Nervous System Organization, Structure, and Function STUDENT NOTES | Date _____________________

Bas

ics

What is the nervous system? ________________________________ How does it signal? ________________________________ What are its three major, overlapping functions?

• It uses millions of sensory receptors to monitor changes (stimuli) inside and outside of the body – this is ____________________

• It processes and interprets the sensory input and makes decisions about what should be done at each moment – this is _________________

• It effects a response by activating muscles or glands – this is __________________ What system does it work hand-in-hand with? How is it different from this system? _________________

Org

aniz

atio

n

Organization of the nervous system is very complex because of its many functions. It is classified based on ____________________ and ____________________. Structural Classification Central nervous system (CNS):

• What is it? ________________________________________

• What does it do? ________________________________________ Peripheral nervous system (PNS):

• What are nerves? ________________________________________

• The two major types of nerves are spinal and cranial.

- Spinal nerves: ________________________________________

- Cranial nerves: ________________________________________ Functional Classification Sensory (_____________________________) division

• What does it do? ____________________________________________________________ Motor (_____________________________) division

• Carries impulses from the CNS to ________________________ (motor) organs – muscles and _________________.

• Organized as follows: - Somatic nervous system (_________________________________)

Voluntary skeletal muscle movement (except for reflexes)

- Autonomic nervous system (_________________________________) Two Parts: Sympathetic and Parasympathetic

Ner

vous

Tis

sue

CNS supporting cells:

• Astrocytes: star-shaped cells that anchor neurons to blood capillaries; responsible for __________________

• Microglia: dispose of debris, including dead brain cells and bacteria

• Ependymal cells: line brain and spinal cord cavities and circulate __________________________________

• Oligodendrocytes: form __________________________________, which protect and insulate the neurons

• Neuroglia cannot transmit nerve impulses and NEVER lose their ability to divide; these are the cells that typically form brain tumors

PNS supporting cells:

• Schwann cells: form ________________________________ around nerve fibers in the PNS

• Satellite cells: protective, cushioning cells Neurons: ________________________________________________________________ Cell body: contains usual organelles; no _______________________ ____________________________: transmit messages TO the cell body Axon: transmit messages __________________________ cell body Axon terminal: ______________________________________________________ _____________________________ or synapse: space between neurons Myelin: whitish, fatty material that protects and insulates fibers and increases transmission rate of impulses

o Inside the CNS: oligodendrocytes (a single one can coil around MANY neurons at once)

o Outside of the CNS: ___________________________________ (several coil around single neuron)

• Gaps in Schwann cells are called _________________________________

Nerve Impulse: Action Potential and Reflexes STUDENT NOTES | Date __________________

Neu

ron

Cla

ssifi

catio

n Functional classification: ____________________________________________________: dendrites are associated with receptors activated by stimuli, like in the sense organs ____________________________________________________: connect motor and sensory neurons ___________________________________________________: cause some sort of response or movement

Neu

ron

Phys

iolo

gy

Nerve Impulses

• _________________________ cell: polarized (negative on the inside, positive on the outside)

o Negative inside has more __________

o Positive outside has more __________ o Gateways for Na+ and K+ in the membrane are closed; pumps move 2 K+ in and 3 Na+ out

constantly. When the cell is excited by a stimulus…

1. Depolarization/action potential/nerve impulse

a. Stimulus causes the ___________ gates to open in the cell; Na+ rushes in and inside cell is now

more ___________________. Both inside and outside cell are positive.

2. ______________________________________: begins an INSTANT after depolarization

a. All __________ gates open in an attempt to rebalance the cell’s charge; K+ rushes out

b. Now inside the cell is more _________________while the outside is more _________________

(reversed from resting state).

The ____________________________ restores the original polarization (negative inside, positive outside).

