Integumentary System - AnaPhy Lecture Flashcards
- covers the entire body
- has a surface area of 1.2 to 2.2 square meters
- weighs 4–5 kg
- about 7% of total body weight in the average adult
- thickness - 1.5 to 4.0 millimeters
Skin
skin has a surface area of
1.2 to 2.2 square meters
skin weighs
4-5 kg
skin is about what percentage of total body weight in the average adult
7%
skin thickness is
1.5 to 4.0 millimeters
the skin protects deeper tissues from
- Mechanical damage
- Chemical damage
- Bacterial damage
- Thermal damage
- Ultraviolet radiation
- Desiccation
Functions of the skin
- Protects deeper tissues from:
- Mechanical damage
- Chemical damage
- Bacterial damage
- Thermal damage
- Ultraviolet radiation
- Desiccation - Aids in heat regulation
- Aids in excretion of urea and uric acid
- Synthesizes vitamin D
Cells of the Epidermis
- Keratinocytes
- Melanocytes
- Dendritic cells
- Tactile cells
produce keratin, the fibrous protein that helps give the epidermis its protective properties
Keratinocytes
the fibrous protein that helps give the epidermis its protective properties
keratin
most epidermal cells are
Keratinocytes
keratinocytes arise from
stratum basale
undergo almost continuous mitosis in response to prompting by epidermal growth factor, a peptide produced by various cells throughout the body
Keratinocytes
Millions of dead keratinocytes rub off every day, giving us a
totally new epidermis every
25 to 45 days
cell production and keratin formation is accelerated in body areas regularly subjected to _____________, such as the hands and feet
friction
cell production and keratin formation is accelerated in body areas regularly subjected to friction, such as the
hands and feet
the spidershaped epithelial cells that synthesize the pigment melanin
Melanocytes
melanocytes accumulates in membrane-bound granules called
melanosomes
are transferred to nearby keratinocytes
melanin
accumulate on the superficial, or “sunny,” side of the keratinocyte nucleus, forming a pigment shield that protects the nucleus from the damaging effects of ultraviolet (UV) radiation in sunlight
melanin granules
star-shaped cells that arise from bone marrow and migrate to the epidermis
dendritic cells
dendritic cells are also called
Langerhans cells
ingest foreign substances and are key activators of our immune system
dendritic cells
star-shaped dendritic cells arise from
bone marrow
present at the epidermal-dermal junction
Tactile (Merkel) cells
shaped like a spiky hemisphere
Tactile (Merkel) cells
each tactile cell is intimately associated with a
disc-like sensory nerve ending
functions as a sensory receptor for touch.
Tactile (Merkel) disc
Two distinct layers of the skin
Epidermis and dermis
made up of stratified squamous epithelium, hardened by keratin
Epidermis
making up the bulk of the skin, is a tough, leathery layer composed mostly of fibrous connective tissue, vascularized
Dermis
The subcutaneous tissue just deep to the skin is known as the
hypodermis
Layers of the Epidermis
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
deepest epidermal layer
Stratum basale
consists of a single row of stem cells—a continually renewing cell population
Stratum basale
a continually renewing cell population
stem cells
Each time one of these basal cells divides, one daughter cell is pushed into the cell layer just above to begin its specialization into a
mature keratinocyte
10-25% of cells in the stratum basale are
melanocytes
contain a weblike system of intermediate filaments, mainly
tension-resisting bundles of pre-keratin filaments, which span their cytosol to attach to desmosomes
Stratum spinosum
Scattered among the keratinocytes (in stratum spinosum) are
melanin granules and dendritic cells
consists of four to six cell layers in which keratinocyte appearance changes drastically
Stratum granulosum
- process of keratinization begins
- Nutrient-poor layer
Stratum granulosum
Cells flatten, their nuclei and organelles begin to disintegrate
Stratum granulosum
stratum granulosum accumulates two types of granules:
keratohyaline granules and lamellar granules
help to form keratin in the upper layers (darkly stained)
keratohyaline granules
contain a waterresistant glycolipid that prevents water loss
across the epidermis
lamellar granules
- visible only in thick skin
- consists of two or three rows of clear, flat, dead keratinocytes with indistinct boundaries
Stratum lucidum
strong, flexible connective tissue
Dermis
Cells types in Dermis
fibroblasts, macrophages, and occasional mast cells and white blood cells
Dermis has a rich supply of
supply of nerve fibers, blood vessels, and lymphatic vessels
has a rich supply of nerve fibers, blood vessels, and
lymphatic vessels
Dermis
two layers of the dermis
papillary layer and reticular layer
peglike projections
Dermal papillae
contain capillary loops
Papillary layer
house free nerve endings (pain receptors) and touch receptors called tactile or Meissner corpuscles
Papillary layer
the papillary layer house free nerve endings (pain receptors) and touch receptors called
tactile or Meissner corpuscles
Dermal papillae lie atop larger mounds called
dermal ridges
Dermal papillae lie atop larger mounds called dermal ridges,
which in turn cause the overlying epidermis to form
epidermal ridges
These _______________ cause the overlying epidermis to fold into ridges on the fingers that are called fingerprints, which are unique to each individual.
