OcPhysio T1 Flashcards
What is the main role of conj?
To connect the globe to the eyelid
Which part of the eyeball does the conj cover?
The posterior surface.
What kind junction does the conj make with eyeball?
Indirect
Is there a true conj on the medial side of the eye?
Nope.
It is an extendable plica.
Are the eyelids and globe independent of each other?
Yes
What is another role of conj?
To stabilize the tear film.
How is the tear film organized?
Complicated arrangement of microvilli and microplicae
What is the importance of the outfoldings of the surface cell membranes?
Supporting, stabilizing, and anchoring the tear film.
Prevents irregular streams and flow patterns.
Deeper circulation of conj furnishes blood supply to….
peripheral corneal arcades, the iris, and ciliary body.
Where do superficial vessels dilate in the eye?
Moving away from the limbus.
Where do the deeper vessels dilate in the eye?
Moving towards the limbus.
How is the patterns of the bulbar conj characterized?
Randomly.
No real differentiation into specific functional units.
What is the the significance of localized venous dilation?
Nothing. They can appear in normal ppl and ppl with a disease.
What does topically applied 1:5000 epinephrine do to capillary bed?
What about heat, cold, wind?
Constricts the precapillary sphincter; thus closing and emptying the capillary bed.
Wind, heat, and cold constricts the vessels.
Where layer are mast cells found in?
Adenoid layer.
Are mast cells found in the conj stroma or conj epithelium?
Found in the conj stroma. NOne will be present in the epithelium unless you got a nasty bug. This includes basophils and eosinophils.
How is the mast cell released?
When activated by neurogenic or antigenic stimulation.
Mast cells degranulate in what sort of manner?
Controlled manner.
What kind of shape are the IgE antibodies?
Y-shaped. THey are attached on the cell membrane
What happens when the antigen binds to two IgE molecules?
THe membrane becomes more permeable to calcium
What becomes active when calcium is allowed in?
Phosphlipase A2
What is a componenet of the immediate reaction?
Histamine.
Gets released to the outside environment
What are components of the inflammatory phase?
Prostaglandins and leukotrienes.
When does clinical papillae occur?
When the substantia propria abnormally bulges into the overlying epithelial layer, levating the latter tissue.
Where does the leakage of fluid come from in papillae?
Vascular core.
How is papillae distinguished from follicles?
Presence of blood vessels in their centers.
Is a papillae specific or nonspecific clinical sign?
nonspecific.
Can result from any type of inflammation or chronic irritation.
What do the areas of hypertrophy in a papillae contain?
Neutrophils and eosinophils
What layer is the follicle contained in?
Adenoid layer.
Contains lymphocytes and macrophages
Describe how a follicle look like?
Clear, fluid filled pickets.
Never has blood vessels passing through the middle.
What does a follicle sign indicate?
A specific clinical sign.
Present in conditions of cell immune reaction: viral infections and hypersensitivity.
WHo are the primary regulators of conjunctival goblet cell secretion?
Nerves
What are the three types of nerves that conj is innervated by?
Efferent Symp
Efferent Parasymp
Afferent sensory
Who does goblet cells have receptors for NTs for?
Symp nerves
Parasymp nerves
What NTs parasymp stimulate the goblets cells
Ach
VIP - vasoactive intestinal peptide.
Who is the driving force for conj fluid secretion?
Basolateral Na+/K+ ATPase
The Levator Palpebrae Superioris is supplied by which nerve?
CN III
Which nerve is supplies the Mueller’s muscle
Sympathetic nerves
Which nerve supplies the Frontalis
Facial nerve
What is the function of the orbital portion of Orbicularis oculi
closes lid forcefully
What are the three eyelid elevators?
Frontalis
LPS
Mueller’s
What is the function of the palpebral portion of O.O
Closes lid gently.
What is the function of the muscle of Riolan
Holds the eyelid to the globe
What is the purpose of Horner’s muscle and rest of O.O.
dilates lacrimal sac to let tears in and out
What is bell’s phenomenon?
Upward and outward rotation of the eyes on bilateral closure (or attempted closure of eyelids)
Synergism of what two muscles take place in Bell’s phenomenon?
LPS and SR
What are the 5 Relex blinking types
THink Mr. Toad Menace Tactile Orbicularis Auditory Dazzle MTO = Cortical central connection
Who has a cortical Central connection?
MTO
Menace
Touch
Orbicularis
What is the afferent CN for Orbicularis Oculi?
CN V
Is the LPS inhibited or excited during a blink?
inhibited. In bell’s phenomenon it is not inhibited. It works together with the SR to make it happen.
What is the rate for spontaneous blink?
15 times per minute.
What is the purpose of spontaneous blink?
It redistributes the precorneal tear film
What has the highest EMG amplitude?
Voluntary blink.
Least is spontaneous blink
As for intervals and frequencies, which phase is faster?
Closing phase is faster than the opening phase.
Closing phase has a shorter duration.
Closing phase is actually closing your eyeball. 1:2 ratio
Tell me about the blink rate for dry eye and dry eye with tears?
The blink rate is more for dry eye patients without tears.
Tell me about gaze position and blink rate?
Blink rate increases significantly as you look up.
Compare blink rates of reading, conversation and rest
Blink rate from low to high
- reading
- rest
- conversation
What is Bell’s Palsy?
A idiopathic hemi-facial paralysis.
What is blepharospasm?
Involuntary closure of both eyelids
It is eliminated with SLeep!!!
Which part of the sclera has the highest internal radial stress?
Anterior sclera
Equatorial sclera.
Y? Thinnest in these areas
Who has the highest circumferential wall stress?
