Integumentary System

• Cells no longer have nuclei or organelles.
• The integumentary system consists of the skin and accessory structures, such as hair, glands, and nails.
• Cells stain more lightly.
• Integument means covering.
• The appearance of the integumentary system can indicate physiological imbalances in the body.
• One of the major functions of the integumentary system is protection, as the skin is the covering of the body, providing protection against abrasion and ultraviolet light.
• The skin detects heat, cold, touch, pressure, and pain, which comes from the brain.
• The skin produces a molecule that can be transformed into vitamin D, an important regulator of calcium homeostasis, through exposure to ultraviolet light.
• The skin helps regulate body temperature through blood flow beneath the skin’s surfaces and the activity of sweat glands in the skin.
• The skin excretes small amounts of waste products through gland secretions and the loss of water through the skin.
• The skin is composed of two major tissue layers, the epidermis and the dermis.
• The epidermis is the superficial layer of the skin, consisting of stratified squamous epithelial tissue and rests on the dermis, a layer of connective tissue.
• The skin rests on the subcutaneous tissue, or hypodermis, a layer of loose connective tissue.
• The subcutaneous tissue is not part of the skin or the integumentary system, but it does connect the skin to underlying muscle or bone.
• The skin is the largest organ of the body, protecting our whole body.
• The skin weighs 9 lbs and covers an area of 2 square meters.
• The skin accounts for about 15% of body weight.
• The skin has an average of 300 million different cells.
• The skin is its thickest on the feet (1.4mm) and thinnest on the eyelids/blepharo (0.2mm).
• Changes in your skin can sometimes signal changes in your overall health.
• The skin renews itself every 28 days.
• The epidermis is the outer layer of skin and the first major skin region, composed of stratified squamous epithelium, where new cells are produced by mitosis.
• The stratum basale is the deepest layer of epidermis, a single layer of cells firmly attached to the dermis, and consists of cuboidal or columnar cells that undergo mitotic divisions about every 19 days.
• The stratum corneum is the outermost layer of epidermis, consisting of 20-30 layers of dead squamous cells filled with keratin, accounts for 75% of epidermal thickness, and is the layer that flakes off in dandruff.
• The stratum granulosum cells are flat and diamond shaped, accumulate more keratin and release the contents of the lamellar bodies to the extracellular space, and have a grainy appearance due to degeneration of cell’s nuclei and organelles, and the cells die.
• The stratum corneum acts as a waterproofing material that prevents fluid loss from the skin.
• The stratum lucidum is the 2nd outermost layer of epidermis, a thin, clear zone between the stratum granulosum and stratum corneum.
• Callus forms when stratum corneum has frequent friction or frequent usage, common location of callus is small toes, big toe, big toe joint.
• The most superficial layer of skin is the stratum corneum, a layer of epithelial tissue that rests on the dermis, where cells prevent water loss and resist abrasion.
• One daughter cell becomes a new stratum basale cell and can divide again.
• The epidermis consists of five strata: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.
• As new cells form, they push older cells to the surface, where they slough, or flake off.
• The stratum spinosum has a flattened appearance and accumulate lipid-filled vesicles called lamellar bodies.
• The skin constantly sheds dead cells, about 30,000 to 40,000 cells every minute.
• More than half of the dust in your home is actually dead skin.
• The skin is home to more than 1,000 species of bacteria.
• Skin that is severely damaged may try to heal itself by forming scar tissue, which is different from normal skin tissue because it lacks hair and sweat glands.
• The skin can form additional thickness and toughness — a callus — if exposed to repeated friction or pressure.
• Some of the nerves in your skin are connected to muscles instead of the brain, sending signals (through the spinal cord) to react more quickly to heat, pain, etc.
• The skin has at least five different types of receptors that respond to pain and touch.