Chapter 8 – Nervous System

Two message centers: Functions of these systems:

1. *

2. *

Overview of the Nervous System

Parts: General Functions:

Functions

Sensory input: Sensation via nerves

Integration: interpretation of data by brain and spinal cord

Motor Output: Motor response

Divisions of the Nervous System

The central Nervous System (CNS)

Peripheral Nervous System (PNS)

Consists of Cranial and spinal nerves

Two subdivisions

Afferent (sensory) Efferent (motor)

Nervous Tissue:

Neurons Neuroglia

5 types of Neuroglial cells

Structure of a Neuron:

Cell Body:

Dentrites:

Axon:

Myelin Sheath:

Function: Insulation and conduction of nerve impulse

Formed by: Schwann cells in the ____________

Oligodendrocytes in the _________

Nodes of Ranvier:

Structural Classification of Neurons:

Unipolar:___________ axon that enters and exits the cell body

Bipolar: one dendrite and one axon

Found :

Multipolar: many dendrites and _____ axon

Motor Neurons

Efferent

Sensory Neurons

Afferent

Interneurons

Association Neurons

Where

Found?

Function?

Structural

Classification Uni-

Bi- polar

Multi-

Pathway

Stimulated by

Sensory Neuron: Interneuron:

Neuroglial Cells and Transmission of Action Potential

6 Types of Neuroglial or Glial Cells:

Glia = greek word for glue

Special types of ________________________ that help ___________

and provide _________________ for nerve cells.

___________________ neurons and

______________________________.

Supply ____________ and _______________ to neurons.

______________________ one neuron from another.

Destroy ___________________ and remove ______________neurons.

Motor Neuron:

Name of the Cell Found in CNS or PNS Function

Astrocytes

Oligodendrocytes

Microglia Cells

Ependymal Cells

Schwann Cells

Satellite Cells

Nerve Impulse

An __________________________ that travels along a nerve fiber.

Travels about _________________________________________.

Rapid ____________________ and ________________ of a small

portion of the plasma membrane

Nerve Signal Conduction

_____________________ potential followed by an _______________

potential

Resting Potential

Electrical charge across the ______________________

Inside of cell is _______ compared to the outside

Sodium ions _________

Potassium ions ________

Depolarization

Neurotransmitters open _____________ channels

___________ rushes into the cell

inside of cell is now ______________________

Repolarization

_________________ channels open

__________ flows out of the cell

Inside becomes more _________________

Refractory Period

• Time which the neuron is ________________________________

• In mammals, the absolute refractory period is about ______________ and

the maximum firing frequency is about ______ impulses per second

Synapses

• The ___________ between a nerve cell and another cell.

• To cross a synapse _________________are released.

Transmission across a synapse

• Neurotransmitters stored in______________ in the ________ terminal

• Impulse reaches terminal

• ____________ channels open

• Vesicles fuse with ________________ membrane

• _______________________ are released

• Receptors bind to ______________ membrane

Common Neurotransmitters

• _____________________ (ACh)

• ______________________ (NE)

• Once released must be removed from synapse

____________________ (AChE) breaks down ACh

Brain Structure and Function

CNS: The Brain and Spinal Cord

Gray matter-

White matter-

Meninges: The Protective Coverings

Dura Mater (Outermost) Arachnoid Mater Pia Mater (Innermost)

Dura mater-

• Tough, fibrous, _____________________ tissue

• Made of ___________________________________ layers

• Separation of layers to form

_______________________________________________

– Collection of _____________________ and extra _________________

Arachnoid Mater-

• ________________________________ connective tissue

• CSF in the _______________________________ space

– CSF-clear fluid, _______________________________________

Pia Mater-

• Very thin layer

• Follows ________________________________________________________

CSF

• Made by the ____________________________________ lining the ventricles

• Fills all ________________________ and the __________________________

• Hydrocephalus-_________________________________________ in an infant

The Spinal Cord

• Is an extension of the brain

• Exits the cranial cavity via _________________________________________

• Runs through the _______________________________________________

• Ends between L ____ & L ____

• Cauda equina (horse’s tail)

The Vertebral Column

• Made of individual vertebrae separated by ________________________

– _____________________

– Disk herniation

Anatomy of the Spinal Cord

• Inner _______________________ with a central canal

• Outer ________________________________________

Spinal Nerves

• Posterior (dorsal) root of a spinal nerve:

