Biology 322 Human Anatomy I Integument. Functions of Integumentary System (skin & its products)...
-
Upload
hilary-warner -
Category
Documents
-
view
214 -
download
1
Transcript of Biology 322 Human Anatomy I Integument. Functions of Integumentary System (skin & its products)...
Functions of Integumentary System (skin & its products)
Barrier to keep water and solutes in
Barrier to keep bacterial, dirt, etc. out
Protection against abrasion
Contains sensory receptors for touch, temperature, pressure, pain, etc.
Temperature regulation via hair, sweat, & amount of blood flow
Blood reservoir
Synthesis of vitamin D
Excretion
= Single row of dividing cells
(Epidermis)
= Three or four layers of cells; Some cell division
= Three or four layers of cells; Actively synthesizing protein keratin
= One or two layers of dying cells Not present in thin skin
= Many layers of flat, dead, scale-like cells full of keratin
(Connective tissue)
Two related forms of melanin:
Black or brown Responsible for dark skin or hair
Red or pink Responsible for pink skin (lips, nipples, glans of clitoris or penis, freckles) and red hair
Both synthesized
Keratinocytes move from stratum basale to stratum corneum, dying as they do so. Average = 5 - 6 wks
- Keratinocytes in stratum basale (& stratum spinosum) lie along basement membrane; divide by mitosis
- Older cells die but remain attached to each other
- Older ones pushed toward surface by newer cells
- Cells eventually shed from stratum corneum
- Keratinocytes synthesize large amounts of keratin and flatten out as they move toward surface
- Melanocytes transfer melanin to keratinocytes
(Epidermis)
Dermis:
Contains many types of sensory receptors for touch, pressure, vibration, pain, temperature, etc.
Some = simple nerve endings
Others = complex structures with multiple cell types
Hair
- Distribuled over all skin except: palms of hands soles of feet nipples glans of penis & clitoris minor labia
- Formed in follicles located deep in dermis
- Consists of layers of dead, highly keratinized keratinocytes
Sebaceous (oil) glands:
- Branched tubular glands
- Duct opens into opening of hair follicle
- Secretes sebum, consisting of lipids, proteins, ions, carbohydrates,
Nails:
- Tips of fingers and toes - Thick layer of densely packed keratinocytes - Produced by
Deeper layers of epidermis =
Average growth:0.5 mm per week
Carcinomas (cancers) of the skin:
Basal Cell Carcinoma: Keratinocytes of stratum basale proliferate, invade dermis Relatively low malignancy
Squamous Cell Carcinoma: Keratinocytes of epidermis proliferate. May invade dermis Moderate malignancy
Malignant Melanoma: Melanocytes of epidermis proliferate, invade dermis Highly malignant