Ch 17 Flashcards
What is smell
A chemical taste
Lots of connections to cortex for taste and limbic for emotion
Receptor potential
Has a synapse and a NT
Olfactory receptors are
- 1-month lifespan
- Bipolar axon with a dendrite
- The hair /cilia is the site of transduction
Olfactory hairs
- Site of transduction (Eventually produce receptor potential)
Supporting Cell of olfaction does what?
- support nourish protect dtoxify (part of olfactory epitehelium)
Basal stem cells
Cells from which cell division takes place (new receptors will grow)
One of the few places CNS regrowth is common
- Olfactory (Bowman’s) glands
- Produces mucous that flows into mucous cavity
- Traps odorant and moisten cavity
Olfactory Adaptation and Thresholds
- How quickly do u stop register smell
- Within 1 second there is 50% reduction of smell
- After 1 minute it is almost all gone
- Very low threshold for smelling
Olfactory Pathway
- Bundles of unmyelinated axons of olfactory receptors extend through olfactory foramina
- Form left and right olfactory nerves
- Olactory bulbs (frontal lobe cortex)
- Olfactory tract
5.A Cortex olfactory area - Frontal Lobe
5.B Limbic and hypothalamus
- emotion and memory
Hyposmia
reduced ability to smell, occurs with age as number of receptors decrease also drugs smoking traumatic brain injury, dementia (appetite decreases)
5 types of tastes
Salty (ant lat)
Sweet
Sour (lateral)
Bitter (Back)
Umami (beefy)
Taste buds
- Elevations called papilla (texture and taste)
- Foliate not common in adults (disappear in childhood)
Supporting cells to taste buds
- Brown ones
- Support recpeot (whole taste bud)
- Gustatory Receptor Cells
- Microgilia sticking up to surface.
Gustatory Hair
- Site of transduction (RP and the AP)
Taste pore
- Openings where food saliva can fall into whole
- If food not chewed then you wont get same taste out of food (doesn’t fall into hole with
Basal Cells
Produce new taste buds (receptor cell) ten day life span
Papillae
b) Papillae (elevations on tongue)
- Mosst have conc of tastebuds
(Contain taste buds)
Vallate
- Larger elevations with 200-300 per papillae
- More food goes into it
Fungiform
- Fungiform (Typically five buds per) typicalluy extends over entire tongue
Foliate
- Lateral lines, disappear after breast feeding
(No taste buds)
Filiform
- Located over entire surface for tactile sensations only
Gustation sequence
- Tastant (Food + Saliva)
- Gustatory hairs
- Synapse
- Recepotr Potential
- 1st Order Neuron
How do different tastes occur?
Different combos od taste recepors
Which taste has the highest threshold
Sweet + Salty
Which taste has the lowest threshold and wy
Sour + Bitter
- More likely to harmful
3 Cranial Nerves in Gustatory Pathway
- Facial (VII) – anterior 2/3 of tongue
- Supplies anterior 2/3 of tongue
- Glossopharyngeal (1X) – posterior 1/3 of tongue
- Vagus (X) – throat and epiglottis
All three connnect to gustatory nuc,eus in medullla and priamary gustatory nerve in the cortex
Taste aversion
- Avoid foods that upset stomach
- Emotion + memory says lets avoid this food
- Sweet usually present
- Brain injuries and chemo and pregnancy can cause aversions
Primary Gustatory area located
Part of Parietal Lobe
What helps a person remeber food more
Anything with emotional reaction
Accessory structures in vision
eyelids, eyelashes, eyebrows, lacrimal (tearing) apparatus, and extrinsic eye muscles. (Figure 17.5) (Lab study)
- Everything on exterior
- Deal with Unnecessary light
Palpebrae
Eyelids
Lacrimal Caruncle
Oil and sweat glands
Tarsal Plate
COnnective Tissue Under eyelid
Meibomian Glands
Fluid Secretion and tear ducts
Conjunctiva
Mucous Membrane of eyeball stratified squamous and goblet cells (for secretion)
Palpebral Conjuctiva
Underneath eyelids
Bulbar Conjuctiva
Whites of eyes
- Bloodshot eyes = congestion/dialation of vessels here_
Sebaceous Ciliary Glands
- At base of each hair follicle
- Styes form here’
-Next to base of eyelashes
Flow of tears
- lacrimal glands (Produce tears)
↓ - lacrimal (excretory) ducts - distribute over surface of eye (moisten + antibiotiscs protect
↓ - superior/inferior lacrimal canal – drain tears into …
↓ - lacrimal sac – drains tears into
↓ - nasolacrimal duct – drains into
↓ - nasal cavity
Why do tears run over cheeks
– parasympathetic system producing too many tears and they overfolow onto cheecks
If something gets into eye, where will it be pushed to?