dermal papillae
about 80% of the thickness of the dermis
reticular layer
coarse, irregularly arranged, dense fibrous connective tissue
reticular layer
orientation of collagen fibers in the dermis, and are
generally parallel to the orientation of the underlying
muscle fibers
Cleavage (tension) lines
are important to surgeons because when an incision is made parallel to these lines, the skin gapes less and heals
more readily.
Cleavage lines
dermal folds that occur at or near joints, where the dermis is tightly secured to deeper structures
Flexure line
Three pigments contribute to skin color:
Melanin, Carotene, Hemoglobin
Yellow, brown or black pigments; produced by melanocytes
melanin
pigments produced by melanin
Yellow, brown or black pigments;
Melanin production depends upon
genetic and exposure to sunlight
Orange-yellow pigment from some vegetables
carotene
Red coloring from blood cells in dermis capillaries
Hemoglobin
determines the extent of red coloring
Oxygen content
Low oxygen content creates a bluish appearance
Cyanosis
Many alterations in skin color signal certain disease states or even emotional states:
- Redness, or erythema
- Pallor, or blanching
- Jaundice or yellow cast
- Bronzing
- Black-and-blue marks, or bruises
embarrassment (blushing), fever, hypertension, inflammation, or allergy
Redness, or erythema
fear, anger, and certain other types of emotional stress; may also signify anemia or low blood pressure.
Pallor, or blanching
usually signifies a liver disorder, in which yellow bile pigments accumulate in the blood and are deposited in body tissues
Jaundice or yellow cast
a sign of Addison’s disease; or a pituitary gland tumors that inappropriately secrete melanocyte-stimulating hormone (MSH)
Bronzing
hematomas
Black-and-blue marks, or bruises
Skin appendages include:
- Hair and hair follicles
- Nails
- Sweat glands
- Sebaceous (oil) glands
functions of hair and hair follicles:
- sense insects on the skin before they bite or sting us
- hair on the scalp guards head against physical trauma, heat loss, and sunlight.
- eyelashes shield the eyes, and nose hairs filter large
particles like lint and insects from the air we inhale
Produced by the hair bulb
hair
Consists of hard keratinized epithelial cells
hair
- tougher and more durable
- individual cells do not flake off
hair
provide pigment for hair color
Melanocytes
three layers of the hair shaft:
central medulla, cortex, cuticle
consists of large cells and air spaces
central medulla
the only part of the hair that contains soft keratin
(absent in fine hairs)
central medulla
surrounds medulla and has several layers of flattened cells
cortex
- on outside of cortex
- single layer of cells
- overlapping one another like shingles on a roof
Cuticle
the deep end of the follicle
hair bulb
knot of sensory nerve endings wrapping
each hair bulb
hair follicle receptor, or root hair plexus
contains a knot of capillaries that supplies nutrients to the growing hair and signals it to grow
hair papilla
actively dividing area of the hair bulb that produces the hair
hair bulge
pulls the hair follicle upright and dimples the skin surface to
produce goose bumps in response to cold temperatures or fear
arrector pili muscle
3 Structures of a Hair
central medulla, cortex, cuticle
Structure of a Hair Follicle
- hair bulb
- hair follicle receptor, or root hair plexus
- hair papilla
- hair bulge
- arrector pili muscle
Types and Growth of Hair
vellus hair and terminal hair
pale, fine body hair of children and adult
females
vellus hair
coarser, longer hair of the eyebrows and
scalp, also darker
terminal hair
terminal hairs grow in response to the stimulating effects of
androgens
phases of hair growth cycle
anagen (active growth phase), catagen (transition phase), telogen (resting phase)
permanent hair removal can only occur during this active growth phase
anagen (3-10 years)
club hair transitions upwards towards skin pore and dermal papilla begins to separate from follicle
catagen (2-3 weeks)
dermal papilla fully separates from follicle
telogen (3-4 months)
dermal papilla moves upwards to meet hair follicle once again and hair matrix begins to for new hair
return to anagen
hair growth cycle
- permanent hair removal can only occur during this active growth phase
- club hair transitions upwards towards skin pore and dermal papilla begins to separate from follicle
- dermal papilla fully separates from follicle
- dermal papilla moves upwards to meet hair follicle once again and hair matrix begins to for new hair
faster shedding of hair leading to hair thinning and some
degree of baldness
alopecia
By age 35, noticeable hair loss occurs in _____ of men, and by age 60 that number jumps to _______
40%; 85%
is a genetically determined, sex-influenced condition
Male pattern baldness
