31 Questions
What is the main function of the retina?
Processing electromagnetic energy in the retinal image into neural signals
Which part of the eye supports the retina only at two regions?
Vitreous humor
Which layer of the retina is firmly attached at two regions, around the optic disc and at the ora serrata?
Pigment epithelium
What is the average thickness of the retina?
200μm
Which layer of the retina forms a junction with the vitreous?
Internal limiting membrane
What is the total area of the retina?
950mm2
What is the function of the retinal pigment epithelium (RPE) cells?
To absorb stray light and provide a pathway for metabolites to the receptors
What is the structure that links the outer segment to the inner segment of the photoreceptor cell?
Cilium
What is the total length of the outer & inner segments of both rods & cones?
60μm
What is the composition of the outer segments in cones?
Series of discs formed by infolding of the cell membrane
What fills all the extracellular space in the layer containing the cell membrane of the receptors and Müller cell membranes?
Muco-polysaccharide ground substance
What is the function of the zonular adhesions linking the cell membrane of the receptors and Müller cell membranes?
Provide mechanical stability to the tips of the receptors
What is present in the cell body of retinal pigment epithelium (RPE) cells?
Large amount of endoplasmic reticulum, mitochondria, & melanin granules
What does Bruch's membrane do?
Forms part of the basement membrane that adheres to RPE cells
Where do rods replace cones entirely?
At the ora-serrata
What is the structure that extends from the ora-serrata to the edge of the optic disc?
External limiting membrane
What is the function of the extraocular muscles?
To enable high-velocity ocular movements
Which muscle is responsible for moving the eye laterally?
Lateral rectus
How does a muscle contraction initiate in the extraocular muscles?
Depolarization of the sarcolemma triggered by a nerve impulse
What provides for the precise fine motor control of extraocular muscles?
Innervation of 3 to 10 fibers by each axon
What characterizes the extraocular muscles compared to skeletal muscles?
Denser blood supply and delicate connective tissue sheaths
What is the velocity of saccades, as supported by the extraocular muscles?
Up to 1000 degrees per second
What is the first step in the sliding ratchet model of muscle contraction?
Calcium release
Which event occurs after the binding of calcium ions to the troponin-tropomyosin complex in muscle contraction?
ATP breakdown
What is the last step in the sliding ratchet model of muscle contraction?
Reset
Which of the following represents the anatomical sequence of the spiral of Tillaux involving the extraocular muscles?
Medial rectus, inferior rectus, lateral rectus, superior rectus
What is the function of the largest extraocular muscle, the medial rectus?
Moves the eye medially (adducts)
What does ATP attachment enable in muscle contraction?
Formation of cross-bridges
What initiates the exposure of an active site on the actin protein in muscle contraction?
Calcium release
In muscle contraction, what causes the head to tilt towards the shaft of the myosin filament?
ATP breakdown
Which structure marks the start and end points of the spiral of Tillaux involving extraocular muscles?
"Limbus"
Explore the general view and histology of the retina, the innermost nervous tunic of the eye, including its color, area, thickness variations, and attachment points. Gain insight into the biology of the retina in ocular studies.
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