206 SSNS - Histology Flashcards by Ina Vong

What are the 3 coats of tunic of the eye?

Fibrous tunic
Vascular tunic
Retinal tunic

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What are the pigments in rods & cones?

Rods - rhodopsin

Cones - iodopsin

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What are the 2 photoreceptor cells responsible for?

Rods - dim, black & white

Cones - bright, color

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What are the 10 layers of the retina? (from inner region to outer region)

Retina layers (from inner region to outer region)

My - Membrane (Inner limiting membrane); (adjacent to vitreous)
Nerves - Nerve fibers 
Get - Ganglions
In - Inner plexiform
Knots - Inner nuclear
Outside - Outer plexiform
Our - Outer nuclear
Easy - External limiting membrane
Practice - Photoreceptors (rods & cones)
Review - Retinal pigment epithelium

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What’s the Bruch’s membrane & its function?

Innermost layer of choroid

Separates choroid from pigment epithelium

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What are the 5 layers of Bruch’s membrane? (from inside to outside)

The basement membrane of the retinal pigment epithelium
The inner collagenous zone
A central band of elastic fibers
The outer collagenous zone
The basement membrane of the capillaries

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What is the fovea?

A shallow depression in the inner retinal surface, entirely cones, specialized for maximum visual acuity

Located in the center of macula lutea

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What is the macula lutea?

A yellowish region surrounding fovea, mainly cones but start to gain rod at the periphery

Ganglion cells & fibers are pushed to the sides to allow light to pass uninterrupted

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What are the 5 types of neurons in the retina?

Photoreceptors (rods & cones) 
Bipolar cells
Ganglion cells
Horizontal cells 
Amacrine cells

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What are the 2 glial cells found in the retina?

Astrocyte

Müller cells

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What are the functions of the retinal pigment epithelium (RPE)?

Light absorption
Production of extracellular matrix
Visual cycle - storage of vit A (precursor of 11-cis retinal) & regeneration of rhodopsin
Phagocytosis of shredded outer segments

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Fill in the blanks:

During darkness, receptors are ______.

Depolarized

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Fill in the blanks:

During light, receptors are ______.

Hyperpolarized

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How do rod bipolar cells communicate with retinal ganglion cells (RGCs)?

They do not contact ganglion cells directly.

Contact amacrine cells which spread out rod info before covering on ganglion cells

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How do cone bipolar cells communicate with retinal ganglion cells (RGCs)?

Synapse with RGC directly

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What’s the vertical pathway for retinal ganglion cells?

Photoreceptor → bipolar cell → ganglion cell chain

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What’s the lateral pathway for retinal ganglion cells?

Photoreceptor → horizontal cell → bipolar cell → amacrine cell → ganglion cell chain

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What are the 2 principal types of human retinal ganglion cells?

Midget (Type P) - small receptive field

Parasol (Type M) - large receptive field

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What cells are responsible for lateral inhibition?

Horizontal + Amacrine

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What are the classical findings in Central Retinal Artery Occlusion?

Cherry red spot, pale optic disc

Pathogenesis of diabetic retinopathy

Capillary basement membrane thickening
Loss of pericytes
Distention of retinal capillary walls
Breakdown of blood-retinal (endothelial) barrier

What is glaucoma due to?

↑ intraocular pressure

Loss of blood flow to the optic nerve

What are the functions of the integumentary system (skin & its appendages)? (4)

Protection
Excretion
Sensation
Secretory

3 main composition of skin & its appendages

Epidermis
Dermis
Hypodermis/subcutis

Epidermal appendages: hair, nail, sweat, oil, mammary glands

5 layers of epidermis (superficial to deep)

"Come Lets Get Some Beers" (from superficial to deep) Stratum Corneum - outermost; stack of squamous cells w keratin filaments Stratum Lucidum - no organelles, keratin filaments, eleidin Stratum Granulosum - keratohyalin granules Stratum Spinosum - intercellular bridges (desmosomes) Stratum Basale - innermost, cuboidalcells

Cell types in epidermis (4)

Keratinocytes Melanocytes Langerhans cells (dendritic cells) Merkel's cells

What is a type of skin determined by?

Thickness of epidermis

Where is thick skin & thin skin found?

Thick: palm & sole Thin: rest of body

How do thick skin & think skin differ?

Stratum lucidum is absent in thin skin | Thin skin has thin stratum corneum

Where are melanocytes located?

Basal layer of epidermis

What's the function of melanosomes?

Synthesize & release brown pigment - melanin

How does exposure to UV affect melanin production?

It accelerates the rate of melanin production, to provide a darker color to protect UV damage to cells

What are Langerhans cells?

Tissue-resident macrophages, contains organelles - Birbeck granules

What's the function of the Birbeck granule?

Uptake of foreign antigens for processing within the lysosomal system before releasing or presenting to T lymphocytes

Langerhans cells derived from?

Monocytes

Where are Langerhans cells found?

All layers of the epidermis of skin, more in stratum spinosum

What are Merkel cells?

Modified epidermal cells in stratum basale - touch receptor

What are the 2 layers of the dermis?

Papillary & Reticular

Where are Meissner's corpuscles found?

Papillary layer | Dermis of fingertips, soles, nipples, eyelids, lips & genitalia

Where are Pacinian corpuscles found?

Hypodermis layer | Skin of hands & feet

Which layer of dermis contains adipocytes?

Hypodermis/subcutaneous

What's the function of skin circulation?

Nutrition of skin & appendages | Regulate blood flow to increase or reduce heat loss

What are the 4 skin appendages?

Hair Sebaceous glands Sweat glands Nails

What's the type of secretory (sebum) mechanism of the sebaceous gland?

Holocrine

What are the 3 modes of secretion?

Merocrine - no part of cell is lost Apocrine - top of cell lost with secretion Holocrine - whole-cell detaches with secretion

What is the hardness of the nail dependent on?

Keratin & sulfur

What is skin repair dependent on?

Proliferation of keratinocytes in stratum basale

What are the 4 phases of wound healing?

1. Hemostasis 2. Inflammation 3. Proliferation of granulation 4. Remodeling or maturation