Biology of Photoreceptors and Retinal Pigment Epithelium

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What is the function of melanozymes in the RPE?

Phagocytosis of photoreceptor outer segments (correct)

Absorbing photons of light

Synaptic transmission between photoreceptors and bipolar cells

Transport of ions, water, and metabolites between the choroid and retina

What is the approximate number of rods in the human retina?

200 million

6-8 million

300 million

120 million (correct)

What is the function of the photoreceptor layer?

To produce melanozymes

To absorb photons of light (correct)

To transmit light signals to the brain

To regulate ion transport

What is the shape of the photoreceptors in the photoreceptor layer?

Spherical (B) Signup and view all the answers

What is the function of the cilium in photoreceptors?

To connect the outer segment to the inner segment (D) Signup and view all the answers

What is the function of the disk lamellae in rod outer segments?

To store photopigments (D) Signup and view all the answers

What is the function of the triad-type synapse in cone pedicles?

To connect photoreceptors to bipolar cells (C) Signup and view all the answers

What is the approximate number of cones in the human retina?

6-8 million (A) Signup and view all the answers

What type of cells project to the magnocellular layer of the LGN?

Ganglion cells (D) Signup and view all the answers

Which of the following layers is absent over the optic disc?

Internal limiting membrane (A) Signup and view all the answers

What type of cells provide structure, support, and protection to the retina?

Neuroglial cells (D) Signup and view all the answers

What is the primary function of the photopigment molecules in the photoreceptor outer segment?

To absorb light (C) Signup and view all the answers

Which layer starts peripherally around the fovea?

Nerve fiber layer (A) Signup and view all the answers

What is the function of the papillomacular bundle?

Carries signals from the macula to the optic disc (A) Signup and view all the answers

What is the approximate number of lipid bilayered discs in the outer segment of a rod or cone cell?

500-1000 (D) Signup and view all the answers

Which region of the photoreceptor inner segment is involved in metabolic activity and photopigment synthesis?

Ellipsoid region (C) Signup and view all the answers

What type of cells have a role in signal processing?

Ganglion cells (B) Signup and view all the answers

Where are the axons of ganglion cells collectively found?

Optic nerve (D) Signup and view all the answers

What is the function of the cilium in the photoreceptor cell?

To transport photopigment molecules to the outer segment (C) Signup and view all the answers

What is the purpose of Müller cells in the retina?

To provide structure and support (B) Signup and view all the answers

What is the name of the region in the photoreceptor inner segment where mitochondria is found?

Myoid region (D) Signup and view all the answers

What is the primary function of the outer nuclear layer in the retina?

To transmit visual signals to the brain (A) Signup and view all the answers

What is the name of the lipid bilayered structure that surrounds the photopigment molecules in the outer segment?

Discs (B) Signup and view all the answers

What is the name of the structure that connects the photoreceptor inner segment to the outer segment?

Connecting cilium (A) Signup and view all the answers

What is the primary function of the macula lutea?

To see color and detail (B) Signup and view all the answers

What is the purpose of the xanthophyll pigments, lutein and zeaxanthin?

To absorb short wavelength visible light and reduce chromatic aberration (D) Signup and view all the answers

What is the approximate diameter of the macula lutea?

5.5 mm (B) Signup and view all the answers

What is the characteristic of the foveal avascular zone?

A region entirely free of capillaries (C) Signup and view all the answers

What is the primary function of the fovea?

To facilitate discrimination of detail and color vision (D) Signup and view all the answers

What is the diameter of the foveola?

0.35 mm (D) Signup and view all the answers

What is the characteristic of the cone photoreceptors in the foveola?

A high concentration of cones (A) Signup and view all the answers

What is the region of best visual acuity?

The foveola (C) Signup and view all the answers

What is the primary function of the Outer Plexiform Layer?

Facilitating the first synapse in the visual pathway (A) Signup and view all the answers

What is the difference between rod spherules and cone pedicles?

Cone pedicles are larger than rod spherules (B) Signup and view all the answers

What is the purpose of Henle's fiber layer?

Supporting the macular area (D) Signup and view all the answers

What type of synapses do rod bipolar cells form with rods and cones?

Invaginating synapses (B) Signup and view all the answers

What is the function of horizontal cell processes in the Outer Plexiform Layer?

Both A and B (D) Signup and view all the answers

What is unique about the Outer Plexiform Layer in terms of blood supply?

It is the only layer that receives blood supply from both the choroid and retina (D) Signup and view all the answers

What is the primary difference between the external and internal bands of the Outer Plexiform Layer?

The external band is composed of inner fibers of rods and cones, while the internal band is composed of synapses (C) Signup and view all the answers

What type of synapses do flat cone bipolar cells form with cone pedicles?

Flat synapses (B) Signup and view all the answers