Download presentation
Presentation is loading. Please wait.
Published byAshley Joseph Modified over 9 years ago
1
Chapter 8 Part A Vision Essentials of Human Anatomy & Physiology
Seventh Edition Elaine N. Marieb Chapter 8 Part A Vision Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
2
The Senses General senses of touch Special senses Temperature Pressure
Pain Special senses Smell Taste Sight Hearing Equilibrium Slide 8.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
3
The Eye and Vision 70 percent of all sensory receptors are in the eyes
Each eye has over a million nerve fibers Protection for the eye Most of the eye is enclosed in a bony orbit A cushion of fat surrounds most of the eye Slide 8.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
4
Accessory Structures of the Eye
Eyelids Eyelashes Figure 8.1b Slide 8.3a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
5
Accessory Structures of the Eye
Ciliary glands – modified sweat glands between the eyelashes Meibomian glands – modified sebacious glands produce an oily secretion to lubricate the eye Figure 8.1b Slide 8.3b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
6
Accessory Structures of the Eye
Conjunctiva Membrane that lines the eyelids Connects to the surface of the eye Secretes mucus to lubricate the eye Slide 8.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
7
Conjunctivitis “Pink Eye”
8
Accessory Structures of the Eye
Lacrimal apparatus Lacrimal gland – produces lacrimal fluid Lacrimal canals – drains lacrimal fluid from eyes Figure 8.1a Slide 8.4b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
9
Accessory Structures of the Eye
Lacrimal sac – provides passage of lacrimal fluid towards nasal cavity Figure 8.1a Slide 8.4c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
10
Accessory Structures of the Eye
Nasolacrimal duct – empties lacrimal fluid into the nasal cavity Figure 8.1a Slide 8.4d Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
11
Function of the Lacrimal Apparatus
Properties of lacrimal fluid Dilute salt solution (tears) Contains antibodies and lysozyme Protects, moistens, and lubricates the eye Empties into the nasal cavity Slide 8.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
12
Extrinsic Eye Muscles Muscles attach to the outer surface of the eye
Produce eye movements Figure 8.2 Slide 8.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
13
Structure of the Eye The wall is composed of three tunics
Fibrous tunic – outside layer Choroid – middle layer Sensory tunic – inside layer Figure 8.3a Slide 8.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
14
The Fibrous Tunic Sclera Cornea White connective tissue layer
Seen anteriorly as the “white of the eye” Cornea Transparent, central anterior portion Allows for light to pass through Repairs itself easily The only human tissue that can be transplanted without fear of rejection Slide 8.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
15
Choroid Layer Blood-rich nutritive tunic
Pigment prevents light from scattering Modified interiorly into two structures Cilliary body – smooth muscle Iris Pigmented layer that gives eye color Pupil – rounded opening in the iris Slide 8.9 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
16
Sensory Tunic (Retina)
Contains receptor cells (photoreceptors) Rods Cones Signals pass from photoreceptors via a two-neuron chain Bipolar neurons Ganglion cells Signals leave the retina toward the brain through the optic nerve Slide 8.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
17
Neurons of the Retina Figure 8.4 Slide 8.11
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
18
Neurons of the Retina and Vision
Rods Most are found towards the edges of the retina Allow dim light vision and peripheral vision Perception is all in gray tones Slide 8.12a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
19
Neurons of the Retina and Vision
Cones Allow for detailed color vision Densest in the center of the retina Fovea centralis – area of the retina with only cones No photoreceptor cells are at the optic disk, or blind spot Slide 8.12b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
20
Cone Sensitivity There are three types of cones
Different cones are sensitive to different wavelengths Color blindness is the result of lack of one cone type Slide 8.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.6
22
Normal Retina
23
Retinal Detachment
24
Macular Degeneration – age related
25
Advanced Gloucoma
26
Advanced Diabetic Retinopathy
27
Retinitis Pigmentosa
28
Retinal Scans Normal Macular Degeneration
29
Retinal Scan Retinal Detachment
30
Lens Biconvex crystal-like structure
Held in place by a suspensory ligament attached to the ciliary body Figure 8.3a Slide 8.14 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
31
Cataracts Opaqueness or clouding of lens
Occurs with age and UV exposure, etc
32
Internal Eye Chamber Fluids
Aqueous humor Watery fluid found in chamber between the lens and cornea Similar to blood plasma Helps maintain intraocular pressure Provides nutrients for the lens and cornea Reabsorbed into venous blood through the canal of Schlemm Slide 8.15a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
33
Internal Eye Chamber Fluids
Vitreous humor Gel-like substance behind the lens Keeps the eye from collapsing Lasts a lifetime and is not replaced Slide 8.15b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
34
Lens Accommodation Light must be focused to a point on the retina for optimal vision The eye is set for distance vision (over 20 ft away) The lens must change shape to focus for closer objects Slide 8.16 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.9
35
DISORDERS OF VISUAL ACUITY
Myopia
36
DISORDERS OF VISUAL ACUITY
Hyperopia
37
DISORDERS OF VISUAL ACUITY
Presbyopia
38
DISORDERS OF VISUAL ACUITY
Astigmatisim
39
Images Formed on the Retina
Figure 8.10 Slide 8.17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
40
Visual Pathway Photoreceptors of the retina Optic nerve
Optic nerve crosses at the optic chiasma Figure 8.11 Slide 8.18a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
41
Visual Pathway Optic tracts Thalamus (axons form optic radiation)
Visual cortex of the occipital lobe Figure 8.11 Slide 8.18b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
42
Eye Reflexes Internal muscles are controlled by the autonomic nervous system Bright light causes pupils to constrict through action of radial and ciliary muscles Viewing close objects causes accommodation External muscles control eye movement to follow objects Viewing close objects causes convergence (eyes moving medially) Slide 8.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.