Chapter 5 - Integumentary System Flashcards
What are the 6 functions of the integumentary system?
- Regulates body temperatures
- Stores blood
- Protects body from external environment
- Detects cutaneous sensations
- Excretes and absorbs substances
- Synthesizes vitamin D
What is the integumentary system?
A group of organs working together - the skin, hair, oil and sweat glands, nails and sensory receptors
What does a bluish skin colour indicate?
Hypoxia - oxygen deficiency at the tissue level
A sign of heart failure
What is the dermatology?
The medical specialty that deals with the diagnosis and treatment of integumentary system disorders
What is the cutaneous membrane?
The skin
Covers the external surface of the body
What are the two main parts that make up the skin?
- Epidermis
2. Dermis
Describe the epidermis.
The superficial, thinner portion which is composed of EPITHELIAL TISSUE
Avascular
Describe the dermis.
The deeper, thicker, CONNECTIVE TISSUE portion
Vascular
What is the subcutaneous layer?
Also called the hypodermis
Consists of areolar and adipose tissues
Fibers that extend from the dermis anchor the skin to the subcutaneous layer
What does the subcutaneous layer serve as?
Storage deposit for fat and contain large blood vessels that supply the skin
What are pacinian (lamellated) corpuscles?
Nerve endings in the subcutaneous layer, and sometimes in the dermis that are sensitive to pressure
What is the epidermis composed of? What 4 kinds of cells?
Keratinized stratified squamous epithelium cells
- Keratinocytes
- Melanocytes
- Langehans cells
- Merkel cells
What do keratinocytes do?
Produce the protein keratin - a tough fibrous protein that helps protect the skin and underlying tissues from abrasions, heat, microbes, and chemicals
Arranged in 4 or 5 layers
What are lamellar granules?
Release a water-repellant sealant that decreases water entry and loss and inhibits the enters of foreign materials
What do melanocytes do?
Produce the pigment melanin
Their long slender projections extend between keratinocytes and transfer melanin granules to them
What is melanin?
A yellow-red or brown-black pigment that contributes to skin colour and absorbs damaging ultraviolet light
What do melanin granules do once they’re inside keratinocytes?
They cluster to form a protective veil over the nucleus, on the side towards the skin surface
They shield nuclear DNA from damage
What are langerhans cells?
Also called epidermal dendritic cells
Arise from red bone marrow and migrate to the epidermis
They participate in immune responses against microbes that invade the skin
What are merkel cells?
Located in the deepest layer of the epidermis, where they contact the flattened process of a sensory neuron called a merkel disc
Detect touch sensations
What are the layers of thin skin called?
- Stratum basale
- Stratum spinosum
- Granulosum
- Thin stratum corneum
What are the layers of thick skin called?
- Stratum basale
- Stratum spinosum
- Stratum Granulosum
- Stratum lucidum
- Thick stratum corneum
Describe the stratum basale.
Deepest layer
Composed of a single row of cuboidal or columnar keratinocytes
Some cells in this layer are stem cells that produce new keratinocytes
Describe stratum spinosum
Superficial to the stratum basale
Consists of keratinocytes arranged in 8-10 layers
Cells in more superficial layers become flattened
Some cells retain their ability to divide
Describe the stratum granulosum
Superficial to the stratum spinosum
Consists of 3-5 layers of flattened keratinocytes that are undergoing apoptosis - programmed cell death
Father away from their source of nutrition
What is the distinctive feature of the cells in the stratum granulosum layer?
The presence of darkly staining granules of protein called keratohyalin
What is keratohyalin?
It assembles keratin intermediate filaments into keratin
What marks the transition between the deeper, metabolically active strata and the dead cells of the superficial strata?
The stratum granulosum
What is stratum lucidum?
Present only in thick skin
Consists of 4-6 layers of flattened CLEAR, dead keratinocytes that contain large amounts of keratin and thickened plasma membranes
What is the stratum corneum?
Consists of 25-30 layers of flattened dead keratinocytes
Can range from a few cells to many
Cells no longer contain organelles
Cells are continuously shed
What is kertiniziation?
A process whereby cells accumulate more and more keratin as they are slowly pushed to the surface
How long does it take for cells on the stratum basale to rise to the surface?
