Name: Date: Class:
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 18
Unit 4 Outline: The Nervous System, Special Senses, and the Endocrine System
The Nervous System and Nervous Tissue
♦ Nervous System Functions
• - gathering
information
� Monitor inside and
outside the body
•
� Process and interpret sensory input and decide
if is needed
•
� Response to integrated stimuli
� Activates or glands
♦ Nervous System Structural Classification
• nervous system (CNS)
�
�
• nervous system (PNS)
� Nerves the brain
and spinal cord
♦ Functional Classification of the PNS
• Sensory ( ) division
� Nerve fibers that carry information
to the
• (efferent) division
� Nerve fibers that carry impulses
the CNS
� Two subdivisions
* Somatic nervous system = voluntary
* Autonomic nervous system = involuntary
♦ Nervous Tissue: Support Cells (Neuroglia)
•
� Abundant, -shaped cells
� neurons
� Form barrier between capillaries and neurons
� Control environment
of the brain
•
� Spider-like
� Dispose of
• cells
� Line of the
brain and spinal cord
� Circulate
fluid
•
� Produce sheath around
nerve fibers in the CNS
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 19
• cells
� Protect neuron cell
• cells
� Form myelin sheath in the
♦ Nervous Tissue: Neurons
• = nerve cells
� Cells specialized to
messages
� Major regions
* Cell - nucleus and
metabolic center of the cell
* - fibers that
extend from the cell body
♦ Neuron Anatomy
• Cell body
� substance- specialized
rough ER
� - intermediate
cytoskeleton that maintains cell shape
�
� Large
• Extensions outside the cell body
� - conduct impulses
toward the cell body
� - conduct impulses
away from the cell body
♦ Axons and Nerve Impulses
• end in axonal terminals
• Axonal :
� Contain with
neurotransmitters
� Axonal terminals are separated from the next
neuron by a
* Synaptic - gap
between adjacent neurons
* - junction
between nerves
♦ Nerve Fiber Coverings
• sheaths - jelly-roll
like covering (Schwann cells)
• Nodes of - gaps
in myelin sheath along the axon
♦ Neuron Cell Body Location
• Most are found in the
� matter- cell bodies and
unmylenated fibers
� - clusters of cell
bodies within the white matter of the CNS
• - collections of
cell bodies outside the CNS
Neuron Classification and Nerve Impulses
♦ Functional Classification of Neurons
• (afferent) neurons
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 20
� Carry impulses from the sensory
* sense organs
* - detect
stretch or tension
• Motor ( ) neurons
� Carry impulses from the CNS
• (association
neurons)
� Found in neural in
the CNS
� Connect sensory and neurons
♦ Structural Classification of Neurons
• neurons- many
extensions from the cell body
• neurons- one axon and
one dendrite
• neurons- have a short
single process leaving the cell body
♦ Functional Properties of Neurons
• - ability to
respond to stimuli
• - ability to
transmit an impulse
• The plasma membrane at rest is
� Fewer ions are
inside the cell than outside the cell
♦ Starting a Nerve Impulse
• - a stimulus
depolarizes the neuron’s membrane
• Depolarized membranes allow
(Na+) to flow inside
• Exchange of ions initiates an
in the neuron
♦ The Action Potential
• If the action potential (
) starts, it is propagated
over the entire axon
• ions rush out
of the neuron after sodium ions rush in, which
repolarizes the membrane
• pump
restores the original configuration
� Requires
♦ Nerve Impulse Propagation
• Impulse continues to move toward
the
• Impulses travel faster when fibers have a
sheath
♦ Nerve Impulse Continuation between Neurons
• Impulses cross the synapse to another nerve
� is released
from a nerve’s axon terminal
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 21
� Dendrite of the next neuron has
that are stimulated by the neurotransmitter
� An action potential is started in
the
♦ The Reflex Arc
• - rapid, predictable,
and involuntary responses to stimuli
• - direct route from a
sensory neuron, to an interneuron, to an effector
♦ Types of Reflexes and Regulation
• reflexes
� muscle regulation
� and blood pressure
regulation
� Regulation of
� system regulation
• reflexes
� Activation of muscles
Regions of the Brain
♦ Central Nervous System (CNS)
• and spinal cord
• Develops from the embryonic
tube
� Neural tube opening becomes
* chambers within the brain
* Filled with
fluid
♦ Regions of the Brain
• hemispheres
•
• Brain
•
♦ Cerebral Hemispheres (Cerebrum)
