A&P Chapter 5: Integumentary System

Protection, Excretion (urea), Thermoregulate, Synthesis of Vitamin D3, Storage (nutrients, and Detection of stimuli (pressure and heat).

skin

superficial epithelium

underlying connective tissues

hair, nails, multicellular exocrine glands

connective tissue, separates the integument from the deep fascia around the other organs (muscles, bones)

body’s most abundant epithelial cell type, stratified squamous

palms and feet, more layers of cells

rest of the body, less layers of cells

• starting from the bottom up:
• 1.Stratum Germinativum
• 2.Stratum Spinosum
• 3.Stratum Granulosum
• 4.Stratum Lucidum
• 5.Stratum Corneum

can receive nutrients that diffuse from the dermis, therefore has the energy for mitosis

extend into the dermis, area of contact between dermis and epidermis. Epidermal ridges are unique to individuals, finger prints do not change over a life time

dermal side of epidermal ridges

germinative cells for regeneration, most abundant cell type in stratum germinativum

in areas that the skin does not contain hair, fine touch sensitive specialized epithelial cells

pigment producing cells that processes extend into stratum spinosum and injected melanosomes into nearby keratinocytes.

‘spiny layer’, daughter keratinocytes moving up and dividing, 8-10 cell layers thick

‘grainy layer’, no more dividing, keratinocytes kick in and make lots of keratin, organelles disintegrate, cells get thinner, 3-5 cell layers thick

a fibrous protein produced by keratinocytes

a protein that cross links keratin fibers and promote dehydration of the cell

‘clear layer’, only in thick skin areas, keratinocytes are flat and densely packed

exposed surface of the skin, 15-30 cell layers thick, water resistant, not water proof

formation of protective superficial layers of keratinocytes filled with keratin

evaporation of water from body (about 1 pint, 500 ml/ day)

water loss due to active sweat glands for thermoregulation (cooling)

dependent on epidermal pigmentation and dermal circulation

Color

orange yellow pigment accumulates in epidermal cells. Carotene can be converted to vitamin A (carrots, squash rich with carotene)

brown black pigment produced by melanocytes from tyrosine residues

in stratum germinativum (10-15% stratum germinativum cells are melanocytes). Melanocytes form and package melanin into melanosomes that are transferred through the melanocyte’s processes to keratinocytes. Race color is dependent on the amount of melanin produced not the number of melanocytes.

nicks the DNA, causes replication errors, and mutations. Some UV radiation is good to convert vitamin D3 from an inactive to active form. Vitamin D3 deficiency can cause Rickets (Fig. 5-7)

• attributed to hemoglobin, blood pigment (O2 bou
• nd bright red, without O2 bound dark red). ‘White with fright’ due to blood draining from dermis.

blue coloring due to oxygen deprived, evident in lips and beneath the nails

more melanin in a localized area

Bile can not be excreted by liverso a yellow pigment accumulates in body fluids. In advance stages skin and the whites of the eyes turn yellow.

autoimmune attack on healthy melanocytes

increased levels of adrenocorticotropin hormone (ACTH), ACTH similar to melanocyte stimulating hormone (MSH), skin turns bronze in color

In the stratum germinativum and stratum spinosum a cholesterol related steroid is converted to Vitamin D3 (cholecalciferol) with the help of UV radiation.

goes to the liver and is converted to calcitriol precursor (2,5 hydroxy D3) and then gets further processed in the kidneys.

hormone produced by the kidneys that increases the intestinal absorption of calcium and phosphorus

• peptide growth factor produced by salivary glands and glands in the duodenum
• Functions: Promote mitotic divisions of germinative cells (Stratums germinativum and spinosum), accelerate the production of keratin in differentiating epidermal cells, stimulates epidermal development and repair, therapeutic use in burn victims (grow skin in culture, 300x area/ week).

• Liposomes with DNA fragments for skin cancer antigens
• Transdermal administration with patch application for nitroglycerin, nicotine, and hormones.