The limbus
Y?
A two-fold higher amount of stress is req’d to sustain the curvature change from the cornea to the sclera.
What is the dual function of the sclera?
Posterior: extensible. Acts as a mechanical buffer or cushion against acute increase in IOP
Anterior and equatorial: Rigid support and stability of the globe.
What happens when IOP increases or stress is applied to a system?
The sclera’s elastic stress-strain curve increases exponentially.
This will also reveal a slower time-dependent viscous response decrease with time.
What is the shape of the stress-strain curve for sclera?
J-shaped
How does the J-shaped curve arise for sclera?
Its extensible elastin fibers and the wavy collagen fibrils that take up slack at first.
Get used to stress and resistance is built up
Is the level of sceral distensibility fixed or not fixed?
Not fixed
How is scleral distensibility determined?
Pressure changes
The amount of time acting on the sclera
Innate biomechanical properties and thickness of the sclera.
What order kinetics is the sclera responsible for?
First-order kinetics.
What are the two types of mucin?
Secreted
Membrane
What are the three main important membrane associated proteins?
MUC 1, 4, and 16
Which cells produce the membrane associated proteins?
Apical cells of stratified corneal and conjunctival epithelium.
Which cells express the popular secreted mucin?
goblet cells of the conj epithelium
What is the purpose of the MAMs?
A barrier to protect the ocular surface against pathogen invasion.
Provide a hydrating, lubricating surface.
What is the purpose of MUC5AC
It is secreted into the tear film.
Lids move the soluble mucin over the surface of the eye to trap and remove foreign debris.
Does conj epithelium have both secreted and membrane associated mucins?
Yep
On which side of cellular surface is glycocalyx found?
apical plasma membrane of the superficial cell layer.
What is the purpose of glycocalyx layer?
Serve as a barrier to pathogens.
Allows the mucous layer to move over the ocular surface.
What does the carbohydrate side chains of glycocalyx hold?
Water!!!
What does the mucous layer backbone consist of?
Gel-forming mucin MUC5AC, synthesized and secreted by conj goblet cells.
Which mucin is the glycocalyx layer composed of?
MUC1, 4, 16
IN what structure does the aqueous layer play a big role in?
Tear film
98%
What is the purpose of the anterior lipid layer?
Prevent evaporation of the water component.
Reduces evaporation to about 10% of that found in the fluid systems without a lipid surface.
Which interface does the outer non-polar and inner polar components of anterior lipid layer consist of?
Outer nonpolar: air interface
Inner polar: aqueous interface
What electrolytes are found in the Basic Tear Solution?
NaCl KCl CaCl MgCl NaCHO3- NaPO3-
What are not essential in BTS
Glucose and large molecules
What are the four possible origins of tear proteins?
Proteins from ocular surface blood vessels
Lacrimal gland proteins
-Proteins from ocular surface epithelium
-Proteins from ocular mucus.
What are the two types of lacrimal gland proteins?
- Consitutively secreted proteins
2. Regulated proteins
What are the three proteins from ocular surface blood vessels?
IgG
Albumin
Transferrin
What are the two consitutevely secreted proteins?
IgA
IgM
What are the four Regulated Proteins?
Lactoferrin
Lipocalin
Lysozyme
Peroxidase
What differentiates constitutively secreted proteins from regulated proteins?
Cons sec proteins will get reduced with reflex tearing while Regulated proteins will get increased with reflex tearing.
What are the three predominant serum proteins?
albumin
transferrin
IgG
Are the proteins from ocular surface blood vessels found in high or low levels in tears?
Very low levels in tears.
They are found at its highest in nonstimulated tears and decline with stimulation of tearing.
Of the three proteins from ocular surface blood vessels, which are found the most in the ocular surface blood vessels?
Albumin
Albumin is responsible for….
Osmotic pressure in the capillary and draws water in
Transports small molecules through the plasma and extracellular fluid.
Transferrin is responsible for….
Iron transport
IgG is responsible for
Immunity against blood-borne diseases.
What are the consituteively secreted proteins secretion controlledy by?
The rate of protein synthesis.
It is independent of the rate of fluid secretion.
Who is the major constitutively secreted lacrimal gland protein?
Secretory IgA
Who has the largest immunoglobulin?
Tear IgM
What is IgM responsible for….
Detects early immune response
Enchances phagocytosis
Fixes complement
What is IgA responsible for?
Protect mucosal surfaces of the eye by….
Immunologic barrier to the adherence
Colonization
Cellular entry of microbial organisms and antigenic marcromolecules
What is the IgG/IgA ratio in tears?
1:1.
In plasma it is 7:1
What is the role of secretory component?
Facilitates the transport o fthe IgA dimer and protects it from proteolytic digestion in the tear secretions.
who produces secretory component?
Conj epithelium.
Not produced by corneal epithelium.
What does a flourescein stain reveal?
Disruption of cell-cell junctions
What does Rose begnal staining reveal?
Insufficient protection by preocular tear film
How many seconds constitute an abnomral TBUT?
10 seconds
What is the purpose of Dilation of bulbar and limbal vasculature?
Detects ocular irritation
Purpose of non-invasive TBUT?
Measures tear stability
Purpose of Fluoresceint TBUT akorn DET
Measures tear stability
Purpose of phenol red thread test?
Measures tear volume
Purpose of tear film osmolality?
Increased osmolality in dry eye conditions
Purpose of tear lactoferrin
Decreased in dry eye conditions
Purpose of Tear IgE?
Increased in dry eye condition
Purpose of impression cytology?
Squamos metaplasia seen in dry eyes
Purpose of lisssamine green?
Indicates integrity of conj cells.
