Histology 1: Integument

Question 1

dermal ridges OR dermal papillae

Answer 1

projections coming up from the dermis which interlock with complimentary ridges in the epidermis.
Create fingerprints

Question 2

Keratinocytes

Answer 2

Principal cells of the epidermis

Produces keratin

Question 3

Stratum basale

Answer 3

Bottom most layer of the epidermis, single layer of cuboidal cells - only layer in which mitosis takes place. Adjacent cells of stratum basale are bound together by desmosomes, and cells are bound to the dermis by hemidesmosomes. Contains scattered course filaments: tonofilaments

Question 4

Stratum germinativum

Answer 4

Layer made up by the stratum basale and stratum spinosum.

Question 5

Stratum spinosum

Answer 5

Characterized by cells which have shrunken away from each other but are still connected by desmosomes and therefore look spikey– “prickle cells”. Also contains tonofilaments– increase in amount and combine to become tonofibrils. Stratum spinosum also contains membrane-coated granules (lamellar bodies) that contain glycolipids (maintains waterproof barrier function of the skin)

Question 6

Stratum granulosum

Answer 6

3-5 layers of cells. Cells in this layer have begun to flatten out. Contain densely packed granules of keratohyalin associated with tonofibrils. Produces keratin (with tonofibrils). Apoptosis of keratinocytes occurs in this layer as cells fill with keratin. lamellar bodies empty their glycolipid contents into intercellular space.

Question 7

Stratum lucidum

Answer 7

Only seen in thick skin. Characterized by the loss of nuclei, and tonofilaments are oriented parallel to the skin

Question 8

Stratum corneum

Answer 8

Surface layer of the epidermis, cells are now dead, flattened, and completely keratinized. Cells have no nuclei, organelles, or cell junctions.

Question 9

Melanocytes

Answer 9

Determines skin pigmentation. skin color = 2 pigments: carotene - yellowish pigment found in stratum corneum and fat. Melanin pigment - produced by melanocytes, is either brownish-black OR reddish-yellow in color. Fxn: to protect stratum basale from harmful ultraviolet radiation.
*Found in stratum basale and project into stratum spinosum. Functionally related to 4-10 keratinocytes = epidermal-melanin unit. Deposit granules into keratinocytes within their unit.

Question 10

Langerhans’ cells

Answer 10

*found in all layers of epidermis, but especially upper layer of stratum spinosum.
Fxn: trap antigens that penetrate the skin surface and transport them to regional lymph nodes.
*Involved in the occurrence of contact dermatitis

Question 11

Merkel’s cells

Answer 11

widespread, especially in stratum basale.
*Found close to intraepithelial free nerve endings
Fxn: mechanoreceptors involved with touch reception.

Question 12

Papillary layer of the dermis

Answer 12

forms dermal ridges (“dermal papillae”). Lies immediately deep to the epidermis. Less fibers, more cells.

Question 13

Reticular layer of the dermis

Answer 13

Lies below the papillary layer, blends in with the hypodermis. Contains abundant amounts of collagen fibers. In some areas contains Langer’s lines

Question 14

Langer’s lines

Answer 14

parallel lines of collagen fibers within the reticular layer of the dermis. Of surgical importance: incisions made along Langer’s lines gape less and heal with less scar tissue than incision made perpendicular to Langer’s lines.

Question 15

Encapsulated nerve endings found in the dermis

Answer 15

1) Meissner’s corpuscle
2) Pacinian corpuscle
3) Ruffini corpuscle
4) Krause end bulb

Question 16

Meissner’s corpuscle

Answer 16

Touch receptor found in the papillary layer of the dermis

Question 17

Pacinian corpuscle

Answer 17

Deep pressure receptor found in the deep dermis and hypodermis

Question 18

Ruffini corpuscle

Answer 18

mechanoreceptor

Question 19

Krause end bulb

Answer 19

mechanoreceptor found in the superficial dermis