Accessory structures extend into the dermis, plus dermis contains lymph vessels, blood vessels, and nerve fibers

• 1. Papillary Layer
• 2. Reticular Layer

superficial dermis, areolar connective tissue with blood vessels and sensory nerves

deeper dermis, dense irregular connective tissue

Collagen fibers are strong and resistant to stretching, can be bent and twisted. Elastic fibers go back and recoil. As we age we lose water, have decreased hormone levels, plus the cumulative effects of UV exposure takes a toll on our skin. Increase of age decrease amount of elastin in the dermis, we get wrinkles and sagging of the skin.

due to excessive weight gain (pregnancy) and the skin does not snap back

flexibility and resilience of skin

Vitamin A derivative that increases blood flow to the dermis, therefore expediates dermal repair and decrease rate of wrinkle formation.

bundles of fibers that run parallel to a line to resist a common directional force. Surgeons use lines of cleavage for the orientation of the incision. Wound will heal faster with limited scar tissue built up if incision is made parallel to the line of cleavage.

supplies epidermis (via diffusion), dermis, and subdermis with nutrients and waste disposal

• Ulcer
• Decubitis ulcers
• Necrosis
• Birth marks
• Contusions
• Cavernous Hemangiomas
• Capillary Hemangiomas

local shedding epithelium

circulation restrictions (pressure of body against bed) starves epidermis and dermis. Prevent by repositioning body constantly.

tissue death

dermal blood vessel tumors before birth

type of bithmark in dermis, increase in size after birth and then reduce in size as toddler grows

type of birthmark which has port wine stains, large blood vessels in dermis, remove by laser surgery (stork bite – on nape of neck or back of head, visible through adulthood; angel kisses – stains on eyelids and foreheads, disappear by the age of 2 years)

rupture dermal blood vessels

Merkel cell (Stratum Germinativum) + sensory terminals (in dermis) that detect light touch in epidermis.

in dermal papillae, sensitve to light touch

in reticular layer of dermis, sensitive to deep pressure and vibration

inflammation of the skin that involves primarily the papillary layer

occurs in response to strong chemical irritants, produces an itchy rash that may spread to other areas, example: poison ivy.

dermatitis that can be triggered by temperature changes, fungi, chemical irritants, greases, detergents or stress. Hereditary factors environmental factors, or both can promote its development.

localized dermatitis caused by a combination of moisture, irritating chemicals from fecal or urinary wastes, and flourishing microorganisms.

extensive allergic response to a food, a drug, an insect bite, infection, stress, or some other stimulus

not part of the integument but stabilizes position of integument, permits independent movement of skin (pinch a fold of skin)

comprised of areolar connective tissue, adipose connective tissue, blood vessels (rich blood reservoir)

Babies – baby fat needed to reduce heat loss and shock absorber, Men – on arms, neck, bum, and lower back, and Women – breasts, bum, thighs, hips; adult distribution is different due to hormonal influences. Fat in excess increases risks of diabetes, stroke, and other diseases.

tears and rips tissue and subcutaneous fat from body with a uniform applied vacuum (contusions, painful recovery, uneven surfaces, baggy skin, risks with anesthesia, bleeding, fluid loss). Fat will come back if behaviors do not change.

subcutaneous layer so heavily vascularized, avenue for injections because substances will be taken through general circulation

produce hair (Fig. 5-10)

• 1. Hair Root:
• 2. Hair Shaft:
• 3. Cuticle:
• 4. Hair Papilla:
• 5. Hair Bulb:

is non-living material, 2.5 million hairs /body, 75% not on head (only 500,000 hairs on your head)

anchors hair into the skin

part we see on surface

outer surface of shaft, dead keratinized cell shell

base of hair follicle, connective tissue with blood vessels and nerves

epithelia cells around the hair papilla

• lanugo
• Velous
• Terminal

3 month embryo, shed before birth

peach fuzz located over most of the body’s surface. Velous hair can turn to terminal hair based hormones circulating

heavier, more pigmented hair on head, eyelashes, eyebrows etc.

dependent on structure of melanosomes and pigment variation at hair papillae – genetically determined and environmentally induced

protection from UV radiation, insulates head, guard orifices

nerve tissue around each hair follicle

smooth muscle attaches to each hair to raise hair, in response to fear, temperature (goose bumps), autonomic regulation

