Lecture 25: Integument 1 Flashcards

1
Q

List the epithelial layers of thick skin in the correct order:

A
Stratum basale (germinativum)-deepest
Stratum spinosum
Stratum granulosum
Stratum lucidum 
Stratum corneum -superficial
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2
Q

Discriminate btw the 2 layers of the dermis and list characteristics of each layer.

A

Papillary layer: loose CT, separated from epidermis by basal lamina. Network of fine elastic fibers and abundant capillaries.

Reticular layer: dense irregular CT. Includes fibrocytes, macrophages, and adipocytes.

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3
Q

List characteristics of the hypodermis

A

Loose CT underlying dermis.
Corresponds to superficial fascia of gross anatomy.
Technically not part of the skin.
May contain fat cells that can form a thick layer called panniculus adiposus.

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4
Q

Identify each layer of thick skin epidermis and dermis from photomicrographs.

A

Stratum lucidum is only in THICK skin

Dermis: papillary and reticular layer

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5
Q

Compare thick skin to thin skin.

A

Thick skin: occurs on palms. ALL 5 layers.

Thin: rest of body. Thinnest on eyelids. Thickest is on back. Thinner on flexor than extensors. LACKING STRATUM LUCIDUM

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6
Q

Explain how ridges are created in the skin to form the basis for fingerprinting.

A

Primary dermal ridge: r/t fingerprinting. Formed 3rd to 4th mon of life. Subdivided into 2 secondary dermal ridges by interpapillary peg (downward growth of epidermis along crest)

Secondary occurs in double rows and branched.

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7
Q

Describe the process of keratinization

A

Simple cuboidal nucleated cells that begin to divide and lose nuclei. Leaving only keratin in cell.

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8
Q

List the characteristics and functions of langerhans cells, merkel cells, and melanocytes.

A
Langerhans cells= dendritic cells 
From monocytes, 
Antigen-presenting cells,
Primarily in stratum spinosum, 
Migrate from epidermis to lymph nodes,
Birbeck granules 

Meckel’s cells= mechanoreceptors, may also act as diffuse neuroendocrine cells, usually in stratum germinativum, contain catecholamine-like granules

Melanocytes: from melanoblasts, dont form desmosome attachments in epidermis, inject melanin granules into keratinocytes.

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9
Q

list major characteristics of each layer of epidermis:

A

Stratum basale (germinativum): columnar high cuboidal keratinocytes. Keratin 5 and 14. Single layer of cells. High mitotic activty.

Stratum spinosum: polyhedral shaped cells (prickle). Keratins 1 and 10. Keratohyalin granules develop. Membrane-coating granules 1st appear. Tonofibrils.

Stratum granulosum: multilayered. Keratins 2e and 9. Flattened nucleated keratinocytes. Keratohyalin aggregates, lamellar bodies. Tonofilaments.

Stratum lucidum: flat keratinocytes w/o nuclei/organelles. Only in thick skin. Contains eleiden

Stratum corneum: multilayer, thicker in thick skin, enucleated, flattened, dead keratinocytes. Cytoplasm replaced w/ keratin.

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10
Q

Explain the embryonic origins of the epidermis and dermis.

A

Epidermis starts as a single layer of ectodermal.- divide during the 6th week to form.

Dermis is derived from mesoderm.

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