5: Integumentary System ANATOMY AND PHYSIOLOGY

Gel Austin Diego Pascua || 2022

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Integumentary system – composed of skin and  Some waste products are excreted through the skin
accessory structures: hair, glands, nails, and sensory and glands. (contained in sweat)
receptors.
Skin
Dermatology – medical specialty; deals with the - Also known as the cutaneous membrane
structure, function, and disorders of the integumentary - Largest organ in our body (covering its entirety)
system
- Has 2 layers: Epidermis and dermis; and a
supporting structure: Hypodermis (not considered a
part of the skin)

Epidermis
- Composed of keratinized stratified squamous
epithelium.
- Skin's superficial layer, resists abrasion on the skin's
surface and minimizes water loss through the skin
- Contains four principal types of cells: keratinocytes,
melanocytes, intraepidermal macrophages, and tactile
epithelial cells.
 composed of up to five layers, or strata: stratum
Basale, spinosum, granulosum, lucidum, and corneum

Cells of the Epidermis

Functions of the Integumentary System
Keratinocytes
Protection - Makes up most of the epidermis; arranged in four or
 Skin = covering of the body; five layers
 Reduces the negative and harmful effects of - Connected by desmosomes throughout the epidermis
ultraviolet light; - Produce keratin (in a process called keratinization)
 Keeps microorganisms from entering the body and  Keratin - tough, fibrous protein that helps protect
 Reduces water loss from the body, preventing the skin and underlying tissues; produce lamellar
dehydration. granules, which release a water-repellent sealant
that decreases water entry and loss.
Sensation
 Sensory receptors that can detect heat, cold, touch, Melanocytes
pressure, and pain. - Produce the pigment melanin (Group of pigments
primarily responsible for skin, hair, and eye color.) into
Temperature regulation vesicles called melanosomes in a process called
 Skin regulates body temperature through the melanogenesis
modulation of blood flow through the skin and the  More melanin = darker body
activity of sweat glands. - Has slender projections extending between the
keratinocytes and transfer melanin granules to them.
Vitamin D production
1. UV light causes skin to produce a precursor Langerhans’ cells
molecule of vitamin D (70Dehydrocholesterol) - a.k.a. Intraepidermal macrophages
2. Precursor is carried by blood to be modified in the - Part of the immune system which form a network
liver (Vitamin D3) across the epidermis at stratum spinosum (easily
3. Carried by blood to the kidney for further damaged by UV light.)
modification
4. Formation of active vitamin D (regulator of calcium Merkel cells
homeostasis) - a.k.a. Tactile epithelial cells
- Least numerous of the epidermal cells.
Excretion

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- Close to the nerve endings (tactile disc) and are  Lamellar granules - fuse with the plasma
responsible for detecting light touch and superficial membrane and release a lipid-rich (water repellant)
pressure. secretion.
Epidermal Strata (5 layers of skin)
Stratum Basale
Stratum Lucidum
- Deepest layer; consisting of a single layer of cuboidal
- Present only in the thick skin of areas such as the
or columnar cells.
fingertips, palms, and soles
- Contain scattered keratin intermediate filaments
- also known as the "Clear Layer", as the cell appears
(tonofilaments);
transparent due to keratohyalin granules, which was
- Also known as the stratum germinativum (to indicate its
evident as granules in the stratum granulosum, are
role in forming new cells
already dispersing around keratin fibers.
 Stem cells in this layer continue to divide and form
keratinocytes;
Stratum Corneum
- Anchored to the basement membrane by
- most superficial stratum; is composed of 25 or more
hemidesmosomes;
layers of dead squamous cells.
Keratinization and Growth of Epidermis - Consists of cornified cells: dead cells, with a hard
Keratinization – process where cells that are formed in the protein envelope, filled with the soft keratin.
stratum basale accumulate more and more keratin as they - Lipids are release from lamellar bodies responsible for
move upward the cellular layers, until the organelles are all many of the skin’s permeability characteristics
replaced by keratin (become keratinized) and eventually
slough off as new cells arise.  Eventually, the desmosomes break apart, and the cells
 This process takes about six weeks are shed from the surface of the skin.
 Excessive shedding = dandruff
The epidermal cells of stratum basale are the closest to blood
vessels, hence, is the layer that is metabolically active and
can form new cells: As the new keratinocytes are pushed
farther from the blood supply by continuing cell division, the
epidermal strata above the basale receive fewer nutrients, and
the cells become less active and eventually die.
(*the desmosomes that holds these cells together also breaks
down causing the cells to slough off)

