2438970 Physiology Autonomic Nervous System and Senses Part 1 iBookstk

7/29/2019 2438970 Physiology Autonomic Nervous System and Senses Part 1 iBookstk

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BIO 1414 Human Anatomy &

Physiology II

Unit 3 Autonomic Nervous System

and Senses

Part 1

By: Robert F. Allen, Professor of Biology


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Conjunctiva


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Conjunctiva

Covers the inner

surface of theeyelids and the

anterior surface of

the eye. Membrane which

produces mucous

that lubricates theeye and prevents

dryness.

Protects the eye.


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Fibrous Tunic


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Fibrous Tunic

Sclera Functions:

Protects eye

Shapes eye

Anchors eye muscles

Cornea Functions:

Transparent window

for light entry

Refracts light


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Vascular Tunic


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Vascular Tunic Choroid Functions:

Provides nutrients to all eye tunics. Absorbs light preventing reflecting & scattering

of light within the eye.

Ciliary Body Functions:

Ciliary processes secrete aqueous humor.

Suspensory ligaments hold lens in place.

Ciliary muscles pull on the ligaments to change the

thickness of the lens.

Iris Functions:

Constricts or dilates to adjust the amount of light

entering the eye.


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Vascular Tunic

Ciliary Processes

Ciliary Muscles


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Aqueous Humor

Helps support the eye internally due to the

intraocular pressure it produces inside theeye.

Supplies nutrients & oxygen to the cornea,

lens and portions of the retina. Carries away metabolic wastes from the

cornea, lens and portions of the retina.


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The pupil allows light to enter the posterior

segment of the eye.

The iris constricts or dilates to adjust size of the pupil.


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Vitreous Humor

Transmits light within the posterior segment. Supports the lens posteriorly.

Holds the retina in place.

Contributes to intraocular pressure.


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Sensory Tunic


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Retina

Pigmented Layer

Absorbs light

Carries out phagocytosis

Stores Vitamin A

Neural Layer

Contains photoreceptors

(rods and cones) forvisual perception

Contains bipolar cells &

ganglion cells for visual

impulse transmission


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Retina

Fovea Centralis

Contains only closely

packed cones Provides acute color

vision in bright light

Macula Lutea

Contains more widely

spaced cones

Other areas of Retina

Contain only rods

Provide night, dim light& peripheral vision

Shades of grey only

Optic Disc

Contains no receptors

Blind spot


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Optic Disc

Retina


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Photoreceptors


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Cones

Are located in macula lutea but are mosthighly concentrated in the fovea centralis.

Are sensitive to bright light (daylight)

situations in which light is very intense. Each cone synapses with a single bipolar

cell which synapses with a single ganglion

cell. The axons of ganglion cells form the optic

nerve to conduct visual images to the brain.

Provide acute (sharp) color images (vision).


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Cones


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Photoreceptors


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Rods

Most highly concentrated in the retina outsidethe macula lutea

Many rods synapse with a single bipolar cell

Many bipolar cells may synapse with a singleganglion cell which carries stimuli to brain

More sensitive & function only in dim light,

night and peripheral vision Images areblurry and only in shades ofgray


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Visual Pigments

Composed of two components

Retinal - light absorbing molecule (made from

Vitamin A)

Opsin (four types made from protein)

Opsin combined with retinal = visualpigment

OPSIN + RETINAL = Visual Pigment

Depending on the type of opsin retinal is

bound to, each of the four pigments will

only absorb certain wavelengths of light.


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Visual Pigments: RODS Retinal + Opsin = Rhodopsin (visual purple)

Absorbs light throughout entire visible lightspectrum (most sensitive to green)

Functions only in dark, dim light & peripheral

vision

Light causes Retinal to change shape & separate

from opsin causing nerve impulse

Regenerate only in dark or dim light situations

RHO DOPSINOPSIN RETINAL

(Light)

Impulse


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Visual Pigments: Cones Retinal + Red, Green orBlue Opsin = Red,

GreenorBluevisual pigments Each Opsin absorbs light only in the area of

the visible light spectrum it is sensitive to,

ie, red cones, green cones & blue cones Function only in bright light (daylight)

Provide sharp color images

Red Cone Red Opsin RETINAL

(Light)

Impulse

Green Cone Green Opsin RETINAL Impulse


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Lens

Refracts (bends) light

Focuses precise image on the retina (fovea)

through accommodation (changing thickness)


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Myopia (Nearsighted)

Eyeball too long

Distant objects focused in front of retina

Image striking retina is blurred

Correction:

Concave lens or

laser surgery to slightly flatten the cornea


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Hyperopia (Farsighted)

Eyeball too short, lens too thin or too stiff.

Nearby objects are focused behind retina.

Image striking the fovea is blurred.

Correction:

Convex lens


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Astigmatism

Irregular Curvature in parts of the cornea or

lens

Causes blurry image

This may be corrected by specially ground

lenses which compensate for the irregularity

or laser surgery.


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Cararact

Clouding of lens due to aging, diabetes

mellitus, heavy smoking, frequent exposure

to intense sunlight or congenital factors

Treatment: Lens Implant


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Conjunctivitis

Inflammation of the conjunctiva by: Bacteria, fungi or viruses

Trauma


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Glaucoma

Most common cause of blindness.

Increasing intraocular pressure compresses

retina, optic nerve & blood vessels.

Late symptoms include blurred vision &

halos around bright objects

Canal of Schlemn


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Glaucoma


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Color Blindness Congenital lack of one or more cone types

Deficit or absence of red or green cones

most common

Sex-linked trait

Most common in males

What numbers can you see in each of these?


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Night Blindness

Impaired vision at night or in dim light

situations

Rhodopsin deficiency affecting rods

Most common cause - prolonged Vitamin A

deficiency

Rods degenerate


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Macular Degeneration Most common cause of vision loss after 65.

Progressive deterioration of macula

causing loss of central vision

Dry Form - due to accumulation of pigments in macula due

to reduced phagocytosis of cone debris by pigmented layer

Wet Form - due to invasion of macula with new blood

vessels from choroid causing scarring & retinal detachment


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Middle Ear


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Middle Ear


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Inner Ear

Vestibule


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Vestibule

SacculeUtricle


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Maculae

Monitors position of head in space

Responds to straight-line changes in speed

& direction

Receptors for static equilibrium


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Macula

Receptor for Static Equilibrium


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Inner Ear

Semicircular Canals


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Semicircular Canals

Semicircular Canals


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Semicircular Canals

Christa ampularis - receptor for dynamic

equilibrium Responds to rotational (angular) movements

Changes in rotatory velocity movements

Semicircular Canals


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Semicircular Canals

Dynamic Equilibrium


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Inner Ear

Oval Window


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Inner Ear

Cochlea


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Cochlea Unrolled

Sprial Organ of Corti


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Spiral Organ of Corti

Receptor organ of hearing

Different frequencies of vibrations

(compression waves) in cochlea stimulatedifferent areas of Organ of Corti

Interpreted as differences in pitch

I E


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Inner Ear

Round Window


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Cochlea

Oval Window

Round Window


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AcknowledgementsMost of the figures used in this presentation came from the Benjamin Cummings Digital Library

Version 2.0 for Human Anatomy & Physiology, Fifth Edition. Other figures came from public

domain internet sources and software in the possession of the author.

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2438970 Physiology Autonomic Nervous System and Senses Part 1 iBookstk

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