BIO10004 Week 3.1 - The Integumentary System

Flashcards based on Dr. Greg Davis's lecture on the integumentary system, covering epidermis, dermis, hypodermis, skin color, hair, glands, nails, injury repair, and aging effects.

Integumentary System

Largest system of the body, approximately sixteen percent of body weight.

Two major parts of the Integumentary System

Cutaneous membrane (skin) and accessory structures.

Components of the cutaneous membrane

Outer epidermis (superficial epithelium) and inner dermis (connective tissues).

Accessory structures of the integument

Hair and hair follicles, exocrine glands, and nails.

Functions of the integument

Protection, excretion, temperature maintenance, melanin/keratin production, vitamin D3 synthesis, lipid storage, and sensory detection.

Epidermis

Stratified squamous epithelium.

Keratinocytes

The body’s most abundant epithelial cells, containing large amounts of keratin.

Thin skin

Covers most of the body and has four layers of keratinocytes.

Thick skin

Covers the palms of the hands and soles of the feet and has five layers of keratinocytes.

Five strata (layers) of keratinocytes in thick skin (from basement membrane to free surface)

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum.

Dermis

Located between epidermis and subcutaneous layer; anchors epidermal accessory structures.

Two components of the dermis

Outer papillary layer and deeper reticular layer.

Papillary layer

Consists of areolar tissue and contains capillaries, lymphatic vessels, and sensory neurons. Includes dermal papillae.

Reticular layer

Consists of dense irregular connective tissue and contains collagen and elastic fibers.

Tension lines (cleavage lines)

Produced by parallel bundles of collagen and elastic fibers in the dermis; resist forces applied to skin.

Two pigments in the epidermis that influence skin color

Melanin and carotene.

Melanin

Red-yellow or brown-black pigment produced by melanocytes.

Carotene

Orange-yellow pigment found in orange vegetables.

Accessory structures of the integument

Hair, hair follicles, sebaceous and sweat glands, and nails.

Sebaceous glands (oil glands)

Holocrine glands that discharge lipid secretion (sebum) into hair follicles.

Two types of sweat glands

Apocrine and Eccrine.

Apocrine sweat glands

Glands found in armpits, around nipples, and in pubic region; secrete products into hair follicles via merocrine secretion.

Eccrine (merocrine) sweat glands

Coiled, tubular glands that discharge directly onto skin surface (sensible perspiration).

Other integumentary glands

Mammary glands (produce milk) and ceruminous glands (produce cerumen/earwax).

Nails

Protect tips of fingers and toes and are made of dead cells packed with keratin.

Nail body

Visible portion of the nail that covers the nail bed.

Nail production

Occurs in an epidermal fold called the nail root

Repair of the integument following an injury

Bleeding, swelling, and pain; mast cells trigger inflammatory response; scab forms; macrophages clean area; fibroblasts and endothelial cells produce granulation tissue.

Effects of aging on skin

Epidermis thins, dendritic cells decrease, vitamin D3 production declines, melanocyte/glandular activities decline, blood supply reduces, hair follicle function declines, dermis thins, repair rate slows.