Please Note: There are sub pages for the the Integumentary System which are: Clinical Views & Case Study, Fun Facts & In the News, & Integument System Review.

Learning Objectives

• Gain knowledge of the skin and its derivatives
  
• Become familiar with the function and structures of the Integument System
  
• Identify skin abnormalities, conditions and disorders
  

Notes, Pictures and Videos

An Introduction to the Skin describes the anatomy of the integumentary system through a series of photomicrographs.

The integumentary system is made of the largest organ called "skin". It is made up of multiple layers of epithelial cells that protect underlying muscles and organs. Could you image everyone walking around without skin?
The skin has TWO main layers the Epidermis, Dermis. Not included as part of the skin but often discussed with the two main layers is the Subcutaneous or fat layer deep to the Dermis.

Animated illustration of skin anatomy


Epidermis (outer portion of the skin consisting of 4-5 layers)
Stratum Basale: This is the layer of skin attached to the dermis, it is continually multiplying the cells are pushed upward, and it looses nutrients and oxygen and dies, it take 6-8 weeks to complete this process. Stratum Spinosum: This layer is formed by many-sided keratinocytes attached by spine-like projections. Stratum Granulosum: This layer consist of 3-5 layers of keratinocytes, in this layer keratinocytes begin to die. Stratum Lucidum: This layer consists of 2-3 layers of dead, flat cells. This Layer is only found on the soles of the feet, the palms of the hands and the lips of the mouth. Stratum Corneum: This layer consists of 20-30 layers of flattened, dead, scale-like cells which are continually shed.Mnemonic for remembering the Epidermis layers from the deepest to the surface layer is: Come, Let's, Get, Sun, Burned-C, L, G, S, B.-(Stratum) Corneum, Lucidum, Granulosum, Spinosum, Basale.Animated photomicrograph of epidermis
Dermis (deeper and thicker than the epidermis)

• Papillary Layer (stratum papillarosum): This is the upper layer which is in contact with the epidermis. This layer contains dermal papillae and epidermal ridges. The dermal papillae have capillaries that supply cells of the epidermis. The papillae also house sensory receptors that continuously monitor touch on the surface of the epidermis.
  
  
  
• Reticular Layer (stratum reticularosum): This layer is between the papillary and subcutaneous layers. It is where most of the structures of the dermis are located, such as hair follicles, sebaceous and sweat glands, nerves, and blood vessels. It's mesh work of collagen and elastic fibers gives the skin it's strength and elasticity and contribute to physical characteristics such as stretch marks and wrinkles. These fibers also make up the skin's lines of cleavage (or tension lines) which are surgically significant.
  

• Nails: They are scale-like modifications of the epidermis that protect the tips of the fingers and toes.
  

They are hard derivatives from the stratum corneum layer that are densely packed with parallel fibers of hard keratin.

• Hair: Although, a single hair extends deep into the dermis and at times into the subcutaneous layer, it is produced by the epidermal layer.
  
• It's swelling base with epithelial cells is called the "bulb".
  
  
• It originates at the base of the epithelial cell lined "follicle" which surrounds the hair.
  
  
• The remainder of the hair within the follicle is called the "root" that is pushed upward as cells divide, become keratinized, and die.
  
  
• The portion of the hair that extends beyond the skin surface is called the "shaft" which is composed of dead keratinized cells.
  

• Glands: see below
  

Type	Products Secreted/Description
Sweat (Sudoriferous)Glands
Apocrine Glands	Most superficial layer of epidermis; 20-30 layers of dead, flattened, anucleate, keratin filled karatinocytes, called corneocytes
Merocrine Glands	Produce non-viscous, watery secretion. Controlled by nervous system. Provides some antibacterial protection. Functions in thermo regulation and excretion. Flushes surface of epidermis.
Sebaceous Glands	Lipid material called sebum; coats epidermis and shaft of hair. Also Lubrication and antibacterial activity
Other Glands
Mammary Glands	Milk to nourish offspring
Ceruminous Glands	Cerumen (ear wax)

Animated illustration of hair formation

Functions of Skin	Functions of Hair
Protection Prevention of water loss Temperature regulation Metabolic regulation Sensory receptors Excretion by means of secretion Vitamin D synthesis. Getting plenty of vitamin D — more than diet can offer — appears to provide potent protection against colds, flu and even pneumonia, a new study reports. Produce melatonin Produce keratinocytes	Protection Heat retention Facial expression Sensory receptors Visual identification Chemical signal dispersion (pheromones) Heighten attractiveness

Animated illustration of body temperature regulation


The elements of the integumentary system demonstrate an astounding capability to respond to stresses and damage as explained below.

