Basics Flashcards
Function of skin
- protection from environment
- containment for body’s structures and vital substances
- heat regulation by evaporation of sweat and constriction/dilation of superficial blood vessels
- sensation using superficial nerves
- synthesis of vitamin D
Epidermis
superficial layer that provides protection; has no blood vessels –> nourished by dermis which is vascularized
Dermis
made of deep connective tissue of interlacing collagen and elastic fibres; supplied by arteries and afferent nerve endings
Layer of skin responsible for sensation
dermis because it contains the afferent nerve endings
Hair follicles
found in deep layer of dermis
Arrector muscles of hairs
small muscles around hair follicles that contract to cause hair to stand up; contraction also allows for secretion of oil from sebaceous glands
Sebaceous glands
secrete oil, exocrine gland that lies on the side of hair follicle
Skin ligaments
small fibrous bands that connect deep surface of dermis to deep fascia underneath; longer ligaments mean more mobile skin
Subcutaneous tissue
superficial fascia lying superficial to deep fascia, composed mainly of connective tissue and stores fat; contains sweat glands, superficial blood vessels, lymphatic vessels, and nerves
Structures of skin involved in heat regulation
blood vessels constrict or dilate; sweat glands release water that evaporates to remove heat; arrector muscles contract to raise hair up which traps warm air close to body
Structures of skin involved in protection
epidermis; sebaceous glands secreting sebum
Structures of skin involved in sensing
superficial nerves in dermis
Langer’s lines
lines corresponding to the natural orientation of collagen fibres in the dermis
Epithelia
cells that cover or line all body surfaces, tubes and cavities
Function of epithelia
form interfaces between different fluid compartments
How epithelial cells are held together
tight junctions
Basement membrane
separates epithelial cells from underlying tissues; composed of two layers –> basal lamina and reticular connective tissue
Basal lamina
thin proteoglycan layer laid down by epithelial cells; part of basement membrane
Reticular connective tissue
bed for epithelial cells to anchor to; part of basement membrane
Carcinoma
cancer in the epithelial cells caused in part by rapid division of ep. cells to replace those that have desquamated
Characteristics of epithelia
cells packed together with high cell density, basement membrane underneath which orients cells
Simple epithelia
one layer of epithelial cells; all cells directly attached to BM
Where is simple epithelia found?
sites in body where quick diffusion or absorption is needed:
- lungs
- digestive system
Stratified epithelia
multiple layers of epithelial cells, creating basal and apical cells
Basal cells
cells in stratified epithelia that are in contact with BM
Apical cells
cells in stratified epithelia that are in contact with lumen
Where is stratified epithelia found?
sites in body where there is a need for protection from friction, trauma, or caustic content
- stomach
- bladder
Epithelial cell shapes
squamous, columnar, cuboidal
