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37 Cards in this Set

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THE EYE & VISION
__% of sensory receptors reside in
important for?
interpreted by?
-70%
-important for receiving & transforming light energy into a chemical/electrical signal
-interpreted by the visual ctrs of the cortex
EYE ANATOMY
what is it?
3 structural layers?
-hollow, fluid filled sphere
-3 structural layers (fibrous tunic, vascular tunic, sensory tunic)
FIBROUS TUNIC
what is it?
comprised of?
layers?
-outermost layer
-comprised of dense connective tissue
-layers: sclera & cornea
SCLERA
description
function
glistening white, opaque materal
-shapes eyeball & offers protection
-allows for anchoring of eye muscles
CORNEA
description?
functions
-transparent arangement of collagen fibers
-forms window that allows for entry of light
-well supplied with pain fibrs (serve as protective role)
VASCULAR TUNIC
divided into __ layers?
choroid
ciliary body
iris
CHOROID
description
functions
highly vascular membrane
-provides nutrients to various layers of eye
-pigmented w/ melanocytes to help obsorb light
CILIARY BODY
description
function
-ring of tissue that encircles the lens
-is involved in controlling lens shape
IRIS
description
opening of it is called?
underlying pigment of iris is?
lack of this pigment?
-colored portion of eye
-opening of iris is called pupil
-underlying pigment of iris is brown
-lack of pigment is what allows for green, blue, & hazel coloration
SENSORY TUNIC
location?
contains?
innermost layer
contains retina & various photoreceptors
PHOTORECEPTORS
contains?
rods & cones
RODS
functions
contains?
absorbs dim light, involved in peripheral vision. retina c ontains approximately 120 mill rods
CONES
functions?
contains?
absorb bright light
involved in color vision
eye contains approximately 7 million cones
PHOTORECEPTION
how does this happen in the dark?
what does this cause?
-in the dark, receptors are continually depolarized and releasing glutamate onto the horizontal bipolar cells
-depolarization occurs because Na channels are continually open allowing for continual release of glutamate
PHOTORECEPTION CONT'D
describe the steps of photoreception
1. The glutamate is secreted onto the horizontal cells
2. The horizontal cells release inhibitory GABA in response to the glutamate
3. GABA inhibits transmission of impulses to other receptor cells & bipolar cells
4. stops the signal
PHOTORECEPTORS
what do they contain?
contains photopigments that allow for conversion of the light energy to a chemical signal
PHOTORECEPTORS
what do they contain?
contains photopigments that allow for conversion of the light energy to a chemical signal
PHOTOPIGMENT
what is it?
what is it called?
-complex of a protein called opsin, and retinal, an alcohol derivative of vitamin A
-complex is called rhodopsin
RHODOPSIN
how does it exist in dark?
-in dark, it exists in a specific form called 11-cis-retinal. This chemical fits perfectly into its specific receptor.
PHOTORECEPTION IN LIGHT
steps
1. when light hits the receptor cells, they undergo a series of chemical changes (an isomerization) that in effect polarizes the reception
2. as a result, Na channels close & receptors stop secreting glutamate. This causes the horizontal cells to stop secreting GABA, which removes the inhibition of receptor cells & horizontal cells
3.This again causes receptor cells to secrete glutamate
4. glutamate can stimulate the previously inhibited bipolar cells
5. the bipolar cells send the signal along to the amacrine cells & ganglion cells
6. The signal is then sent by the ganglion cells to the optic nerve tract.
VISUAL PATHWAYS
optic nerve pathway?
what does the thalamus do?
how is this info processed?