Stratum Spinosum (spinous layer)

- Superficial to stratum basale; consists of numerous
keratinocytes arranged in 8–10 layers.
- Spiny in appearance due to flattening of the cell except
the desmosomes, causing protrusion.
- Where keratinization begins:
 Keratinocytes of this layer produce coarser bundles
of keratin

 Cells in this layer and the following ones become

flattened. Thick And Thin Skin
Skin is classified as thick or thin based on the structure of the
epidermis.
Stratum Granulosum
- Consists of three to five layers of flattened
Thick Skin
keratinocytes that are undergoing apoptosis - Has all five epithelial strata, and the stratum corneum has
- Has a grainy appearance due to the accumulation of many layers of cells.
granules of keratohyalin and lamellar granules - Found in areas subject to pressure or friction,(palms of
 Keratohyalin - assembles keratin intermediate the hands, the soles of the feet,)
filaments into keratin. - Has no arrector pili muscles

Thin Skin
- Stratum lucidum is absent.
♥멈추지 말고 계속 해나가기만 한다면 늦어도 상관없다 Page 2 of- 8 Covers the rest of the body and is more flexible than thick
skin.
- Each of its strata contains fewer layers of cells.
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Albinism
a recessive genetic trait that results from an inability to
produce tyrosinase. Results in little or no production of the
pigment melanin
Psoriasis Dermis
- Common and chronic skin disorder - Composed of dense irregular connective tissue
- Keratinocytes divide and move more quickly than containing collagen and elastic fibers
normal from the stratum basale (shed prematurely  Has great tensile strength (resists pulling or
in as little as 7 to 10 days.) stretching forces).
- Immature keratinocytes make an abnormal keratin, - Supply nutrients and removes waste products to
forming silvery scales at the skin surface, most epidermis.
often on the knees, elbows, and scalp. - Divided into a thin superficial papillary region and a
thick deeper reticular region.
Skin Color
The factors that determine skin color include:  The dermis is filled with receptors:
A. Pigments in the skin Meissner corpuscles – touch receptors on the dermal
The structural basis of skin color depends on the layer of hairless skin; responsible for the skin’s
combination of these items: sensitivity to light touch.
 Melanin - Group of pigments primarily responsible
for skin, hair, and eye color; Provides protection Hair root plexuses – fast-adapting touch receptors
against ultraviolet light from the sun found in hairy skin.
a. Pheomelanin – yellow/red
b. Eumelanin – brown/black Ruffini corpuscles – sensitive to skin stretching/
 Production of more melanin is stimulated by exposure
to sunlight. Lamellated/Pacinian corpuscles - receptor for deep
pressure (respond to high-frequency vibrations)
 Carotene – orange-yellow pigment (a precursor of
vitamin A) present in orange, deep-yellow, or leafy Ruffini end organs - slowly adapting; for sensing
green vegetables continuous touch or pressure

B. Blood circulating through the skin Nociceptors – receptors for pain

 Hemoglobin – pigment in RBCs in the dermal
vessel.

C. The thickness of the stratum corneum.

Conditions that affect skin color

Jaundice
Condition which causes our skin, sclera, and mucous
membranes to turn yellow, could be a sign of liver infection,
an overdose of certain drugs, chronic liver disease, and
pancreatic cancer.

