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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

� Produce sheath around

nerve fibers in the CNS

• 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

� 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

• 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

� Dendrite of the next neuron has

that are stimulated by the neurotransmitter

� An action potential is started in

♦ 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

� Neural tube opening becomes

* chambers within the brain

* Filled with

♦ 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

� 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 (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

• Reflex centers for and

hearing

• Bulging center part of the brain

• Mostly tracts

• Includes nuclei involved in the control

♦ 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

• (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

♦ 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

• 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

♦ Autonomic Nervous System

• branch of the

nervous system

• Only nerves

• Two divisions

� 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

� 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

• 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

� neurons

� cells

• Signals leave the retina toward the brain through

♦ 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

• 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

� 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

� 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

♦ External Ear

• only

• Structures

� (auricle)

� External canal

♦ External Auditory Canal

• Narrow chamber in the

• 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

* 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

♦ Mechanisms of Hearing

• Vibrations from sound waves move

membrane

• cells are bent by

the membrane

• Action potential starts in the

• Continued stimulation can lead

♦ Organs of Equilibrium

• Receptor cells are in two structures

� canals

• Two functional parts of 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

• 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

♦ Taste Sensations

• receptors

� Some acids

• 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

• 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

♦ 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

(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

� 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

� 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

Unit 4 Outline - MR. CRAMERmrcramersrhs.weebly.com/uploads/3/9/1/4/39145505/unit_4_outline.pdfUnit 4...

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