In direction of tears
What can cause dry eyes
Surgery
Extrinsic Eye muscles
extend from bony orbit and attatch to eye muscle
- Muscles are small motor units (fine control)
Anatomy of eyeball: Fibrous Tunic
(most outer division)
- Avascular
- Superficial
Cornea
- Transparent
- First site of refraction
- Curved to focus light on the retina
- Laser eye surgery is CORNEA
Sclera
Connective tissue *doesn’t cover cornea
- Shape and rigidity to eyeball
- Lots of collogen lots of fibroblasts
sclera venous sinus (canal of Schlemm)
- An opening bw scelear and cornea allowing fluid to drain from front of eyeball out
Vascular Tunic
(ciliary body and iris)
- choroid
- Most vascular part (very post.)
- Give good blood supppy and nutrition to retina
- ciliary body
(process and ciliary muscle)
Ciliary Process
Folds of ciliary body
Blood vessels
Produce aqueous humor
Replaced every hour- hour and half for nutrion of cornea
Ciliary Muscle
Attach to help change shape of lens
Zonular Fibers
(suspensory ligaments)
- Extend from ciliary process and attatch to lens
- As lens changes shape zonular fibers do this
Older adults lose ability for lens to change shape
Ora Serrata
End/jagged margin of retina (serrated appearance)Iris
Iris
- Coloured ring (pigment)
- Dialate or constrict pupil to control amount of light coming in and hitting retina
Pupil
- The hole
- Parasymp muscles constrict pupil
- Symp dialates
Circular pupil muscles
Sphincter pupillae
- Bright light
- Less light in
- Parasymp NS
Radial Pupil Muscles
Dilator Pupillae
- More light
- Sympathetic NS
3rd Major diviison of the eye
Retina
layers of retina
Pigmented Layer
Neural Layer
Pigmented Layer of Retina
Melanin absobs light that comes into light preventing scattering
- Begins process of visual pathway
Neural Layer of Retina
- Outgrowth of brain, light is process ed by rods and cones photoreceptors
Three layers of Retina Nerves
Photoreceptor Layer
Bipolar Cell Layer
Ganglion Cell Layer
(Last two part of outer-synaptic Layer)
Photoreceptor Layer of Retina nerves
rods black and white
-Work in dim light (shades)
- Low threshold
Cones only function in bright light – see blue-green and red (high threshold)
Ganglion Cell Layer
- Last cell involved before we orduce receptor potential and then AP
Colour blindness
One type of cones are not functioning
Two types of cells in bipolar layer
Horizontal Cells
Amacrine Cells
Horizonatal Cells
- To make sure only portion of visual pathway is on
- Adjacent areas beside stimulated area are “turned off” allowing for better contrast and better vision
Amacrine Cells
- The ceelll that turbo boosts, turns on intensity of visual patheay activated system (Contrast even brighter so vision is better)
- macula lutea
- Midline/visual axis of light coming i
- central fovea
- Cones only, a depression in middle of macular lutea
- Area of sharpest vision
- blind spot
- Where optic nerve leaves back of retina
- No rods or cones
- No image in this area
- detached retina
- Fluid accumulating bw two layers of retina
- Trauma disease age
- Retina begins to bulge
- Blindenss can result
- AMD (macular degeneration)
- Loss of vision in straight ahead
- Only see on peripheral
- Macular lutea is degenerate
- Wet or dry (atrophe NOT treatable)
- Wet implies leaky blodd vessels – can be treated
- Cataeratct
- Lens no longer as clear as it should be
- Smoking, age, drinking, diabetes serioids, UV exposure
- Articifial lens put in
- Glycoma
- Pressure inside eye behind lens puts pressure on retina causing damage to optic nerve
- Intraocular pressure meauseured
Lens
- Crystallins (protein layer composing lens)
- No blood vessels
- Held in position by zonular fibers
Two Cavities in Eyeball
Anterior cavity
Vitreous Chamber
Anterior Chamber
Part of anterior cavity
- Bw cornea and iris
Posterior Chamber
Part of Anterior Cavity
- Behind iris and in front of lens
Aqueous Humor
- Fluid in ant cavity
- Designed to nourish lens and conrea (replaced every 90 minutes)
-intraocular pressure
- Pressure inside the eyeball including aqueous humor and vitreous body (abt 16mm of pressure for me)
- Too much pressure can be from hyperactive thyroid disease – can cause blindness/visual problems
ii) vitreous chamber (between lens and retina)
- From lens back to retina
- vitreous body
- Fluid inside v chamber
- Jelly like
- Not replaced
- Holds retina in correct position (just enough pressure)
- Average pressure is 16mm
Overactive thyroid decreases intra ocular pressure
What are the floaties that can move across vision
are proteins, WBCs moving across vitreous body, as light comes in, they cast shadow over retina
How often is the vitreous boyd replaced?
