The four basic categories of molecules for building life are carbohydrates, lipids, proteins, and nucleic acids.
-Carbohydrates serve many purposes, from energy to structure to chemical communication, as monomers or polymers.
-Lipids, which are hydrophobic, also have different purposes, including energy storage, structure, and signaling.
-Proteins, made of amino acids in up to four structural levels, are involved in just about every process of life.
-The nucleic acids DNA and RNA consist of four nucleotide building blocks, and each has different purposes.
-papillary region makes up about one-fifth of the thickness of the total layer. contains thin collagen and fine elastic fibres. (Contains thin collagen and elastin fibres
Surface area increased by dermal papillae
small nipple shaped projections into the undersurface of the epidermis
Contain capillary loops - blood vessels
Some contain corpuscles of touch (Meissner Corpuscles) - nerve ending sensitive to touch
Some contain free nerve endings (give rise to warmth, coolness, pain, itch, tickle)
Fit together with epidermal ridge (finger prints)
-reticular region attaches to the subcutaneous layer, contains bundles of thick collagen fibres, scattered fibroblasts, and various wandering cells (Contains thick bundle of collagen fibres, scattered fibroblasts, and wandering cells (macrophages)
Some adipose cells in deepest part of layer.
Fibres arranged as nets, more regular that papillary region (resists stretching of skin)
Blood vessels, nerves, hair follicles, sebacceous (oil) glands, and sudorferous (Sweat) glands occupy spaces between fibres)
-The skin contains 4 types of glands.
Sebaceous (oil) glands are connected to hair follicles.Sebaceous (oil) glands
Simple, acinar (rounded) glands
Connected to hair follicles. Lies in the dermis opens into neck of hair follicle. Open direct to surface on lips, glans penis, labia minora, eyelids. Predominant on face, neck, superior chest, breasts. Secret sebum - coats hair, prevents excess water evaporation
Eccrine sweat glands are the most numerous.Simple, coiled tubular glands
More common than apocrine
Distributed throughout skin - espcially forehead, palms and soles
Not in lips, nail beds, glans penis/clitoris, labia minora or eardrum
Secretory portion in deep dermis.
Thermoregulators - sensible and insensible perspiration, emotional sweating
Apocrine sweat glands are located mainly in hairy skin.located mainly in hairy skin
Simple, coiled tubular glands
Larger ducts and lumens than eccrine glands
Located in lower dermis/upper subcutaneous layer
Excretory duct opens into hair follicle
Found in axilla, groin, areolae, bearded regions of face in males
Sweat interacts with bacteria on skin to - odour
Don't function until puberty, don't thermoregulate, emotional sweating
Ceruminous glands are modified sweat glands located in the ear canal. modified sweat glands located in the ear canal. Produce waxy lubricating secretion - cerumen
This waterproofs and protects the ear canal
Lie in the subcutaneous layer