Chapter 5 - The Integumentary System Flashcards
Epidermis
Superficial surface coat. Avascular. Made up of layers of epithelial cells and made to protect the body.
Dermis
Stong, flexible connective tissue. It has nerve fibers, macrophages, WBCs, and blood vessels. It has cutaneous receptors, glands, and hair follicles.
Hypodermis
Deepest region. It anchors the skin to organs. It has insulation, mostly adipose tissue. Acts as a shock absorber and contains nerves.
Keratinocytes
Produce keratin, a protein that waterproofs and hardens the skin. The most numerous cell type
Melanocytes
In the lower epidermis. Produce the pigment melanin
Merkel’s cells
Sensory cells, they have cell receptors. Are associated with nerve endings. Found deep in the epidermis.
Langerhan’s cells
Dendritic cell. Macrophage that helps activate the immune system
5 layers of the epidermis
Stratum Basale Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
Stratum Basale
Deepest layer. attached to the dermis, it rests on the basement membrane. Usually a single layer of stem cells. There is rapid division of cells there and melanocytes synthesize melanin there which protects the cells from UV radiation.
Stratum Spinosum
About 8- 10 rows of cells. Has prekeratin filaments, flat spine-like projections bound together by desmosomes. Contains melanin and Langerhan’s cells, that protect against bacteria and cancer cells.
Stratum Granulosum
Granular, thinner layer 3-5 rows. Where keratinization begins. Cells make keratin and keratohyalin.
Stratum Lucidum
Clear layer, very thin, only appears in thick epidermis (soles of feet, palms of hands). Made up of a few rows of flat, dead keratinocytes.
Stratum Corneum
Outermost layer of dead flat cells. Accounts for about 3/4 of the thickness of the epidermis. 20-30 rows of cells, constantly being shed. There to waterproof and act as a barrier against physical, chemical, and biological factors.
2 dermal layers
Papillary
Reticular
Papillary
Consists of areolar connective tissue with collagen and elastic fibers. It has blood vessels, and nerve endings and Meissner’s corpuscles. Dermal papillae are the superior surface protruding into the epidermis forming patterns called fingerprints.
Reticular
About 80% of the thickness of the dermis. Made of dense connective tissue. The less dense regions form lines, lines of cleavage, which surgeons try to follow.
Melanin
It runs yellow, to brown, to black. Produced by melanocytes, the more melanin, the darker the color. Tyrosine, an amino acid, is very prominent in melanin.
Carotene
Runs from yellow to orange. Found mainly in the stratum corneum, and the adipose tissue of the hypodermis. Most obvious in the palms of hands and soles of feet.
Hemoglobin
Pinkish hue, due to the oxygenation of the blood.
Hair Functions
Alerts body to the presence of insects. Guards scalp against physical trauma, heat loss, and sunlight.
Hair Shaft
Protrudes above the skin.
Hair Root
Has three layers:
1) The central core, the medulla
2) The cortex, outer layer made of hard keratin
3) Cuticle, has the most hard keratin.
Hair Color
Determined by the amount and kind of melanin.
Hair Folicle
Extends into the dermis, sometimes the hypodermis. The outer part is connective tissue, and the inner part is epithilial root sheath. Has nerve endings, sebaceous glands, and smooth muscle structures. Has matrix cells that form the hair.
Types of Hair
1) Vellus, which is very fine, very pale body hair.
2) Terminal, very coarse, scalp, eyebrows, etc.
Alopecia
Thinning and baldness. Terminal hair stops producing, vellus takes it’s place.
Nails
Scale-like modifications of the epidermis.
Types of Sweat Glands
1) Merocrine
2) Apocrine
Merocrine Glands
Numerous, coiled, tubular glands. They secrete sweat through pores. Their major function is thermal regulation. Excrete through exocytosis. Secretes a watery fluid that is 99% water, NaCl, Vitamin C, Igs, and waste material.
Apocrine
Mainly auxillary & anogenital areas. Same basic components of an eccrine gland, as well as fatty acids and proteins (cause of the small).
Ceruminous Glands
Modified apocrine glands, found in the lining of the external ear canal. Excretes earwax (cerumin).
Mammary Glands
Special type of apocrine gland. Secretes milk.
Sebaceous Glands
Simple alveolar glands that mostly develop from hair follicles. Secrete sebum which prevent bacteria and softens hair and skin.
Functions of Skin:
Excretion
Excretes nitrogen containing wastes and salts through sweat
Simple Alveolar Glands
Most develop from hair follicles
Functions of Skin:
Protection
.
Secretes Sebum
Prevents bacteria. Softens hair and skin.
Functions of Skin:
Body Temperature Regulation
Helps Maintain homeostatic body temperature through presperation
Extra
Extra
Functions of Skin:
Cutaneous sensation
Receptors that deal with temperature, touch, pressure and pain.
Functions of Skin:
Vitamin D Synthesis
a metabolic function used in calcium absorption
Functions of Skin:
Blood reservoir
Hold up to 5% of blood volume
Burns
Tissue damage, proteins are denature. Cells die due to intense hear, radiation, or chemical damage.
Immediate threat from burns
The loss of fluids causes dehydration and electrolyte imbalance. Can lead to renal shut down and circulatory shock. Metabolism is altered and can lead to infection.
1st degree burn
Only the Epidermis had been damaged. Redness, swelling and pain.
2nd degree burn
The epidermis and upper dermis are damaged. Blisters form
3rd degree burn
The entire thickness of the skin is damaged. Can be gray, white, red or black. Skin grafts are usually needed.
Burns are critical if
a) More than 25% of the body has 2nd degree burns
b) More than 10% of the body has 3rd degree burns
c) The face, hands, or feet bear 3rd degree burns.
Basal Cell Carcinoma
Least malignant and most common. Stratum basale cells are altered, they proliferate and slowly invade the dermis and hypodermis which become so thin they cant form keratin. an usually be surgically removed.
Squamous Cell Carcinoma
Second most common. Occurs in the keratinocytes of the stratus spinosum. Most common on scalp, ears, lower lip, and hands. Primarily sun induced. Treated by radiation or surgery.
Malignant Melanoma
The most dangerous, but very rare. Cancer of the melanocytes, and spreads quickly.
Aging Changes
a) Epidermis thins, gets dryer, repair takes longer
b) Langerhan’s cells and melanocytes decrease.
c) Subcutaneous fat and elasticity decrease.
d) Vitamin D production decreases
e) Glandular activity decreases
f) Hair follicles either stop growing or decrease
g) Secondary sex characteristics fade
