Download The skin - It is heaviest and biggest organ of the body forms

The skin
- It is heaviest and biggest organ of the body forms approximately 16% of
body weight and it is 1.2 to 2.3 squared meters.
- The function of the skin is to:
1. Keep the body in homeostasis.
2. Provides boundaries for body fluids.
3. Protects underlying tissues from microorganisms.
4. Modulates body temperature.
5. Synthesize vitamin D.
- Skin layers:
1. The epidermis: is the most superficial layer, it is devoid of blood
vessels and has two layers:
a. An outer horny layer of dead keratinized cells.
b. An inner cellular layer where both melanin and keratin are formed.
It depends on the dermis for its nutrition.
2. The dermis: is well supplied with blood. It contains connective tissue,
sebaceous glands, sweat cells and hair follicles.
3. Subcutaneous tissue (adipose tissue).
- Hair, nails and sebaceous and sweat glands are considered appendages
of the skin.
- Adult has two types of hair:
1. Vellus hair: This is short, fine, inconspicuous and relatively
unpigmented.
2. Terminal hair: This is coarser, thicker, and more conspicuous and
usually pigmented e.g. scalp hair, eye brows.
- Nails protect the distal end of the fingers and toes.
- Nail plate: are firm, rectangular and usually curving. It gets its pink
colour from the vascular nail bed to which the plate is firmly attached.
- Lunula: is whitish moon and the free edge of the nail plate.
- Nail folds: they are either proximal or distal.
- Sebaceous glands: are present on all skin surfaces except the palms and
soles, they produce a fatty substance that is secreted onto the skin surface
through hair follicles.
- Sweat glands: are two types
1. Eccrine glands: are widely distributed, open directly onto the skin
surface and their sweat production help to control body temperature.
2. Apocrine glands: found chiefly in the auxiliary and genital usually
open into hair follicles and are stimulated by emotional stress. Bacterial
decomposition of apocrine sweat is responsible for adult body odder.
- The colour of normal skin depends primarily on four pigments:
1. Melanin: is the brownish pigment of the skin, it genetically
determined and is increased by sun light.
2. Carotene: is a golden yellow pigment that exists in subcutaneous
fat and in heavily keratinized areas such as palms and soles.
3. Oxyhemoglobin: is a bright red pigment, predominates in the
arteries and capillaries, increase result in redness and decrease
result in pallor.
4. Deoxyhemoglobin: a darker and some what bluer pigment, increase
result in bluish colour of skin known as cyanosis.
- Cyanosis: depending on oxygen level in the arterial blood.
1. Peripheral cyanosis occurs when cutaneous blood flow
decreases or slows. It may be a normal response to anxiety
or cold environment.
2. Central cyanosis: occurs when oxygen level is low.
- Common symptoms:
1. Hair loss.
2. Rash.
3. Moles.
- Examination of skin
1. Inspect skin in good light preferably natural light, artificial
lights often distorters colours.
2. Palpation
- Characteristics
1. Colour: look for change in colour e.g. increased pigmentation,
decreased pigmentation, redness, pallor, cyanosis, and
yellowing.
a. Redness: seen in finger nails, lips and mucous membranes
especially mouth and palpebral conjunctiva.
b. Peripheral cyanosis: seen in the nails and hands.
c. Central cyanosis: seen in the lips, oral mucosa and tongue.
d. Yellow colour of jaundice: seen in the sclera, palpebral
conjunctiva, lips, hard palate, under surface of tongue,
tympanic membrane and skin.
e. Yellow colour of high carotene: seen in palms, soles and face.
2. Moisture:
a. Dryness
b. Sweaty
c. Oiliness
3. Temperature: use back of your fingers
a. Generalized warmth
b. Generalized coolness
c. Localized warmth
4. Texture: roughness or smoothness
5. Mobility and turgor:
a. Decreased mobility
b. Decreased turgor
6. Lesions:
a. Anatomic location and distribution
b. Arrangement
c. The type of skin lesions
d. Colours
- Nails: inspect and palpate for colour, shape and lesions.
- Hair: inspect and palpate for quantity, distribution and texture.
- Skin lesions: look for type, location and distribution.