Chapter 5 Flashcards
Epidermis
Function
Composed of keratinized stratified squamous epithelium
4-5 layers
Cells on top are very flat and keratinized (dead)
Protect from foreign particles, water, and heat loss
Keratinocytes
Produce the fibrous protein keratin Desmosomes connect them arise from deepest part of epidermis from cells that are continuously in mitosis dead at the surface life 25-45 days
Melanocytes
Produce and synthesize melanin
found in deep layers
pigment shields nucleus of keratinocytes from UV
Langerhans’ Cell
AKA dendritic cells
machrophages that arise from bone marrow and migrate to epidermis
extend among the surrounding keratinocytes
plays a part in skin immune system
Merkel Cells
AKA Tactile Cells
Function as touch receptors
All are associated with a nerve ending
Variation in thickness of _______ depends on
epidermis; thin or thick skin
_____ skin has ___________ than _________ skin
thin; less layers; thick
Thick and thin skin refer to
only the epidermis
Thick skin
palms, fingertips, and soles of feet
Thickest skin is found on the upper back
Layers of the Epidermis
Stratum Basale Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
Stratum Basale
- Attached
- Made of
- types of cells
AKA Basal layer deepest epidermal layer - firmly attached to the dermis single row of the youngest keratinocytes cells undergo rapid division - Stratum germinativum 25% are melanocytes and occasional merkel cells
Stratum Spinosum
AKA Prickly layer
cells contain web-like system of intermediate filaments attached to desmosomes
abundant melanin granules and Langerhans’ cells
cells begin to die above this layer
Stratum Granulosum
AKA Granular Layer thin; 1-5 cell layers dies keratinization Keratohyalin and lamellated granules accumulate in cells Plasma membrane becomes thick
Keratinization
Cells fill with keratin
Stratum Lucidum
AKA Clear Layer
thin, transparent band
consists of a few rows of flat, dead keratinocytes
PRESENT ONLY IN THICK SKIN
Stratum Corneum
AKA Horny Layer Outermost layer of keratinized cells - filled with keratin -cornified cells, tough 20-30 cell layers thick accounts for three quarters of the epidermal thickness
Dermis
contains strong, flexible connective tissue
mainly dense irregular connective tissue
embedded with collagen, elastin, and reticular fibers
supplied with nerve fibers, blood vessels, lymphatic vessels
Epidermis cell types
Keratinocytes
Melanocytes
Merkel Cells
Langerhans’ cells
Melanin
Reddish yellow to brownish black Everyone has same amount of melanin Freckles and moles: clumps of melanin Responsible for dark skin colors protect skin from UV radiation found only in the deep layer of the epidermis
Mitosis occurs in which layer
Stratum Basale
Functions of the Stratum Corneum
- waterproofing
- protection from abrasion
- body insensitive to biological, chemical, and physical assaults
Dermis cell types
Fibroblasts
Macrophages
Occasionally mast cells and white blood cells
Dermis Layers
Papillary Layer
Reticular Layer
Papillary Layer
thin Areolar connective tissue with collagen and elastic fibers Dermal Paillae Many blood vessels Part of dermis
Dermal Papillae
Peg-like projections of the superior surface Contain - capillary loops - Meissner's corpuslces - free nerve endings
arranged in definite patterns on hands and feet (epidermal ridges)
Meissner’s Corpuscles
touch receptor in skin that lack hair
palms, soles, lips, eyelids, genitals
Reticular Layer
Accounts for about 80% of the thickness of the dermis
collagen fibers add strength and resiliency
elastin fibers provide stretch-recoil properties
Where are stretch marks formed
in tears in the reticular layer
Hypodermis
Subcutaneous layer deep to the skin
Composed of adipose and areolar connective tissue
not part of the skin
superficial fascia
anchors skin to underlying tissue (usually muscle)
Functions of the Hypodermis
Shock absorber
Insulator
Half o the body’s fat stores are
in the hypodermis
Pigments involved in skin color
Melanin
Carotene
Hemoglobin
Carotene
yellow to orange pigment
most obvious on palms and soles of feet
found in stratum corneum and fatty tissue of the hypodermis
Hemoglobin
reddish pigment
located in red blood cells in dermal capillaries
Cyanosis
blue
heart, respiratory failure
Redness
embarrassment fever hypertension inflammation allergy
Pallor
pale
fear, anger, other emotional stress
anemia or low blood pressure
Jaundice
Yellow
Liver disorder
Bronzing
Metallic Appearance
Addison’s disease
Black and Blue Marks
Bruises
reveals where blood escaped from circulation and clotted beneath the skin
Sweat glads
Sudoriferous Glands
Eccrine sweat glands
Apocrine sweat glands
Ceruminous sweat glands
Mammary glands
Eccrine sweat glands
Merocrine sweat glands
Most numerous
Abundant on palms and soles of feet and forehead
thermoregulation (sweating)
99% water with lactic acid, vitamin C, NaCl, and calcium
Apocrine Sweat Glands
Axillary and anogenital areas
Same contents as eccrine (plus fats and proteins
No odor until decomposed by bacteria
What may be analogous to sex scent glands in animals?
Apocrine sweat glands
Ceruminous glands
Modified apocrine glands in external ear canal
secrete cerumen (ear wax)
Protects from water and insects
antibacterial
Mammary Glands
Specialized sweat glands that secrete milk
Appendages of skin
Sebaceous glands
hair follicles
Arrector Pili Muscles
Nails
Sebaceous glands
found all over the body
secretes oil
causes pimples
hair follicles
protective
nerve ending at the base of each
produced by a follicle
- mainly fused, keratinized cells
Eyelashes
sense insects on skin
Arrector Pili Muscles
Smooth muscle
makes hair stand up
contracts with cold or fight/flight reaction
Nails
modification of the epidermis
heavily keratinized
functions of the integumentary system
protection body temperature regulation cutaneous sensation metabolic functions blood reservoir excretion
Protection of the integumentary system
chemical, physical, and mechanical barrier
body temperature regulation (Integumentary system)
accomplished by
- dilation (cooling) and constriction (warming) of dermal vessels
- increasing sweat gland secretions to cool the body
Cutaneous Sensation (Integumentary system)
extereceptors sense touch and pain
Meissners and lamellar corpuscles
Metabolic Functions (Integumentary system)
synthesis of vitamin D in dermal blood vessels
Blood reservoir (Integumentary system)
skin blood vessels store up to 5% of the body’s blood volume
Excretion (Integumentary system)
limited amounts of nitrogenous wastes are eliminated from the body in sweat
Burns
when burned you lose body fluids
can cause renal failure and circulatory shock
First degree burns
only the epidermis is damaged
localized redness, swelling and pain
Second degree burns
epidermis and upper regions of dermis are damaged
same as first degree but with blisters
Third degree burns
entire thickness of the skin is damaged
burned area appears gray-white, cherry red, or black
no initial edema or pain (nerve endings are destroyed
Rules of nines
estimates the severity of burns by computing the percentage or body surface burned
11 areas, 9% each, 1% for genitals
When are burns considered critical?
over 25% of the body has second degree burns
over 10% of the body has third degree burns
there are third degree burns on the face, hands, or feet
what is the main risk factor for skin cancer?
UV light
Major types of skin cancer
basal cell carcinoma
Squamous cell carcinoma
Melanoma
basal cell carcinoma
slow growing
don’t often metastasize
can be cured by surgery
squamous cell carcinoma
grows rapidly
metastasizes if not removed
chances are food
Melanoma
most dangerous type
highly metastatic
resistant to chemotherapy
