Chapter 5 Integumentary System

Epidermis

the outermost layer of skin, part of the cutaneous membrane; consisting largely of stratified squamous epithelial cells

Dermis

part of the cutaneous membrane; located below the epidermis and consisting of the papillary and reticular layers

Subcutaneous tissue

Tissue, largely adipose tissue (with some areolar connective tissue), that lies directly under the dermis and serves as an insulator of the body.

Hypodermis

Aso called a subcutaneous layer, this is a layer of adipose tissue located under the dermis of the skin. The hypodermis helps to insulate the body and protects underlying muscles and other structures.

Keratinocyte

cell that is full of keratin and is the most predominant type of cell type found in the epidermis

Melanocytes

a mature melanin-forming cell, typically in the skin.

Melanin

a dark brown to black pigment occurring in the hair, skin, and iris of the eye in people and animals. It is responsible for tanning of skin exposed to sunlight.

Dendritic Cells

specialized white blood cells (similar to a macrophage) that patrol the body searching for foreign antigens that produce infections

Skin

cutaneous membrane

Stratum Basale/Germinativum

the deepest layer of the epidermis consisting of stem cells capable of undergoing cell division to form new cells

Stratum Spinosum

The spiny layer (8-10 cells thick) just above the stratum germinativum/basale layer. Comprised of keratinocytes.

Stratum Granulosum

a layer of the epidermis that marks the transition between the deeper, metabolically active strata and the dead cells of the more superficial strata

Stratum Lucidum

a clear, transparent layer of the epidermis found only in the thick skin of the fingers, palms, and soles

Stratum corneum

the most superficial layer of the epidermis consisting of dead, squamous keratinized cells

Papillary dermis

layer of dermis directly under the epidermis; consists f areolar tissue; rich in capillaries

Friction ridges

markings on the fingertips that leave distinctive oily fingerprints on surfaces we touch

Reticular Dermis

dense irregular connective tissue; deep layer of dermis

Cleavage lines

Collagen and elastic fibers in the dermis
Arranged in parallel bundles to resist force in a specific direction - directions in which the skin is most resistant to stretch

Skin appendages

include nails, sweat glands, sebacous (oil) glands, and hair follicles and hair.

Hair/pili

flexible strands produced by hair follicles and consist largely of dead, keratinized cells; primary functions are protection, reduction of heat loss, and sensing touch

Hair follicle

a small tubular cavity containing the root of a hair

Hair bulb

Lowest part of a hair strand; the thickened, club-shaped structure that forms the lower part of the hair root.

Arrector pili

a smooth muscle attached to hair follicles that causes "goose bumps" to appear on the skin when contracted

Vellus hair

pale, fine body hair of children and adult females

Terminal hair

coarse, long pigmented hair of eyebrows, scalp, axillary, and pubic regions

Nail matrix

the part of the nail beneath the body and root from which the nail is produced

Nail folds

Folds of normal skin that surround the natural nail plate

cuticle/eponychium

The small fold of skin above the lower part of the nail

Hyponychium

Slightly thickened layer of skin that lies between the fingertip and free edge of the natural nail plate.

Sweat glands

The glands that secrete sweat, located in the dermal layer of the skin. Two types eccrine and apocrine

Sudoriferous glands

glands that secrete sweat to the outside of the body; also assist in body temperature regulation; found in the dermis all over the entire body

Eccrine sweat glands

Secreting glands found all over the body and respond primarily to elevated body temperature; are far more numerous and are abundant on palms, soles of feet and forehead. Each is a simple, coiled, tubular gland. Ducts connect to pores. Sweat: 99% water, NaCl, antibodies, dermcidin and metabolic wastes.

Apocrine sweat glands

Found in armpits, around nipples, and groin; Secrete products into hair follicles; Produce sticky, cloudy secretions; Products are broken down by bacteria and cause odours;

Ceruminous glands

modified sweat glands, located in external ear canal, secretes cerumen (earwax)

Mammary glands

Specialized organs in mammals that produce milk to nourish the young

Sebaceous glands

secrete sebum (oil) into the hair follicles where the hair shafts pass through the dermis

sebum

oily substance secreted by sebaceous glands

Acid mantle

low pH of skin inhibits bacterial multiplication

Cutaneous sensory receptors

Receptors located throughout the skin that respond to stimuli (including touch, temperature and pain) arising outside the body; part of the nervous system.

Basal cell carcinoma

Most common and least severe type of skin cancer; malignant tumor of the basal cell layer of the epidermis

Squamous cell carcinoma

malignant tumor of the squamous epithelial cells in the epidermis; Type of skin cancer more serious than basal cell carcinoma; often characterized by scaly red papules or nodules.

Melanoma

The most serious form of skin cancer

First degree burns

only epidermis is damaged, skin is red and swollen

Second degree burns

epidermis and upper dermis are damaged, skin is red with blisters

Third degree burns

Third-degree burns are a type of burn in which the entire thickness of the skin is destroyed, regeneration is not possible, the skin is gray and blackened, and must be treated by skin grafts. It is significant because it can be harmful to the body.

Ulcer

open sore or lesion in the skin or mucous membrane

Eczema

Noncontagious skin rash that produces itching, blistering, and scaling

Albinism

congenital hereditary condition characterized by partial or total lack of pigment in the skin, hair, and eyes

Dermatitis

inflammation of the skin

Vitiligo

white patches on the skin caused by the destruction of melanocytes associated with autoimmune disorders

Dermis: Papillary Layer

The papillary layer consists of areolar connective tissue. It supplies nutrients to select layers of the epidermis and regulates temperature. Both of these functions are accomplished with a thin, extensive vascular system that operates similarly to other vascular systems in the body.

Dermis: Reticular Layer

Comprised of dense irregular connective tissue
Contains:
-Blood vessels
-Glands
-Nerve receptors

Pacinian (lamellated) corpuscles

sensory nerve endings that are sensitive to deep pressure and vibration

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.

Thermoreceptors

Sensory nerve endings under the skin that respond to changes in temperature at or near the skin and provide input to keep the body's temperature at 37 degrees Celsius.

Ruffini corpuscles

sensory nerve receptors in the reticular region that detect stretching sensations

Tactile corpuscles (Meissner's corpuscles)

Located in dermal papillae; small egg-shaped; just beneath the epidermis; sensory nerve receptors that detect light pressure, discriminative touch, vibration

merocrine secretion

product is released from secretory vesicles by exocytosis

holocrine secretion

release of a substance caused by the rupture of a gland cell, which becomes part of the secretion; e.g. sebum

apocrine secretion

release of a substance along with the apical portion of the cell

Rickets disease

faulty mineral deposit in bones of children due to a vitamin D deficiency. This results in soft, deformed bones, bowed legs.

calcitonin

Lowers blood calcium levels; produced by the thyroid gland

parathyroid hormone

A hormone of the parathyroid gland that regulates the metabolism of calcium and phosphorus in the body. Increases blood calcium levels.

epidermal ridges and dermal papillae

Connective tissue protrusions between epidermis and dermis. These give rise to fingerprints.