Chapter 5 Review - Integumentary System Flashcards
Integument consists of:
Cutaneous Membrane (skin) serving as a barrier along with Accessory structures (hair, nails & glands).
Integument functions
Along w/subcutaneous fascia, the integument functions include:
- Protection
- Excretion
- Maintenance of body temperature
- Synthesis of Vit. D3
- Storage of lipids
- Detection of environmental changes
Protection
prevents water & heat loss and protects mechanical & chemical damage
Excretion
water, salts and organic wastes by integumentary glands.
Maintenance of body temperature
cooling by evaporation of sweat along w/heat loss
Synthesis of Vit. D3
UV radiation stimulation increasing - - Vit D synthesis which is later converted to the hormone Calcitriol (stimulates calcium absorption in gut).
Storage of Lipids
in dermal and subcutaneous (hypodermal) layers
Detection of environmental changes
receptors monitoring changes in touch, pressure, pain and temperature.
Cutaneous membrane
skin consists of outer epidermis (epithelium) and inner dermis (CT)
Epidermis
water-resistant stratified squamous epithelium with 4 stratum (layers) in thin skin which covers most of the body, and 5 layers in thick skin as present on the sole of feet and palm of hands.
Stratum (deep to superficial)
- Stratum Germinativum (Basale)
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum*
- Stratum Corneum
Epidermis
Stratum Germinativum (Basale)
mitotically active keratinocytes attached to basement membrane by hemidesmosomes. Underlying dermis projects dermal papillae to interlock with epidermal ridges which reflects outward as fingerprints.
Epidermis
Keratinocytes
Young keratinocytes have many tonofilaments necessary for desmosomes and hemidesmosomes.
Epidermal Growth Factor (EGF)
ocal hormones which promote mitosis for growth & repair.
Melanocytes
cells which release melanosomes (vesicles w/melanin) which are release to higher layers to protect nuclei from DNA damage from UV radiation during mitosis.
Merkel Cells
specialized epithelium that respond to light touch stimulating neurons.
Stratum Spinosum
8-10 layers of keratinocytes which appear spiny owing to tonofilaments and shrinkage of cells during staining process.
- Langerhan Cells
Epidermis
Stratum Granulosum
3-5 layers of thin keratinocytes packed w/lipogranules & keratohyalin (which serve to convert tonofilaments to keratin). Cells undergo apoptosis at this level.
Epidermis
Stratum Lucidum
3-5 layers of flat dead keratinocytes found only on thick skin (palms of hand & soles of feet).
why thick skin has another layer
Epidermis
Stratum Corneum
15-30 layers of dead keratinocytes on the outermost, exposed surface.
a. Cornification
b. Insensible perspiration
c. sensible perspiration
Epidermis
tonofilaments
intermediate filaments
Langerhan Cells
Stratum Spinosum.
-stimulate body defenses activating lymphocytes.
Cornification
process of keratinization which occurs during a 15 to 30 day journey from the germinativum to the corneum. Mitosis increases w/Psorasis (typically 10 day journey and cells not fully keratinized in the corneum).
Insensible Perspiration
1 pt./day evaporates through skin goes unnoticed
Sensible Perspiration
active sweat glands utilized to cool down the body.
Dermis
contains all the cells of CT Proper w/blood & nerve supply. There are two distinct layers of dermis that blend together seamlessly. Sits on top of hypoderims (subcutaneous).
- Papillary
- Reticular
Hypodermis
subcutaneous
Papillary Layer
superficial layer of areolar CT which secretes lamina densa of basement membrane. Areas subject to abrasion have more dermal papillae (finger tips).
a. Decubitus ulcers (bed sores)
b. Transdermal patches
c. Tactile discs
d. Free-nerve endings
Decubitus ulcers (bed sores)
Dermis - Papillary Layer
- from compression of papillary capillary against boney surface (like ilium) causing necrosis of epithelium.
Transdermal patches
Dermis- Papillary Layer
- deliver pharmaceuticals into dermal layer & blood vessels.
Free-nerve endings
Dermis - Papillary Layer
-detect pain & temperature.
Tactile Discs
Dermis - Papillary Layer
- sensory terminal for Merkel receptors.
Reticular Layer
Dermis.
- deeper dermis is mainly dense irregular CT w/ collagen & elastin.
a. Striae
b. Lines of cleavage
c. Blood & lymph supply
d. Pacinian corpuscles
e. Accessory organs
Striae
Dermis - Reticular Layer
- stretch marks from overcoming elastic barrier of reticular layer.
Lines of Cleavage
Dermis - Reticular Layer
- direction of collagen & elastic fibers arranged in pattern.
Blood and Lymph supply
Dermis - Reticular Layer
- receives blood & lymph from deeper layers traveling up to dermal papillae.