• parts of the brain
(left and right)
• More than of the brain mass
• Surface ridges ( ) and
grooves (sulci)
♦ Lobes of the Cerebrum
• divide the cerebrum
into lobes
• Surface lobes of the cerebrum
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 22
� lobe
� lobe
� lobe
� lobe
♦ Specialized Areas of the Cerebrum
• sensory area- receives
• impulses from the body’s sensory receptors
• Primary area- sends
impulses to skeletal muscles
• area- involved in speech
• Cerebral areas involved in special senses
� area (taste)
� area
� area
� Area (smell)
• Interpretation areas of the cerebrum
� /language region
� Language
region
� General interpretation area
♦ Layers of the Cerebrum
• matter
� layer
� Mostly of
cell bodies
• matter
� Fiber tracts the
gray matter
� Ex: corpus connects
hemispheres
• nuclei- internal islands
of gray matter
♦
• Sits on top of the brain
• Inside the
hemispheres
• Three parts
�
�
�
♦
• for sensory
impulses
• Transfers impulses to the correct part of the
for localization and interpretation
♦
• Under the
• Important nervous
system center
� Regulates body
� Controls balance
� Regulates
• Important part of the
system (emotions)
• Attached to gland
♦
• Houses the gland
• Includes the plexus- forms
cerebrospinal fluid
♦ Brain
• Attaches to the cord
• Parts of the brain stem
�
�
�
♦
Mostly of nerve fibers
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 23
• Reflex centers for and
hearing
♦
• Bulging center part of the brain
• Mostly tracts
• Includes nuclei involved in the control
of
♦ Medulla
• part of the brain stem
• Merges into the
• Important control centers
� control
� Blood regulation
�
�
�
♦ Formation
• Diffuse mass of matter along
the brain stem
• control of visceral organs
• Reticular activating system plays a role in
cycles and consciousness
♦
• hemispheres with convoluted surfaces
• coordination of body
movements
The Spinal Cord and CNS Protection
♦ Spinal Cord
• Extends from the medulla oblongata to the region
of
• (collection of spinal nerves)
• and lumbar region
enlargements
♦ Spinal Cord Anatomy
• white mater- conduction
tracts
• Internal matter- mostly cell
bodies
� (posterior) horns
� Anterior ( ) horns
• Central filled with
cerebrospinal fluid
• cover the spinal cord
• Nerves leave at the level of each
� root
� root
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 24
♦ Protection of the CNS
• and skin
• Skull and vertebral column
•
• fluid
• barrier
♦ Meninges
•
� Double-layered
covering
* - attached to skull
* layer- outer
covering of the brain
• layer
� layer
� -like
•
� layer
� Clings to the of
the brain
♦ Cerebrospinal Fluid
• Similar to blood
composition
• Formed by the
• Watery cushion to protect the brain
• Circulated in space,
ventricles, and central canal of the spinal cord
♦ Blood Barrier
• Least permeable
of the body
Excludes substances
• Useless against:
� /fat soluble molecules
� Respiratory
�
�
�
♦ Traumatic Brain Injuries
•
� injury
� No damage
•
� Nervous tissue
� Tissue does not
• Cerebral
� from
inflammatory response
� May and
kill brain tissue
♦ Cerebrovascular Accident (CVA)
•
• Ruptured vessel
supplying a brain region
• Brain tissue supplied with
from that blood source dies
• Possible loss of some functions or
♦ Disease
• Progressive
brain disease
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 25
• Mostly the , but may begin
in middle age
• Structural brain changes include abnormal
deposits and twisted
fibers within neurons
• loss, irritability, confusion
and ultimately, hallucinations and death
The Peripheral Nervous System (PNS)
♦ Peripheral Nervous System
• Nerves and ganglia outside the
• = neuron fibers bundled by
tissue
♦ Structure of a Nerve
• surrounds
each fiber
• - group of fibers by
perineurium
• binds fascicles together
♦ Classification of Nerves
• nerves- sensory and
motor fibers
• (sensory) nerves- carry
impulses toward the CNS
• Efferent ( ) nerves- carry
impulses away from the CNS
♦ Cranial Nerves
• 12 pairs of nerves that serve the
and neck
• Numbered in order, to back
• Nine mixed nerves; sensory only
• Distribution of Cranial Nerves
� I Olfactory nerve- sensory for
� II nerve- sensory
for vision
� III Oculomotor nerve- motor for
muscles
� IV - motor for
eye muscles
� V Trigeminal nerve- sensory for ;
motor for chewing muscles
� VI nerve- motor
for eye muscles
� VII nerve- sensory for
taste; motor for the face
