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