Integument Flashcards
Integument Accessory structures
Hair Nails Various glands Muscles Nerves
Two principal parts
Epidermis (superficial)
Dermis (deeper, thicker)
What is NOT part of the skin?
hypodermis (aka subcutaneous)
consisting of areolar and adipose tissue
Composed of epithelial tissue
epidermis
Composed of dense irregular tissue?
Dermis
Specific functions of the skin
Thermoregulation
Protection from the internal environment
Cutaneous sensation
Excretion
Synthesis of Vit. D
Reservoir for blood
Absorbs substances
____ traps heat?
Hair
Epidermis is composed of _________.
Keratinized stratified squamous epithelium
4 major cells of epidermis
Keratinocytes
Melanocytes
Langerhans cells
merkel cells
Most of the epidermal cells in the skin are _____
keratinocytes
Formed when new cells produced by mitosis become filled with keratin, a tough, fibrous protein
keratinocytes
waterproofs the skin and Helps protect the skin and underlying tissues from heat, microbes, and chemicals
keratinocytes
Organelle called a _____ produces the pigment melanin, a brown-black pigment that contributes to skin color and absorbs damaging ultraviolet light
melanosome
Projections from _____ extend between keratinocytes, and transfer melanin granules to them.
melanocytes
The melanin granules then cluster over the ____ on the side toward the skin surface, shielding nuclear DNA from UV light
nucleus
The melanosomes of melanocytes synthesize melanin from the amino acid ____ in the presence of the enzyme _____
tyrosine
tyrosinase
Participate in immune responses to microbes that invade the skin (they are therefore “immune” cells)
Langerhans Cells
Type of dendritic cell, that present antigens
Langerhans
Reside in the deepest layer of the epidermis where they contact the flattened processes of tactile discs (AKA ___ discs), which are a type of sensory neuron (nerve cell)
merkel cells
merkel discs
Together the ___ cells and tactile discs function in the sensation of touch
Merkel
Layers of skin from top to bottom
Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
Mnemonic—Come, let’s get some beer
Corneum Lucidum Granulosum Spinosum Basale
The ____ is present only where exposure to friction is greatest, such as the fingertips, palms, and soles.
stratum lucidum
Deepest layer of the epidermis and mostly keratinocytes, a few melanocytes and Merkel cells
Stratum Basale
Keratinocytes have intermediate filaments called _____ composed of a protein that will later form keratin
Stratum Basale
tonofilaments
Keratinocytes continuously undergo ____, thereby forming new skin cells
mitosis
Just superficial to the stratum basale
Stratum Spinosum
8-10 layers of keratinocytes; few Langerhans cells
Spinosum (cells are still alive, some divide)
Here the older cells start to flatten
Spinosum
3-5 layers of flattened keratinocytes
Granulosum
Transition between the deeper living cells and the more superficial dead cells
Granulosum
Lamellar granules release a waterproofing lipid solution in?
Granulosum
3-layers of flattened, dead keratinocytes filled with keratin
Lucidum
fingertips, palms, soles
25-30 layers of flattened, dead cells
Corneum
Between cells, lipids from lamellar granules provide water proofing
Corneum
Cells are continuously sloughed off and replaced by cells from deeper strata
Corneum
Dense irregular connective tissue; collagen and elastic connective tissue
dermis
Dermis’ contents
bood vessels
nerves
glands (sebaceous and sudoriferous)
hair follicles
Arrectores pilorum
Dermis divided into two componentss
papillary region (superficial)
reticular region (deeper)
____ greatly increase papillary region surface area
Dermal papillae
Receptors present in papillary region
Touch corpuscles (Meissner corpuscles) for touch/light touch
Free nerve endings with no apparent structural specialization that give rise to sensations of warmth, coolness, pain, tickle, itch
More elastic and collagen
Reticular regions
Reticular regions has these features
adipose cells, hair follicles, nerves, sebaceous glands, and sudoriferous glands
Hypodermis contains:
Fat
Fibers that attach the dermis to deeper tissues
Larger blood vessels
Sensory receptors: Pacinian corpuscles (lamellated corpuscles) sense pressure
corpuscles that sense pressure
Pacinian
Commonly called fingerprints
epidermal ridges
Epidermal ridges develop during the ___ fetal months
3rd and 4th
Skin color due to combination of:
Melanin
Carotene
Hemoglobin
The amount and expression of _____ are genetically determined, and are associated with the classic races of humans
melanin and carotene
Differences in skin color among different races are mainly due to the amount of pigment the melanocytes produce and distribute, since the ____ of melanocytes is about the same in all races
number
Exposure to UV light increases the enzymatic activity of ____, leading to increased melanin production, which gives the skin a tanned appearance and further protects the body against UV radiation
melanosomes
__ is a yellow-orange pigment that is a precursor to vitamin A, which is used to synthesize pigments needed for vision
Carotene
Sebaceous glands: in the dermis; secrete sebum (oil) into a ___
hair follicle
___ is the superficial portion of the hair
Shaft
Shaft and root have three layers:
medulla, cortex, cuticle
Surrounding the root of the hair is a hair follicle that has an external root sheath which is a downward continuation of the ___
epidermis
Hair is composed of dead, keratinized cells bonded by ___
proteins
Root of the hair is in the ___
dermis
Growth is by division of cells at the base of the hair follicle whereby new cells produced by mitosis in the hair matrix push the growing hair through the ____
pilary canal
The ___ is an enlargement at the base of the hair follicle
bulb
Within the bulb (hair) is a germinal layer of cells called the ____ which arises from the stratum basale, and is the site of cell division that produces the hair
matrix,
A bundle of smooth muscle called the ____, along the sebaceous glands which are associated with hair follicles
arrector pili
Under physiologic or emotional stress (cold, fright) autonomic nerve endings stimulate _____ muscles to contract, causing “goose bumps
arrectores pilorum
Groups of dendrites and nerve fiber endings that form a network around a hair follicle
Hair root plexus
Act as receptors to generate nerve impulses when hair shafts are moved. Shaft of hair acts like a fulcrum.
