Guided Notes for Understanding the Skin

Chapter 4

1. The two major groups of body membranes are the (1) epithelial membranes, which include the cutaneous, mucous, and serous membranes, and (2) connective tissue membranes, represented by synovial membranes.

2. Epithelial membranes are actually simple organs because their epithelial sheet is always combined with an underlying layer of connective tissue.

3. A mucous membrane is composed of epithelium resting on a loose connective tissue membrane. Mucous membranes line all body cavities that open to the exterior, such as those of the hollow organs of the respiratory, digestive, and urinary systems.

4. The epithelium of the mucosae is often adapted for absorption or secretion.

5. A serous membrane is composed of a layer of simple squamous epithelium resting on areolar connective tissue. Serous membranes line body cavities that are closed to the exterior. They occur in pairs.

5. Serous layers are separated by serous fluid. It allows the organs to slide easily across the cavity walls and one another without friction.

6. Synovial membranes are composed of soft areolar connective tissue and contain no epithelial cells at all. They surround joints, where they provide a smooth surface and secrete a lubricating fluid.

7. Your skin is also known as a cutaneous membrane. It is the major organ of the integumentary system.

Functions of the Skin

-Protection: cushions deeper organs and protects the body from damage from outside elements

-Temperature Regulation: capillary network and sweat glands disperse heat

-Vitamin D Synthesis: modified cholesterol molecules are converted to vitamin D by sunlight

-Information Gathering: cutaneous sensory receptors are a part of the nervous system.

9. The epidermis of the skin is made up of stratified squamous epithelium that is capable of keratinizing, which means becoming hard and tough.

10. The dermis underlies the epidermis and is made of dense connective tissue.

11. The hypodermis, which is essentially adipose tissue, anchors the skin to underlying organs. It serves as a shock absorber and insulates the deeper tissues from temperature changes.

12. The epidermis is avascular, that is, it has no blood supply of its own.

13. The deepest cell layer of the epidermis, the stratum basale, lies closest to the dermis and is the only layer that receives nourishment from the dermis.

14. The stratum lucidum is a flat, clear, dead layer of epithelial cells that occur only where the skin is hairless and extra-thick, such as the palms of the hands and soles of the feet.

15. The outer layer of the epidermis is the stratum corneum. It contains dead cell fragments, filled completely with keratin. These cells are often referred to as cornified or horny cells.

16. Melanocytes, which are found mainly in the stratum basale, produce a pigment called melanin. When skin is exposed to sunlight, which stimulates the melanocytes to produce more of the melanin, tanning occurs.

17. The papillary layer is the upper dermal region. It is uneven and has finger-like projections called dermal papillae, which indent the epidermis above. The papillae furnish nutrients to the epidermis. Papillary patterns are genetically determined.

18. The reticular layer is the deepest skin layer. It contains blood vessels, sweat glands, oil glands, and deep pressure receptors called Pacinian corpuscles.

3 pigments that contribute to skin tone

1. The amount and kind of melanin in the epidermis

2. The amount of carotene deposited in the stratum corneum

3. The amount of oxygen bound to hemoglobin in the dermal blood vessels

20. The sebaceous glands, or oil glands, are found all over the skin, except on the palms of hands and soles of feet. Sebaceous glands produce sebum, which is a mixture of oily substances and fragmented cells. It is a lubricant that keeps the skin soft and moist and prevents the hair from becoming brittle.

21. Sweat glands are also called sudoriferous glands. There are 2 types in the body.

22. Eccrine glands produce sweat, a clear solution that is mostly water, plus salt, vitamin C, wastes and lactic acid. Eccrine sweat glands are an important and highly efficient part of the body’s heat-regulating equipment. They secrete sweat when the external temperature or body temperature is high.

23. Apocrine glands are confined to the axillary regions and genital areas. Their secretions contain fatty acids and proteins, which can give them an unpleasant odor. Their precise function is unknown, but they are activated during stress.

24. A burn is tissue damage and cell death caused by intense heat, electricity, UV radiation, or chemicals. When the skin is burned, two life-threatening problems can result. First, the body loses its supply of fluids containing proteins and electrolytes.

Later, infection becomes the most important threat and is the leading cause of death in burn victims. After 24 hours, pathogens such as bacteria and fungi easily invade areas where the skin has been destroyed.

The 3 Types of Burns

1st: only the epidermis is damged redness/swelling usually heals in 2-3 days2nd: injury to the epidermis and upper region

of the dermis producing very painful blisters

3rd: destroys the entire skin, appearing white or blackened.

regeneration is not possible/skin must be grafted

26. A wart, a neoplasm caused by a virus, is one example of a benign skin tumor.

27. The most important risk factor for skin cancer is overexposure to UV radiation.

28. Basal cell carcinoma is the least malignant and most common skin cancer. The cancer lesions occur most often on sun-exposed areas of the face and appear as shiny, dome-shaped nodules. They are cured in 99% of the cases where surgery is involved.

29. Squamous cell carcinoma appears most often on the scalp, ears, and dorsal regions of the hands and neck. It grows rapidly and metastasizes to adjacent lymph nodes if not removed.

30. Malignant melanoma is a cancer of melanocytes. It usually appears as a spreading brown to black patch that metastasizes rapidly to surrounding lymph and blood.

ABCD Rule for recognizing melanoma

A: asymmetry—the 2 sides of the mole do not match

B: border irregularity—indentations in a smooth border

C:color—different colors presentD:diameter—larger than 6mm.