Avian organ systems Flashcards
T/F: Avian visual acuity is 2-5x that of humans
FALSE–it’s 2-8x that of humans
T/F: The size of bird eyes are very large in relation to the size of the skull
TRUE
What are the 3 different shapes of avian eyes?
Flat, globular, tubular
T/F: The upper eyelid has more motility than the lower
FALSE
What kind of margin does the 3rd eyelid have?
What direction does it sweep the eye?
Pigmented
Sweeps cornea from superionasal to inferiotemporal
What occurs during the palpebral reflex in birds?
Partial lid closure while nictitans make a brisk, complete excursion
What does the nasolacrimal duct empty into?
Nasal cavity dorsal to the choanal cleft
What are sclera osscicles?
Ring of interdigitating pneumatic bones
Why do birds move their entire head instead of just their eyes?
Limited occular motility–scleral osscicles + skull
Why won’t commonly used mydriatics work in birds? What must you use instead?
Bird eyes have striated muscles instead of smooth
Must use general anesthesia instead (isoflurane as advantage)
Is the avian retina vascular or avascular? Is it pigmented?
Avascular
Both pigmented and non-pigmented
What provides nutrients to the retinal tissue?
Pecten
What is the advantage of a large fundus? Does it vary with the shape of the eye?
Greater visual activity, regardless of shape
What is the area of greatest visual acuity?
Fovea
What is the difference between these two retinas?
what are the black arrows pointing to?
Left = pigmented
Right = non-pigmented
Black arrows = fovea
T/F: There is no direct PLR in birds
TRUE
The opposite side will not dilate!
What cells can be seen in a slit lamp?
Inflammatory cells in anterior chamber
How does the avian heart compare to hearts of mammals?
4 chambers (like mammals)
Greater cardiac output
Higher blood pressure
T/F: The heart is centrally located and large vessels are easily visualized on radiographs
TRUE
What covers the apex of the heart on radiographs?
Is the cardiac silhouette visualized?
Liver
Yes
What do avian RBCs look like?
What are heterophils?
Nucleated RBCs, oval shape
Heterophils = neutrophils
How do you perform a WBC count?
40x objective
Count # WBC in 10 fields
Multiply average # x 200 = total WBC estimate/microliter
What’s the rule of thumb for safe blood sampling amount?
1cc/100g
-or-
1% of body weight
What vessel is being sampled?
Median metatarsal
