Integumentary System Flashcards
Functions of the body membranes
▪ Cover body surfaces
▪ Line body cavities
▪ Form protective sheets around organs
What are the types of body membranes
Epithelial membranes
▪ Cutaneous membranes
▪ Mucous membranes
▪ Serous membranes
Connective tissue membranes
▪ Synovial membrane
What are epithelial membranes and what layers do they have
▪ Epithelial membranes are simple organs ▪ Also called covering and lining membranes ▪ These membranes contain: ▪ Epithelial tissue layer ▪ Connective tissue layer
What is the cutaneous membrane
Skin
Dry membrane
▪ Outermost protective boundary
Construction ▪ Epidermis is composed of keratinized stratified squamous epithelium ▪ Dermis is mostly dense (fibrous) connective tissue
Mucous membranes
▪ 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)
Serous membranes
▪ 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
Specific serous membranes and positions
▪ Peritoneum- Abdominal cavity
▪ Pleura- Around the lungs
▪ Pericardium- Around the hear
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
Integumentary system consists of
▪ Skin (cutaneous membrane) ▪ Skin appendages: Sweat glands Oil glands Hair Nails
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
2 kinds of skin tissue
▪ Epidermis
▪ Dermis
What is 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
Epidermis
outer layer ▪ 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)
Deepest epidermis to most superficial
▪ Stratum basale ▪ Stratum spinosum ▪ Stratum granulosum ▪ Stratum lucidum (thick, hairless skin only) ▪ Stratum corneum
Explain the stratus basale
▪ 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
Stratum spinosum
▪ Cells become increasingly flatter and more keratinized
Stratum lucidum
▪ Formed from dead cells of the deeper strata
▪ Occurs only in thick, hairless skin of the palms of
hands and soles of fee
Stratum corneum
▪ Outermost layer of epidermis
▪ Shingle-like dead cells are filled with keratin (protective
protein prevents water loss from skin)
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
▪ Melanin accumulates in membrane-bound granules
called melanosomes
▪ Amount of melanin produced depends upon genetics
and exposure to sunlight
Epidermal dendritic cells
Alert and activate immune cells to a threat (bacterial or
viral invasion)
Merkel Cells
▪ Associated with sensory nerve endings
▪ Serve as touch receptors called Merkel discs
Dermis
Connective tissue - composed of collagen and elastic fibres
Underlies the epidermis
Collagen - provides toughness and keeps inner skin moist
elastic fibres - keeps skin looking young without sagging
Two layers of the dermis
Papillary layer
Reticular layer
Papillary layer
(upper dermal region) contain
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
Reticular layer
deepest skin layer
▪ Blood vessels
▪ Sweat and oil glands
▪ Deep pressure receptors (lamellar corpuscles)
Dermal features
Cutaneous sensory receptors
▪ Phagocytes
▪ Collagen and elastic fibers
▪ Blood vessels
3 Pigments contributing to skin colour
- 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
Skin colour changes and causes
Redness (erythema)—due to embarrassment,
inflammation, hypertension, fever, or allergy
▪ Pallor (blanching)—due to emotional stress (such
as fear), anemia, low blood pressure, impaired
blood flow to an area
▪ Jaundice (yellow cast)—indicates a liver disorder
▪ Bruises (black and blue marks)—hematomas
Appendages of the skin
▪ Cutaneous glands are all exocrine glands Sebaceous glands Sweat glands ▪ Hair ▪ Hair follicles ▪ Nails
Sebaceous 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 is sudoriferous glands and two types
Sweat (sudoriferous) glands ▪ Produce sweat ▪ Widely distributed in skin ▪ Two types of sudoriferous glands 1. Eccrine glands 2. Apocrine glands
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
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
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
Hair anatomy
▪ Central medulla - air space, large cells
▪ Cortex surrounds medulla - formed by a single layer of cells
▪ Cuticle on outside of cortex
▪ Most heavily keratinized region of
the hair
Hair follicle
▪ 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
Nails features
▪ Heavily keratinized, scalelike modifications of the
epidermis
▪ Stratum basale extends beneath the nail bed, which is
responsible for growth
▪ Lack of pigment makes nails colorless
Parts of a 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
Disorders and injuries of the skin
▪ Burns
▪ Infections of the skin and membranes
▪ Viral infections
▪ Fungal infections (e.g., athlete’s foot, jock itch,
ringworm)
▪ Bacterial infections (e.g., impetigo, cellulitis)
▪ Inflammatory conditions of the skin and
membranes (e.g., pleurisy, peritonitis, psoriasis)
▪ Cancers of the skin
