CHAPTER 14 MUCOUS MEMBRANE (mucosae)

SKIN AND BODY MEMBRANE • Moist membrane

• Lines all body cavities that open to the exterior
BODY MEMBRANES body surface
-Functions of the body membranes • Adapted for absorption or secretion
• Construction / layer
• cover body surface • -Epithelium type depends on the site
• line body cavities • - Loose connective tissue (lamina propria)
• form protective sheets around organs (b.) Mucous membranes line body cavities open to
the exterior.
- Classified according to tissue types

• Cutaneous membranes
o Cutaneous membranes
o Mucous membranes
o Serous membranes
• Connective tissue membranes
o Synovial membranes

EPITHELIAL MEMBRANES

• Epithelial membranes are simple organs

• Also called COVERING and LINING MEMBRANES SEROUS MEMBRANES (serosae)
• These membranes contains:
o Epithelial tissue layer • Line open body cavities that are closed to the
o Connective tissue layer exterior of the body
• Occur in pairs, separated by serous fluid, with a
visceral and parietal layer
CUTANEOUS MEMBRANE = skin • Construction / layer
o Simple squamous epithelium
• Dry membrane o Areolar connective tissue
• Outermost protective boundary
• Construction / layer (c.) Serous membranes line body cavities closed to
o Epidermis is composed of keratinized exterior.
stratified squamous epithelium
o Dermis is mostly dense (fibrous)
connective tissue
(a.) Cutaneous membrane (the skin) covers the
body surface
EPITHELIAL MEMBRANES Function of Integumentary System

-Specific serous membranes • Insulates and cushion deeper body organs

• Protects the entire body from:
• Peritoneum
o Mechanical damage (bumps and cuts)
o Abdominal cavity
o Chemical change (acid and bases)
• Pleura
o Thermal damage (heat or cold)
o Around the lungs
o Ultraviolet (UV) radiation (sunlight)
• Pericardium
o Microbes (bacteria)
o Around the hear
o Desiccation (drying out)
CONNECTIVE TISSUE MEMBRANES
• Aids in loss or retention of body heat as
• Synovial membranes controlled by the nervous system
o Loose areolar connective tissue only (no • Aids in excretion of urea and uric acid
• Synthesizes vitamin D
epithelial tissue)
o Line fibrous capsules surrounding joints
STRUCTURE OF THE SKIN
-Line bursae
-Line tendon sheaths • Two kinds of tissue compose the skin
o Secrete a lubricating fluid to cushion o Epidermis
organs moving against each other o Dermis
during muscle activity • Hypodermis (subcutaneous layer)
o Anchors the skin to underlying organs
o Not technically part of the
integumentary system
o Composed mostly of adipose tissue
o Serves as a shock absorber and
insulates deeper tissues

INTEGUMENTARY SYSTEM ❖ Epidermis- outer layer

o Capable of being hard and tough
- Integumentary system consists of the: o Stratified squamous epithelium
o Keratinocytes (the most common cell)
• Skin (cutaneous membrane)
o Avascular
• Skin appendages o Composed of five layers (strata)
o Sweat glands
o Oil glands • Summary of layers of the epidermis from
o Hair deepest to most superficial
o Nails o Stratum Basale
o Stratum spinosum
 o Stratum granulosum Two layers of the dermis
o Stratum lucidum (thick, hairless skin • Papillary layer (upper dermal region) contains
only) projections called dermal papillae
o Stratum corneum o Indent the epidermis above
o Many projections contain capillary
• Stratum Basale (stratum germinativum) loops, and others house pain and touch
o Deepest layer of epidermis receptors
o Lies next to dermis o On palm and sole surfaces, papillae
o Wavy borderline with the dermis increase friction and gripping ability
anchors the two together o Fingerprints are identifying films of
o Cells undergoing mitosis sweat
o Daughter cells are pushed upward to • Reticular layer (deepest skin layer)
become the more superficial layers o Blood vessels
o Sweat and oil glands
• Stratum spinosum o Deep pressure receptors (lamellar
o Cells become increasingly flatter and corpuscles)
more keratinized

• Other dermal features

• Melanin o Cutaneous sensory receptors
o Melanin is a pigment produced by o Phagocytes
melanocytes o Collage and elastic fibers
o Melanocytes are mostly in the stratum o Blood vessels
basale of the epidermis
o Color is yellow to brown to black SKIN COLOR
o Melanin accumulates in membrane- • Redness (erythema) - due to embarrassment,
bound granules called melanosomes inflammation, hypertension, fever, or allergy
o Amount of melanin produced depends • Pallor (blanching) - due to emotional stress
upon genetics and exposure to sunlight (such as fear), anemia, low blood pressure,
• Epidermal dendric cells impaired blood flow to an area
o Alert and activate immune cells to a • Jaundice (yellow cast) - indicates a liver disorder
threat (bacteria or viral invasion) • Bruises (black and blue marks) – hematomas
• Merkel cells
o Associated with sensory nerve endings APPENDAGES OF THE SKIN
serve as touch called Merkel discs • Cutaneous glands are all exocrine glands
o Sebaceous glands
o Sweat glands
❖ Dermis • Hair
o Connective tissue • Hair follicles
o Underlies the epidermis • Nails
➢ Sebaceous (oil) gland
• Located all over the skin except for palms and
soles
• Produces sebum (oil) ➢ Apocrine glands
o Makes skin soft and moist o Ducts empty into hair follicles in the
o Prevents hair from becoming brittle armpit and genitals
o Kills bacteria o Begin to function at puberty
o Release sweat that also contains fatty
• Most have ducts that empty into hair follicles;
acids and proteins (milky or yellowish
other open directly onto skin surface
color)
• Glands are activated at puberty
o Play a minimal role in body
temperature regulation

