Chapter 7 – 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- Overview of the Brain:

• The brain acts as the main ______________ and __________ of the N.S. • The cranial nerves ____________ the brain and go to specific body areas

– Sensory

– Motor

Brain 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 ________________________

– _____________________

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- Left and Right Side of Brain

• The brain senses and controls most of the body in a __________________

• Connection by a collection of white matter = _______________________

Major Sections of the Human Brain

The cerebrum The diencephalon:

– Hypothalamus – Thalamus – Pineal gland

The cerebellum The brainstem

Lobes of Cerebrum • Named for the skull bones that

cover them • Occur in pairs (usually)

General Functions of each Lobe ___________________motor function, behavior, emotions, memory, thinking and smell ___________________body sense, perception, speech ___________________Vision ________________________hearing, taste, language, comprehension, integration of emotions Diencephalon

Contains: • ___________________relays info going to cerebrum

• ___________________regulates temp, water balance, thirst, appetite,

some emotions, regulates pituitary gland

• ___________________secretes melatonin

• ___________________secretes hormones for various functions

Grey Matter in the brain

• Basal nuclei:

• Limbic system:

Cerebellum:

______________gray matter, ___________is white

Responsible for:

Brain Stem

Divided into three sections:

General functions:

Contains reticular system responsible for:

(anasthesia inhibits this causing unconsciousness)

Medulla oblongata-

Pons-

Midbrain-

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)