a drug used to reduce high blood pressure, has the interesting side effect in some bald men (and balding women) of stimulating hair regrowth
Minoxidil (rogaine)
factors affecting thinning of hair and baldness
- acutely high fever
- surgery
- severe emotional trauma
- certain drugs (excessive vitamin A, some antidepressants and blood thinners, anabolic steroids, and most chemotherapy drugs)
_______________________________________ lead to hair thinning
Protein-deficient diets and lactation
the immune system attacks the follicles and the hair
falls out in patches
alopecia areata
- scalelike modification of the epidermis
- clear protective covering on the dorsal surface of the distal part of a finger or toe
- useful as “tools” to help pick up small objects or
scratch an itch
Nails
nails (like hairs) contain
hard keratin
responsible for nail growth
nail matrix
proximal nail fold that projects onto the nail body
Eponychium
skin folds overlapping proximal and lateral borders of the nail
nail folds
proximal nail fold projecting onto the nail body
cuticle or eponychium-
free edge of the nail where dirt and debris tend to accumulate
Hyponychium
yellow-tinged nails
may indicate a respiratory or thyroid gland disorder
thickened yellow nails
may signal a fungus infection
outward concavity of the nail
may signal an iron deficiency
horizontal lines (Beau’s lines)
may hint of malnutrition
Widely distributed in skin
Sweat glands
two types of sweat glands
- Eccrine and Apocrine
eccrine glands are also called
merocrine sweat glands
- abundant on the palms, soles of the feet, and forehead
- simple, coiled, tubular gland
Eccrine glands
duct extends to open in a funnel shaped pore at the
skin surface
Eccrine glands
a hypotonic filtrate of the blood that passes through the secretory cells of the sweat glands
sweat
- with some salts (mostly sodium chloride), vitamin C, antibodies, a microbe-killing peptide dubbed dermcidin
- traces of metabolic wastes (urea, uric acid, and ammonia)
sweat
pH of sweat
between 4 and 6
sympathetic division of the autonomic nervous system regulates
sweating
sweat is released by
exocytosis
largely confined to the axillary and anogenital areas
Apocrine glands
apocrine glands produces
sweat, plus fatty substances and proteins
- Most with ducts that empty into hair follicles
- Glands are activated at puberty
Apocrine glands
activated by sympathetic nerve fibers during pain and stress
Apocrine glands
Modified Apocrine Glands
Ceruminous glands and Mammary glands
found in the lining of the external ear canal
Ceruminous glands
Ceruminous glands secretion mixes with sebum produced by nearby sebaceous glands to form a sticky, bitter substance called
cerumen or earwax
secrete milk
Mammary glands
- simple branched alveolar glands
- found all over the body except in the thick skin of the palms and soles
Sebaceous (oil) glands
sebaceous glands secrete an oily substance called
sebum
accumulated sebum blocks a sebaceous gland duct
Whitehead
oxidized and dried whitehead (darkens)
Blackhead
active inflammation of the sebaceous glands accompanied by “pimples” (pustules or cysts)
acne
caused by bacterial infection, particularly by staphylococcus
acne
acne is caused by bacterial infection, particularly by ___________________
staphylococcus
overactive sebaceous glands can cause, sloughed off oily scales
Seborrhea
Functions of the Integumentary System
- Protection
- Chemical Barrier
- Physical Barriers
- Biological Barriers - Body Temperature Regulation
- Metabolic Functions
- Blood Reservoir
- Excretion
acid mantle, dermcidin in sweat, bactericidal substances in sebum, natural antibiotics called ______________- punch hole in bacteria
defensins
- acid mantle
- dermcidin in sweat
- bactericidal substances in sebum
- natural antibiotics called defensins- punch hole in bacteria
Chemical Barrier
Substances that do penetrate the skin in limited amounts include
- Lipid-soluble substances, such as oxygen, carbon dioxide,
fatsoluble
- vitamins (A, D, E, and K), and steroids (estrogens)
- Oleoresins of certain plants, such as poison ivy and poison oak
- Organic solvents, such as acetone, dry-cleaning fluid, and paint thinner, which dissolve the cell lipids
- Salts of heavy metals, such as lead and mercury
- Selected drugs (nitroglycerine, nicotine, seasickness
medications)
Physical Barrier
Substances that do penetrate the skin in limited amounts include
- Lipid-soluble substances, such as oxygen, carbon dioxide,
fatsoluble - vitamins (A, D, E, and K), and steroids (estrogens)
- Oleoresins of certain plants, such as poison ivy and poison oak
- Organic solvents, such as acetone, dry-cleaning fluid, and paint thinner, which dissolve the cell lipids
- Salts of heavy metals, such as lead and mercury
- Selected drugs (nitroglycerine, nicotine, seasickness
medications)
- Dendritic cells of the epidermis-act as antigen “presenters.”