– _____________________ (__________________________) fibers

• Anterior (ventral) root of a spinal nerve:

– _______________________ (_________________________) fibers

• Spinal nerve – joining of posterior & anterior roots

The Human Brain:

Gyri-

Sulci-

Major Sections of the Human Brain

The cerebrum

The diencephalon:

– Hypothalamus

– Thalamus

– Pineal gland

The cerebellum

The brainstem

Peripheral Nervous System (PNS)

All the rest of the nerves of your body

Two branches

o _______________ Nervous System

o _______________ Nervous System

Nerve Anatomy

____________________ = covers nerve itself

____________________ = covers bundles of axons

____________________ = covers individual axons

Somatic NS

_______ pairs of Cranial Nerves

_______ pairs of Spinal Nerves

Types of Nerves

Mixed = ____________________________

Sensory = ___________________________

Motor = ____________________________

Cranial Nerves Spinal Nerves

Nerve Plexus: ______________________________________

Name of Plexus Nerves found in

plexus

Services what

part of the body

Cranial

Nerve #

Name of Cranial

Nerve

Function Type of Nerve

I Sense of Smell

II Sense of sight

III Movement of eyelid and eyeball

IV Muscles of the eyes

V Muscles for chewing (motor) & pain

and touch for face and mouth

(sensory)

VI Muscles for eye movement

VII Sense of taste (sensory) & facial

expressions (motor)

VIII Sense of Hearing

IX Sense of taste (sensory), blood

pressure, tongue movement (motor)

X Innervates smooth muscle of the

gut(motor) & feelings of

distension/bloating (sensory)

XI Movement of neck muscles

XII Movement of the tongue

The Autonomic Nervous System

Two divisions:

– Sympathetic (__________________________________)

– Parasympathetic (__________________________________)

General Characteristics of Sympathetic and Parasympathetic

• Both divisions are ________________________ (involuntary)

• Both innervate all ___________________

• Both have 2 ______________________ and 1 ___________________

– Ganglion:

– place where __________________ of the 2nd ANS

neurons exit outside the CNS

Some Important functions of the ANS

• Regulation of _________________________________________

• Regulation of _________________________________________

• Control of secretions from ______________________

Setup of 2 ANS Neurons

Neuron 1 (pre-ganglionic neuron):

• Cell body ___________________(spinal cord) and the axon

______________ of the CNS

• Synapses with neuron 2 in the __________________________

Neuron 2 (post-ganglionic neuron):

• Cell body in the ________________ and the axon continues to the

______________

• Dendrites synapse with neuron 1 in the __________ and the axon terminals

synapse with the _______________

Neuron Setup in the Parasympathetic Nervous System

Neuron 1

Neuron 2

The ganglion lies far from the spinal cord

Neuron Setup in the Sympathetic Nervous System

Neuron 1

Neuron 2

The ganglion lies close to the Spinal cord

Origin of Sympathetic Nerves

Origin of Sympathetic Nerves __Origin of Parasympathetic Nerves

Functions of the Sympathetic Division

prepares the body for

emergencies (Fight or flight)

• increases heart rate

• raises blood pressure

(vasoconstriction)

• dilates the pupils

• dilates the trachea and bronchi

• Converts liver glycogen into

glucose

• shunts blood away from the skin

and organs (vasoconstriction)

• pushes blood toward the skeletal

muscles, brain, and heart

• inhibits peristalsis in the

gastrointestinal (GI) tract

• inhibits contraction of the

bladder and rectum

Functions of the Parasympathetic

Division

• The “housekeeper” division

• “Rest and Digest”

• Manages functions associated

with a relaxed state

• Contraction of the pupils

• Promotes digestion of food

• Slows down the heart rate

and decreased heart

contraction

• Increased blood flow to the

visceral organs (GI tract),

normal peristalsis

Sympathetic Neurotransmitters

Parasympathetic Neurotransmitters

Reflexes

• ________________________________responses

• Occur quickly

• ____________________________ mechanisms

• Cranial Reflexes:

– Blinking of eyes with sudden clapping near eyes

• Spinal Reflexes:

– Quick movement of hand away from the hot pan

Reflex Arc

1. Sensory transducer (hitting of patellar tendon)

2. ______________________________

3. ______________________________

4. Motor neuron

5. ____________________________ (muscle contraction)