Cerebrum or cortex
- involved in coordination of voluntary motor movement,
balance and equilibrium and muscle tone
Cerebellum or little brain
Layer of gray matter that
constitutes the outer layer of
the cerebrum and is responsible for
integrating sensory impulses and for higher
intellectual functions
Cerebral cortex
6 Layers of the cerebrum
- Molecular or plexiform layer
2.External granular layer
3.External pyramidal layer:
4.Internal granular layer:
5.Internal pyramidal layer or ganglionic layer (Betz cells)
6.Multiform layer:
- chiefly composed of cell processes.
Molecular or plexiform layer
- contains small pyramidal cells and numerous closely packed stellate cells
External granular layer
- Composed mainly of large pyramidal cells and some stellate cells
External pyramidal layer
: consists of closely packed stellate cells
Internal granular layer
- contains large pyramidal cells., stellate cells and Martinotti cells
Internal pyramidal layer or ganglionic layer (Betz cells)
contains neurons of many shapes.,pyramidal
cells, stellate cells and Martinotti cells
.Multiform layer
Cells of the Cerebral cortex
- Pyramidal cells
- Non pyramidal cells
cells of Non pyramidal cells
- stellate cells ( granular cells)
- Horizontal cells
- Martinotti cells
The most numerous neurons in the cerebral
cortex
Pyramidal cell
multipolar neuron, large vesicular nucleus
Pyramidal cell
one main apical dendrites that run
towards the most superficial part of the
cerebral cortex and some other smaller
dendrites
Pyramidal cell
arises from the center of base and
runs in the white mater
Axon
also called as granule cells
because of their small size
Stellate cells
found in most superficial layer
Horizontal cells
found in the deeper layers
Martinotti cells
Cerebellum:3 layers of cerebellar cortex
- Molecular layer
- Purkinje cells
- Granular layer
Cell population is low
Mainly composed of cell processes
Stellate cells and basket cells are present here
Molecular layer
Large, multipolar neurons
Vesicular nucleus with a prominent nucleolus
Large number of Nissl granules in the cytoplasm
Purkinje fiber
Population of small neurons are called
Granule cells
appear as closely packed nuclei, stain deeply basophilic
Granule cells
Golgi type II cells are also present
Granular layer
short axon which make synapse with terminal branches
of Mossy fibers
Granular layer
sends sensations to brain from the body
Spinal cord
returns motor commands to the various parts
of the body
Spinal cord
has primary role in reflexes and in autonomic
nervous system
Spinal cord
Central canal is present lined by
Ependymal cells
shaped arrangement of gray
matter
Inner butterfly
Nerve made up of bundle of axons, CT and blood
vessels
Peripheral Nervous System
Carry sensory information and motor
commands in PNS ( into and out of the
CNS).
Peripheral nervous system
2 categories of Peripheral nervous system
- Cranial nerves
- Spinal nerves
connected to the brain
Cranial nerves
attached to spinal cord
spinal nerves
helps bring information in and helps carry
direction that are given to it by the brain
out of the CNS
Peripheral nervous system
Functional division of PNS
- Afferent division ( Accessing)
- Efferent division ( Exiting)
carries
sensory information from
PNS to CNS
Afferent division (Accessing)
carries motor
commands out of CNS to
PNS muscles glands and
other tissues
Efferent division (Exiting)
2 parts of the Afferent division
- Receptors
- Effectors
pick up a change or stimulus
Afferent division
- bring the information to the CNS for
interpretation
Afferent division
neuron and specialized cells
Afferent division
Afferent division complex sensory organs Ex:
eyes, ears, etc
respond to afferent signals or to the information
picked up by the receptors
Efferent division
- cells and organs
Efferent division
2 parts of the Efferent division
- Somatic nervous system
- Autonomic nervous system
controls skeletal muscle contraction
Somatic nervous system
voluntary and involuntary muscle
contractions (reflexes)
Somatic nervous system
control subconscious actions, contractions
of smooth and cardiac muscles and
glandular secretions
Autonomic nervous system
“Fight or Flight response”– has a
stimulating effect
Sympathetic
“rest and digest” – has a
relaxing effect
Parasympathetic
Serve as relay station to transmit nerve
impulses
PNS Ganglia
– large cell bodies has thin sheetlike
extension of small glial satellite cell
Central Sensory or cranio-spinal ganglia
Supported by connective tissue capsule
Central Sensory or cranio-spinal ganglia
receive impulses to be delivered to CNS
Central Sensory or cranio-spinal ganglia
example of Central Sensory or cranio-spinal ganglia
Dorsal root of ganglia
– clusters of neuron cell bodies that
transmit sensory signals from the
periphery to the integration centers in the
CNS
Autonomic Ganglia/ Visceral or Peripheral Motor
Ganglia
Nerves that effect the activity of smooth
muscles, all involuntary activities like
secretion of glands, heart rate
Autonomic Ganglia/ Visceral or Peripheral Motor ganglia
two types of PNS ganglia
- Central Sensory or cranio-spinal ganglia
- Autonomic Ganglia/ Visceral or Peripheral Motor
Ganglia
3 Peripheral nerve endings:
- Ending in epithelium
- Endings in connective tissue
- Endings in musc
Endings in Epithelium- Example
T
N
F
Tactile Disc of Merkel (for touch)
neuroepithelium in taste buds,
free nerve endings
Endings in Connective tissues- Example
M
R
Meissner’s corpuscles (for touch),
Ruffini’s cylinder (for heat)
Endings in Muscles
( found in ends of efferent
nerves in contact with muscles, glands)
Motor nerve endings
Endings in muscle
( arising from ganglia of
spinal cord and cerebral nerves)
Sensory nerve endings
outer tube like layer of dense
irregular CT
Epineurium
encases fascicle thicker and more resistant than epineurium
Perineurium
encloses nerve fiber
Endoneurium
-thin cytoplasmic covering
- produced by Schwann cells
Neurolemma/ sheath of Schwann
regular interval interruption
of myelin over whole length of axon
Nodes of Ranvier
Classification of Nerve Fibers
- Medullated nerve fibers w/ neurolemma
- Medullated nerve fibers w/o neurolemma
- Non – Medullated nerve fibers w/ neurolemma
- Non – Medullated nerve fibers w/o
neurolemma
white, multi layered, fatty covering for some
nerve processes
Myelin Sheath (Medullary Sheath)
arranged in segments, separated by Nodes of
Ranvier (enables salutatory conduction)
Myelin Sheath (Medullary Sheath)
segment b/w 2 nodes of Ranvier
Internode
In fixed preparation, myelin darkened by Osmium
tetroxide or Weigert’s staining method
Myelin sheath (Medullary Sheath)
Weigert’s staining method result
The axon (lipoprotein complex)remained unstained
Function of Myelin sheath (Medullary sheath)
Insulation of nerve process
Increased speed of conduction
– the glial cell does not form the wrapping of
the myelin sheath
Unmyelininated Fibers
- With the absence of rudolf myelin sheath,
nodes of Ranvier are not visible
Unmyelininated Fibers
