Integumentary System

SAP2. Students will analyze the interdependence of the integumentary, skeletal, and muscular systems as these relate to the protection, support and movement of the human body.

a. Relate the structure of the integumentary system to its functional role in protecting the body and maintaining homeostasis. EQ: What role does the integumentary system play in protecting the body and maintaining homeostasis?

Cutaneous Membranes Cutaneous – (skin); only epithelial membrane that is dry

Integumentary System Most roles are protective Helps maintain homeostasis Insulates body Keeps water and molecules in body Protects organs from bumps, cuts, etc.

Make-up of epidermis Epidermis has no blood supply (avascular) Most cells are keratinocytes Produce keratin (tough fibers which make skin tough but pliable)

Stratum Basale Basement membrane of epidermis Vascularized Constantly undergoing mitosis By the time cells reach the surface, they are dead.

Melanin Cells in stratum basale take in melanocytes (cells produce pigment) Melanin = body’s natural sunscreen

Dermis Layer directly beneath the epidermis Highly Vascularized Connective tissue

Make-up of Dermis Mostly collagen and elastic fibers Fibers bind with water and keep skin hydrated Fibers decrease with age, and skin sags

Deep to the Dermis Subcutaneous layer Also called hypodermis Adipose tissue Absorbs impact from bumps, protects organs; insulation

Skin Cancer Melanin serves to protect cellular DNA from ultraviolet light When damage is done to DNA, cancer can occur Basal Cell carcinoma (least malignant) Squamous cell carcinoma Melanoma – darkened blotches Cancer of the melanocyte

Papillary Layer Upper dermal region Protrusions into epidermis called dermal papillae Nourishes epidermis

Also in Papillary Layer Meissner’s corpuscles – sensory receptors (touch) Pain receptors Papillary pattern is genetic, and forms fingerprint

Reticular Layer Deep to papillary layer Contains blood vessels, sweat glands and oil glands. Phagocytes prevent bacterial intrusion

Sweat Glands Controlled by nervous system Two types 1) Eccrine 2)Appocrine

Sebaceous Glands Oil Glands Ducts usually empty into a hair follicle Secretes sebum Sebum keeps skin moist and pliable Also produces acidic compounds that kill bacteria

Problems with oil glands Clogged oil gland becomes whitehead As whitehead oxidizes, it becomes darker (blackhead) Acne – infection of oil gland Seborrhea- “cradle cap”