CHAPTER
10
FUNCTIONAL
ORGANIZATION OF NERVOUS TISSUE
FUNCTIONS OF NERVOUS SYSTEM:
1. Sensory
input
2. Integration
3. Control
of muscles and glands
4. Homeostasis
5. Mental
activity
NEURONS
A neuron is a nerve cell that is the basic building block
of the nervous system. Neurons are similar to other cells in the human body in
a number of ways, but there is one key difference between neurons and other
cells. Neurons are specialized to transmit information throughout the body.
TYPES OF NEURONS
GLIAL
CELLS
ASTROCYTES
Astrocytes are star shaped glial cells that
perform a variety of functions in the CNS. Astrocytes provide physical
support to neurons and clean up debris within the brain. They also
provide neurons with some of the chemicals needed for proper functioning and
help control the chemical composition of fluid surrounding neurons. Finally,
astrocytes play a role in providing nourishment to neurons.
OLIGODENDROCYTES
The principle function of oligodendrocytes is to
provide support to axons and to produce the Myelin sheath, which insulates
axons. Myelin is 80% lipid and 20% protein and allows for the efficient
conduction of action potentials down the axon. Oligodendrocytes unlike
Schwann cells of the PNS, form segments of myelin sheaths of numerous neurons
at once.
MICROGLIA
Microglia are the smallest of the glial
cells. Some act as phagocytes cleaning up CNS debris. Most serve as
representatives of the immune system in the brain. Microglia protect the brain
from invading microorganisms and are thought to be similar in nature to
microphages in the blood system.
SCHWANN CELLS
Schwann cells are the supporting cells of the
PNS. Like oligodendrocytes schwann cells wrap themselves around nerve
axons, but the difference is that a single schwann cell makes up a single
segment of an axon's myelin sheath.
ACTION
POTENTIALS
PARASYMPATHETIC
AND PARASYMPATHETIC
SYNAPSE
It
is the junction between two cells, where two cells communicate each other.
-Electrical
synapse
-Chemical
synapse
