Transcript Integumentary system notes

Integumentary System
• Dermatology – the branch of medicine that
specializes in diagnosing and treating skin
disorders.
• Integumentary system includes – skin, hair and
nails. It is the largest organ of the body in
surface area and weight! Adults – covers an area
of about 2 square meters and weighs about 1011 lbs
Epidermis
• Composed of keratinized stratified squamous
epithelium.
• Outermost region of the skin
• 4 types of cells
• Keratinocytes
• Melanocytes
• Langerhans cells
• Merkel cells
Epidermis
1. Keratinocytes – produce keratin, which is a tough,
fibrous protein that helps protect the skin and
underlying tissues from heat, microbes, and chemicals.
They also release a water-repellent sealant.
2. Melanocytes – produce the pigment melanin, which
gives us our skin color and absorbs damaging UV light.
Melanocytes are particularly susceptible to damage by
UV light!
Epidermis
3. Langerhans cells – participate in immune
responses against microbes that invade the
skin. Langerhans are easily damaged by UV
light.
4. Merkel cells – involved in the process of
sensory neurons (nerve cells). They detect
touch sensations.
Dermis
• 2nd layer – composed of connective tissue containing
collagen and elastic fibers
• In the superficial part of the dermis there are papillae
that contain tactile receptors called Corpuscles of
touch or Meissner corpuscles. These are sensitive to
touch!
Dermis
• In the deeper part of the dermis is adipose cells, hair
follicles, nerves, oil glands and sweat glands and
blood vessels.
• Collagen and elastic fibers give it strength, the ability
to stretch, and elasticity (ability for it to return to the
original shape.
• Extreme stretching may produce tears in the dermis
causing stretch marks.
Dermis
• Albinism – is the inherited inability of a person to produce melanin.
Most albinos do not have melanin in their hair, eyes, and skin.
• Freckles – accumulation of melanin in patches
• Hair
• Primary function is protection
• Present on most skin surfaces except the palms, fingers, soles of
feet and toes.
• Hair on your head guards the scalp from injury and the suns rays,
eyebrows and eyelashes protect the eyes from foreign particles
and hair in the nostrils protects against inhaling particles
Dermis
• Hair continued
• Shaft – superficial portion
• Root – below the surface
and penetrates into the
dermis
• Hair follicle – surrounded
by nerve endings,
sensitive to touch. At the
base of each follicle is the
bulb (onion shaped).
Dermis
• Arrector pili – smooth muscle that is attached to the side of the hair
follicle. Under stress, such as cold, or fright, nerves stimulate the
muscles to contract, which pulls the hair shafts perpendicular to the
skin surface…..creating “goose bumps”.
• The color of your hair is due to melanin. Gray hair occurs with a
decline in the synthesis of melanin.
• Androgenic alopecia or male-pattern baldness – genetically
predisposed inhibiting hair growth.
Glands
• Sebaceous glands – oil glands are connected with hair
follicles. They secrete an oily substance called sebum which
keeps hair from drying out, prevents excessive evaporation
of water from the skin, keeps the skin soft and inhibits the
growth of certain bacteria.
• When sebaceous glands become enlarged, blackheads
develop because the sebum is nutritive to certain bacteria
and pimples result. The color is due to melanin and oxidized
oil, not dirt! Sebaceous gland activity increases during
adolescence. Acne may result.
Glands
• Sudoriferous Glands – sweat glands, produce
perspiration
• Eccrine sweat glands – distributed throughout the
skin, located in the dermis. The sweat produced is
mainly to help regulate body temperature through
evaporation.
• Apocrine sweat glands – mainly in the axilla
(armpit), they open to hair follicles, do not begin to
function until puberty
Nails
• Plates of tightly packed, hard, dead, keratinized
cells of the epidermis
• Nail body – is the portion of the nail that is
visible
• Lunula – whitish semilunar area near the nail
root
• The average growth of fingernails is about 1 mm
per week
Functions of the skin
• Body temperature regulation – contributes to the
homeostatic regulation of body temperature by liberating
sweat and adjusting the flow of blood in the dermis
• Protection – protects underlying tissue, microbes, heat,
abrasion
• Cutaneous sensations – tactile sensations, touch, pressure,
warmth, coolness
• Synthesis of Vitamin D – exposure to UV radiation activates
production of Vitamin D
Aging
• Langerhans cells dwindle – decreasing immune
responses
• Sebaceous glands decrease – skin and hair more dry
• Gray hair – less melanocytes, atypical skin
pigmentation
• Dermis becomes thinner causing wrinkles
• Hair and nails grow slower, nails become brittle
Skin cancer
• Basal cell carcinoma – most common type of skin
cancer
• Melanoma – can metastasize and spread to other
organs
• ABCD of skin cancer
• A – asymmetry
• B – border
• C – color
• D - diameter
Burns
• 1st degree – involves only the epidermis
• 2nd degree – destroys a portion of the epidermis
and part of the dermis
• 3rd degree – destroys the epidermis, the
underlying dermis, and subcutaneous layer
Pressure ulcers
• Bed sores – prolonged pressure against an object
such as a bed, cast, or splint
Terms and conditions
• Athletes foot – a superficial fungus infection of the
skin of the foot
• Cold sore – a lesion, usually in the mouth area, caused
by type 1 herpes simplex virus. Can be triggered by UV
light, hormonal changes, and emotional stress. Also
called a fever blister
• Pruritus – itching of the skin
• Topical – refers to a medication applied to the skin
surface rather than ingested or injected