4-6 weeks
What is the dermis composed of?
Dense, irregular connective tissue containing collagen and elastic fibers
Which is thicker, the dermis or the epidermis?
The dermis
What kinds of cells are present in the dermis?
Fibroblasts, macrophages, adipocytes
What are embedded in the dermis?
Blood vessels, nerves, glands and hair follicles
What are the two main regions of the dermis?
- Papillary region
2. Reticular region
Describe the papillary region of the dermis.
1/5th of the thickness of the total layer
Dense irregular connective tissue with thin collagen and fine elastic fibers
Contains dermal ridges, Meissner corpuscles, and free nerve endings
What greatly increases the surface area of the papillary region?
Dermal papillae - small, nipple shaped structures that project into the undersurface of the epidermis
Contain capillary loops
What are capillary loops? Where are the located?
In the dermal papillae
They are blood vessels
What are Meissner corpuscles? Where are they located?
Nerve endings that are sensitive to touch
In the dermal papillae
What free nerve endings? Where are they located?
In the dermal papillae
Dendrites that lack any apparent structural specialization
Give rise to sensations of warmth, coolness, pain, tickling, and itching
What is the reticular region?
Deeper portion of the dermis (about 4/5th)
Consists of dense irregular connective tissue with thick collagen and some coarse elastic fibers
Spaces between fibers contain some adipose cells, hair follicles, nerves, sebaceous glands, sudoriferous glands
What are epidermal ridges?
Downward projections of the epidermis into the dermis between the dermal papillae of the papillary region
Increases surface area of the epidermis, helps with grip by increasing friction
Where do sweat glands open onto?
On the tops of epidermal ridges, the sweat and ridges form fingerprints! Cool!
What are the three pigments that contribute to skin colour?
- Melanin
- Hemoglobin
- Carotene
What are the two different kinds of melanin? What colours do they produce?
Pheomelanin - yellow to red
Eumelanin - reddish-brown to black
What are freckles?
Melanin that has accumulated in patches
What is a mole?
A round, flat or raised area that represents a benign localized overgrowth of melanocytes
What is albinism?
The inherited inability of an individual to produce melanin
What is hemoglobin?
The oxygen carrying pigment in red blood cells
What colour does carotene give?
Yellow-orange pigment that gives egg yolks and carrots their colour
What is tattooing?
A permanent colouring of the skin with a foreign pigment into the dermis
What is body piercing?
The insertion of jewelry through an artificial opening
What are the accessory structures of the skin?
Hair, skin glands, and nails
Where is hair not found on the body?
Palms, palmar surfaces of the fingers, the soles and plantar surfaces of the feet
What are the functions of hair?
Hair on the head protects the scalp from injury and sun’s rays
Decreases heat loss
Functions in sensing light touch
What is each hair composed of?
Hair is composed of columns of dead, keratinized epidermal cells bonded together by extracellular proteins
What are the two main parts of the hair?
Shaft
Root
What is the shaft?
The superficial portion of the hair, projects above the surface of the skin
What is the root?
The portion of the hair deep to the shaft that penetrates into the dermis
What are the three concentric layers of cells in hairs called?
- Medulla
- Cortex
- Cuticle
What is the hair follicle?
Made up of the external root sheath and internal root sheath
Also called the epithelial root sheath
What is responsible for the growth of existing hairs?
Hair matrix cells
What produces new hairs?
Hair matrix cells, when old hairs are shed
What is the outermost layer of the hair?
The dermal root sheath
What is the bulb of a hair?
At the base of each hair follicle
Contains the papilla of the hair, contains areolar tissue and many blood vessels
What causes goose bumps?
The smooth muscle (arrector pili)
Under physiological or emotional stress, autonomic nerve endings stimulate the arrector pili muscles to contract and the hair stand upright
What generates nerve impulses if the hair shaft is moved?
The hair root plexus (dendrites of neurons that surround the hair follicle)
What are the three stages of hair growth cycle?
- Growth stage
- Regression stage
- Resting stage
What happens during the growth stage?
Cells of the hair matrix divide
Existing cells are pushed upwards are new cells are added
What happens during the regression stage?
