NERVOUS SYSTEM
By: Abby & Tessa
TERMS
Brain- encephal/o- coordinates all activities of the body and receives and transmits
messages throughout the body.
Spinal Cord- myel/o- transmits nerve impulses between the brain, limbs and lower
part of the body
Nerves- neur/i, neur/o- receive and transmit messages to and from all parts of the
body
MORE TERMS
Central Nervous System (CNS)- includes the brain and spinal cord
Peripheral Nervous System (PNS)- includes the 12 pairs of cranial nerves extending
from the brain and the 31 pairs of spinal nerves extending the spinal cord
Autonomic Nervous System (ANS)- includes the peripheral nerves and ganglia on
either side of the spinal cord
DIVIDED INTO TWO SUB-DIVISION
Central Nervous system
(CNS)
Brain and spinal cord
Integrating and command
center of the nervous system
Peripheral Nervous System
(PNS)
Part of nervous system that
extends from the brain and spinal
cord
Afferent (sensory)
Efferent (motor)
1. Cranial nerves: carry signals to and from the brain
2. Spinal nerves: carry signals to and from the spinal cord
FUNCTIONS AND ORGANIZATION OF THE
NERVOUS SYSTEM
https://youtu.be/tm-YGOFhhHE
The efferent (motor) division is divided into the
somatic nervous system and the automatic
nervous system
The automatic nervous system is further
divided into the sympathetic and
parasympathetic divisions
The activities of the nervous system can be
grouped into sensory, integrative and motor
functions
NERVE TISSUE
Neurons are the nerve cells that transmit impulses
The conducting cell that transmits impulses
Structural unit of the nervous system
The other type of cell is neuroglia or glial cell
 Means “nerve glue”
These cells are nonconductive and provide a support system for the neurons
They are a special type of nerve tissue
Supporting cells are neuroglia, protect and nourish the nerouns and they are capable
of mitosis
NERVE IMPULSES
The ability to respond to a stimulus (excitability) and transmit impulses (conductivity)
At rest the outside of a neuron is positive charge and has a higher concentration
inside
The cell membrane of non conducting neuron is polarized with an abundance of
sodium ions outside the cell and an abundance of potassium ions and negatively
charged proteins inside cell
A stimulus alters the permeability of cell membrane
In response to a stimulus the cell membrane becomes permeable to sodium ions
They enter cell and depolarize(sodium diffuses) the membrane Followed by reverse
polarization
Saltatory conduction occurs in myelinated fibers where the action potential jumps
from node to node
To initiate an impulse is called a threshold (liminal) stimulus
CENTRAL NERVOUS SYSTEM
The brain is surrounded by the cranium and the spinal cord is protected by the
vertebrae
In addition to bone the CNS is surrounded by connective tissue membranes
called Meninges and cerebrospinal fluid (CSF)
Meninges
The outer layer is tough white fibrous connective tissue
The middle layer is the arachnoid whish resembles a cobweb in looks and contains blood
vessel underneath
The innermost layer is pia matter it is delicate and thin and tightly bound to the surface of
the brain and spinal cord
CONT.
The spinal cord consist if a central core of gray matter surrounded by white
matter
Gray matter consists of neuron cell bodies
White matter is myelinated nerve fibers
Two enlargements of the spinal cord are in the cervical and sacral regions
The primary sensory area of the brain is the post central gyrus in the parietal
lobe
Ascending tracts carry sensory impulses to brain
 corticospinal tracts are descending tracts that begin in the cerebral cortex
CHAPTER QUIZ RECALL: MATCH THE DEFINITIONS ON
THE LEFT WITH THE APPROPRIATE TERM ON THE RIGHT
1.
Outermost covering of the CNS
A. Axon
2.
Produces cerebrospinal fluid
B.
3.
Occurs along myelinated axons
C. Dura mater
4.
Supporting cells of the nervous system
D. Medulla oblongata
5.
White, fatty covering of axons
E.
Myelin
6.
Controls contraction of skeletal muscles
F.
Neuroglia
7.
Lowest part of the brain stem
G. Occipital lobe
8.
Contains visual cortex
H. Parietal lobe
9.
Efferent Process of a neuron
I.
Saltatory conduction
J.
Somatic nervous system
10. Contains somatosensory cortex
Choroid plexus
CHAPTER QUIZ RECALL ANSWERS
1.
Outermost covering of the CNS
Axon
2.
Produces cerebrospinal fluid
Choroid plexus
3.
Occurs along myelinated axons
Dura mater
4.
Supporting cells of the nervous system
Medulla oblongata
5.
White, fatty covering of axons
Myelin
6.
Controls contraction of skeletal muscles
Neuroglia
7.
Lowest part of the brain stem
Occipital lobe
8.
Contains visual cortex
Parietal lobe
9.
Efferent Process of a neuron
Saltatory conduction
10. Contains somatosensory cortex
Somatic nervous system
1. NEURONS LOCATED ENTIRELY WITHIN THE CNS
ARE
a) Motor neurons
b) Association neurons
c) Efferent neurons
d) Sensory neurons
ANSWER: B
Association neurons
It is a link
which conveys impulses in an arc from sensory to motor neurons
2. SELECTED EVENTS IN IMPULSE CONDUCTION ARE GIVEN.
ARRANGE THESE EVENTS IN THE ORDER IN WHICH THEY OCCUR
1) SODIUM GATES OPEN
2) POTASSIUM GATES OPEN
3) STIMULUS ALTERS MEMBRANE PERMEABILITY
4) ACTIVE TRANSPORT OF SODIUM AND POTASSIUM
5)REVERSE POLARIZATION
3,1,2,4,5
3,1,5,4,2
3,4,1,5,2
3,1,5,2,4
ANSWER: D
3,1,5,2,4
3. WHITE MATTER
a) Forms the cerebral cortex
b) Consists of neuron cell bodies
c) Forms the outer covering of the brain
d) Consists of myelinated fibers
ANSWER D
White matter consists of myelinated fibers
Not the gray matter
4. THE THREE REGIONS OF THE BRAIN STEM ARE
THE
a) Thalamus, hypothalamus, pineal body
b) Thalamus, pons, cerebellum
c) Midbrain, pons, medulla oblongata
d) Thalamus, midbrain, cerebral peduncles
ANSWER IS C
Midbrain
Pons
medulla
oblongata
5. THREE CRANIAL NERVES THAT HAVE ONLY
SENSORY FUNCTIONS ARE
a) Optic, olfactory, and trigeminal
b) Optic, olfactory, and vestibulocochlear
c) Optic, oculomotor, and glossopharyngeal
d) Vagus, trigeminal, and facial
ANSWER IS B
Three cranial nerves that have only sensory functions are Optic, olfactory, and
vestibulocochlear