Cyanosis
Low oxygen in the blood which causes a person's skin to
have a bluish color.
Papillary layer
Erythema - Superficial portion of dermis; makes up about one-fifth
A condition in which the skin turns a reddish hue when the of the thickness of the total layer
amount of blood flowing through the skin increases; on the - Composed of areolar connective tissue.
contrary - IT contains:
- A decrease in blood flow, as occurs in shock, can
make the skin appear pale.
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 Dermal papillae – finger-like projections that  Women have proportionately more adipose tissue
project into the epidermis; contains capillary loops than men, especially over the thighs, buttocks, and
(blood vessels) that nourishes epidermis. breasts.
♥Arranged in parallel, curving ridges that shape
into finger-/footprints

 Corpuscles of touch (Meissner corpuscles) –

nerve endings that are sensitive to touch.
Accessory Structures of the Skin
 Free nerve endings - dendrites that lack any - Consist of hair, skin glands, and nails which all develop
apparent structural specialization from the embryonic epidermis.

Hair
Reticular Layer - Also known as “Pili”
- Deeper portion of dermis; - Present on most skin surfaces except the palms, the
- Spaces between fibers contain some adipose cells, soles, the lips, the nipples, parts of the external
hair follicles, nerves, sebaceous glands, and genitalia.
sudoriferous glands
- Consists of dense irregular connective tissue with  Hair structure and coloration change as a person ages:
bundles of thick collagen (arranged in a netlike  Lanugo – unpigmented hair during fifth or sixth
manner) and some coarse elastic fibers. month of fetal development
*Incision across cleavage  Terminal hairs – replaces lanugo near the time of
Cleavage lines lines = ↑ healing time, scar birth
 Formed due to  Vellus hairs – short, fine, and usually unpigmented,
the elastic and replace the lanugo on the rest of the body
collagen fibers
of the reticular Hair Structure
layer being - Divided into:
oriented more in 1. Shaft – protrudes above surface of skin
some directions 2. Root – located underneath surface; penetrates
than in others dermis/subcu
 The shaft and root of the hair both consist of three
Direction of an incision concentric layers of cells: medulla, cortex, and cuticle:
determines the healing 1. Medulla - the central axis of the hair, and it consists of
rate and severity of two or three layers of cells containing soft keratin
scar tissue of the 2. Cortex - surrounds the medulla and forms the bulk of
incision. *Incision parallel to the hair; contain hard keratin.
cleavage = ↓ healing time, 3. Cuticle – Covers the cortex; single layer of cells also
containing hard keratin.

Hypodermis (Subcutaneous tissue)

- Attaches the skin to underlying bone and muscle and
supplies the skin with blood vessels and nerves
- A loose connective tissue (mainly areolar and adipose
tissue)
- Contains about half the body’s stored lipids, where
they function in insulation and padding and as a source
of energy.

 The amount of adipose tissue in the subcutaneous

tissue varies with age, sex, and diet:
 Babies have proportionately more adipose tissue
than adults.

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 Hair follicle – Surround the root of the hair; made Eccrine sweat glands
up of an external root sheath and an internal root  More numerous than apocrine glands
sheath  Distributed throughout skin of most regions of body,
 External root sheath - downward continuation especially skin of forehead, palms, and soles
of the epidermis, covers entire HF.  Duct of the gland runs to an opening on the skin
 Internal root sheath - produced by matrix; called the pore to secrete sweat (consists primarily
surrounds and protects the growing hair of water, with small amounts of ions, urea, uric
 Dermal root sheath - dense dermis acid, ammonia, amino acids, glucose, and lactic
surrounding the hair follicle acid.)
Function: Regulation of body temperature, waste removal,
 Hair bulb - onion-shaped structure; base of each stimulated during emotional stress.
hair follicle; it houses:
 Papilla of the hair – nourish growing hair Apocrine sweat glands
follicle.  Become active in puberty because of sex
 Hair matrix - germinal layer of cells; hormones. (most likely to produce pheromone)
responsible for the growth of existing hairs, and  Have larger ducts and lumens than eccrine glands
they produce new hairs when old hairs are  Mainly in the skin of the axilla, groin, areolae of the
shed. (occurs within the same follicle) breasts, and bearded regions of the face.
 Secretory portion is in the lower dermis or upper
 Sebaceous (oil) glands - connected to hair subcutaneous layer; excretory duct opens into hair
follicles; secrete an oily substance called sebum follicles
(lubricates hair)  Produce a special kind of sweat that contains fatty
substances and proteins that appears milky or
 Arrector pili – a smooth muscle; contracts, which yellowish in color.
pulls the hair shafts perpendicular, in response to  Odorless until it interacts w/ bacteria on the skin
nerve ending stimulation when in emotional stress, surface that metabolize its components causing the
cold, or fright musky odor (b.o.)

