Integumentary and Lymphatic System Vocabulary

Comprehensive vocabulary flashcards covering key definitions, cell types, tissue layers, and organs of the integumentary and lymphatic systems.

Integumentary System

The largest organ system, derived from the Latin "integumentum" (meaning a covering), which comprises the skin, pigments, exocrine glands, hair, nails, and specialized nerve receptors, making up about $16\%$ of human body weight.

Melanin

Skin pigments produced by melanocytes that absorb and reflect the sun's harmful ultraviolet radiation and determine skin, hair, and eye color.

Mantle

A heavy fold of tissue surrounding a mollusc's internal organs that secretes a hard shell made of calcium carbonate.

Exoskeleton

A strong, impermeable external body covering in arthropods composed of layers of protein and the polysaccharide chitin.

Chitin

A tough polysaccharide that, along with protein layers, forms the exoskeleton of arthropods such as spiders, insects, lobsters, and shrimp.

Periderm

Plant tissue containing cork cells that replaces the epidermis in stems and roots when a plant grows in diameter, forming a waterproof outer covering.

Epidermis

The outermost layer of skin composed of stratified squamous epithelium, ranging in thickness from approximately $0.3\,mm$ on eyelids to $1.5\,mm$ on palms and soles.

Stratum Basale

The deepest layer of the epidermis resting on the basement membrane, consisting of a single layer of columnar or cuboidal stem cells that replenish superficial layers.

Stratum Spinosum

An epidermal layer consisting of spiny prickle cells that interlock to support the skin.

Stratum Granulosum

The thin middle layer of the epidermis that initiates keratinization.

Stratum Lucidum

An epidermal layer consisting of several layers of flattened dead cells, found only in thick, frequently used areas such as the palms of the hands and soles of the feet.

Stratum Corneum

The thick outermost layer of the epidermis containing rows of dead cells filled with soft keratin to maintain elasticity and prevent drying out.

Keratinocytes

Cells that comprise approximately $90\%$ of all epidermal cells and produce keratin to waterproof and protect the skin.

Melanocytes

Cells comprising approximately $8\%$ of epidermal cells that produce melanin pigments responsible for skin, hair, and eye color.

Langerhans Cells

Epidermal cells arising from bone marrow that process antigens to assist in the body's immune response.

Merkel Cells

Sensory cells located in the deepest regions of the epidermis that associate with sensory neurons for touch reception.

Dermis

Known as the "true skin," this layer beneath the epidermis consists of collagen, reticular fibers, and elastic fibers.

Reticular Layer

The deep layer of the dermis containing criss-crossing collagen fibers that form Langer's lines, as well as Pacinian corpuscles, sweat glands, hair follicles, and lymph vessels.

Papillary Layer

The dermal layer directly beneath the epidermis that connects to it via papillae and contains capillaries and Meissner's corpuscles.

Pacinian Corpuscles

Sensory receptors located in the reticular layer of the dermis that detect deep pressure.

Meissner's Corpuscles

Sensory touch receptors located within the papillae of the dermal papillary layer.

Hypodermis

Also known as subcutaneous tissue, this layer consists mostly of connective tissue and adipose cells, storing up to half of the body's fat and attaching skin to underlying bones and muscles.

Hair Bulb

The expanded base of the hair root located beneath the surface of the skin.

Lunula

The whitish, semilunar area located at the proximal end of the nail body.

Eponychium

Also known as the cuticle, a narrow band of epidermis extending from the lateral border of the nail wall.

Nail Matrix

Epithelial tissue deep to the nail root where actual nail growth occurs.

Sebaceous Glands

Oil glands located in the dermis and connected to hair follicles that secrete oily sebum to lubricate skin and hair and hinder bacterial growth.

Eccrine Sweat Glands

Also known as merocrine sweat glands, these simple coiled tubular glands open directly onto skin pores to excrete sweat for temperature regulation and are most numerous on palms and soles.

Apocrine Sweat Glands

Compound coiled tubular glands that open into hair follicles superficial to sebaceous gland openings.

Ceruminous Glands

Cutaneous glands located in the ear canal that produce earwax.

Uropygial Glands

Also known as preening glands, these are specialized glands in birds that produce secretions to repel water from feathers.

Lymphatology

The scientific study of the lymphatic system.

Lymph

A colourless, mobile fluid connective tissue derived from intercellular tissue fluid, containing a fluid plasma matrix and leucocytes.

Thoracic Duct

A major lymphatic trunk arising from the receptaculum chyli that drains lymph from the entire body except the right side of the head, neck, thorax, and right arm, emptying into the left subclavian vein.

Right Lymphatic Duct

The lymphatic vessel that drains lymph from the right side of the head, neck, thorax, and right arm, emptying into the right subclavian vein.

Receptaculum Chyli

An abdominal sac into which intestinal lacteals empty and from which the thoracic duct arises.

Lacteals

Lymphatic vessels of the intestine that absorb fats, giving the transported fluid a milky appearance.

Lymphatic Nodes

Capsule-wrapped masses of reticular tissue along lymphatic vessels that filter lymph, entrap foreign microbes, and add lymphocytes and antibodies to the fluid.

Spleen

The largest organ of the lymphatic system, measuring $7 - 10\,cm$ in diameter, which serves as a reservoir for red blood cells, produces antibodies, and phagocytizes worn-out erythrocytes.

Red Pulp

Vascular reticular tissue within the spleen rich in red blood cells where free and fixed macrophages destroy worn-out erythrocytes.

White Pulp

Small patches of lymphatic nodules scattered throughout the red pulp of the spleen.

Thymus

A lymphatic organ in the upper chest near the neck that "educates" foetal lymphocytes to distinguish self cells from foreign cells.

Tonsils

Lymphatic tissues located in the throat that protect against infection without filtering lymph.