2. NERVOUS TISSUE
Nervous tissue is found in the brain, spinal
cord, and nerves.
It is responsible for coordinating and
controlling many body activities.
It stimulates muscle contraction, creates an
awareness of the environment, and plays a
major role in emotions, memory, and
reasoning.
To do all these things, cells in nervous tissue
need to be able to communicate with each
other by way of electrical nerve impulses.
3. NERVOUS TISSUE
Nervous tissue is responsible for sensing
"stimuli" and transmitting "signals" to
and from different parts of the body.
Neurons are the basic unit of nervous
tissue.
4. A NEURON CONSISTS OF
TWO MAJOR PARTS:
1. Cell Body - contains the neuron's nucleus and
associated cytoplasm/organelles.
Also known as soma, cyton or perikaryon
2. Nerve Processes - are "finger-like"
projections from the cell body that are able to
conduct and transmit signals.
There are two types:
1. Axons: typically carry signals away from the
cell body.
2. Dendrites: typically carry signals toward the
cell body.
5.
6.
7. NEUROGLIA
Supporting tissue intermingled with
the essential elements of nervous
tissue especially in the brain, spinal
cord, and ganglia.
Functions include
providing support for the brain,
assisting in nervous system repair and
maintenance,
assisting in the development of the
nervous system and
providing metabolic functions for
neurons.
8. THERE ARE SEVERAL TYPES OF GLIA
PRESENT IN THE NERVOUS SYSTEM OF
HUMANS:
Astrocytes are found in the brain's
capillaries and form the blood-brain barrier
that restricts what substances can enter the
brain.
Microglia are extremely small cells of the
central nervous system that remove cellular
waste and protect against microorganisms.
Oligodendrocytes are central nervous
system structures that wrap some neuronal
axons to form an insulating coat known as the
myelin sheath.
Schwann Cells are peripheral nervous
system structures that wrap some neuronal
axons to form an insulating coat known as the
myelin sheath.
9. CLASSIFICATION OF NEURONS
ACCORDING TO THEIR
STRUCTURE,
1. Unipolar Neurons. have only a single
process or fibre which divides close to
the cell body into two main branches
(axon and dendrite). Because of their
structure they are often referred to as
unipolar neurons.
2. Multipolar Neurons, which have
numerous cell processes (an axon and
many dendrites) are often referred to as
multipolar neurons.
3. Bipolar Neurons. are spindle-shaped,
with a dendrite at one end and an
axon at the other . An example can be
found in the light-sensitive retina of the
eye.
10.
11.
12. THERE ARE THREE MAIN TYPES OF
NEURONS, CLASSIFIED ACCORDING
THEIR FUNCTION
Sensory Neurons move from the
receptor to the Central Nervous System.
Afferent neuron.
Motor Neurons move from the Central
Nervous System to the effector muscle.
Interneurons (also known as
connector neurons or association
neurons) are those that connect sensory
neurons to motor neurons.