Ref

lexe

s

What are they? __________________________________________________________ Reflex arc: __________________________________________________________

• Autonomic reflexes: __________________________________________________________ o Examples: __________________________________________________________

• Somatic reflexes: __________________________________________________________

o Examples: __________________________________________________________

Central Nervous Systems STUDENT NOTES | Date __________________

CN

S

CNS develops from the __________________________________________. When? _____________________

• What does the neural tube become? ____________________________________

• Opening of neural tube comes ventricles aka four chambers within brain filled w/ cerebrospinal fluid (CSF)

CN

S –

Bra

in: C

ereb

ral H

emis

pher

e

• Cerebral Hemisphere

o Largest section of the brain compared to the other three sections; covers all other parts

o _________________________( left and right)

o Surface consists of ridges called _______________, separated by grooves called ______________

§ Deeper grooves are called fissures. Fissures divide the brain into __________________

o Functions: _________________________________: speech, memory, logical and emotional

response, consciousness, interpretation of sensations

o Various lobes

§ Parietal lobe: ________________________________________

• Interprets ____________________________ from pain, cold, or light touch • Pathways are crossed – left side of body for right side of brain, and vice versa

§ Occipital lobe: _______________________________________________

§ Temporal lobe: _______________________________________________

§ Frontal lobe: __________________________________________________

• Conscious movement; most neurons control parts of body with finest motor control, like face, mouth, and hands

• Anterior frontal lobe is thought to be for _________________________________

o Gray matter: _________________________________________________ o White matter: ________________________________________________

CN

S –

Bra

in: D

ienc

epha

lon • Diencephalon

o Interbrain; sits on top of ______________________________, covered by cerebral hemispheres

o Consists of…

§ Thalamus: ________________________________________________

§ Hypothalamus: regulates __________________________, water balance, and metabolism;

involved in many drives and emotions; regulates pituitary gland and produces hormones

§ Epithalamus: contains the pineal body (involved in sleep and waking) and produces CSF

CN

S –

Bra

in: B

rain

Ste

m • Brain Stem

o Consists of…

• Midbrain: conveys ___________ to and from the brain, involved in vision & hearing

• Pons: involved in __________________ regulation • Medulla oblongata: regulation of vital visceral activities, controls _________________,

__________________, breathing, swallowing, vomiting, etc. § Reticular formation: extends the entire length of the brain stem and is involved in motor

control of visceral organs; damage can cause coma

CN

S –

Cer

ebel

lum

• Cerebellum

o Provides precise timing for skeletal muscle activity, controls ___________________________ and

_____________________________

o Receives signals from inner ear, ___________, ____________________ and

___________________ receptors from muscles and tendons, and many other areas.

CN

S –

Prot

ectio

n

Meninges: connective tissue membranes ____________________________________

Cerebrospinal fluid (CSF): similar to blood plasma, it is constantly formed from ___________________________

in the brain. It forms a watery cushion and _____________________ the nervous system from blows and other

trauma. It is constantly moving and circulating.

Blood-brain barrier: composed of the least permeable capillaries in the body; metabolic wastes, toxins, proteins,

and most drugs cannot enter the brain tissue.

• Basically useless against _______________, respiratory gases, and ______________________________

molecules that diffuse easily through all plasma membranes

• Dangerous because… ______________________________________________________

CN

S –

Spin

al C

ord

• Approximately 17 in. long; continuation of the _________________________

• Two-way ___________________________________ to and from the brain; major _______________ center

• Protected by ___________________________________

• Cushioned and protected by _______________________________ and ___________

• Contains _______________ matter on the inside of the spinal cord and ____________________ matter

around it on the outside.

Peripheral Nervous Systems STUDENT NOTES | Date __________________ PN

S –

Ner

ves

What is a nerve? _____________________________________ outside of the CNS

How are they classified? ________________________________________________________________________

• Mixed nerves: carry both sensory and motor impulses

• Afferent (______________________) nerves: carry impulses TO the CNS

• Efferent (______________________) nerves: carry impulses AWAY from the CNS

Types of Nerves (based on location)

• Cranial nerves – 12 types, mostly serving head and neck; they are sensory, motor, or both.

o In order:

1. _________________________________: smell

2. _________________________________: sight

3. _________________________________: eye movement, lens shape, pupil size

4. _________________________________: eye movement

5. _________________________________: senses on skin of face, nose, and mouth; chewing

6. _________________________________: lateral eye movement

7. _________________________________: facial expression, salivary glands, taste

8. _________________________________: balance, hearing

9. _________________________________: swallowing, saliva production, taste

10. _________________________________: speaking, digestion, heart activity

11. _________________________________: movement of neck/shoulders

12. _________________________________: tongue movements, taste

To remember: Old Opie Occasionally Tries Trigonometry And Feels Very Gloomy,

Vague, And Hypoactive.

