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Module 2c - A&P
Introduction to the Human Body
| Question | Answer |
|---|---|
| epidermis | thin outer layer of the skincomposed of stratified squamous epithelium |
| no blood supply of its own,oxygen and nutrients diffuse into lower epidermis from the rich supply of blood in the underlying dermis | |
| divied into five layers, two if them are stratum germinativum and stratum corneum | |
| stratum germinativum | is on top of the dermis and has access to a rich supply of blood |
| cells of this layer are continuously dividing, producing millions of cells per day, as the cells divide they push the older cells up toward the surface of the epidermis | |
| as the cells move away from the dermis two changes take place, fit rsthey move from their source of nourishment and begin to die | |
| second the cells undergo a process of keratinization | |
| keratin | tough protein is deposited in the cell, it hardens and flattens the cells as they move |
| toward the outer suface, it makes the skin water resistant | |
| stratum corneum | surface later of the skin, composed of 30 layers of dead, flattened keratinized cells |
| dead cells are continously sloughed off (exfoliated or desquamated) through wear and tear, called dander, every month new layer of epithelium | |
| dandruff | dander clumped together by the oil on the skull |
| insensible perspiration | 500ml/day of water is lost through the skin |
| sensible perspiration | due to activity of the glands |
| hypovolemic shock | shock due to low volume |
| dermis | located under the epidermiscomposed of dense fibrous connective tissue |
| contains numerous colagen and elastin fibers that are surrounded by gel-like substance | |
| striae | stretch marks |
| accessory structures | hair, nails and certain glands are embedded with dermis |
| dermis | has blood vessels, nervous tissue, and some muscle tissuemany of the of the nervous tissue has sensory receptors that detect pain, temperature, pressure and touch |
| herpes zoster (shingles) | imflammation of nerves caused by the chickenpox virus, develop painful skin lesions along the path of nerve |
| scalded skin syndrome | staphylococcal infection in which the skin appears scaled and peels off in layers |
| subcutaneous layer | dermis lies on the subcutaneous layernot considered a part of the skin |
| subcutaneous layer | or hypodermiscomposed primarily of loose connective and adipose tissue |
| performs two main roles: helps insulate the body from extreme temperature changesit anchors the skin to underlying structures | |
| subcutaneoulsy | SC - drugs can be injected because the hypodermis has a rich supply of blood vessels |
| transdermally | across the skin |
| systemic effect | within the body |