� VIII Vestibulocochlear nerve- sensory for
and hearing
� IX Glossopharyngeal nerve- sensory for
; motor for the pharynx
� X nerves- sensory and
motor for pharynx, larynx, and viscera
� XI Accessory nerve- motor for
and upper back
� XII Hypoglossal nerve- motor for
♦ Spinal Nerves
• pairs of spinal nerves at the level of each
vertebrae
• Spinal nerves formed by combination of spinal
cord and dorsal roots
• Named for the where they arise
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 26
♦ Autonomic Nervous System
• branch of the
nervous system
• Only nerves
• Two divisions
� division
� division
♦ Somatic and Autonomic Nervous Systems
Differences
•
� - one motor neuron
� Autonomic- - and ganglionic
nerves
• organs
� Somatic- muscle
� Autonomic- muscle,
cardiac muscle, and glands
•
� Somatic-
� Autominic- acetylcholine, ,
or norepinephrine
♦ Sympathetic Division
• Originates from through
• Norepinephrine and
are neurotransmitters
• “ ”
� Response to unusual stimulus
� Takes over to activities
� - exercise,
excitement, emergency, and embarrassment
♦ Parasympathetic Division
• Originates from the brain stem and
through
• is the
neurotransmitter
activities
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 27
� Conserves
� Maintains daily necessary
functions
� - digestion, defecation,
and diuresis
♦ Development Aspects of the Nervous System
• Formed during the month of
embryonic development
• infections can have
harmful effects
• Hypothalamus- one of the areas of
to develop
• No formed after birth;
growth and maturation continues for several years
• Brain reaches maximum
as a young adult
Special Senses: The Eye
♦ The Senses
• General senses of touch
�
�
�
• Special senses
� Smell
� Taste
� Sight
� Hearing
�
♦ The Eye and Vision
• of all sensory receptors are in the eyes
• Each eye has over a million
• Protection for the eye
� Mostly enclosed in a bony orbit
� Surrounded by cushion of
♦ Accessory Structures of the Eye
•
•
• glands- modified
sebacious glands lubricate the eye
• glands- modified
sweat glands between the eyelashes
•
� Membrane that lines the
� Connects to the surface of the eye
� Secretes to lubricate the eye
•
� Lacrimal - produces
lacrimal fluid
� Lacrimal - drains
lacrimal fluid from eyes
• Lacrimal - provides passage of
lacrimal fluid toward
• duct- empties
lacrimal fluid into nasal cavity
♦ Function of the Lacrimal Apparatus
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 28
• Properties of lacrimal fluid
� Dilute salt solution ( )
� Contains
and lysozyme
• Protects, moistens, and lubricates the eye
♦ Extrinsic Eye Muscles
• Muscles attach to the outer surface of the eye
• Produce eye
♦ Structure of the Eye
• Wall is composed of three tunics
� - outside layer
� - middle layer
� - inside layer
♦ The Fibrous Tunic
•
� White
tissue layer
� Seen anteriorly as the “
”
•
� , central
anterior portion
� Allows to pass through
� itself easily
� Only human tissue that can be
without fear of rejection
♦ Choroid Layer
• -rich nutritive tunic
• Pigment prevents light from scattering
• Modified interiorly into two structures
� body- smooth muscle
�
* Pigmented layer that gives eye
* - rounded opening
in the iris
♦ Sensory Tunic ( )
• Contains receptor cells (photoreceptors)
�
�
• Signals pass from photoreceptors via a two-neuron
chain
� neurons
� cells
• Signals leave the retina toward the brain through
the
♦ Neurons of the Retina and Vision
•
� Found mostly toward retinal
� Dim light vision and
vision
� Perception is all in tones
•
� Detailed vision
� Densest in the of the retina
o - area
of the retina with only cones
• No photoreceptor cells are at the optic disk
( )
♦ Cone
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 29
• types of cones
• Each sensitive to different light
• - result of lack
of one cone type
♦ Lens
• crystal-like structure
• Held in place by a
ligament attached to the ciliary body
♦ Internal Eye Chamber Fluids
• humor
� Watery fluid found between the
and
� Similar to
� Maintains intraocular
� Provides for the
lens and cornea
� Reabsorbed into venous blood through the canal
of Schlemm
• humor
� substance
behind the lens
� Keeps the eye from
� Lasts a and is
not replaced
♦ Lens
• Light must be focused on the retina for optimal
vision
• Eye is set for distance vision (over ft away)
• Lens must change shape to focus for
objects
♦ Visual Pathway
• of
the retina
• Optic nerve
• Optic nerve crosses at the optic