To help remember function…S = sensory, M = motor, B = both: Some Say Marry

Money But My Brother Says Big Business Marries Money.

PNS

– N

erve

s • Spinal Nerves: movement of body

o Cervical

§ Phrenic nerve: diaphragm, muscles of _________________________________

o Brachial: _______________________

• Axillary nerve: deltoid muscle • Radial nerve: tricep and extensor muscles of forearm • Median nerve: flexor muscles of forearm and some hand muscles • Musculocutaneous nerve: flexor muscles of arm • Ulnar nerve: wrist and many hand muscles

o Lumbar and Sacral: ______________________________________________

• Lumbar:

- Femoral nerve: lower abdomen, buttocks, anterior thighs, skin of leg and thigh - Obturator nerve: adductor muscles, skin of thigh and hip

• Sacral:

- Sciatic: (largest nerve in the body) lower trunk and thigh - Superior and inferior gluteal nerve: gluteus muscles of the hip

Special Senses STUDENT NOTES | Date: __________________

Maj

or

Sens

es

_______________________: general sense _______________________: special sense

_______________________: special sense _______________________: special sense

_______________________: special sense _______________________: special sense

Eye

________ of all sensory receptors are located here. Vision is the sense that requires the most __________________. Ciliary body: smooth muscle, focuses the lens Cornea: “__________________________________________________________ (appears to be part of the sclera, but only covers the iris and pupil portions of the eye) Iris: pigmented smooth muscle that ____________________________ ___________________________ Pupil: dark spot in the middle of the eye; regulates the amount of light passing into the eye Aqueous humor: _____________ filling the anterior portion of the eye Lens: attached to the _____________________; focuses light onto the retina Vitreous humor: liquid filling the inside of the eye Sclera: thick, white connective tissue ______________________________ Choroid: middle covering of the eyeball; ____________________ and covers a dark pigment that prevents light from scattering inside of the eye Retina: light sensitive area of the eye that contains _________________________ Fovea centralis: contains only cones and gives us the most ___________________________ possible Optic nerve: nerve that runs from the eye to ________________________ Optic disk: __________________________ – point where optic nerve exits the eye

Eye

How do we see?

• In the retina, there are ___________ and _______________.

o Rods: detect movement and give us basic __________________________________.Most active in

the dark.

o Cones: give us detained, ___________________________________________.

§ Most active in the light. o When we see light, rods and cones are stimulated and send electrochemical impulses to the brain.

o The adjustment of the ____________ and the _______________ refracts light into our

__________________ in different ways.

Problems with the eye: night blindness, color blindness, cataracts, glaucoma, retinoblastoma (cancer)

Ear

Pinna: outer ear funnels sound into the external auditory canal Tympanic membrane: ___________________; vibrates when sound occurs, causing it to vibrate the bones of the inner ear Ossicles

• Hammer (malleus): vibrates first with sound • Anvil (incus): vibrates second as a result of the hammer vibrating • Stirrup (stapes): passes the vibration to the oval window in the inner ear

Cochlea: snail-shaped structure filled with fluid in the inner ear; its ______________________________________ to the brain that recognize sound Semicircular canals: canals filled with fluid in the inner ear; its vibrations/fluid movement send signals to the brain that help us maintain ____________________________________________ Major Problems with the Ear: _________________

Smel

l

• _______________________ sense

• About how many different smells can humans recognize? _____________________

• What types of receptors are responsible? __________________________________

o These receptors are EXTREMELY SENSITIVE and quickest to fatigue of all sensory receptors.

Tas

te

• _______________________ sense

• Very tightly tied to ______________________

• Taste buds are receptors on the tongue – about how many do we have? _________________________

• There are FIVE taste regions on the tongue:

sweet, salty, bitter, sour, umami (what’s that??? _______________________________________________)