The cells in the hair matrix stop dividing
The hair follicle atrophies (shrinks)
What happens during the resting stage?
Nothing, the hair follicle rests
Following a rest cycle, a new growth cycle begins
What are lanugo?
Very fine, non pigmented, downy hairs that cover the body of the fetus
What are terminal hairs?
Hairs that replace the lanugo of the eyebrows, eyelashes, and scalp with long, coarse, heavily pigmented hairs
What are vellus hairs?
Short, fine, pale hairs that are barely visible
Replace lanugo on the rest of the body
What causes hair colour?
The amount and type of melanin in its keratinized cells
What pigment does brown/black hair contain?
Eumelanin
What pigment does blond/red hair contain?
Variants of phenomelanin
What are the exocrine glands associated with the skin?
Sebaceous (oil) glands
Sudoriferous (sweat) glands
Ceruminous glands
Describe sebaceous glands.
Oil glands
Simple, branched acinar (rounded) glands
Connected to hair follicles
What do sebaceous glands secrete?
Sebum - a mixture of triglycerides, cholesterol, proteins, and inorganic salts
What is acne?
An inflammation of sebaceous glands
Describe sudoriferous glands.
Sweat glands
Release sweat into hair follicles or onto the surface of the skin
What are the two main types of sweat glands?
- Eccrine
2. Apocrine
Describe eccrine sweat glands.
Simple, coiled tubular glands that are much more common than apocrine sweat glands
Main function is to regulate body temperature
What are the two different kinds of perspiration?
- Insensible - sweat that evaporates from the skin before it is perceived as moisture
- Sensible - sweat that is excreted in large amounts and is seen as moisture
Describe apocrine sweat glands.
Simple, coiled tubular glands
Mainly found on the skin of the armpit, groin, nipples, beaded region on the face
How is apocrine sweat different from eccrine sweat?
Apocrine sweat appears milky or yellowish in color
Odourless
BUT when apocrine sweat mixes with bacteria on the skin, it causes body odor
Do not function until after puberty
Describe ceruminous glands
Modified sweat glands in the external ear
Produce a waxy lubricating secretion
What are nails?
Plates of tightly packed, hard, dead, keratinized epidermal cells that form a clear, solid covering over the dorsal surfaces of the distal portions of the digits
What are the three parts of a nail?
- Nail body
- Free edge
- Nail root
What is the nail body?
Visible portion of the nail
Appears pink because of blood flowing through the capillaries in the underlying dermis
What is the free edge?
Part of the nail body that may extend past the distal end of the digit
It is white b/c there are no underlying capillaries
What is the nail root?
Is the portion of the nail that is buried in a fold of skin
What is the lunula?
The whitish, crescent shaped area of the proximal end of the nail body
What is the nail bed?
Hyponychium
Secures the nail to the fingertip
What is the cuticle?
Eponychium
A narrow band of epidermis that extends from and adheres to the margin of the nail wall
What are the functions of nails?
- Protect the distal end of the digits
- Provide support and counter pressure to enhance touch perception and manipulation
- Allow us to grasp and manipulate small objects
What are the two different types of skin?
Thin (hairy) skin
Thick (hairless) skin
What are the functions of the integumentary system?
Thermoregulation Storage of blood Protection Cutaneous sensations Excretion and absorption Synthesis of vitamin D
Compare thick skin to thin skin.
Thick - hairless, no oil glands, more sweat glands, epidermal ridges, thicker strata spinosum and corneum, palms and soles
Thin - hairy, oil glands, fewer sweat glands, no epidermal ridges, thinner strata spinosum and corneum, all parts of the body expect palms and soles
What is thermoregulation?
Homeostatic regulation of body temperature
How does the skin contribute to thermoregulation?
By liberating sweat at its surface and by adjusting the flow of blood to the dermis
How much blood does the skin house?
8 - 10% of the total blood in an adult
How does the skin provide protection?
Keratin protects underlying tissues from microbes, abrasion, heat, and chemicals
Lipids inhibit the evaporation of water
Sebum stops hair and skin from drying out, and kills bacteria
What are cutaneous sensations?
Sensations that arise in the skin - touch, pressure, vibration, tickling, warmth, coolness, pain,
What substances can penetrate the skin?