• Optic t
• (axons form
optic radiation)
• Visual of the
occipital lobe
♦ Eye Reflexes
• Internal muscles controlled by
nervous system
� and muscles
constrict pupils in bright light
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 30
� Viewing close objects
causes
• External muscles control eye movement to follow
objects
• Viewing close objects causes
(medial movement)
Special Senses: The Ear
♦ The Ear
• senses
�
� (balance)
•
• Different organs house receptors for each sense
♦ Anatomy of the Ear
• Divided into areas
� (external) ear
� ear
� ear
♦ External Ear
• only
• Structures
� (auricle)
� External canal
♦ External Auditory Canal
• Narrow chamber in the
bone
• Lined with
• (wax) glands
• Ends at the
♦ Middle Ear ( Cavity)
• -filled cavity within the
temporal bone
• Only involved in
• Two tubes are associated with the inner ear
� The opening from the auditory canal is covered
by the membrane
� The auditory tube connecting the middle ear
with the
* Equalizing pressure during yawning
or
* Otherwise it is
♦ Bones of the Tympanic Cavity
• bones
� (hammer)
� (anvil)
� (stirrip)
• Vibrations from eardrum move the
• Bones transfer sound to the ear
♦ Inner Ear (Bony )
• Sense organs for hearing and balance
• Filled with
• Maze of bony chambers within the temporal bone
�
�
�
♦ Organs of Hearing
• Organ of
� Located within the
� = hair cells
on the basilar membrane
� Gel-like tectorial membrane is capable of
bending hair cells
� Cochlear nerve attached to hair cells transmits
nerve impulses to the brain
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 31
♦ Mechanisms of Hearing
• Vibrations from sound waves move
membrane
• cells are bent by
the membrane
• Action potential starts in the
nerve
• Continued stimulation can lead
to
♦ Organs of Equilibrium
• Receptor cells are in two structures
�
� canals
• Two functional parts of equilibrium
� equilibrium
� equilibrium
♦ Equilibrium
• - receptors in
the vestibule
� Report on the
of the head
• Anatomy of the
� Hair cells are embedded in the
membrane
� (tiny stones)
float in a gel around the hair cells
� Movements cause
to bend the hair cells
Head Upright Head Tilted
♦ Equilibrium
• - receptors
in the semicircular canals
� of hair cells
� (gelatinous cap) covers
the hair cells
• Action of
head movements
� stimulates the
hair cells
Special Senses: Smell and Taste
♦ Senses- Taste and Smell
• Both senses use chemoreceptors
� Stimulated by
in solution
� Taste has types of receptors
� Smell differentiates a large range of chemicals
• Both each
other and respond to many of the same stimuli
♦ - Sense of Smell
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 32
• Olfactory receptors are in the roof of the
� Neurons with long
� Chemicals must be dissolved in
for detection
• are transmitted
via the olfactory nerve
• Interpretation of smells is made in the
♦ Sense of
• Taste house the
receptor organs
• Location
� Most are on the
� Soft
�
♦ The Tongue and Taste
• tongue is covered with projections called
� papillae- sharp
with no taste buds
� papillae- rounded
with taste buds
� papillae- large
papillae with taste buds
• Taste buds are found on the
of papillae
♦ Structure of Taste Buds
• cells are the receptors
� Have gustatory hairs (long
)
� Hairs are stimulated by chemicals dissolved in
• Impulses are carried to the gustatory complex by
several nerves because
taste buds are found in different areas
� nerve
� nerve
� nerve
♦ Taste Sensations
• receptors
�
�
� Some acids
• receptors
�
• receptors
�
• receptors
� ions
♦ Developmental Aspects of the Special Senses
• Formed early in
development
• Eyes are of
the brain
• All special senses are
at birth
The Endocrine System
♦ The Endocrine System
• Uses messages
(hormones) released into the blood
• control several
major processes
�
� and development
� Mobilize of body
� Maintain
� Regulate
♦ Hormone Overview
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 33
• Produced by specialized
• Secreted by cells into
fluids
• Transferred to target sites by
• the activity of
other cells
♦ Chemistry of Hormones
• -based hormones
• - made from
cholesterol
• - made
from highly active lipids
♦ Mechanisms of Hormone Action
• Hormones affect only target
or organs
• Target cells have specific
• Hormone influences the
work of the cells
♦ Effects Caused by Hormones
• Changes in
permeability or electrical state
• of proteins,