Affect	Example	Action	Result	Example
Stresses	Walking about without shoes	Stratum basale stem cells stimulate mitotic activity; thickening of the epidermis occurs	Improved ability to withstand stress; more protection for the underlying tissues	Tough and/or callused soles of feet
Minor damage	Superficial wound	Regeneration: epithelial cells at edge of wound divide replacing damaged/dead cells with the same cell type	Organ structure and function is restored	No scar
Major damage	Deep wound	Fibrosis: fibroblasts from surrounding margins of wound fill in the gap with tissue composed of collagen fibers	Partial organ structure is restored but organ function is not restored	Scar

Phases of Wound Healing
The entire wound healing process is a complex series of events that begins at the moment of injury and can continue for months to years. This overview will help in identifying the various stages of wound healing.
(a) Inflammatory Phase
1. Immediate to 2-5 days
2.Hemostasis

• Vasoconstriction
  
• Platelet aggregation
  
• Thromboplastin makes clot
  

3. Inflammation

• Vasodilation
  
• Phagocytosis
  

(b) Proliferative Phase
1. 2 days to 3 weeks
2. Granulation

• Fibroblasts lay bed of collagen
  
• Fills defect and produces new capillaries
  

3. Contraction

• Wound edges pull together to reduce defect
  

4. Epithelialization

• Crosses moist surface
  
• Cell travel about 3 cm from point of origin in all directions
  

(c) Remodeling Phase
1. 3 weeks to 2 years
2. New collagen forms which increases tensile strength to wounds
3. Scar tissue is only 80 percent as strong as original tissue
Eventually, all components of the integumentary system are affected by age in the ways described in the table below.
Albinism: Pale skin, white hair, iris of the eyes are pink.
Bronzing: Skin appears golden brown, copper or bronze in color.
Cyanosis: Skin appears blue as a result of oxygen deficiency in circulating blood.
Erythema: Skin appears abnormally red.
Hematoma: A bruise that is observable through the skin.
Jaundice: Skin and sclera (whites of the eyes) appear yellow.
Pallor: Skin appears an ash tone, pale due to white collagen fibers housed within the dermis.

For more info try this link Body Guide



Acne: a skin disorder that causes hair follicles on the skin become infercted and clogged and is characterized by pimples on the chest, back, and face.
Carcinoma: a cancerous tumor that occurs in the mucous membrane, skin, or similar tissue of the body.
Malignant melanoma: Cancer of the melanocytes; the most serious type of skin cancer.
Warts: Small growths caused by a viral infection of the skin or a mucous membrane.
Athlete's foot: aka: Tinea Pedis is a common fungal infection that causes the skin between the toes to crack and peel away, and become itchy and sore. Athlete's Foot fungi live only on dead body tissue like hair, nails, and the epidermis. Dermatitis: An inflammation of the skin. There are multiple types of dermatitis, which is known for a pink or red itchy rash. The two most common types are contact dermatitis (an allergic reaction to an irritant on the skin) and seborrheic dermatitis. Dermatitis herpetiformis: an autoimmune disease causing clusters of intensely itchy small blisters and hivelike swellings. Cellulitis: a spreading bacterial infection of the skin and the tissues immediately beneath the skin.

• Redness, pain, and tenderness are felt over an area of skin, and some people have a fever, chills, and other more serious symptoms.

Vitiligo: a disorder in which a localized loss of melanocytes causes patches of skin to turn white.

• Patches of whitened skin are present on various parts of the body.
• Corticosteroid creams or phototherapy plus light-sensitizing drugs may darken the skin, or, if needed, skin grafts may be used.

Ringworm (tinea): a fungal skin infection caused by several different fungi and generally classified by its location on the body.

• The fungi that cause ringworm infections tend to spread in moist areas of the skin.
• Symptoms include rashes, scaling, and itching.
• Doctors usually examine the affected area and view a skin sample under a microscope or in a culture.
• Antifungal drugs applied directly to the affected areas or taken by mouth usually cure the infection.

A close up view of Acne. Carcinoma


The Integument covers muscles and organs underneath it. It can also send messages to the brain signaling hot/cold & hard/smooth.

The integument also works with the Hypothalamus when the body needs to release heat by sweating.

1. What are the five layers of the epidermis? Stratum(Come, Let's, Get, Sun, Burned)
2. What is the name and function of the two layers of the dermis?
3. During the healing process of the skin, what type of tissue is an open wound filled with?
4. What type of gland produces a non-viscus, watery solution which helps regulate body temperature?
5. In what layer does the body store fatty tissue?
6. In what areas of the body would you find an extra layer of skin, known as the strantum lucidum?
7. Name one function the Integumentary system does to release heat.
8. What Abnormal skin coloration deals with pale skin, whit hair, and pink color of the iris in the eye?
9. Name three functions of the skin.
10. What are the two Sweat glands?