 Hair root plexus – formed by dendrites of neurons Other glands:

surrounding hair follicle; sensitive to touch; 1. Mammary glands
generate nerve impulses if their hair shafts are  Secrete milk.
moved. 2. Ceruminous glands
 Secrete cerumen, a waxy material (ear wax).
Glands
The major glands of the skin are the sebaceous glands and Nails
the sudoriferous glands. - Plates of tightly packed, hard, dead, keratinized
epidermal cells that form a clear, solid covering over
Sebaceous Glands the dorsal surfaces of the distal portions of the digits.
- Simple, branched acinar (rounded) glands. - Consists of: (1) a nail body, (2) a free edge, and (3) a
- Associated with hair follicle. nail root
- Secreting portion of a sebaceous gland lies in the
Nail body (plate)
dermis and usually opens into the neck of a hair follicle
 Visible portion of the nail (comparable to the
- Secrete an oily substance called sebum.
stratum corneum)
 Sebum - coats the surface of hairs and helps keep
them from drying and becoming brittle; prevents
Free edge
excessive evaporation of water from skin.
 Part of the nail body that extend past the distal end
of the digit
Sudoriferous Glands
- sweat glands (produce sweat)
Nail root
- Found everywhere except nipples and parts of the
 Portion of the nail that is buried in a fold of skin
external genitalia.
- Simple, coiled tubular glands
- Divided into two main types: eccrine and apocrine

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Autoimmune disease, Idiopathic, and Iron Deficiency
Anemia.

Clubbing – When the nails thicken and curved around the

fingertips; possible causes are hereditary, lungs/heart
problem, early signs of AIDS.

Leukonychia – White dots on the nail or it could be in the

entire nail. It is not associated in any serious medical
condition
Parts of the nails Onychatropia – Atrophy or wasting away of the nail plate
Lunula which causes to lose its luster, become smaller and
- Whitish, crescent-shaped area of the proximal end of sometimes shred entirely; gives initial itching and
nail bed unattractive appearance

Hyponychium
- Located beneath free edge; junction between the free
edge and skin of the fingertip and secures the nail to
Disorders: Homeostatic
the fingertip Imbalances
Skin cancer
Nail bed
- Most common type of cancer
- Skin below the nail plate that extends from the lunula
- Most result from damage caused by exposure to UV
to the hyponychium; its epidermis lacks stratum
radiations from sunlight;
granulosum
 UV radiation – damages genes (DNA) in epidermal
cells causing mutations (in TP53 tumor-suppressor
Eponychium
gene)
- A narrow band of epidermis that extends from and
 TP53 gene - gene that helps stop the growth of
adheres to the margin (lateral border) of the nail wall;
tumors (p53-protein)
occupies the proximal border of the nail
- Can be induced by chemicals, x-rays, inflammation, or
inherited
Matrix
- Portion of the epithelium proximal to the nail root
Risk factors
- It is a root area where new cells are generated to form
nails.  Amount of melanin: fair-skinned individuals who
- Contains nerves and blood and lymph vessels. lack protective melanin are at higher risk of
developing melanin.
 Frequent exposure to UV rays: older individuals
Functions: who have been repeatedly exposed to sun/sunburn
1. Protect the distal end of the digits. are at increased risk,
 Areas widely exposed to the sun’s rays—face,
2. Provide support and counterpressure to the palmar neck, and hands—are highly vulnerable
surface of the fingers to enhance touch perception and
manipulation. Types
Basal cell carcinoma
3. Allow us to grasp and manipulate small objects, and  Most common type,
they can be used to scratch and groom the body in affects cells in the
various ways. stratum basale.
 Metastatic spread is rare
Nail Abnormalities because these tumors do
Onycholysis – Painful lifting of the nail plate from the nail not invade blood or
bed lymph vessels

