Ch.4: Skin and Body Membranes Flashcards
What are the functions of body membranes?
• Cover body surfaces
• Line body cavities
• Form protective sheets around organs
*Classified according to tissue types
Which types of membranes are classified as epithelial membranes?
- Cutaneous membranes
- Mucous membranes
- Serous membranes
Which types of membranes are classified as connective tissue membranes?
• Synovial membranes
What are epithelial membranes?
- Simple organs
* Also called covering and lining membranes
What are the two main layers of epithelial membranes?
- Epithelial tissue layer
* Connective tissue layer
What are the main properties of cutaneous membranes?
• Dry membrane
• Outermost protective boundary
• Construction:
*Epidermis is composed of keratinized stratified squamous epithelium
*Dermis is mostly dense (fibrous) connective tissue
• Cutaneous = skin
What are the main properties of mucous membranes (mucosae)?
• Moist membranes
• Line all body cavities that open to the exterior body surface
• Adapted for absorption or secretion
• Construction:
*Epithelium type depends on site
*Loose connective tissue (lamina propria)
What are the main properties of serous membranes (serosae)?
• Line open body cavities that are closed to the exterior of the body
• Occur in pairs, separated by serous fluid, with a visceral and parietal layer
• Construction:
*Simple squamous epithelium
*Areolar connective tissue
What are specific serous membranes and where are they located?
• Peritoneum *Abdominal cavity • Pleura *Around the lungs • Pericardium *Around the heart
What are the main properties of synovial membranes?
• Loose areolar connective tissue only (no epithelial tissue)
• Line fibrous capsules surrounding joints
*Line bursae
*Line tendon sheaths
• Secrete a lubricating fluid to cushion organs moving against each other during muscle activity
What does the integumentary system consist of?
• Skin (cutaneous membrane) • Skin appendages *Sweat glands *Oil glands *Hair *Nails
What are the functions of the integumentary system?
• Insulates and cushion deeper body organs
• Protects the entire body from:
*Mechanical damage (bumps and cuts)
*Chemical damage (acids and bases)
*Thermal damage (heat or cold)
*Ultraviolet (UV) radiation (sunlight)
*Microbes (bacteria)
*Desiccation (drying out)
• Aids in loss or retention of body heat as controlled by the nervous system
• Aids in excretion of urea and uric acid
• Synthesizes vitamin D
Which two kinds of tissue compose the skin?
- Epidermis
* Dermis
What are the main functions of the hypodermis (subcutaneous layer)?
- Anchors the skin to underlying organs
- Not technically part of the integumentary system
- Composed mostly of adipose tissue
- Serves as a shock absorber and insulates deeper tissues
What are the main properties of the epidermis, the outer layer of the skin?
- Capable of being hard and tough
- Stratified squamous epithelium
- Keratinocytes (the most common cell) produce a fibrous protein called keratin
- Avascular
- Composed of five layers (strata)
What are the layers of the epidermis from deepest to most superficial?
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum (thick, hairless skin only)
- Stratum corneum
What are the main properties of the stratum basale (stratum germinativum)?
- Deepest layer of epidermis
- Lies next to dermis
- Wavy borderline with the dermis anchors the two together
- Cells undergoing mitosis
- Daughter cells are pushed upward to become the more superficial layers
What is the main property of the stratum spinosum?
Cells become increasingly flatter and more keratinized
What are the main properties of the stratum lucidum?
- Formed from dead cells of the deeper strata
* Occurs only in thick, hairless skin of the palms of hands and soles of feet
What are the main properties of the stratum corneum?
- Outermost layer of epidermis
* Shingle-like dead cells are filled with keratin (protective protein prevents water loss from skin)
What is melanin?
- Melanin is a pigment produced by melanocytes
- Melanocytes are mostly in the stratum basale of the epidermis
- Color is yellow to brown to black
- Amount of melanin produced depends upon genetics and exposure to sunlight
Melanin accumulates in membrane-bound granules called:
Melanosomes
What is the main function of epidermal dendritic cells?
Alert and activate immune cells to a threat (bacterial or viral invasion)
What are the main functions of Merkel cells?
