Nervous Tissue

Main component of the nervous system

Brain, Spinal cord, Peripheral Nerves

It regulates and controls bodily functions

Nervous system

transmit impulses, and neuroglial cells which assist in the propagation of nerve impulses as well as providing nutrients to the neurons

Nervous tissue

Nervous tissue is composed of?

Neurons

Glia means

from the greek word meaning glue

All types of nerve cells have an?

Axon

It sends action potential signal to the next cell

Axon

Functions of the nervous system

1. Sensory input

2. Integration

3. Control of muscles and glands

4. Homeostasis

5. Mental activity

enclosed by a cell/plasma membrane and has a central nucleus

Cell body

granules found in the cytoplasm of the cell bod

Nissl bodies

extremely fine fibers within the cell body from the dendrites to the axon

Neurofibrils

whitish, non-cellular fatty layer that surrounds the axon

Myelin sheath

Myelin sheath surrounds the?

axon

cellular layer outside of the myelin sheath (outer)

Neurilemma or sheath of Schwann cells

Myelin sheath together with the neurilemma (inner)

Medullary sheath

interrupted intervals along the medullary sheath

Nodes of ranvier

All living cells have ability to

react to stimuli

Nervous tissue specialized to _______________________ to various organs in the body which bring about response to stimuli

react to stimuli and conduct impulses

Nerve are made up of?

nerve fibers

Nerve fibers are bound together by?

connective tissue

surrounds the nerve and penetrates the nerve to form the perineurium which surrounds bundles of nerve fibers

Epineurium sheath of dense connective tissue

a thin layer of loose CT which surrounds individual nerve fibers

Endoneurium

Majority of neuron are generated before?

birth

Mature neurons do not?

mitotically divide

Persisting stem cells give rise to new neurons throughout?

lifetime

Key to understanding function of neuron lies in:

1. Shape of the neuron and its processes

2. Chemicals the neurons uses to communicate (neurotransmitters)

3. Ways in which neurons may react to the neurotransmitters released by other neurons

Shape of neuron

long processes that extend from the body cell body

part of receptive surface of neuron

Dendrites

One or several primary dendrites which divide into?

secondary and tertiary dendrites

Maybe smooth or studded with small, mushroom-shaped appendages called

spines

Axon are never more than?

one

Point of origin from perikaryon is

axon hillock

Axon is the ________ of the neuron

Transmitting process

Small bulb-shaped swellings called? at the end? or along the course?

Boutons

Terminal boutons (at the end)

Boutons en passant (along the course)

The meeting point between two nerve cells separated by a tiny gap, involving a presynaptic neuron (sending the signal) and a postsynaptic neuron (receiving the signal).

Synapse

Synapse involves a?

Presynaptic neuron and postsynaptic neuron

Synapse that sends the signal

Presynaptic neuron

Synapse that receives the signal

Postsynaptic neuron

A small bump-like part of the presynaptic neuron filled with tiny sacs called synaptic vesicles.

bouton in a neuron

Tiny sacs inside the bouton that gather near the point closest to the postsynaptic neuron.

synaptic vesicles

What happens when a signal reaches the bouton?

triggers synaptic vesicles to release neurotransmitters into the synaptic cleft

The space between two neurons where neurotransmitters are released.

synaptic cleft

They cross the synaptic cleft, bind to postsynaptic receptors, and pass the signal along

Neurotransmitter transferring a signal across neurons

Nerve cells send electrical signals called?

Impulses

How do nerve cells communicate?

Sends impulses, then convert it to chemical messages at the synapse

Converted chemical messages

Neurotransmitters

Synapse is where neurons almost?

touch but dont actually connect

Neurons use this to bridge the gap and pass on information

Neurotransmitter

Neurotransmitter can _______________ postsynaptic neurons

Exhibit or inhibit

Most prominent excitatory transmitter of CNS is

L-glutamate

Most prominent inhibitory transmitter is

gamma- amino butyric acid (GABA)

Other main neurotransmitters are

Dopamine

Serotonin

Acetylcholine

Noradrenaline

Glycine

Each neuron uses only one

main transmitter

Star-shaped cells which processes are often in contact with blood vessels (perivascular foot processes)

Astrocytes (astroglia)

Astrocytes provides which support to the neurons of the CNS?

mechanical and metabolic support

Astrocytes participate in maintenance composition of?

ECF

Maybe involved in removal of transmitters from synapses and metabolism of transmitters

Astrocytes

Astrocytes are the

scar forming cells of CNS

Fewer and shorter processes. Form myelin sheath around axons in the CNS, homologue of peripheral Schwann cells

Oligodendrocytes

The oligoglia, unlike Schwann cells, may form parts of

myelin sheath of several axons

Small cells with complex shapes

Microglia

Microglia are _______________ origin

of mesodermal origin

Microglia derived from cell lines which gives rise to?

Monocytes

In case of tissue damage, microglia can?

proliferate and differentiate into phagocytic cells

Line the ventricles of the brain and central canal of the spinal cord

Ependymal cells

Ependymal cell shape

Often ciliated and of simple cuboidal or low columnar epithelium

Ependymal cells lacks _________ between cells which allow free exchange between CSF and nervous tissue

tight junction

Ependymal cells can specialize into

Tancytes

are rarely ciliated with long basal processes; form ventricular lining over a few CNS regions in which the (blood-brain barrier) BBB is incomplet

Tancytes

Many glial cells express

neurotransmitter receptors

has only one process, the axon  Present in developing or embryonic nervous system and is also common in insects

Unipolar neuron

neuron has 2 processes, one axon and one dendrite that fuse close to the cell body but separate at som

Pseudounipolar

has 2 processes, one axon and one dendrite that originate at opposite poles of the soma

Bipolar neuron

has many processes, one axon and several dendrites that arise from an oval, pyramidal or stellate soma

Multipolar neuron

Glial cells may communicate with each other via the

gap junctions

Oval or spindle-shaped cells with scanty cytoplasm and round nucleus at expanded part of th

Amphycytes or satellite cells (gliocytes of the PNS)

Form rosary-like capsule around individual cell bodies of neurons located in cranial and spinal ganglia

Amphycytes or satellite cells (gliocytes of the PNS)

Cells enclosing both the unmyelinated and myelinated axons in the PNS

Neurolemmocytes of Schwann cells

Type of neuron in which only one protoplasmic process (neurite) extends from the cell body

Unipolar neuron

Unipolar neurons that begins as bipolar neurons during development are known as

pseudounipolar neurons

Neurolemmocytes of Schwann cells produce ____________ of myelinated fibers in the PNS

myelin sheath

Scar-forming cells of CNS

Astrocytes

Amphycytes forms ________________ around individual cell bodies of neurons located in cranial and spinal ganglia

rosary-like capsule