Integumentary System
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.
This page was updated in November 2005.