Pacinian Corpuscles
Dermis - Reticular Layer
- deep-pressure receptors that are fast to adapt so good for sensing vibrations.
Accessory Organs
Dermis - Reticular Layer
- hair follicles and sweat glands.
Subcutaneous layer
Hypodermis Layer. - mainly adipose and areolar CT, it blends with reticular dermis to allow skin & muscles to move independently. Contains: Blood Reservoir Carotene pigment Subcutaneous fat
Blood Reservoir
Subcutaneous Layer
- Very rich blood & lymph supply.
Carotene pigment
Subcutaneous Layer
- yellow-orange pigment which serves as precursor for Vit. A., Excess carotene can give light-skin people an orange hue.
Subcutaneous fat
Subcutaneous Layer
- serves as energy source and padding & insulation.
Accessory Structures (Subcutaneous layer)
Includes hair, skin glands & nails
Hair
Subcutaneous Layer
- formed from epidermal origins and appears all over skin except regions of thick skin (palms & soles). Made of dead keratinized cells which serve as a fine touch receptor, heat insulation, protect against UV rays and prevent entrance of bacteria.
1. Hair Bulb
2. Hair Follicle
3. Dermal root sheath
4. Hair root
5. Hair shaft
6. Hair growth
Hair Bulb
from which hair grows w/in reticular dermis
- Hair Papillae
- Hair Matrix
Hair Papillae
areolar CT from hypodermis which supplies capillary to matrix.
Hair Follicle
epidermal sheath surrounding the hair root.
- Internal Sheath: grows up from hair matrix.
- External Sheath: extending downward from germinativum to hair matrix
Hair Matrix
mitotic germinativum cells which migrate down & provide hair growth
Internal Sheath
grows up from hair matrix.
External Sheath
extending downward from germinativum to hair matrix
Dermal Root Sheath
dense irregular CT which surrounds the hair follicle.
Arrector Pili
smooth muscle originating from papillary dermis and attaching to sheath to make hair stand on end and goose bumps.
Hair Root Plexus
Nerve endings wrap around sheath to detect slight movement of hair (fine touch) and relay information to CNS.
Hair Root
hair under surface of skin which grows from matrix.
a. Medulla of hair
b. Cortex of hair
c. Cuticle of hair
Medula of hair
innermost layer with flexible, soft keratin.
Cortex of hair
wraps around medulla with stiffer, hard keratin.
Cuticle of hair
outermost layer with most heavily keratinized stiff keratin with the cells arranged as overlapping shingles on a roof.
Hair Shaft
terminology for hair root after it emerges through the epidermis.
Hair Growth
occurs in cycles
Growth Period (hair)
when matrix is mitotically active and hair lengthens.
Resting stage
matrix becomes inactive and hair ceases to grow, referred to as club hair, typically 15% of hair is club hair. Club hair falls out when follicle becomes active.
Alopecia
partial or complete hair loss. Chemotherapy delivers anti-metabolites which destroys hair matrix. Electrolysis destroys matrix.
Hair Color
determined by variations in pigmentation of melanin (ultimately determined by DNA which is transcribed by Melanocytes).
Types of hair
adult hair is thin (vellus) or thick (terminal)
Lanuga
fine unpigmented hair seen in fetus and typically shed off around birth.
Vellus Hair
hort fine hair over most of body as peach fuzz (not on thick skin)
Terminal Hair
thicker course hair on head, eyebrows. After puberty, vellus hair of axilla & groin is replaced by terminal hair.
Glands of skin
two major exocrine glands of skin are sebaceous and sudiferous (sweat)
Sebaceous glands
- oily holocrine secretion of sebum from acinar cells. Sebum coats hair, inhibits bacterial growth and water evaporation, but is not found on thick skin. It is under control of the Autonomic Nervous System (ANS) to secrete at the same time.
Sebaceous glands of hair follicles:
- deep to dermis and empties into hair follicle. Arrector Pili muscle helps squeeze sebum out.
Isolated sebaceous follicles
- duct empty directly onto epidermis of face, back, chest, nipples and external genitalia.
Vernix Caseosa
just prior to parturition (childbirth), fetal sebaceous glands become active producing a coat of sebum which mixes w/shed epidermal cells to make the newborn slippery. Sebaceous glands are then quiescent until puberty.
Acne
sebaceous follicle becomes colonized by bacteria. Destruction of epidermal tissue can lead to permanent scarring seen with cystic acne.
Sudiferous Glands
releases a more aqueous secretion known as perspiration:
- Apocrine sweat glands
- Merocrine (eccrine) sweat glands
Apocrine sweat glands
- of axilla and groin releases sticky, odiferous (lipids & proteins) secretion initially thought to be apocrine (but is actually merocrine) and stimulated by Sympathetic Nervous System (of ANS) during stress or sexual excitement.
