Integumentary System: Functions, Skin Structure, and Accessory Organs

Protection

Protects the body.

INTRAEPIDERMAL MACROPHAGES

Protects from bacteria (microbial invaders).

MACROPHAGES IN THE DERMIS

Second line of defense of the body found in the dermis.

CUTANEOUS SENSATIONS

Detects sensations of the body (heat, cold, pain); sensation is detected in nerve endings (found in dermis).

SYNTHESIS OF VITAMIN D

Production of vitamins in the body through ultraviolet ray (UV); calcitriol produced by the kidney and liver.

THERMOREGULATION

To regulate the internal temperature of the body (by sweating, adjusting the flow of blood).

EXCRETION & ABSORPTION

Elimination of substances from the body; absorbs materials to deliver in body cells.

BLOOD RESERVOIR

Blood vessels serve as storage for blood.

SKIN

The integumentary system.

Epidermis

Seen with the naked eye, composed of stratified squamous epithelium.

Keratinocytes

Produce keratin.

Melanocytes

Produce melanin, responsible for the color of skin.

Langerhans cells

Participate in immune response but can be easily damaged by UV.

Merkel cells

Found in the deepest layer of epidermis (stratum Basale); responsible for sensation of touch.

THICK SKIN

Up to 6mm thick, has 5 to 6 layers of epidermis (sole, palm), hairless.

THIN SKIN

Only has 4 layers of epidermis, 1-2 mm thick, found most of the body.

STRATUM BASALE

Deepest layer where production of new cells occurs.

STRATUM SPINOSUM

Provides strength and flexibility to the skin; contains intraepidermal macrophages.

STRATUM GRANULOSUM

Contains granules, creates a barrier to water, has lipids that block water.

STRATUM LUCIDUM

Present only in thick skin; provides additional toughness.

STRATUM CORNEUM

Constantly in the process of flaking off; serves as protection exposed to the environment.

KERATINIZATION

Formation of new cells in stratum Basale.

DANDRUFF

Excessive number of keratinization.

PSORIASIS

Keratinocytes divide and move more quickly to the surface (7-10 days).

SKIN GRAFT

Unable to produce new cells.

DERMIS

Beneath the epidermis, thick layers, has the ability to stretch and return to shape (collagen, elastic fibers).

PAPILLARY REGION

Thinner, has capillaries, has dermal ridges.

MEISSNER CORPUSCLE

Contains nerve endings that are sensitive to touch.

RETICULAR REGION

Thicker, contains hair follicles, nerves, sebaceous glands, etc.

RETICULAR LAYER

Resists stretching.

STRETCH MARKS

Internal scarring.

EPIDERMAL RIDGES

Patterns of loops and whorls that increase grip.

TENSION LINES & SURGERY

Also known as cleavage lines; important for plastic surgeons.

HYPODERMIS

Attaches the skin to the organs and tissues; composed of adipose tissues (provides insulation).

SUBCUTANEOUS LAYER

Not a layer of skin; attaches the dermis to the muscles; contains fat cells.

FREE NERVE ENDINGS

Perceive touch, pressure, and pain.

MERKEL DISK

Sensitive to sustained pressure and fine details; located in the epidermis.

MEISSNER'S CORPUSCLE

Located in dermal papule; sensitive to light touch and low frequency vibration.

RUFFINI ENDINGS

Found in the dermis and subcutaneous tissue; respond to skin stretching and sustained pressure.

PACINIAN CORPUSCLE

Located in deeper dermis; sensitive to deep pressure and high frequency vibration.

SKIN PIGMENTS

Contribute to skin color.

BLOOD CIRCULATION

Affects skin color.

MELANIN

Produce by melanocyte, protects us from UV.

PHEOMELANIN

Yellow and red color skin.

EUMELANIN

Brown to black color.

FRECKLES

Patches on face.

AGE SPOTS

Range in color, flat blemishes.

NEVUS (MOLE)

Round flat and overgrown of melanocytes.

ALBINISM

Cause by mutation of TRP-1 gene (can't produce Tyrosinase).

OCULOCUTANEOUS ALBINISM

Affects skin, hair, and eyes.

CUTANEOUS ALBINISM

Poor vision, and repetitive and uncontrolled eye movements.

VITILIGO

Some parts of skin that are different color or pigment, often appears at age 20, autoimmune in nature.

CAROTENE

Orange pigment precursor of vitamin A.

HEMOGLOBIN

Oxygen carrying pigment in red blood cells.

CYANOSIS

Oxygen is low and may appear as bluish skin.

JAUNDICE

Yellowish appearance due to buildup of bilirubin.

ERYTHEMA

Redness of skin caused by engorgement or inflammation.

PALLOR

Paleness of skin.

TATTOOING

Foreign pigment.

BIRTHMARKS

Caused by the overgrowth of cells that create pigments.

HAIR SHAFT

Projects from skin surface.

HAIR ROOT

Penetrating the dermis, composed of medulla, cortex, and cuticle.

HAIR BULB

Houses the papilla that contains the blood vessels.

HAIR MATRIX

Responsible for hair growth.

ARRECTOR PILI MUSCLE

Responsible for goosebumps.

HAIR ROOT PLEXUS

Sensitive to touch.

LANUGO

Produced by the hair follicles in the fifth month of development.

TERMINAL HAIR

Replaces lanugo, heavily pigmented.

VELLUS HAIR

Covers the rest of the body, can turn into terminal hair.

GROWTH STAGE (ANAGEN)

Thickening and growth of hair.

REGRESSION STAGE (CATAGEN)

Shrinks of hair or hair loss.

RESTING STAGE (TELOGEN)

Stops hair growth but reproduces again after, lasts 5 to 6 weeks.

ANDROGENIC ALOPECIA

Androgens (hormones) that stop hair production.

ALOPECIA AREATA

Autoimmune disease that attacks hair to stop hair growth.

HIRSUTISM

Excessive body hair in areas that do not usually have hair.

DARK COLOR HAIR

Have more eumelanin.

GRAY HAIR

Have pheomelanin.

BLONDE & RED HAIR

Decline in melanin production.

WHITE HAIR

Lack of melanin, have air bubbles in the shaft.

SUDORIFEROUS GLAND

Produce sweat.

ECCRINE SWEAT GLAND

Secretes cooling sweat, helps body temperature, includes insensible perspiration.

APOCRINE SWEAT GLANDS

Produce milky and yellowish sweat during emotional stress and sexual activity.

SEBACEOUS GLAND

Produce oil, found in the skin where hair is present.

CERUMINOUS GLAND

Produce ear wax or cerumen, providing a barrier.

NAIL ROOT

Not visible to the naked eye.

EPONYCHIUM

Cuticle, stratum corneum of nail.

LUNULA

Little moon, white part of nail.

NAIL BED

The skin below the nail plate.

NAIL BODY

Visible portion of the nail.

FREE EDGE

The white part at the edge of the nail.

HYPONYCHIUM

Connects the nail and the skin, under the free edge.

NAIL MATRIX

Responsible for nail growth.

BEAU LINES

Dents in nail, caused sometimes by infection or diseases.

NAIL CLUBBING

The tips of the fingers become enlarged.

MUEHRCKE'S LINE

Horizontal white lines on the nail.

MEES' LINES

White lines or bands on the nail.