Never
What is the ideal light shining on retina
Focuesed not scattered
Refraction
Bending the light
- Ideally light is focused sharply on retina
-More distorted light= more distorted vision
Abt 75% of bending of light is the cornea
25% of bending of the light is the lens
Surgery reshaping the cornea alters refraction.
Accomodation of the lens
- Bending of lens by the ciliary muscle to help focus the light
Near point vision
- As object brought closer lens must bend more
- In older people lens loses ability to bend
c) Constriction of the Pupil
- Hole allowing light in gets smaller therefore less light is allowed in
- Prevents scattering of unwanted light
- emmetropic vision
Normal 20/20
Myopic Vision
Near sighted
- Eye is too long
- Focal point is in front of the retina
- Corrective lens push focus point back
Hypermetropia
- hypermetropia (farsighted)
- Light crosses behind the retina
- Eyeball is stubby
Astigmatism
- Uneven vision (some parts hazy some clear)
- Surface of cornea (and lens somewhat) is not smooth
Presbyopia
: Old eyes
- Near point is farther away
- Lens lose ability to be
Convergence
- As things come closer to u your eyeballs rotate medially towards your nose
- Binocular vision (both eyes focused on same object)
Lazy Eye
Muscle control issue
Photopigments
integral protein s in the receptors that help absorb the light
- Each photopigment has a glycoprotein component which is called opsin AND retinal component (comes from Vit A) which is light absorbing component.
Two types of phtoreceptors
Rods ; low threshold, black and white, night vision
- Cones: High threshold, need intense light: Blue, green, and red cones (Different amino acid sequences on photoreceptors absorbs different wavelength of light)
Bleaching of photopigment
Photopigment no longer able to absorb any more light
Cis means
Bent
Isomerization
Change in shape and structure but not in components
In relation to absorption of light
The ear consists of three anatomical subdivisions.
external (outer) ear
middle ear (tympanic cavity)
internal (inner) ear
Auricle
The flap of the ear
Parts of the external ear
auricle (pinna), external auditory canal (meatus), and tympanic membrane (eardrum)
Purpose of external ear
- Directs soundwaves into canal (external auditory or medius)
-Hand to ear increase ear flap directing sound into ear)
Ceruminous gland
in the external auditory canal secrete cerumen (earwax) to help prevent dust and foreign objects from entering the ear.
MIddle ear contatins
auditory (Eustachian) tube (connects to throat), auditory ossicles (middle ear bones, the malleus, incus and stapes)- increase frequency of sound coming in , the oval window connects to the cochlea, and the round window.
Tensor tympanny muscle
attatched to tympanny (ear drum) – limits how much ear drum vibrates , protecting it from loud sounds
Stupidious muscl
attatches to stapes and oval window and protects how much the stapes vibrates
What could loud sounds close to ear cause?
- Loud sounds close to ear can damage ear drum and stapes
The internal ear also called the
Labyrinth because of its complicated series of canals.
What is the middle ear?
is a small, air-filled cavity in the temporal bone that is lined by epithelium(basement membrane and cells).