- Associated with sensory nerve endings
* Serve as touch receptors called Merkel discs
What are the main functions of the dermis?
- Connective tissue
* Underlies the epidermis
Which two layers compose the dermis?
• Papillary layer (upper dermal region)
•
What are the main properties of the papillary layer (upper dermal region)?
- Contains projections called dermal papillae
- Indent the epidermis above
- Many projections contain capillary loops, and others house pain and touch receptors
- On palm and sole surfaces, papillae increase friction and gripping ability
- Fingerprints are identifying films of sweat
What are the main properties of the reticular layer (deepest skin layer)?
- Blood vessels
- Sweat and oil glands
- Deep pressure receptors (lamellar corpuscles)
What are other dermal features?
- Cutaneous sensory receptors
- Phagocytes
- Collagen and elastic fibers
- Blood vessels
What are the three pigments which contribute to skin color?
- Melanin
• Yellow, reddish brown, or black pigments - Carotene
• Orange-yellow pigment from some vegetables - Hemoglobin
• Red coloring from blood cells in dermal capillaries
• Oxygen content determines the extent of red coloring
What causes skin redness (erythema)?
- Embarrassment
- Inflammation
- Hypertension
- Fever
- Allergy
What causes pallor (blanching)?
- Emotional stress (such as fear)
- Anemia
- Low blood pressure
- Impaired blood flow to an area
What does jaundice (yellow cast) indicate?
A liver disorder
What is another term for “bruises?”
Hematomas
What are the appendages of the skin?
• Cutaneous glands are all exocrine glands *Sebaceous glands *Sweat glands • Hair • Hair follicles • Nails
What are the main functions and properties of sebaceous (oil) glands?
• Located all over the skin except for palms and soles
• Produce sebum (oil)
*Makes skin soft and moist
*Prevents hair from becoming brittle
*Kills bacteria
• Most have ducts that empty into hair follicles; others open directly onto skin surface
• Glands are activated at puberty
What are the two types of sudoriferous (sweat) glands?
- Eccrine glands
* Apocrine glands
What are the main functions of eccrine glands?
• Open via duct to sweat pores on the skin’s surface
• Produce acidic sweat
*Water, salts, vitamin C, traces of metabolic waste
• Function in body temperature regulation
What are the main functions of apocrine glands?
- Ducts empty into hair follicles in the armpit and genitals
- Begin to function at puberty
- Release sweat that also contains fatty acids and proteins (milky or yellowish color)
- Play a minimal role in body temperature regulation
What are the main properties of hair?
- Produced by hair follicle
- Root is enclosed in the follicle
- Shaft projects from the surface of the scalp or skin
- Consists of hard keratinized epithelial cells
- Melanocytes provide pigment for hair color
- Hair grows in the matrix of the hair bulb in stratum basale
What is the anatomy of hair?
• Central medulla
• Cortex surrounds medulla
• Cuticle on outside of cortex
*Most heavily keratinized region of the hair
What are the main functions and properties of hair follicles?
- Composed of an epithelial root sheath and fibrous sheath
- Dermal region provides a blood supply to the hair bulb (deepest part of the follicle)
- Arrector pili muscle connects to the hair follicle to pull hairs upright when we are cold or frightened
What are the main properties of nails?
- Heavily keratinized, scale-like modifications of the epidermis
- Stratum basale extends beneath the nail bed, which is responsible for growth
- Lack of pigment makes nails colorless
What are the parts of the nail?
- Free edge
- Body is the visible attached portion
- Nail folds are skin folds that overlap the edges of the nail; the cuticle is the proximal edge
- Root of nail is embedded in skin
- Growth of the nail occurs from nail matrix
What is athlete’s foot and what is it caused by?
- Caused by fungal infection (Tinea pedis)
* Itchy, red peeling skin between the toes
What are boils (furuncles) and carbuncles and what are they caused by?
- Caused by inflammation of hair follicles
* Carbuncles are clusters of boils caused by bacteria
What are cold sores (fever blisters) and what are they caused by?
- Caused by human herpesvirus 1
* Blisters itch and sting
What is contact dermatitis and what is it caused by?
- Caused by exposure to chemicals that provoke allergic responses
- Itching, redness, and swelling of the skin
What is impetigo and what is it caused by?
