Science Olympiad-Anatomy and Physiology Integumentary System

Functions

Protection from injury
Protection against infection
Regulates body temperature
Regulates water loss
Chemical synthesis
Sensory perception

Epidermis

outermost layer of the skin composed of squamous cells. This layer is characterized into two distinct types: thick skin and thin skin.

Dermis

thickest layer of skin that lies beneath and supports the epidermis. Contains nerve tissue, blood vessels, etc.

Hypodermis (Subcutis/subcutaneous)

innermost layer of the skin that helps to insulate the body and cushion internal organs.

keratinocytes

90 % of epidermal cells are keratinized contains keratin (fibrous protein) protects and waterproofs the skin

Langerhans cells

Arise from red bone marrow and migrate to the epidermis -Constitute small portion of epidermal cells -Participate in immune responses Easily damaged by UV light

stratum corneum

(epidermal sublayer) top layer of dead, extremely flat cells. Cell nuclei are not visible.

stratum lucidum

(epidermal sublayer) thin, flattened layer of dead cells. Only contained in thick skin. (palms of hands and soles of feet)

stratum granulosum

(epidermal sublayer) rectangular-shaped cells that become increasingly flattened as they move to the surface of the epidermis.

stratum spinosum

(epidermal sublayer) polyhedral-shaped cells that flatten as they get closer to the stratum granulosum.

stratum basale (germinativum)

(epidermal sublayer) innermost layer of elongated columnar (column-shaped) cells. Consists of basal cells that produce new skin cells.

holocrine glands

glands that release entire cells filled with secretory products

sebaceous glands

produce globules of a fatty material that accumulates, causing the cells to swell and burst. The resulting mixture of fatty material and cellular debris is called sebum.

melanocyte

8% of the epidermal cells produces melanin, contributes to skin color, and absorbs UV light

Pacinian corpuscles

located deep within the reticular layer, are sensitive to deep pressure and vibrations.

Merkel cells

Least numerous of the epidermal cells Found in the deepest layer of the epidermis-Along with tactile discs, they function in sensation of touch

papillary layer

contains loose (areolar) connective tissue with a rich supply of blood capillaries. It also contains the nerve endings for touch and pain.

dermal papillae

part of the papillary layer of the dermis, finger-like projections that extend toward the epidermis, providing it with nutrients and oxygen plus being able to get nerve sensations through the epidermis.

reticular layer

layer of the dermis that lies below papillary layer. Contains dense irregular bundles of collagen, elastic and reticular fibers. These fibrous bundles blend into the papillary layer above and into the underlying subcutaneous layer.

nail root

portion of nail found under surface of skin

nail body

visible external portion of nail

nail matrix

source from which nails grow, surrounds nail root

eponychium

layer of epithelium that overlaps and covers the edge of the nail body

lunula

small white crescent near the root of the nail where the edge of the nail matrix may be seen

eccrine sweat glands (merocrine)

found in almost every region of the skin and produce a secretion of water and sodium chloride (which is delivered via a duct to the surface of the skin and is used to lower the body's temperature through evaporative cooling.)

Ceruminous glands

special exocrine glands found only in the dermis of the ear canals, produce a waxy secretion known as cerumen to protect the ear canals and lubricate the eardrum.

keratinization (cornification)

the process of keratin accumulating within keratinocytes.

apoptosis

programmed cell death where the cell digests its own nucleus and organelles, leaving only a tough, keratin-filled shell behind.

vasodilation

the process through which smooth muscle lining the blood vessels in the dermis relax and allow more blood to enter the skin. During hyperthermia draws heat away from core and lets it radiate through skin.

vasoconstriction

the process of smooth muscles in the walls of blood vessels in the dermis contracting to reduce the flood of blood to the skin. During hypothermia allows heat to stay near core.

melanin

a brown or black pigment produced by melanocytes to protect the skin from UV radiation

carotene

a pigment present in the skin that produces a yellow or orange cast to the skin and is most noticeable in people with low levels of melanin.

hemoglobin

the red pigment found in red blood cells, can be seen through the layers of the skin as a light red or pink color. Hemoglobin is most noticeable in skin coloration during times of vasodilation when the capillaries of the dermis are open to carry more blood to the skin's surface.