• 1. Hair Growth Cycle
• 2. Club Hair:

scalp hair lasts about 2-5 years; absorbs nutrients and toxins as it grows

hair of an inactive hair follicle, hair is shed at the end of its growth cycle

two exocrine glands

oil glands, holocrine mode of secretion

mixture of triglycerides, cholesterol, proteins, and electrolytes that inhibit bacterial growth as well as lubricate skin and hair shaft

sebaceous glands not associated with hair follicles; vent directly to the skin. Present on face, back, and chest

blocked gland can become a boil

large sebaceous glands are prone to infection (pimple forms) Sex hormones increase secretion of sebum and then the gland may plug housing bacteria with it

inflammation around sebaceous gland

• Apocrine Sweat Glands
• Merocrine (Eccrine) Sweat Glands

tubular glands located in armpits and groin. Produce a viscous smelly secretion into the hair follicles starting at puberty (merocrine mode of secretion)

contract and squeeze gland to discharge the secretion

• produce 99% water secretion (pH 4-6.8) with some salt; merocrine sweat glands are all over the body and in high number
• Functions: Cooling, Excreting, Defensive.

apocrine mode of secretion, Oxytocin and Prolactin stimulate activity

ear sweat glands

ear wax. Ear wax plus ear hair trap particles from going further

autonomic nervous system control over sebaceous and apocrine sweat glands. Activation is all sebaceous or all apocrine glands, not gland at a time

help you grab things better, protect fingers and toes

visible portion of nail

underlying epidermis under nail body

where nail production occurs

skin area that covers nail

• Scab
• Granulation tissue
• Scar tissue
• keloid

temporary surface of fibrin clot, restores integrity and blocks invasion

repair crew combination of fibroblasts, blood clot, and capillary network

fibrous tissue replacement over damaged area

thickened area of scar tissue, raised, and has shiny epidermal surface

As we age, skin gets thinner, slower healing, decreased stem cell activity, decreased gland activity, decreased vitamin D3 activation, decreased hair follicle production, and decreased melanin production in hair (thinner hair, thinning hair)

About 10,000 people in the US die a year as a result of burns

First few layers of the epidermis are affected

redness, inflammation on skin surface

entire epidermis affected, and some dermis involved result in blister, pain, swelling

full thickness burn, epidermis, dermis, hypodermis are destroyed along with accessory structures

from cadaver or self (cultured with epidermal growth factor)

plastic epidermis with dermis collagen (cow skin) and ground cartilage (sharks)

• •fluid balance and electrolyte balance is upset
• •open to infection
• •no thermoregulation without eccrine glands

• Basal Cell Carcinoma
• Squamous Cell Carcinoma
• Malignant Melanoma

• •most common skin cancer
• •2/3 basal cell carcinoma appear in areas chronic exposure of UV
• •some people have a genetic predisposition
• •metastasis to other tissues is not likely

• •prevented by sunscreen
• •squamous cell carcinoma appears in areas exposed to UV
• •metastasis to other tissues is not likely
• •less common than basal cell carcinoma

• * deadly, 75% of skin cancer deaths
• * melanocytes metastasize through lymphatics

• A asymmetry, irregular shape, ooze or bleed
• B border unclear, irregular and/or notched
• C color, many colors (tan, brown, pink, red, black, white, blue)
• D diameter, >5mm (0.2 inches), more than a pencil eraser

• 164,000 Americans diagnosed/yr (3x more than 30 years ago)
• 8,600 American/ year die from skin cancer
• Fair skinned people more prone to skin cancers, not enough melanin to shield them from the damaging effects of UV radiation
• SPF > 15 absorb, scatter, and/or reflect UV rays. The more SPF the more chemicals. Need to block both UVA and UVB
• Tanning beds pose the same risk as sun exposure!!!!
• Lag time from time of UV exposure to early signs of skin cancer about 15-20 years

second degree

block invasion

Merocrine (eccrine) sweat gland

terminal

hypodermis

Stratum Spinosum

The person with albinism has the same number of melanocytes as the person with black skin but the melanocytes of the person with albinism does not produce melanin.

Decubitis ulcer

Stratum Lucidum

Stratum Germinativum

is a result of a decrease in the activity of the sebaceous glands in the skin.

are a result of a decrease in elastic fibers in the dermis and a decrease in thickness of the subcutaneous layer of the skin.

are due to an increase of activity melanocytes in localized areas (such as the hands and face, areas exposed to UV) or melanosomes clumping in these areas and a decrease of melanocytes in other areas of the body. Causes of age spots are UV exposure, age, and genetics.

occur in aging as a result of a decrease or a lack of melanin production in the hair. The number of melanocytes may also decrease.

In the elderly blood flow to the skin is decreased. Therefore the skin can’t dissipate heat from the body as well as it used to (when vessels close to the surface vasodilate to radiate heat from the body). In addition the elderly have less sweat gland activity so cooling the body is hard to do.