What is the bony labyrinth
a series of cavities in the petrous portion of the temporal bone.
What is perilymph
Similar to CSF helps set up health and conduct electrical impulses, surrounds membranous labbyrinth
What is the membranous labyrinth?
The membranous labyrinth is a series of sacs and tubes enclosed within the bony labryth and having the same general form as the bony labyrinth.
Lined with epithelium
Contains endolymph
What do Utricle and vestibule help with?
Balance and equillibirum
What is the vestibule
The vestibule constitutes the oval portion of the bony labyrinth. The membranous labyrinth in the vestibule consists of two sacs called the utricle and saccule.
What two sacs does the vestibule contain?
utricle and saccule.
scala vestibuli
A channel of the cochlea above the bony partition is the scala vestibuli, which ends at the oval window.
scala tympani
The channel of the cochlea below is the scala tympani, which ends at the round window. The scala vestibuli and scala tympani both contain perilymph and are completely separated except at an opening at the apex of the cochlea called the helicotrema.
Cochlear duct
The third channel of the cochlea (Scala media) separated from the scala tymapni by the vestibular membrane
Sound waves result from
result from the alternate compression and decompression of air molecules.
Pitch is
Frequency of sound vibration
Cochlear branch of vestibocochlear nerve goes to
The medulla
What happens to hair cells when they get damaged
No longer generate RPs like they should
Normal conversation tone is how many Hz
60 Hz
Physiology of hearing (pathway)
1) The auricle directs sound waves into the external auditory canal.
2) Sound waves strike the tympanic membrane, causing it to vibrate back and forth
^ Outer ear
3) The vibration conducts from the tympanic membrane through the ossicles (through the malleus to the incus and then to the stapes).
4) The stapes moves back and forth, pushing the membrane of the oval window in and out.
^ MIDDLE EAR
5) The movement of the oval window sets up fluid pressure waves in the perilymph of the cochlea (scala vestibuli). 6) Pressure waves in the scala vestibuli are transmitted to the scala tympani and eventually to the round window, causing it to bulge outward into the middle ear. 7) As the pressure waves deform the walls of the scala vestibuli and scala tympani, they push the vestibular membrane back and forth and increase and decrease the pressure of the endolymph inside the cochlear duct. 8) The pressure fluctuations of the endolymph move the basilar membrane slightly, moving the hair cells of the spiral organ against the tectorial membrane; the bending of the hairs produces receptor potentials that lead to the generation of nerve impulses in cochlear nerve fibers. ^ INNER EAR 9) Pressure changes in the scala tympani cause the round window to bulge outward into the middle ear. (Cochlea (lower channel) ends at the round window.)
Differences in heard pitch is related to
differences in the width and stiffness of the basilar membrane and sound waves of various frequencies that cause specific regions of the basilar membrane to vibrate more intensely than others.
Where do High-frequency or high-pitched sounds cause the basilar membrane to vibrate?
near the base of the cochlea.
Where do Low-frequency or low-pitched sounds cause the basilar membrane to vibrate?
Near apex of the cochlea.
How to hair cells act as receptors?
convert a mechanical force (stimulus) into an electrical signal (receptor potential); hair cells release neurotransmitter, which initiates nerve impulses
Describe the auditory nerve pathway
Nerve impulses from the cochlear branch of the vestibulocochleor nerve pass to the cochlear nuclei in the medulla. Here, most impulses cross to the opposite side and then travel to the midbrain, to the thalamus, and finally to the auditory area of the temporal lobe of the cerebral cortex.
Cochlear implant
devices that translate sounds into electronic signals that can be interpreted by the brain.
Static equilibrium
refers to the maintenance of the position of the body (mainly the head) relative to the force of gravity.
maculae regulate
Dynamic equilibrium
is the maintenance of body position (mainly the head) in response to sudden movements, such as rotation, acceleration, and deceleration
The maculae of the utricle and saccule
sense organs of static equilibrium; they also contribute to some aspects of dynamic equilibrium
The maculae consist of hair cells, which are sensory receptors, and supporting cells.
- Tips of hair cells touch each other generating RP
Cristae
in the semicircular ducts are the primary sense organs of dynamic equilibrium.