Lamellar corpuscles

found deep in the dermis, sense pressure and vibration of the skin.

cyanosis

bluish color in skin due to sustained reduction in blood supply to the skin. Hemoglobin in blood becomes depleted of oxygen and appears blue through the layers of skin.

vitiligo

In this condition an individual loses their melanocytes. It is thought to be due to an autoimmune disease in which the immune system mistakenly attacks and destroys the body's melanocytes.

Meissner's corpuscles

located within the dermal papillae, they respond to light touch.

Merkel's disks

specialized nerve endings found at the ends of nerve fibers. These disks are closely associated with the epidermal Merkel's cells and respond to fine touch.

Ruffini's corpuscles

located deep in the reticular layer where they respond to distortion or stretching of the skin.

medulla (hair)

the core of the hair made up of cells containing soft flexible keratin.

cortex (hair)

the outer portion of the hair containing hard keratin which stiffens the hair.

cuticle (hair)

a dead layer of cells on the surface of the hair.

hair shaft

(hair) begins at a point about midway between the papilla and the skin surface.

hair bulb

(hair) consists of the epithelium that surrounds the papilla. This structure is an invagination of the epidermis. Cells from the basal layer of this divide and are pushed up into the root of the hair.

hair papilla

(hair) a small clump of connective tissue, capillaries and nerves which supports the growth of the hair.

internal root sheath (hair)

immediately surrounds the hair root

external root sheath

(hair) contains all the cell layers of the epidermis

glossy membrane (hair)

a thickened basement membrane found at the base of the external root sheath.

arrector pili

small bands of smooth muscle which extend from the connective tissue sheath of the follicle and anchor in the papillary layer of the dermis.

hyponychium

epithelium of the nail bed

serous membranes

Line body cavities that have no opening to the outside and
secrete a watery fluid called serous fluid that lubricates surfaces.

mucous membranes

Line cavities and tubes that open to the outside

synovial membranes

Form the inner lining of joint cavities and secrete a thick fluid called synovial fluid

cutaneous membrane

also known as skin

thin skin

1-2 mm on most of the body and 0.5 mm in eyelids - Hairy; Covers all parts of the body except palms, soles; Thin epidermis and lacks stratum lucidum; Lacks dermal papillae; Has more sebaceous glands; Fewer sweat glands, sensory receptors than thick skin

thick skin

up to 6 mm thick on palms of hands and soles of feet; Hairless; Covers palms, and soles; Thick epidermis and a distinct stratum lucidum; Epiderma; ridges are present due to well-developed, numerous dermal papillae.; Lacks sebaceous glands, has more sweat glands; Sense receptors are also more densely packed

collagen fibers

make up 70% of the dermis and give structural toughness and strength

elastin fibers

are loosely arranged in all directions and give elasticity to the skin.

friction ridges

markings on fingertips characteristic of primates - allow us to manipulate objects more easily-fingerprints are friction ridge skin impressions

flexion lines

on flexor surfaces of digits, palms, wrists, elbows etc.- skin is tightly bound to deep fascia at these points

vellus hair

soft hair that covers most of the body in children and females

terminal hair

coarse, dark hair

Basale cell carcinoma

Least malignant. Most common. Cells of the S. basale are altered and can't form keratin, and no longer honor the boundary between epidermis and dermis. Cells proliferate, invading the dermis and the hypodermic.Occur in areas of the face and appear as shiny, dome-shaped nodules that later develop a central ulcer with a "pearly" beaded edge. Slow grower, seldom metastasizes. 99% cure rate with surgery.

Squamous cell carcinoma

Arises from keratinocytes in the S. spinosum. Lesions appear as a scaly reddened papule that gradually forms a shallow ulcer with a firm raised border. Appears most often on the scalp, ears, dorsum of the hands, and lower lip. Rapid growth and metastasizes to adjacent lymph nodes if not removed. Good cure rate if caught early; removed surgically or radiation therapy.

Malignant melanoma

Cancer of the melanocytes. Accounts for 5% of skin cancers; incidence increasing rapidly. Deadly. Begins wherever there is pigment. Most appear spontaneously. Appear as a spreading brown to black patch that metastasizes rapidly to surrounding lymph and blood vessels. Survival is poor, but early detection helps.

Boils

painful infection of hair follicles and sebaceous glands by Staphylococcus bacteria.

First degree burn

Damage to only the epidermis which results in redness, swelling, and pain

Second degree burn

The entire thickness of the skin is consumed resulting in the burned area appearing white, red, or blackened.

Third degree burn

Injury to the epidermis and the superficial region of the dermis resulting in redness, swelling, pain, and blisters