The integumentary system consists mainly of the skin which is the largest organ of the body. The skin protects the body from microorganisms, dehydration, and injury. It also regulates body temperature, protects against UV rays, and removes waste products from the body.
Other organs of the system include hair, nails, sebaceous glands, and sudoriferous glands.
Cutaneous membrane consists of:
- Epidermis (covers surface and protects underlying tissues)
- Dermis (nourishes the epidermis; provides strength; contains glands)
- Epidermis consists of (part – function):
- Stratum corneum (keratin) – where loss is prevented and, if unbroken, prevents the entry of water, pathogens, and most chemicals
- Stratum germinativum – where continuous mitosis produces new cells to replace worn surface cells
- Melanocytes – produce melanin (determines skin colour) which protects living skin layers from further exposure to UV rays
- Dermis consists of (part – function):
- Papillary layer – contains capillaries that nourish the stratum germinativum
- Hair follicles – includes eyelashes and nasal hair that keeps out dust and scalp hair that provides insulation from temperature extremes
- Nail follicles – protect the ends of fingers and toes from injury
- Receptors – detect changes felt by cutaneous senses (touch, pressure, heat, cold, pain)
- Sebaceous glands – produce sebum (oil) which prevents drying
- Ceruminous glands – produce cerumen (wax) which prevents drying of eardrum
- Sweat glands– produce watery sweat that controls body temperature by evaporating excess heat to cool the body. There are two kinds:
- Eccrine (merocrine) – located mainly in the axillae (arm pits), palms of the hand, soles of the feet, and forehead.
- Apocrine – associated with hair follicles and located mainly in the axillae and genital region.
- Arterioles – dilate in response to warmth to increase heat loss, constrict in response to cold to conserve body heat, and constrict in stressful situations to shunt blood to more vital organs.
- Cholesterol – converts to Vitamin D on exposure to UV rays.
Subcutaneous membrane consists of (part – function):
- Areolar connective tissue – connects skin to muscles – contains WBCs to destroy pathogens that enter breaks in the skin.
- Adipose tissue – contains stored energy in the form of true fats – cushions bony prominences and vital organs, and provides some insulation from the cold.
- Hair follicles– produces hair:
- Hair – provides sensation and some protection for the head
- Sebaceous glands – secrete oil that lubricates the hair
- Sweat glands – produce perspiration for evaporative cooling
- Nails – protect and stiffen tips of fingers and toes
- Sensory receptors – provide sensations of touch, pressure, temperature, and pain
Classification of Burns:
- First degree:
- Superficial cells of the epidermis are killed.
- Deeper layers of the epidermis and papilary dermis are injured.
- Skin becomes red and tender.
- Second degree:
- Superficial and deeper cells of the epidermis are killed.
- Dermis may also be affected.
- Reticular layer of the dermis may be injured, but many accessory structures can remain unaffected.
- Skin will be blistered and very painful.
- Third degree:
- All epidermal and dermal cells are killed.
- Hypodermal and deeper tissues and organs will be injured.
- Skin will be charred, with no sensation.
