Chapter 11 Key Terms
Cerebrum
Cornea
Hypothalamus
Iris
Corpus Callosum
Occipital Lobe
Cerebellum
Medulla Oblongata
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Sclera
Pineal Gland
Stapes
Lens
Retina
Olfactory Sense
Pituitary Gland
Cerumen
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ANATOMY & PHYSIOLOGY
CHAPTER 11: NERVOUS SYSTEM
BRAIN, CRANIAL NERVES, AUTONOMIC NERVOUS SYSTEM, SPECIAL SENSES
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Processing Words and Letters
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Processing Words and Letters
 Aocdcrnig
to rseecrah at Cmabrigde Uinervtisy,
it dseno't mttaer in waht oderr the lterets in a
wrod are, the olny irpoamtnt tihng is taht the frsit
and lsat ltteer be in the rhgit pclae. The rset can
be a taotl mses and you can sitll raed it whoutit
a pboerlm. Tihs is bucseae the huamn mnid
deos not raed ervey ltteer by istlef, but the wrod
as a wlohe.
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The Brain

Divided into 4 main parts

Brainstem

Diencephalon

Cerebrum

Cerebellum
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The Brain

On average weighs about 3 lbs

Protection:
 Cranial
bones
 Meninges
 Cerebrospinal
 Acts
fluid
as shock absorber and circulates nutrients
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The Brainstem
Connects brain to spinal cord
 Very delicate
 Medulla Oblongata

 Contains
all tracts going in and out of the brain
 Controls 3 major reflex centers:
 Vasomotor
Center: regulates diameter of blood vessels
 Cardiac Center: regulates force of contraction and rate of
heartbeat
 Medullary Rhythmicity: adjusts basic rhythm of breathing
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The Brainstem


Pons
 “Bridge”
between spinal cord and brain
 Controls
chewing, breathing, taste
Midbrain
 Also
called Mesencephalon
 Controls
eyes and head movement in response to visual stimulus
 Controls
head and trunk movement in response to auditory
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Diencephalon
Above the midbrain and between
the two cerebral hemispheres
 Contains the thalamus and hypothalamus
 Thalamus

 Relay
station for sensory impulses
 Interpretation of pain and temp
 Hypothalamus


Controls many homeostatic functions and ANS
Controls normal sleep-wake cycles
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Cerebrum

Bulk of the brain

Surface is called cerebral cortex
 Made
up of gray matter

White matter is found below the cortex

Longitudinal fissure

Gyri: folds on surface of hemispheres

Sulci: grooves between folds

Corpus Callossum: connects 2 hemispheres
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Cerebrum

Frontal
 Controls

voluntary muscle functions, moods, aggression, smell
Parietal
 Evaluates

touch, pain, balance, taste, temp
Temporal
 Evaluates
hearing and smell, memory, abstract thoughts,
judgment decisions

Occipital
 Receives
and interprets visual input
Parietal
Frontal
Temporal
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Occipital
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Cerebellum

Also divided into two hemispheres connected by vermis

Functions
 Takes
sensory information about position of body parts to
maintain posture and balance
 Coordination
 Maintains
 Keeps
of muscular movements
body posture
body balanced
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Autonomic Nervous System

Functions without conscious effort (involuntary)

Regulates functions of internal organs and regulates
homeostasis (heartbeat, blood pressure, breathing, temp)

2 parts
 Sympathetic:
prepares body for stressful situation
 Parasympathetic:
normal, non-stressful functions
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Cranial Nerves

12 pairs of cranial nerves, 10 originate out of brain stem

Named according to two methods:
 Function
 Roman
numerals indicating order in which they arise from brain

Olfactory Nerve (I) – only sensory, smell

Optic Nerve (II) – only sensory, sight

Oculomotor Nerve (III) – controls movement of eye and eyelid

Trochlear Nerve (IV) – controls eye movement (only 1 muscle)
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Cranial Nerves

Trigeminal Nerve (V) – largest cranial nerve
 Controls
face
chewing and delivers sensory impulses from teeth and

Abducens Nerve (VI) – controls movement of eyeball (1
muscle)

Facial Nerve (VII) – facial expression muscles, taste sensation

Vestibulocochlear Nerve (VIII) – equilibrium and hearing

Glossopharyngeal Nerve (IX) – swallowing and taste
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Cranial Nerves

Vagus Nerve (X) – controls viscera in thorax and abdomen
 Controls
movements of pharynx, larynx, palate
 Sensory
from larynx, viscera, ear

Accessory Nerve (XI) – swallowing and head movements

Hypoglossal Nerve (XII) – speech and swallowing

See table 11-1 on page 258
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Special Senses

5 senses

Taste

Smell

Sight: interaction of light and receptors

Hearing

Balance
Chemicals interact with receptors
Mechanical factors interact with sensory in the ear
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Sense of Smell

Known as the olfactory sense

Chemicals enter nasal cavity and dissolve in mucous
epithelial lining of superior nasal conchae

Olfactory neurons in lining and are in contact with the
olfactory receptor sites

Receptors transmit smell to olfactory bulb which transmits
impulse to brain for interpretation

Over time, receptors adapt so smell is not as strong
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Sense of Taste

Papillae: raised bumps on tongue that contain taste buds

Taste buds are made of taste cells which are the receptor
sites for taste

Process:
 Saliva
dissolves compound to be tasted
 Hairs
on taste cell absorb mixture
 Taste
cells bond chemicals to receptor sites
 Cranial
nerves VIII, IX, and X take sensations to the brain
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Sense of Taste

Taste Sensations
 All
taste buds taste all sensations; some react more strongly
 Sweet:
 Salty:
side of tongue very close to the tip
 Sour:
side of tongue near the back
 Bitter:

very tip of tongue
back of tongue
Taste sensations are influenced by olfactory sensations
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Sense of Sight

3 layers of the eye
 Sclera:
eye
white, outermost layer of the
 Cornea:
transparent portion of sclera
that lets light enter the eye
 Choroid:
2nd layer, contains blood
vessels, absorbs light
 Retina:
innermost layer, contains rods
and cones
 Cones
see 3 colors: blue, red, green
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Sense of Sight

Ciliary Body: smooth muscle that
holds the lens in place

Lens: changes shape to focus
light as it enters eye

Iris: colored part of eye
 Dilates

and constricts pupil
Pupil: opening that allows light to
enter the eye
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Sense of Sight

Aqueous humor: bends light,
source of nutrients for inner
surface of eye, maintains
ocular pressure
 Produced

by ciliary body
Vitreous Humor: maintains
ocular pressure, refracts light,
holds lens and retina in place
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Sense of Sight

Optic Nerve: rods and cones
connect to other neurons
which come together here
 Takes
info from eye to brain

Optic Disk: blind spot, area
where all nerve fibers meet
and leave the eye

Fovea Centralis: depression
on macula lutea that
produces sharp vision
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Sense of Hearing and Equilibrium

Structure of the ear
 Outer
and middle ear are
involved in hearing
 Inner ear is involved with hearing
and balance

External Ear
 Auricle:
flexible, visible part of ear
 External Auditory Meatus: ear
canal
 Tympanic Membrane: ear drum
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Sense of Hearing and Equilibrium

External Ear
 Ceruminous
cerumen

glands: produce
Middle Ear
 Malleus
 Incus
– “hammer”
– “anvil”
 Stapes
– “Stirrup”
 Eustachian
Tube: allows air
pressure to equalize
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Sense of Hearing and Equilibrium

Inner Ear
Cochlea: involved in hearing
Vestibule: involved in balance
Semicircular Canals: balance