Week 6 Notes
Week 6 Notes CBIO 2200
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This 5 page Class Notes was uploaded by Bailey Dickinson on Tuesday September 13, 2016. The Class Notes belongs to CBIO 2200 at 1 MDSS-SGSLM-Langley AFB Advanced Education in General Dentistry 12 Months taught by in Fall 2016. Since its upload, it has received 10 views. For similar materials see Anatomy and Physiology I in Cellular biology at 1 MDSS-SGSLM-Langley AFB Advanced Education in General Dentistry 12 Months.
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Date Created: 09/13/16
WEEK 6 NOTES (9/13-Exam 2) Another word for Langerhans’s cells (dendritic cells) Stratum lucidum means “the clear layer”: found only in thick skin Dermis • Connective tissue • Papillary region is areolar connective tissue • Reticular region is dense irregular connective tissue Cow-hide (dense irregular connective tissue) very strong and tough in multiple directions Tissue that surrounds the hair is an extension of the epidermis The arrangement of the nipple-like projections of the dermis increases the surface area, functionality, and strength of the skin Appendage Structures • Derivatives of the epidermis (but we find them in the dermis) • Can be sites of disease Shaft vs. hair root Root can actually extend down to the hypodermis Part of hair in the “hair-ball” is called the hair follicle Sebaceous glands are always associated with hair follicles (keeps it functional and keeps it from getting dried out) The arrector pili muscle is also associated with the hair follicle When cats or dogs feel threatened, their hair stands up (protective mechanism) When the hair stands up, it creates a blanket of warm air that’s close to the skin (thermoregulatory mechanism) (you see it when you have goose bumps too) Hair root plexus- nerve ending that curves around the bulb of the hair. Allows you to feel touch when you move the hairs without actually touching the skin. Allows the hairs to serve as a sensory organ. Some hairs grow more quickly than other hairs. Now, zoom in on the hair bulb- in the deepest part of the dermis Dermal papille (extension of the dermis into the hair follicle) is in the middle- where the blood supply is (provides nutrients to the hair cells) (melanin also is one of the pigments that gives hair its color) The cells that are mitotically active are at the hair matrix (the single layer) The growth pattern in hair is similar as it is in the epidermis The cells will eventually die as they get pushed away from the blood supply Protects against UV radiation Keeps things out Inappropriate hair growth: Hircutism A person gets a burn on the forearm that destroys the epidermis and extensive areas of the deep dermis. When the injury heals, will hair grow again in the affected area? No, if the dermis is destroyed, we destroy the follicles and the hair won’t grow back. If just the epidermis is destroyed, then the hair will still grow back because the hair follicle is in the dermis, even though it’s a derivative of the epidermis Nails are more useful for animals then humans Also derivatives of the epithelium (epidermis) Fingernails are similar to hairs because they have a lot of keratin Growth pattern is similar to growth pattern of epidermis and hairs Mitotically active cells are in nail matrix. And they’re pushed out. Glands in the skin (open to epidermis) Sebaceous- oil glands; exocrine; ducted onto hair follicles; mechanism of secretion is holocrine (acne) Sudoriferous- sweat glands -Eccrine -Apocrine Eccrine: Clump of a gland in the dermis, and then a single duct opens Produce normal sweat; releases onto surface of skin to cool; evaporative cooling; Merocrine (exocytosis) Apocrine: The duct of the apocrine sweat gland is associated with the hair follicle; armpit, groin, bearded areas of the face; become more active at puberty; apocrine sweat glands actually don’t secrete their products through apocrine mechanisms (contrary to what we thought long ago)- it’s actually just a merocrine mechanism; the sweat product is different- very attractive to certain kinds of bacteria; this is where body odor comes from Repair of the skin • Regeneration- replacement of damaged tissue with the same kind of tissue • Fibrosis- replacement of damaged tissue with scar tissue Neurons do not regenerate (Parkinson’s disease, Alzheimer’s disease) No blood vessels in the epidermis Superficial healing If cut, we’d see an increase in the rate of mitosis in stratum basale. Individual cells would migrate across the dermis until they bumped into each other. The epidermis is replaced, but there’s not an overgrowth of the epidermis Deep wound healing (where the dermis is involved as well) There is bleeding Repair of the skin • Inflammation • Organization/Proliferation • Regeneration/Fibrosis/Maturation We need to know an overview of what’s happening and compare is to superficial healing In inflammatory stage- vasodilation, cells get bigger and leakier (deliver regenerative factors and white blood cells to the area) The initial tissue- granulation tissue