such as enzymes
• Activation or inactivation of
• Stimulation of
♦ Hormone Action
• Enters
• Bind to a specific in
the nucleus
• Bind to specific sites on the cell’s DNA
• Activate that result in
synthesis of new proteins
♦ Hormone Action
• Binds to membrane
• Does enter the cell
• Sets off a series of reactions that
an enzyme
• a reaction that
produces a second messenger molecule
♦ Control of Hormone Release
• Levels in the blood maintained by
feedback
• (low hormone levels)
in the blood triggers the release of more hormone
• Stops once an appropriate level in the
is reached
♦ Hormonal Stimuli of Endocrine Glands
• glands are
activated by other hormones
♦ Humoral Stimuli of Endocrine Glands
• Changing blood levels of certain
stimulate hormone release
♦ Neural Stimuli of Endocrine Glands
• impulses stimulate
hormone release
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 34
♦ Gland
• Size of a
• Hangs below
• bone protects it
• Two functional lobes
� pituitary- glandular
tissue
� Posterior pituitary-
tissue
♦ Hormones of the Anterior Pituitary
• hormones
� affect non-endocrine targets
� Four stimulate other
glands (tropic hormones)
• Characteristics of all anterior pituitary hormones
� (or peptides)
� Act through -messenger
systems
� Regulated by
stimuli, mostly negative feedback
♦ Hormone (GH)
• General hormone
• Growth of skeletal
and long bones
• synthesized into
proteins
• broken down
for energy
♦ Other Anterior Pituitary Hormones
• (PRL)
� Stimulates and maintains
production after childbirth
� Function in is unknown
•
hormone (ACTH)
� Regulates activity of cortex
• -stimulating
hormone (TSH)
� Influences growth and activity of
♦ Other Anterior Pituitary Hormones
• hormones
� Regulate hormonal activity of the
* -stimulating
hormone (FSH)
o Stimulates
development in ovaries
o Stimulates sperm development in testes
* hormone (LH)
o Triggers
o Causes ruptured follicle to become the
corpus luteum
o Stimulates
production in males
♦ Pituitary - Hypothalamus Relationship
• Hypothalamus produces releasing and
hormones that
affect the pituitary gland
• The 2 hormones are transported the
pituitary
♦ Hormones of the Posterior Pituitary
•
� Stimulates contractions
during labor
� Causes ejection
• hormone (ADH)
� Inhibits production
� Large amounts cause
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 35
(increased blood pressure)
Endocrine Glands and Hormones
♦ Gland
• At base of the
• lobes and connecting isthmus
• Produces two hormones
� hormone
* hormone
�
* Decreases blood
levels (deposited in bone)
♦ Glands
• Tiny masses on thyroid
• Secrete hormone
� Stimulate (remove
calcium from bone)
� Stimulates and
Intestine (absorb calcium)
� Raise levels in
the blood
♦ Glands
• Two glands
� - outer glandular
region (3 layers)
� - inner neural
tissue region
• Sits on top of the
♦ Hormones of the Adrenal Cortex
• (outer layer of AC)
� Regulates content
in blood, water, and electrolyte balance
� Target organ-
• and cortisol (middle
layer of AC)
� Promote metabolism
� Help resist long-term
• hormones (inner layer of AC)
� (male)
� Some (female)
♦ Hormones of the Adrenal Medulla
•
�
�
• Prepare body to deal with
stress
♦
• Mixed gland
• Produces
� - allows glucose
to cross cell membrane
� - allows glucose
to enter the blood
� Both maintain blood homeostasis
♦ Gland
• Found on the third ventricle of the
• Secretes
Unit 4 Outline: The Nervous Systems, Special Senses, and The Endocrine System 36
� Establishes body’s and
sleep cycles
♦
• Posterior to the
• Largest in and children
• Produces
� Matures some types of
blood cells
� Important in
system development
♦ Hormones of the Ovaries
•
� Produced by follicles
or placenta
� Development of secondary female
characteristics
� Matures reproductive
organs
� Prepares to
receive a fertilized egg
� Maintains
� production
•
� Produced by the
� cycle
� Implantation of
in the uterus
♦ Hormones of the Testes
• Produced in
cells of testes
• Produce several androgens
- most important
* Male
characteristics
* Growth and maturation of
reproductive system
* cell production
♦ Endocrine System Development
• Most endocrine organs operate smoothly
until
� caused
by ovaries inefficiency
� Reduced estrogen problems are common
� production declines with age
� Many glands
output with age
♦ Endocrine Regulation of Homeostasis
•
• and Glucagon
♦ Roles of the Hypothalamus and Adrenal Glands in
Stress Response