Special sences CH 15 Flashcards
Palpebae
Eyelids,
Conjunctiva
Transperent membrane that lines the eye lids and covers the inner (palpebral conjunctiva) and outer (ocular conjunctiva) surfaces of the eyes.
The fornix is a pocket of the eye where the two conjunctiva become continous
Lacrimal apparatus
Consists of: lacrimal glands and ducts paired lacrimal canaliculi lacrimal sac nasolacrimal duct
Lacrimal fluid
Contains lysosomes, mucus and antibodies
Extrinsic eye muscles
Control mevement of each eye:
Lateral Rectus
Moves eye laterally
Medial rectus
moves eye medially
Superior rectus
Elevates eye and turns it medially
Inferior rectus
Depresses eye and turns it medially
Interior oblique
Elevates eye and turns it laterally
Superior oblique
Depresses eye and turns it laterally
Diplopia
Seeing double because if uncoordinated eye muscles
Strabismus
Congentital weakness of the external eye muscles
3 layers of the eye
Fibrous layer
Vascular layer
Inner layer
Fibrous layer
The outermost coat, composed of dense connective tissue:
Sclera and Cornea
Supports and protects
Serves as attachment sight for the extrinsic eye muscles
Contains structures that assist in focusing
Sclera
Posterior portion of fibrous layer, glisining white, opaque. “white of the eye” Protects and shapes the eyeball and provides ancoring point for the eye muscles
Cornea
Transparent window, continuous with the sclera.
It allows light to enter the eye.
No blood vessels
Most sensitive portion of the eye
Vascular layer (uvea)
Pigmented middle coat of the eye has 3 regions:
Choroid
Ciliary body
Iris
Choroid
middle layer the encircles the eye between the retina and the sclera. lBlood vessel rich posterior portion, nourishes the eye and make malanocytes that protect the eye from the sun
Ciliary body
Anterior this ring that encircles the lens, controls lens shape and secretes fluid to fill the anterior cavity
Change focus from near to far
Iris
Anterior portion of the eye, colored part the contracts and dilates to control the amount of light that enters the pupil
pupillary constrictor and pupillary dilator
Inner layer
Innermost layer, retina, nervous layer:
Pigmented layer and Neural layer
Pigmented layer of the retina
Single cell think linning, absorb light and act as phagocyles, photoreceptor cell renewal.
Neural layer of the retina
Plays direct role in vision. 3 types of neurons: photoreceptors, bipolar cells, and ganglion cells
Optic disc
Weak spot in the eye where the optic nerve exits,
Rods and Cones
Rods: dim light and peripheral vision receptors
Cones: Color, bright light and HD
Internal chambers and fluids
Anterior chamber: Aqueuous humor
Posterior chamber: Vitreous humor
Lens
Bioconvex, transparent and changes shap to focas light on the retina.
Image is upside down and backwards
Brain re-orientates image
Myopia
Distant objects focus in front of the retina, Eye ball is too long
nearsightedness (can see near)
Hyperopia
Focus is beyond the retina
Eye ball is too short
farsightedness (can see far)
Astigmatisn
Unequal curvatures in different parts of the eye that lead to blurty images.
Phototransduction
Process by which light energy is turned into graded receptor potrntial
Rhodopsin
Deap purple pigment of the rods
Changes to opsin in dark
Photoreceptors active in dark
High rate of action potential
Striate cortex
Primary visual cortex.
Prestriate cortex
Visual association areas
Depth preception
Three denominational vision provided my the slightly different images delivered by the two eyes.
Chemoreceptors
The receptors for smell and taste, they respond to chemicals in aqueous solution.
Olfactory Epithelium
The yellow-tinged patch of pseudostratified epithelium that is the organ of smell
Olfactory sensory neurons
Bowling pin shaped receptors in the olfactory epithelium,
Bipolar,
Surrounded by supporting cells that contain yellow brown pigment
Olfactory stem cells
Line the base of the epithelium.
Olfactory Cilia
Located at the end of each dendrite, increase receptors surface area and are covered by a thin layer of mucus
Largely non-motile
Olfactory Transduction
- Odorant binds to receptor
- Receptor activates G protein
- G protein activated adenylate cyclase
- Adenylate cyclase converts ATP to cAMP
- cAMP opens a cation channel, allowing Na+ and Ca+ influx causing depolarization.
Olfactory pathway
Axons of olfactory sensory neurons form>
Olfactory nerve, with synapse in>
Olfactory bulbs which are the distal end of the>
Olfactory tract, where>
Mitral cells (second-order sensory neurons) synapse in>
Glomeruli
Papillae
Peg like projections of the tongue mucosa that make the tongue slightly abrasive.
Fungiform papillae
Mushroom shaped papillae scattered over the tongue. Taste buds are located mainly on the tops and in the side walls of the foliate papillae
Vallate papillae
Largest and least numerous papillae
7-12 of them form an inverted V at the back of the tongue.
Taste bud
Each flask shaped bud consists of 50- 100 epithelial cells of 2 types:
Gustatory
Basal
Gustatory epithelial cells
The taste cells, contain gustatory hairs
Gustatory hairs
Sensitive portion.
long microvilli called gustatory hairs that extend through a taste poor to the surface of the epithelium where they are bathed in saliva.
Basal epithelium
Stem cells that divide into new gustatory cells
5 tastes sensationss
Sweet Sour Salty Bitter Umami
Activation of taste receptors
Salty: Na+ influx directly depolarizes
Sour: H+ opens cation channels
Sweet, Salty and Umami: common mechanisms in different cells. Couples with G protein gustducin
Gustatory pathway (Cranial nerves)
Facial nerve: from anterior tho thirds of the tongue
Glossopharyngeal: serves posterior tongue and pharynx.
Vagus nerve: epiglottis and lower pharynx
Influence on other sences
80% of taste is smell. Temperature and texture of food enhances taste as well.
3 major ear regions
External ear
Middle ear
Inner ear
External ear structures
Auricle: funnels sound waves into the ear
Auditory canal: short curved tube that extends from the auricle to the eardrum
Tympanic memrane: flattened translucent cone that separates outer and middle ear.
sound waves make eardrum vibrate
Middle ear structures
or tympanic cavity: flanked laterally by the tympanic membrane and medially by a bony wall with the oval and round windows. Houses auditory ossicles
Auditory ossicles
Malleus : hammer
Incus : anvil
Stapes :stirrup
Inner ear structures
Bony labyrinth Membranous labyrinth Vestibule Semicircular canals Cochlea
Bony labyrinth
Canals worming through the bone, filled with perilymph fluid
Membranous labyrinth
Continuous membranous sacs and ducts with in the bony labyrinth. Filled with endolymph fluid.
Vestibule
Central egg shaped cavity of the bony labyrinth, two sacs: saccule and utricle. Houses equillibrim receptors called maculae.
Semicircular canls
Anterior lateral and posterior canals, responds to angular rotational movement of the head.
semicircular ducts inside with ampulla housing equilibrium receptors called crista ampullaris.
Cochlea
Snail shaped and houses the cochlear duct that contains the receptor organ for hearing: the spiral organ or organ of Corti.
3 cochlear chambers (or scalae)
Scala vestibuli
Scala media
Scala tympani
Pathway for sound travel
- sound waves vibrate eardrum
- Auditory ossicles vibrate and amplify
- Pressure waves from the stapes push on oval window and move into the fluid in the scala vestibule
- Sounds in hearing range go through cochlea duct vibrate basilar membrane and deflecting hairs on inner hair cells.
