1. CHAPTER 9
Nervous Tissue

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.

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.

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.

16.  End of Presentation
 EXAM, EXAM, EXAM