- Dermal macrophages
- DNA-absorb UV radiation and transfer it to the atomic nuclei
Biological Barrier
cutaneous receptors are classified as
exteroceptors
allow us to become aware of a caress or the feel of our clothing against our skin
Tactile (Meissner’s) corpuscles & tactile discs
alert us to bumps or contacts involving deep pressure
Lamellar (Pacinian) corpuscles
report on wind blowing through our hair and a playful tug
on a pigtail
Hair follicle receptors
sense painful stimuli (irritating chemicals, extreme heat or cold, and others)
Free nerve endings
modified cholesterol molecules are converted to a
vitamin D precursor
Keratinocyte enzymes can
- “Disarm” many cancercausing chemicals that penetrate the epidermis
- Convert some harmless chemicals into carcinogens
- Activate some steroid hormones—for instance, they can transform cortisone applied to irritated skin
dermal vascular supply can hold about 5% of the body’s entire blood volume
Blood reservoir
- Nitrogenous waste products (ammonia, urea, and uric acid) in sweat
- NaCl excretion
Excretion
abnormal cell mass
Cancer
two types of cancer
Benign and Malignant
Does not spread (encapsulated)
Benign
Metastasized (moves) to other parts of the body
Malignant
is the most common type of cancer
skin cancer
- Least malignant
- Most common type
- Arises from stratum basale
Basal cell carcinoma
- Arises from stratum spinosum
- Metastasizes to lymph nodes
- Early removal allows a good chance of cure
Squamous cell carcinoma
- Most deadly of skin cancers
- Cancer of melanocytes
- Metastasizes rapidly to lymph and blood vessels
- Detection uses ABCD rule
Malignant melanoma
Detection uses ___________ for recognizing melanoma
ABCD rule
ABCD Rule
A = Asymmetry, two sides of pigmented mole do not match
B = Border irregularity, borders of mole are not smooth
C = Color, different colors in pigmented area
D = Diameter, spot is larger then 6 mm in diameter
- tissue damage inflicted by intense heat, electricity, radiation, or certain chemicals
- denature cell proteins and kill cells in the affected areas
Burns
leads to dehydration and electrolyte imbalance, and then renal failure (kidney shutdown) and circulatory shock (inadequate blood circulation due to reduced blood volume)
Burns
kidney shutdown
renal failure
inadequate blood circulation due to reduced blood volume
circulatory shock
In general, burns are considered critical if any of the following conditions exists:
- Over 25% of the body has second-degree burns
- Over 10% of the body has third-degree burns
- There are third-degree burns of the face, hands, or
feet
only the epidermis is damaged. Symptoms include localized
redness, swelling, and pain
1st-degree burn
symptoms of 1st-degree burn
redness, swelling, and pain
injure the epidermis and the upper region of the dermis. Symptoms mimic those of first-degree burns, but blisters
also appear.
2nd-degree burn
symptoms of of 2nd-degree burn
mimic those of first-degree burns, but blisters also appear.
Appears graywhite, cherry red, or blackened, and initially
there is little or no edema; not painful.
3rd-degree burn
keratinocytes undergo almost continuous mitosis in response to prompting by
epidermal growth factor
a peptide produced by various cells throughout the body
epidermal growth factor
is accelerated in body areas regularly subjected to friction, such as the hands and feet
cell production and keratin formation
persistent friction causes a thickening of the epidermis called a
callus
functions as a sensory receptor for touch
tactile or Merkel disc
eccrine sweat glands are abundant on
the palms, soles of the feet and forehead
microbe-killing peptide
dermcidin
apocrine sweat glands are activited by __________________ during pain and stress
sympathetic nerve fibers
force sebum out of the hair follicles to the skin surface
arrector pili contractions