- Caused by bacterial infection
* Pink, fluid-filled raised lesions around mouth/nose
What is psoriasis and what is it caused by?
- Triggered by trauma, infection, hormonal changes, or stress
- Red, epidermal lesions covered with dry, silvery scales that itch, burn, crack, or sometimes bleed
What are the properties of burns?
• Tissue damage and cell death caused by heat, electricity, U V radiation, or chemicals
• Associated dangers
*Protein denaturation and cell death
*Dehydration and electrolyte imbalance
*Circulatory shock
• Result in loss of body fluids and infection from the invasion of bacteria
How is the extent of a burn is estimated?
• Using the rule of nines
• Body is divided into 11 areas for quick estimation
• Each area represents about 9 percent of total body surface area
*The area surrounding the genitals (the perineum) represents 1 percent of body surface area
What classifies a first-degree burn (superficial burn)?
- Only epidermis is damaged
* Skin is red and swollen
What classifies a second-degree burn (partial-thickness burn)?
- Epidermis and superficial part of dermis are damaged
- Skin is red, painful, and blistered
- Regrowth of the epithelium can occur
What classifies a third-degree burn (full-thickness burn)?
- Destroys epidermis and dermis; burned area is painless
- Requires skin grafts, as regeneration is not possible
- Burned area is blanched (gray-white) or black
What classifies a fourth-degree burn (full-thickness burn)?
- Extends into deeper tissues (bone, muscle, tendons)
- Appears dry and leathery
- Requires surgery and grafting
- May require amputation
What are the criteria for deeming burns critical (if any one is met)?
- Over 30 percent of body has second-degree burns
- Over 10 percent of the body has third- or fourth-degree burns
- Third- or fourth-degree burns of the face, hands, feet, or genitals
- Burns affect the airways
- Circumferential (around the body or limb) burns have occurred
What are the two ways which cancer can be classified?
- Benign means the neoplasm (tumor) has not spread
* Malignant means the neoplasm has invaded other body areas
Concept link
Recall that mitosis gone wild is the basis for cancer (Chapter 3, pp. 104–105). In malignant cancers, the stages of mitosis occur so quickly that errors are made. As a result, these cells lack normal control of cell division. Cells experiencing rapid, uncontrolled growth become cancerous.
What are the most common types of skin cancer?
- Basal cell carcinoma
- Squamous cell carcinoma
- Malignant melanoma
What are the properties of basal cell carcinoma?
- Least malignant and most common type of skin cancer
- Arises from cells in stratum basale that are altered so that they can no longer make keratin
- Lesions appear as shiny, dome-shaped nodules that develop a central ulcer
What are the properties of squamous cell carcinoma?
- Believed to be induced by UV exposure
- Arises from cells of stratum spinosum
- Lesions appear as scaly, reddened papules that gradually form shallow ulcers
- Early removal allows a good chance of cure
- Metastasizes to lymph nodes if not removed
What are the properties of malignant melanoma?
- Most deadly of skin cancers, but accounts for only 5 percent of skin cancers
- Arises from melanocytes
- Metastasizes rapidly to lymph and blood vessels
- Detection uses ABCDE rule for recognizing melanoma
What is the ABCDE rule for recognizing melanoma?
A = Asymmetry
• Two sides of pigmented mole do not match
B = Border irregularity
• Borders of mole are not smooth
C = Color
• Different colors in pigmented area
D = Diameter
• Spot is larger than 6 millimeters in diameter
E = Evolution
• One or more of the A B C D characteristics is evolving
What are the developmental aspects of skin and body membranes?
- Lanugo, a downy hair, covers the body by the fifth or sixth month of fetal development but disappears by birth
- Vernix caseosa, an oily covering, is apparent at birth
- Milia, small white spots, are common at birth and disappear by the third week
- Acne may appear during adolescence
- In youth, skin is thick, resilient, and well hydrated
- With aging, skin loses elasticity and thins
- Skin cancer is a major threat to skin exposed to excessive sunlight
- Balding and/or graying occurs with aging; both are genetically determined; other factors that may contribute include drugs and emotional stress