Lipid soluble materials Vitamins A, D, E and K Certain drugs Oxygen and carbon dioxide Topical steroids
What are the two different kinds of wound healing?
- Epidermal wound healing
2. Deep wound healing
How does an epidermal wound heal?
Basal cells of the epidermis surrounding the wound break contact with the basement membrane
The cells then enlarge and migrate across the wound
Basal stem cells divide and replace the ones that have moved into the wound
Relocated basal epidermal cells divide to build new strata, thus thickening the new epidermis
What is contact inhibition?
When epidermal cells encounter one another and stop migrating
What is the hormone that causes basal stem cell to divide?
Epidermal growth factor
When does deep wound healing occur?
When an injury extends into the dermis and subcutaneous layer
What are the 4 phases of deep wound healing?
- Inflammatory phase
- Migratory phase
- Proliferation phase
- Maturation phase
What happens during the inflammatory phase?
A blood clot forms in the wound and loosely unites the wound edges
Involves inflammation - a vascular and cellular response that helps eliminate microbes
Enhance delivery of helpful cells - white blood cells (neutrophils), monocytes and mesenchymal cells
What happens during the migratory phase?
The clot becomes a scab
Epithelial cells migrate beneath the scab to bridge the wound
Fibroblasts begin synthesizing scar tissue and damaged blood vessels begin to regrow
During the migratory phase, what is the tissue filling the wound called?
Granulation tissue
What happens during the proliferative phase?
Extensive growth of epithelial cells beneath the scab
Deposition by fibroblasts of collagen fibers in random patterns
Continued growth of blood vessels
What happens during the maturation phase?
The scab sloughs off
Collagen fibers become more organized
Fibroblasts decrease in number
Blood vessels are returned to normal
What is fibrosis?
The process of scar tissue formation
What is a hypertrophic scar?
A scar that remains within the boundaries of the original wound
What is a keloid scar?
Also called a cheloid scar
A scar that extends beyond the boundaries into normal surrounding tissue
What are the characteristics of scar tissue?
Decreased elasticity
Fewer blood vessels
May or may not contain the same number of hair, skin glands or sensory structures
Usually lighter in colour
What is the epidermis derived from?
The ectoderm - which covers the surface of the embryo
When does the basal layer divide to form the periderm?
Beginning of the 7th week after fertilization
What is the vernix caseosa? When does it form?
Secretions from sebaceous glands mix with peridermal cells and hairs to form a fatty substance called the vernix caseosa
5th month of development
What does the vernix caseosa do?
Covers and protects the skin of the fetus from the constant exposure to amniotic fluid
Facilitates the birth b/c if it’s slippery nature
What develops in the 11th week after fertilization?
Basal layer forms an intermediate layer
Epidermal ridges start to form
What develops in the 12th week after fertilization?
Hair follicles develop as downgrowths of the basal layer into the deeper dermis
What develops in the 4th month after fertilization?
Sebaceous (oil) glands develop as outgrowths from the sides of hair follicles
Most sudoriferous glands are derived from downgrowths of the stratum basale
When do nails develop?
10 weeks
What treatments diminish the effects of aging skin?
- Topical products
- Microdermabrasion
- Chemical peel
- Laser resurfacing
- Dermal fillers
- Fat transplantation
- Botox
- Radio frequency non surgical facelift
- Facelift
What is the most common type of skin cancer?
Basal cell carcinomas (78%)
What are the risk factors for developing skin cancer?
- Skin type - light skin
- Sun exposure
- Family history
- Age
- Immunological status
What are the different classes of burns?
- First degree - involves only the epidermis (sun burn)
- Second degree - involves epidermis and part of the dermis, blister formation, scarring may result
- Third degree - destroys epidermis, dermis and subcutaneous layer. Burned region is numb
What are the systemic effects of a major burn that are life threatening?
- Large loss of water, plasma, and plasma proteins
- Bacterial infections
- Reduced circulation of blood
- Decreased production of urine
- Diminished immune response
How is the seriousness of a burn determined?
Depth and extent of the area involved, age, and general health
10% of body surface for 3rd degree burns
25% of body surface for 2nd degree burns
Any third degree burns on face, hands, feet or groin area
