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-DIVISIONCentral Nervous system (CNS)Brain and spinal cordIntegrating and command center of the nervous system

Peripheral Nervous System (PNS)Part of nervous system that extends from the brain and spinal cordAfferent (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 systemThe 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)

MeningesThe outer layer is tough white fibrous connective tissueThe 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

2. Produces cerebrospinal fluid

3. Occurs along myelinated axons

4. Supporting cells of the nervous system

5. White, fatty covering of axons

6. Controls contraction of skeletal muscles

7. Lowest part of the brain stem

8. Contains visual cortex

9. Efferent Process of a neuron

10. Contains somatosensory cortex

A. Axon

B. Choroid plexus

C. Dura mater

D. Medulla oblongata

E. Myelin

F. Neuroglia

G. Occipital lobe

H. Parietal lobe

I. Saltatory conduction

J. Somatic nervous system

CHAPTER QUIZ RECALL ANSWERS1. Outermost covering of the CNS

2. Produces cerebrospinal fluid

3. Occurs along myelinated axons

4. Supporting cells of the nervous system

5. White, fatty covering of axons

6. Controls contraction of skeletal muscles

7. Lowest part of the brain stem

8. Contains visual cortex

9. Efferent Process of a neuron

10. Contains somatosensory cortex

Axon

Choroid plexus

Dura mater

Medulla oblongata

Myelin

Neuroglia

Occipital lobe

Parietal lobe

Saltatory conduction

Somatic nervous system

1. NEURONS LOCATED ENTIRELY WITHIN THE CNS AREa)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 OPEN2) POTASSIUM GATES OPEN3) STIMULUS ALTERS MEMBRANE PERMEABILITY4) ACTIVE TRANSPORT OF SODIUM AND POTASSIUM5)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 THEa)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 AREa)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