1. Glaucoma

2. Cataracts
Most common cause of vision loss in people over age 40

3. More Vision Impairment Conditions
Diabetic Retinopathy
Damage to blood vessels of retina
Macular Degeneration
Color Blindness
Sex-linked
Genes for red & green cones on X chromosome
Largely affects males (females XX, males XY)

6. More Vision Impairment Conditions
Night blindness  Vitamin A deficiency
Liver stores vitamin A, releases when needed
Vitamin A is required for the formation of rhodopsin (photoreceptor pigment in the retina)
Inadequate intake, fat malabsorption, or liver disorders

7. Organs of Hearing Organ of Corti Located within the cochlea
Receptors hair cells on the basilar membrane
tectorial membrane is capable of bending hair cells
Cochlear nerve attached to hair cells sends nerve impulses

9. Mechanisms of Hearing
Vibrations from sound waves move tectorial membrane
Hair cells are bent by the membrane

10. Organ of Corti
High notes at beginning
Low notes at the end

11. Mechanisms of Hearing

12. Hearing Impairment Sensorineural Deafness: Otosclerosis:
What do you think is damaged?
Otosclerosis:
Fusion of ossicles
approx 3% of the population

13. Chemical Senses: Taste and Smell
Both senses use chemoreceptors
Both senses complement each other and respond to many of the same stimuli

14. Olfaction—The Sense of Smell
Olfactory receptors are in the roof of the nasal cavity  Olfactory Epithelium
Neurons with long cilia covered in mucus
Odor molecules dissolve in mucus and bind to receptor cells
Olfactory tract Brain (no relay center)

15. Olfactory

16. Sense of Taste Taste buds house the receptor organs
Location of taste buds
Most are on the tongue
Soft palate
Cheeks

18. The Tongue and Taste Tongue covered with projections called papillae
Filiform papillae—sharp with no taste buds
Fungifiorm papillae—rounded with taste buds
Circumvallate papillae—large papillae with taste buds

19. The Tongue and Taste
Impulses are carried to the gustatory complex by several cranial nerves because taste buds are found in different areas

20. Taste Sensation Sweet receptors(sugars) Sour receptors
Bitter receptors
Salty receptors
Umami

21. Developmental Aspects
Formed early in embryonic development
Eyes are outgrowths of the brain
All special senses are functional at birth
At birth babies eyes are sensitive to light so pupils remain very small
Over a few months pupils start to dilate and eyes begin to focus on closer objects
Focusing the eyes is learned