Chapter 15: Olfaction: Smell

• Receptor

• Neuron goes through cribriform plate

• Olfactory bulb

• Olfactory tract

• Olfactory cortex (in temporal lobe)

Gustation: Taste

• Sour

• Bitter

• Salty

• Sweet

• Umami

• Tongue

• Taste bud

• Gustatory cells

• Cranial Nerves

• Gustatory Cortex

Vision

Accessory Structures of the eye

• Eyelid; lubrication, keeps foreign objects out, protect from sunlight

• Eyelashes; keeps stuff out of your eye

• Superficial epithelium (conjunctiva); thin layer of skin membrane that covers the eye; ducts on eyelashes tears give oxygen and nutrients to keep skin "alive"

• Structures associated with tears; lacrimal glands

Layers of the eye

• Fibrous layer; sclera, cornea

• Vascular layer: iris, choroid, ciliary body

• Inner layer: retina

Anterior cavity: aqueous humor (watery)

Posterior cavity: vitreous humor (ball shape)

Light entering eye

• Cornea- refracts light

• Pupil- diameter changes by iris (melanocytes controls pigments)

• Lens- accommodated by ciliary body

• Fovea centralis- clearest image, central focus, light hits just above optic nerve

Dilation

• Shrinks

• Decreases light from coming in

Expansion

• Expands

• Allows more light to come in

Accommodation

• Lens changes shape for clear vision

• Object close: lens rounded by muscle contraction (ciliary body)

• Object distant: lens flattened by muscle relaxation

• Presbyopia: Age Lens elasticity

Photoreceptors in retina

Rods

• Dim light

• Black & white

• Dull images

Cones

• Intense light

• Color vision

• Clear images

Blind Spot

• No photoreceptors at optic disc

• Vitamin A

• Retinol in rods

• Important for night vision

• Cones- blue, green, red

• Visual images -> visual cortex of occipital lobe

• Emmetropia- normal vision

• Myopia- nearsightedness- see stuff close to me clearer than things farther than me

• Hyperopia- farsightedness- can see things far away clearer than things closer to me

Structures

External ear

• Auricle (pinna)- funnels sound in

• External Acoustic Meatus

• Tympanic Membrane

Middle Ear

• Auditory Ossicles

  • Malleus

  • Incus

  • Stapes

• Auditory Tube

Inner Ear

• Semicircular canals

• Vestibule

• Cochlea

Functions: Hearing (cochlea)

• Captures & funnels sound

• Vibrates

• Senses sound & sends to brain via CN VIII (vestibulocochlear nerve)

• In cochlea there are hair cells

At a cellular level....

Function: Equilibrium (vestibule & semicircular ducts)

• Senses:

  • Gravity: internal ear can sense gravity

  • Acceleration: can feel acceleration

  • Rotation: when you get dizzy you have not yet stabilized the fluid; sends signals to cerebellum (balance)

Decibel are units of the intensity of sound

Conductive hearing loss -> External or Middle Ear

• Can be temporary

Sensorineural hearing loss -> Internal Ear or CNS

• Permanent

• Can get hearing aids

• Something wrong with internal ear, CN VIII