Merocrine (eccrine) sweat glands
more ubiquitous throughout body (not thick skin) with liquid secretion (99% water) and some electrolytes. Sensible perspiration cools body.
Reduce body temperature: evaporation of sweat from surface. Need to replace water while exercising in hot temperatures. If performing heavy exercise, more blood to muscles and less to dermis so cannot sweat and lead to heat stroke.
Excretion: of water, electrolytes and some organin solutes (eg- medications).
Protection: dilutes chemicals on surface and releases small peptide antibiotics.
Ceruminous glands
Specialized glands.
- modified sweat glands secretions mix w/sebum to produce wax.
Mammary glands
Specialized glands.
-apocrine glands influenced by sex hormones produce milk.
Nails
tightly packed hard, dead keratinized epidermal cells protecting the dorsum of the finger and offering strength to finger tips.
- Nail Root
- Nail Body
Nail Root
the deep proximal non-visual portion where nail grows from
a. Nail Matrix
b. Eponychium
Nail Matrix
mitotically active epithelium from which the nail grows.
Eponychium
is the stratum corneum of most distal portion of nail root before it emerges to the surface.
Nail Body
- visible portion of nail as it emerges to surface.
a. Nail bed
b. Lanula
c. Hyponicium
Nail Bed
epidermis under the nail body, it is pinkish owing to capillaries of the papillary dermis below.
Lanula
proximal white crescent shape of nail body owing to obscuring of papillary dermis by cells of the nail root.
Hyponicium
Area of thickened stratum corneum on distal end of nail body.
Response to Injury
First Intention Healing leaves tissue as it was prior to injury, Second Intention Healing replaces tissue with less functional granular tissues (scarring).
Callous
Increasing mechanical irritation of epidermis results in increased mitosis with increased layers of keratinocytes.
Epidermal wound healing
minor injuries (abrasions & minor burns) w/o effecting dermis. The wound gap will be breached by epithelium (1st intention healing) with the help of EGF.
Deep wound healing
wound extends, at least partially into dermis. Often heals with scarring (2nd intention healing) Four stages of healing:
Inflammatory phase: non-specific response w/vasodilation & local increase in macrophages and fibroblasts and clot forms to prevent microbe invasion.
Migratory phase: germinativum cells migrate across healing platform to breach gap. Fibroblasts produce granulation tissue (w/collagen) to serve as healing platform.
Proliferative phase: New blood vessels grow into area bringing more fibroblasts.
Maturation phase: Excessive collagen crowds region and must start to align the fibers along the lines of stress, creating lines of cleavage.
Hypertrophic Scars: Healing w/fibrosis often presents with raised surface w/excessive collagen and white because blood vessels minimized by collagen.
Keloids: If scar tissue exceeds boundaries of injury, and my leave skin void of dermal organs (hair or glands).
Four Stages of Healing
Four stages of healing:
- Inflammatory phase
- Migratory phase
- Proliferative phase
- Maturation phase
Inflammatory phase
STAGE 1. non-specific response w/vasodilation & local increase in macrophages and fibroblasts and clot forms to prevent microbe invasion.
Migratory phase
STAGE 2. germinativum cells migrate across healing platform to breach gap. Fibroblasts produce granulation tissue (w/collagen) to serve as healing platform.
Proliferative phase
STAGE 3. New blood vessels grow into area bringing more fibroblasts.
Maturation phase
STAGE 4. Excessive collagen crowds region and must start to align the fibers along the lines of stress, creating lines of cleavage.
Hypertrophic Scars
Healing w/fibrosis often presents with raised surface w/excessive collagen and white because blood vessels minimized by collagen.
(Maturation phase)
Keloids
If scar tissue exceeds boundaries of injury, and my leave skin void of dermal organs (hair or glands).
(Maturation phase)
Burns
can occur by heat, friction UV radiation, chemicals or electric shock.
a. First-degree burn
b. Second-degree burn
c. Third-degree burn
First-degree burn
only w/in superficial layers of epidermis & results in erythema.
Second-degree burn
partial thickness burn that extends into upper dermis, typically hair follicles and glands are spared.
Third-degree burn
full thickness burn through entire dermis & enters hypodermis. Destroys hair follicles & glands but may be less painful because nerve endings are lost.
Aging of the Integument
- Epidermis is thinner as stratum germinativum becomes less mitotically active.
- Vit. D declines as much as 75% so less calcium aborption
- Glandular activity declines:
a. Sebaceous activity declines: dry skin, brittle hair.
b. Sweat glands decline: decreased ability to perspire and cool self down. - Reduction in blood flow to dermis: increases feeling of being cold.
- Hair follicle activity declines, thinner, white hair.
- Less elastic fibers in dermis and onset of wrinkles (esp. w/exposure to UV radiation).
- Decline in sex hormones: so decrease in fat distribution.
- Reduction in healing capacity: more prone to recurrent infections.
