Chapter 5 notes

Chap 5 Notes

Main idea of Chap: study of the integumentary system, which consists of skin and epidermal structures

Integument –A.K.A. skin- elaborate system of tissues, protects underlying structures

The skin protects underlying structures and provides sensory information (Temperature, pain, pressure.)  The skin also stores food and water and synthesizes Vitamin D.

Epidermis – outer layer of skin, very thin except on palms of hands and bottom of feet

*Strata are called sub layers.

Stratum corneu- The outer most layer of the epidermis that is composed of dead flat cells that lack blood supply and sensory receptors.  

Stratum germinativum – most important layers of epidermis which includes a basal that forms new cells.

                *After the cells are formed, they migrate to the surface and die. They fill with keratin (a hard protein).

Keratin- Helps prevent the body from losing moisture. (The process from Stratum germinativum to Stratum corneu takes about a month.)

Melanocytes- Specialized cells in the basal layer of the epidermis that has melanin.

Melanin – pigment in skin, filters UV light that is damaging from the sun. Local accumulation of Melanin cause freckles and moles.

Albinism – lack of melanin

Dermis – aka. Corium, directly beneath epidermis, contains nerves, capillaries, sweat glands, hair follicles

Hypodermis/subcutaneous tissue – loose connective tissue that binds dermis to underlying structures

Stores fats, insulates body, protects by cushioning

Accessory Organs of the Skin- These structures are formed from the epidermis.

A)     Exocrine glands – sudoriferous glands (sweat) and sebaceous glands (oils) secrete substances through skin rather than bloodstream

Extremely important in maintaining the body’s homeostasis. Sebaceous glands are most plentiful on the palms, soles, forehead, and armpit (axillae.)

Sebum – oily secretion from disintegration of sebaceous gland cells

                *The acidic nature helps destroy harmful organisms and helps prevent infections.

Sebum regulated by sex hormones called androgens

                *Acne results when sebaceous ductules become blocked.

B)      Hair

Shaft – visible part

Root – part embedded in dermis

Follicle – root with coverings called papilla form follicle

Papilla- The covering for the Loop of the capillaries at the bottom of the follicle.

Alopecia- Baldness- This occurs when hair of the scalp is NOT replaced because of death of the papilla.

Melanocytes- are found at the base of the hair follicle, combine various amounts of melanin compounds (yellow, brown, and black) to give hair its color.

C)      Nail

Nail root – composed of keratinized stratified squamous epithelial cells (makes nails hard)

Nail body sits on nail bed on finger

Nail bed- The area beneath the nail body.

Lunula – where nail growth occurs. This area is white because the vascular tissue does not show through.

Pathology- The general appearance and condition of the skin are clinically important because they may provide clues to body conditions or dysfunctions.

                *Pale skin may indicate shock.

*Red, flushed, and very warm skin may indicate fever and/or infection.

*Rash may indicate allergies or local infections.

*Chewed fingernails may indicate emotional problems. 

Primary skin lesion – initial reaction to pathologically altered tissue – flat or elevated

Secondary skin lesion – changes in the primary lesion due to infection, trauma, scratching, disease

Burns can be local or systemic, where they can be life threatening.

Figure 5-3 describes various lesions.

First degree – epidermis is damaged

Local Burns- Not serious and only effect small areas.

Second degree - epidermis and part of dermis are damaged

Third degree – epidermis, dermis destroyed, some of underlying connective tissue damaged

Systemic effect- A process when malignant cells break loose from the malignant tumor and travel to another region of the body and start a secondary tumor. See page 85, The Rule Of Nines

Neoplasms – abnormal growths of new tissue

Benign neoplasms – non-cancerous

Malignant neoplasms – cancerous growths

Metastasis- A process when malignant cells break lo from the malignant tumor and travel to another region of the body and start a secondary tumor.

Biotherapy (Immunotherapy)- Treatment in which the body’s own defense system is used to fight tumor cells.

Basal Carcinoma- Most common type of skin cancer and is a malignancy of the statum germinativum, basal layer of the epidermis of hair follicles.

Squamous cell carcinoma- Forms a epidermal cells keratinize.

                *In situ (confined to the original site)

                *Invasive (Moves to the other parts of the body)

Malignant Melanoma- Neoplasm composed of abnormal melanocytes that begin as darkly pigmented moles.

                *Relatively rare, but is increasing at alarming rates. This will commonly metastasize extensively to the liver, lungs, or brain.