Glaucoma

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

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)

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

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

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

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

Mechanisms of Hearing

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

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

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)

Olfactory

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

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

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

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

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