1Chapter 11 Key Terms

CerebrumScleraCorneaPineal GlandHypothalamusStapesIris

LensCorpus Callosum RetinaOccipital LobeOlfactory SenseCerebellumPituitary GlandMedulla Oblongata Cerumen

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ANATOMY & PHYSIOLOGYCHAPTER 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

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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 bonesMeningesCerebrospinal fluid

Acts 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 brainControls 3 major reflex centers:

Vasomotor Center: regulates diameter of blood vesselsCardiac Center: regulates force of contraction and rate of

heartbeatMedullary Rhythmicity: adjusts basic rhythm of breathing

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The Brainstem

Pons“Bridge” between spinal cord and brainControls chewing, breathing, taste

MidbrainAlso called MesencephalonControls eyes and head movement in response to

visual stimulusControls 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

FrontalControls voluntary muscle functions, moods,

aggression, smell Parietal

Evaluates touch, pain, balance, taste, temp Temporal

Evaluates hearing and smell, memory, abstract thoughts, judgment decisions

OccipitalReceives and interprets visual input

23Frontal

Temporal

Parietal

Occipital

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Cerebellum

Also divided into two hemispheres connected by vermis

FunctionsTakes sensory information about position of body

parts to maintain posture and balanceCoordination of muscular movementsMaintains body postureKeeps 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 partsSympathetic: prepares body for stressful situationParasympathetic: 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:

FunctionRoman 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 nerveControls chewing and delivers sensory impulses from

teeth and face 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 abdomenControls movements of pharynx, larynx, palateSensory 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 tastedHairs on taste cell absorb mixtureTaste cells bond chemicals to receptor sitesCranial nerves VIII, IX, and X take sensations to the brain

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Sense of Taste

Taste SensationsAll taste buds taste all sensations; some react more

stronglySweet: very tip of tongueSalty: side of tongue very close to the tipSour: side of tongue near the backBitter: back of tongue

Taste sensations are influenced by olfactory sensations

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Sense of Sight

3 layers of the eyeSclera: white, outermost layer of

the eyeCornea: transparent portion of

sclera that lets light enter the eye

Choroid: 2nd layer, contains blood vessels, absorbs light

Retina: innermost layer, contains rods and conesCones 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 eyeDilates 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 pressureProduced 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 hereTakes 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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39Sense of Hearing and Equilibrium

Structure of the earOuter 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

40Sense of Hearing and Equilibrium

External EarCeruminous glands: produce

cerumen Middle Ear

Malleus – “hammer” Incus – “anvil”Stapes – “Stirrup”Eustachian Tube: allows air

pressure to equalize

41Sense of Hearing and Equilibrium

Inner Ear

Cochlea: involved in hearing

Vestibule: involved in balance

Semicircular Canals: balance