The skin consists of what two types of tissues?
Connective and Epithelial
The three layers of skin are...
Epidermis, Dermis, Hypodermis (Subcutaneous Layer)
Name some functions of the skin.
Protection, Sensation, Thermo-regulation and Homeostasis, Metabolism of Vitamin-D, Excretion of Salts and Wastes
Outer layer of skin consisting of stratified squamous epithelium
Epidermis consists of what four cell types?
Keratinocytes, Melanocytes, Langerhans Cells, Merkel Cells
Produce keratin, a protein that hardens and waterproofs the skin. Mature keratinocytes at the skin surface are dead and filled almost entirely with keratin
Produce Melanin, a pigment that protects cells from ultraviolet radiation. Melanin from the melanocytes is transferred to the keratinocytes.
Phagocytic microphages that interact with white blood cells during an immune response.
They occur at the epidermis-dermis boundary. They form merkel discs which, in conjunction with nerve endings, serve a sensory function.
The five layers of the epidermis:
Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale
Second Layer of skin consisting of various connective tissues.
Function of the Dermis:
Provides strength, extensibility (stretchability), elasticity (ability to return to original form).
Two Layers of the Dermis:
Papillary Layer, Reticular Layer
A thin, outer layer of the dermis with finger like projections called dermal papillae that protrude into the epidermis. The dermal papillae create epidermal ridges, which are responsible for finger prints.
Thick layer, below the papillary layer, that makes up most of the dermis
Hypodermis (Subcutaneous Layer):
Layer between the dermis and underlying tissues and organs. Storage site for most body fat.
Functions of the Hypodermis:
Thermal Insulation, Shock Absorption, fastens skin to underlying surface
Accessory organs of the skin:
Hairs, Nails, Sudoriferous (Sweat) Glands, Sebaceous (Oil) Glands
Elongated filaments of keratinized epithelial cells that arise and emerge from the skin of mammals.
Hair Shaft, Hair Root, Hair Follicle, Bulb, Matrix, Arrector Pili
Portion of hair visible on the surface of the skin.
Portion of the hair that penetrates the epidermis and dermis.
Sheath that surrounds the hair in the skin.
Bottom of the hair follicle located inside the bulb where cells actively divide, producing new cells and causing hair growth.
Smooth muscle that is attached to the hair follicle. Muscle contracts, hair becomes erect, goosebumps are produced.
Keratinized epithelial cells
Sudoriferous (Sweat) Glands
Secrete sweat. Sweat consists of water, various salts, and other substances
Four Types Of Sudoriforous Glands:
Eccrine Glands, Apocrine Glands, Ceruminous Glands, Mammary Glands
Glands under most skin surfaces that secrete a watery substance through the pores, which serves to cool the skin as it evaporates
Found under skin surfaces of the armpits and pubic region, these glands secrete a solution into the hair follicles in response to stress and sexual excitement.
Secretes cerumen (ear wax) into the external ear canal. wax helps impede entrance of foreign bodies.
Produce milk that is secreted through the nipples of the breast (females)
Sebaceous (Oil) Glands
Secrete sebum, an oily substance, into hair follicles and through the pores of the skin. Serves to inhibit bacterial growth and prevent drying of hair and skin.