Hair root plexus (snesitive to touch and movt of hair)
Each nail consists of a nail body, a free edge, and a ____
nail root
Nail body is the portion of the nail that is ____
visible
The ___ is the whitish, crescent-shaped area of the proximal end of the nail.
lunula
The epithelium deep to the nail root is the
nail matrix
Cells of the ____divide mitotically to produce growth
nail matrix
Superficial cells of the matrix are transformed into nail cells, and the older, harder cells are pushed along the ____ toward the fingertip
stratum basale
From sebaceous glands, sebum is an oily substance that:
Keeps hair from drying
Prevents excessive evaporation of water from the skin
Inhibits growth of some bacteria
Two main types of sweat (sudoriferous) gland
Eccrine and apocrine glands
The more common, found most places on skin, function in thermoregulation (aka merocrine sweat glands)
Eccrine
Found in association with hair that develops at puberty (axilla, groin, beard)
Apocrine sweat glands
In ___, keratinocytes divide and move more quickly than normal from the stratum basale to the stratum corneum, and are shed prematurely
psoriasis
Most common skin cancers
Basal cell carcinomas (the most common)
Squamous cell carcinomas
Malignant melanomas (the least common overall, and most life-threatening)
In most cases, the melanocytes are unable to synthesize ___
tyrosinase
___ is the partial or complete loss of melanocytes from patches of skin
Vitiligo
May be an autoimmune disorder in which the melanocytes are attacked and killed. There is also an apparent genetic link
___ is due to the fact that hemoglobin that is depleted of oxygen looks deep, purplish blue
Cyanosis
Caused by a buildup in the blood of the yellow pigment bilirubin
jaundice
Erythema caused by ___ of capillaries in the dermis with blood due to
engorgement
A form of scarring of the skin caused by tearing of the dermis
Striae (streaks)
Partial or complete lack of hair
Alopecia
____is an inflammation of the skin characterized by redness, itching, and swelling, and caused by exposure of the skin to chemicals that bring about an allergic reaction
Contact dermatitis
___ occurs following superficial wounds that affect only the epidermis.
Epidermal wound healing
___ occurs when an injury extends to the dermis and subcutaneous layer
Deep wound healing
loss of some function and scar tissue is the rule
____ cells at the margins of the wound break contact with the basement membrane and migrate
(epidermal wound healing)
Basal
When basal cells contact each other, they stop migrating, called ___ and Mitosis of basal cells is stimulated
(epidermal wound healing)
contact inhibition
A blood clot forms and binds wound edges
Blood flow is increased, blood vessels become more permeable
WBCs and mesenchymal cells migrate to the area
(deep wound healing)
Inflammatory phase
Epithelial cells migrate beneath the scab and bridge the wound
Fibroblasts migrate into the wound and begin to produce collagen fibers
(deep wound healing)
Migratory phase
Growth of epidermal cells beneath the scab
Increase in the amount of collagen
Regeneration of blood vessels
(deep wound healing)
Proliferative phase
Scab is lost
Collagen fibers become more organized, fibroblast numbers decrease, blood vessels are restored to normal
(deep wound healing)
Maturation phase
A ___ is tissue damage caused by excessive heat, electricity, radioactivity, or corrosive chemicals that destroy (denature) the proteins in the skin cells
burn
First degree
Second degree
Third degree
Involves only the epidermis
Characterized by mild pain and erythema, but no blisters
Skin functions remain intact
First degree burn
Accompanying pain and damage may be lessened by immediately flushing with cold water
Will heal in a few (3 – 6) days, and may be accompanied by flaking or peeling
Example is a mild sunburn
First degree burn
Destroys a portion of the epidermis and possibly parts of the dermis
Characterized by pain, redness, blister formation, and edema
Some skin functions are lost
Second degree burns
Associated structures (hair follicles, sebaceous glands, sweat glands) are not usually injured
Generally heals in a few (3 – 4) weeks, if there is no infection
Scarring may result
Second degree burns
Destroys a portion of the epidermis as well as the underlying dermis and associated structures
Skin functions are lost
Vary in appearance from marble-white to mahogany to charred, dry wounds
Third degree burns
Is marked edema, and the burned region is numb due to destruction of sensory nerve endings
Regeneration is slow; grafting may be required
Also termed full-thickness burn
Third degree burns
One 9 = total head and neck
One 9 = total each upper limb {18% for both}
Two nines for each front and back of torso (including buttocks)
One 9 each anterior and posterior lower limb {18 entire left lower limb, 18 entire right lower limb}
Remaining 1% is perineum
Rule of nines