Koilonychia – Fingernails have raised edges, sometimes Squamous cell carcinoma

called "spooning”; might be due to, Skin psoriasis

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 Second most common - Involve only the epidermis; may result in redness, pain,
type of skin cancer. and minor edema; caused by sunburn or brief
 Affects cells in the exposure to hot or cold objects
stratum spinosum and - Heals, usually within 7 days, without scarring
can appear as a wartlike
growth Second-Degree Burns
 A persistent, scaly red patch; an open sore; or an - Damages the epidermis and the dermis.
elevated growth with a central depression - very painful; nerve sensation still present.
 Have a variable tendency to metastasize.
- (Minor)
Melanoma  Causes redness, severe pain, edema, and blisters;
 Least common, but most  Healing takes approx. 2 weeks; no scarring results
deadly, type . - (Severe/ Deep-Partial Thickness)
 Malignant tumor of the  Wound may appear red, tan, or white;
skin originating from  May take several months to heal;
melanocytes  Might scar
 May need skin grafting
Melanoma can be detected by routine examination of the
skin and application of the ABCDE rule, which states the Full-Thickness Burns
signs of melanoma. Third-Degree Burns
- Epidermis and dermis are completely destroyed, and
deeper tissues may be involved.
- They make the skin white, blackened, yellowish, tan, or
brown.
- Pain is dramatically decreased because damage to the
sensation receptors on the main region of burn but
since 3rd degree burns are often surrounded with 1 st
and 2nd degree burns, the patient, most probably, will
feel severe pain.
- Skin can NOT heal; skin grafting is necessary.

Deep Full-Thickness
Fourth-Degree Burns
- All the layers are destroyed but it extends to the
muscles, bone, ligaments;
- All sensation of pain is gone.
- Appears black, charred with eschar
- >months to heal and needs skin grafting

Skin grafting – a surgical procedure that involves

removing skin from one area of the body and moving it, or
transplanting it, to a different area of the body.

Debridement - Medical treatment used to remove the

Burns dead tissue from burn
Burn is a tissue damage caused by excessive heat, cold,
electricity, radioactivity, or corrosive chemicals.

Degrees of Burns (depth of burn damage)

Partial-thickness
First-Degree Burns

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- Caused by a constant deficiency of blood flow to
Rule Of Nines tissues (usually on a bony prominence) due to
A calculation used to calculate the total body surface prolonged pressure that leads to tissue ulceration.
area (TBSA) burned for burns partial-thickness or greater.
 The percentage will determine treatment like fluid  Small breaks in the epidermis become infected, and
replacement and if the patient meets the criteria for the sensitive subcutaneous layer and deeper tissues
a burn unit. are damaged. Eventually, the tissue dies

 The body is broken down in areas and nines are - Occur most often in bedridden patients; Pressure
assigned to each area. ulcers, which lead to complications such as infection,
are easier to prevent than to treat.
Pressure Ulcer Stage
STAGE I
 Intact skin with
nonblanchable
redness of a localized
area usually over a
bony prominence
 Area may be painful,
firm, soft, warmer, or
cooler as compared to adjacent tissue

STAGE II
 Partial thickness loss of dermis presenting as a
shallow open ulcer with a red-pink wound bed,
without slough
 Intact or open/ruptured, serum filled blister.

Parkland’s Formula
Fluid treatment is essential for major burns.
 Calculates the amount of fluid (lactated ringers…
LR) needed 24 hours after a burn (this is the time STAGE III
the patient received the burn…. not arrived to you).  Full-thickness tissue loss.
 Give half of the solution for the first 8 hours, Subcutaneous fat may be
and then the other for the next 16 hours. visible, but bone, tendon,
 It is used for patients who have partial-thickness or muscle is NOT
(2nd degree burns) or higher. exposed.

To calculate the amount of LR needed 24 hours after a

burn using the Parkland’s Burn Formula: STAGE IV
Volume of Fluid needed (LR) =  Full-thickness tissue loss
4 mL x percentage of BSA x patient weight kilograms with exposed bone,
tendon, or muscle.
Pressure Ulcers  Slough or eschar may be
- Decubitus ulcers/ bedsores; present on some parts of
- Shedding of epithelium caused by a constant the wound bed
deficiency of blood flow to
tissues.

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