• Hair
o Produced by the hair follicle
o Root in enclosed in the follicle
o Shaft projects from the surface of the
scalp or skin
o Consists of hard keratinized epithelial
cells
o Melanocytes provide pigment for hair
color
o Hair grows in the matrix of the hair bulb
in stratum basale

➢ Sweat (sudoriferous) glands

o Produce sweat
o Widely distributed in the skin
• Two types of sudoriferous glands
o Eccrine glands
o Apocrine glands

➢ Eccrine glands
• Open via duct to sweat pores on the skin’s
surface
• Produce acidic sweat
o Water, salts, vitamin C, traces of
metabolic waste
o Function in body temperature
regulation
• Hair anatomy • Nails
o Central medulla o Heavily keratinized, scalelike
o Cortex surrounds the medulla modifications of the epidermis
o Cuticle on the outside of the cortex o Stratum basale extends beneath the
- Most heavily keratinized region of the nail bed, which is responsible for the
hair growth
o Lack of pigment makes nails colorless
➢ Parts of a nail
o Free edge
o Body is the visible attached portion
o Nail folds are skin folds that overlap the
edges of the nail; the cuticle is the
proximal edge
o Root of the nail is embedded in the skin
o Growth of the nail occurs from the nail
matrix

• Associated hair structures HOMEOSTATIC IMBALANCES OF SKIN

o Hair follicle
- Composed of a epithelial root sheath • Athlete’s foot
and fibrous sheath o Caused by fungal infection (Tinea pedis)
- Dermal region provides a blood supply o Itchy, red peeling skin between the toes
to the hair bulb (deepest part of the • Boils (furuncles) and carbuncle
follicle) o Caused by inflammation of hair follicles
- Arrector pili hairs upright when we are o Carbuncles are clusters of boils caused
cold or frightened by bacteria
• Cold sores (fever blisters)
o Caused by human herpesvirus 1
o Blisters itch and sting
• Infections and allergies
o Contact dermatitis
- Caused by exposure to chemicals that
provoke allergic responses
- Itching, redness, and swelling of the
skin
o Impetigo
- Caused by bacterial infection
- Pink, fluid-filled raised lesions around
mouth/nose
 o Psoriasis • Second-degree burn (partial-thickness burn)
- Triggered by trauma, infection, o Epidermis and superficial part of the
hormonal changes, or stress dermis are damaged
- Red, epidermal lesions covered with o Skin is red, painful, and blistered
dry, silvery scales that itch, burn, crack, o Regrowth of the epithelium can occur
or sometimes bleed • Third-degree burn (full-thickness burn)
o Destroys epidermis and dermis; burned
area is painless
o Requires skin grafts, as regeneration is
not possible
o Burned area is blanched (gray-white) or
black
• Fourth-degree burn (full thickness burn)
o Extends into deeper tissues (bones,
• Burns muscle, tendons)
o Tissue damage and cell death caused by o Appears dry and leathery
heat, electricity, UV radiation, or o Requires surgery and grafting
chemicals o May require amputation
o Associated dangers • Criteria for deeming burns critical (if anyone is
- Protein denaturation and cell death met):
- Dehydration and electrolyte imbalance o Over 30 percent of the body has
- Circulatory shock second-degree burn
o Result in loss body fluids and infection o Over 10 percent of the body has third-
from the invasion of bacteria degree burns
• Extent of a burn is estimated using the rule of o Third or fourth-degree burns of the
nines face, hands, feet, or genitals
o Body is divided into 11 areas for quick o Burns affect the airways
estimation o Circumferential (around the body or
o Each area represents about 9% of the limbs) burn has occurred
total body surface area
- The area surrounding the genitals (the • Skin cancer
perineum) represents 1% of body area o Most common form of cancer in
humans
o Most important risk factor is
overexposure to ultraviolet (UV)
radiation in sunlight and tanning beds
• Cancer can be classified in two ways
o Benign means the neoplasm (tumor)
has not spread
o Malignant means the neoplasm has
invaded other body areas
• Most common types of skin cancer
o Basal cell carcinoma
o Squamous cell carcinoma
o Malignant melanoma

➢ Basal cell carcinoma

o Least malignant and most common type
• First-degree burn (superficial burn) of skin cancer
o Only the epidermis is damaged o Arises from cells in stratum basale that
o Skin is red and swollen are altered so that they can no longer
make keratin
 o Lesions appear as shiny, dome-shaped -Borders of mole are not smooth
nodules that develop a central ulcer C = Color
- Different colors in pigmented area
D = Diameter
- Spot is larger than 6 mm in diameter
E = Evolution
- One or more of the ABCD
characteristics is evolving

➢ Squamous cell carcinoma

o Believed to be induced by UV exposure
o Arises from cells of stratum spinosum
o Lesions appear as scaly, reddened DEVELOPMENTAL ASPECTS OF SKIN AND BODY
papules that gradually form shallow MEMBRANES
ulcers
o Early removal allows a good chance of • Lanugo, a downy hair, covers the body by the
cure fifth or sixth month of fetal development but
o Metastasize to lymph nodes if not disappears by birth
removed
• 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

➢ Malignant melanoma
o Most deadly of skin cancers, but
accounts for only 5 % of skin cancers
o Arises from melanocytes
o Metastasizes rapidly to lymph and
blood vessels
o Detection uses the ABCDE rule for
recognizing melanoma
A = Asymmetry
- Two sides of pigmented mole do not
match
B = Border irregularity