-the optic nerve travels along the optic tracts to the thalamus
-thalamus projects the image to the primary visual cortex
-this info is processed in several steps
VISUAL INTERPRETATION
what types are there?
thalamic
cortical
retinal
THALAMIC
function?
processes info pertaining to movement depth perception & sharpens image contrast
CORTICAL
function?
interprets the meaning of the signal
CHEMICAL SENSES
2 types
their chemicoreceptors respond to ?
gustatioin (taste) & olfaction (smell)
-chemicoreceptors respond to chemicals in aqueous solution
1. taste ( to substances dissolved in saliva)
2. smell (to substances dissolved in fluids of the nasal membranes
CHEMICAL SENSES
2 types
their chemicoreceptors respond to ?
gustatioin (taste) & olfaction (smell)
-chemicoreceptors respond to chemicals in aqueous solution
1. taste ( to substances dissolved in saliva)
2. smell (to substances dissolved in fluids of the nasal membranes
TASTE BUDS
where are they found?
how many are there?
-taste buds are found in papillae of the tongue mucosa
-10,000
PAPILLAE
types
which types contain taste buds?
3
Filiform, Fungiform, & Circumvallate
Filiform does not contain taste buds
ANATOMY OF A TASTE BUD
shape?
what major cell types?
gourd shaped buds
consists of 3 major cell types: supporting cells (insulate receptors), basal cells (dynamic stem cells), & gustatory cells (taste cells)
TASTE SENSATIONS
what are the basic taste sensations
5
Sweet: sugars, saccharin, alcohol, some AAs
Salt: metal ions
Sour: hydrogen ions
Bitter: alkaloids such as quinine & nicotene
Umami: elicited by MSG
PHYSIOLOGY OF TASTE
in order to be tasted...?
binding of the food chemical...?
-In order to be tasted, a chemical must (a) be dissolved in saliva and (b) contact gustatory hairs
-Binding of the food chemical (a) depolarizes the taste cell membrane, releasing neurotransmitter and (b) initiates a generator potential that elicits an action potential.
TASTE TRANSDUCTION
the stimulus energy of taste is converted into?
how?
-The stimulus energy of taste is converted into a nerve impulse by: (a) Na influx in salty tastes, (b) H in sour tastes by directly entering the cell by opening cation channels, or by blockade of K channels, and (c) Gustaducin in sweet & bitter tastes
GUSTATORY PATHWAY
Cranial nerves __ & __ carry impulses from taste buds to?
These impulses then travel to?
And from there fibers branch to the _&_?
Cranial nerves 7 & 9 carry impulses from taste buds to the solitary nucleus of the medulla
-These impulses then travel to the thalamus and from there fibers branch to the: (a) gustatory cortex & (b) hypothalamus & limbic sys.
INFLUENCE OF OTHER SENSATIONS ON TASTE
taste is __ % ___?
what types of receptors influence taste?
what are 2 things that can enhance or detract from taste?
-taste is 80% smell
-Thermoreceptors, mechanoreceptors, & nociceptors can influence tastes
-Temperature & texture can enhance or detract from taste
SENSE OF SMELL
what is the organ of smell & what does it cover?
what are olfactory receptor cells?
olfactory cells are surrounded by?
what type of cells lie at the base of the epithelium
-Organ of smell is the olfactory epithelium & covers the superior nasal concha
-Olfactory receptor cells are bipolar neurons w/ radiating olfactory cilia
-Olfactory receptors are surrounded by supporting cells (Goblet)
-Basal cells lie at the base of the epithelium
PHYSIOLOGY OF SMELL
olfactory receptors respond to?
what happens when olfactory cells bind to ligan?
-Olfactory receptors respond to a variety of odor-causing chemicals
-When bound to ligand, these proteins initiate a G protein mechanism, which uses cAMP as a 2nd messanger
-cAMP opens Na & Ca channels, causing depolarization of the receptor membrane that then triggers an action potential
OLFACTORY PATHWAY
olfactory receptor cells synapse with?
what processes odor signals?
mitral cells send impulses to?
-Olfactory receptors cells synapse with mitral cells
-Glomerular mitral cells process odor signals
-Mitral cells send impulses to (A) olfactory cortex and (B) the hypothalamus, amygdala, & limbic system