The Integumentary System

Anatomy of The Integumentary System

The largest organ of the body, the skin represents about 7 percent of the body’s weight. It is a dynamic protector between the body and its surrounding environment.

It protects the body from disease, external injury, and the environment. The skin also helps to maintain normal body function and homeostasis.

Social recognition, especially facial, is another function of the skin, as well as the expressions that enable us to consciously or unconsciously communicate.

Skin Layers

  • Epidermis
  • Dermis
  • Hypodermis


The protective outermost layer of the skin that has between four and five sublayers. It is composed of stratified squamous epithelium cells.


The middle layer of the skin consists of two sublayers. It is comprised of the following:

  • Smooth muscle fibers
  • Connective tissues fibers
  • Blood vessels
  • Glands
  • Nerve endings
  • Hair follicles

Hypodermis (Subcutaneous)

The deepest layer of the skin that is comprised of the following:

  • Fibrous connective tissues
  • Adipose tissue
  • Blood vessels
  • Lymph vessels

Skin Cells

  • Collagen
  • Melanin
  • Keratin


A protein that is both tough and fibrous, and it is the most common structural protein in the body. An essential part of the bones, tendons, and connective tissues. The body uses collagen to help in holding its tissues and cells together, and to help tissues withstand stretching.


The dark pigment in the skin cells that is primarily responsible for skin color. Also found in hair, the pigmented tissue underlying the iris of the eye, and the stria vascularis of the inner ear.

Brain tissues that contain melanin are the medulla and the pigment-bearing neurons.


A fibrous structural protein in the outer layer of the skin cells that is primarily responsible for strengthening the skin, waterproofing the skin, and protecting the skin cells from damage or stress.

Exocrine Glands and Endocrine Glands

  • Epithelial Tissues
  • Glands
  • Exocrine Glands
  • Endocrine Glands
  • Endocrine System
  • Glands That Are Both Exocrine and Endocrine
  • Hormones

Epithelial Tissues

One of the four main tissue types and widespread throughout the body. Form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands.

Perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.


Refers to organs that make one or more substances in the body, such as hormones, digestive juices, sweat, tears, saliva, or milk. There are two types of glands in the human body:

  • Exocrine Glands
  • Endocrine Glands

Exocrine Glands

Glands that produce and secrete substances into ducts or openings that go to the inside or outside of the body.

Examples of these glands are:

  • sweat glands (see section 8.1.5 below)
  • mammary glands (see section 8.1.6 below)
  • ear glands (see section 8.1.7 below)
  • salivary glands
  • mucous glands
  • lacrimal glands (tear glands that constantly moisten, lubricate, and protect the surface of the eye)
  • sebaceous glands (they produce oily or waxy matter called sebum, to lubricate and waterproof the skin and hair. Sebum production and secretion is regulated by sex hormones. If a blockage occurs in these glands, they can become infected and result in acne)

Many exocrine glands are associated with the digestive system.

Endocrine Glands

Glands that produce and secrete substances directly into the bloodstream. Examples of these glands are:

  • Pituitary
  • Pancreas
  • Adrenal
  • Hypothalamus
  • Thyroid
  • Parathyroid
  • Pineal (produces melatonin, a serotonin-derived hormone that modulates sleep patterns)
  • Testes
  • Ovaries

Endocrine System

A system of endocrine glands and cells that make hormones that are released directly into the blood and travel to tissues and organs all over the body.

The endocrine system controls:

  • Growth
  • sexual development
  • Sleep
  • Hunger
  • the way the body uses food

Glands That Are Both Exocrine and Endocrine

The liver and pancreas are both exocrine and endocrine glands. They are exocrine glands because they secrete bile and pancreatic juice into the gastrointestinal tract through a series of ducts, and endocrine glands because they secrete other substances directly into the bloodstream.


One of many substances made by glands. Hormones circulate in the bloodstream and control a vast number of functions of certain cells or organs.

Sweat Glands

  • Sudoriferous
  • Eccrine
  • Apocrine

Sudoriferous Glands

The sudoriferous sweat glands are located deep within the skin and throughout the entire body. Their primary function is to regulate body temperature by secreting perspiration onto the surface of the skin.

The two main types of sudoriferous sweat glands are:

1. Eccrine

The secretions of the eccrine sweat glands are not odour-producing. Primarily located in the skin of the back, palms, forehead, and soles of the feet.

2. Apocrine

The secretions of the apocrine sweat glands are odour-producing. Primarily located in the skin of the pubic area and armpit area.

Mammary Glands

A unique type of sudoriferous gland located inside the breasts. Their functionality occurs only during a woman’s childbearing years.

Ear Glands

  • Ceruminous Glands
  • Cerumen

Ceruminous glands

Secrete earwax (cerumen), which helps to protect the ear.


Acts as an insect repellent and helps to keep the eardrum pliable.

Types of Hair

  • Lanugo
  • Angora
  • Definitive


Is fine and silky and found on the fetus in the last trimester. Its purpose is not fully understood.


This type of hair grows continuously, such as on the scalp, or on the face of males once they have reached puberty.


This type of hair only grows to a certain length and then stops. Examples are eyelashes, eyebrows, armpit hair (axillary), and pubic hair.

Hair Functions

The primary role of hair is to offer protection to certain areas of the body. For example, hair on the scalp and eyebrows offer protection against sunlight, and hair of the eyelashes and in the nostrils protect against airborne debris.

Another function of hair is that it is a major component of social identity, expression, sexual attraction, and much more.


  • Fingers and Toes
  • Nail Strength and Health

Fingers and Toes

The main purpose of nails is for the protection of the fingers and toes and to assist the fingers in picking up small items. The average growth rate of a healthy nail is about one inch every twenty-five weeks.

Nail Strength and Health

Eating calcium-rich foods, gelatin, or any other nutrient, whether it is food or a supplement, does not improve nail health or nail growth.

In fact, nails are not made of calcium; they are made of protein and extra amounts of protein do not help either. Nail polish can damage your nails. The chemicals used to make nail polish can cause your nails to become irritated and to split.

Integumentary System Injuries and Conditions

Below are the common skin conditions:

  • Dermatitis
  • Erythema
  • Acne
  • Pustule
  • Melanoma
  • Boil
  • Carbuncle
  • Psoriasis
  • Eczema
  • Seborrhea
  • Gangrene
  • Athlete’s Foot
  • Hives
  • Wart
  • Shingles
  • Nevus


Inflammation of the skin.


Redness of the skin.


  • Inflammation of the sebaceous glands.
  • More common during puberty and adolescence because it is affected by gonadal hormones (the gonads are the sex glands; the testes in men and the ovaries in women).
  • The most common locations for the pimples and blackheads of acne are on the face, chest, and back.


A small, localized pimple that contains pus.


A cancerous tumor in the skin.

Boil (Furuncle)

A localized bacterial infection that begins in a skin gland or hair follicle.


A localized bacterial infection that begins in a skin gland or hair follicle. Similar to a boil, except that it affects the tissue of the subcutaneous layer.


A skin disease characterized by inflammation and circular, scaly patches of skin.


A noncontagious skin condition where there may be redness, blistering, oozing, and itching. Also the skin may be scaly, crusty, brownish, or thickened.


A skin disease characterized by overactive sebaceous glands, resulting in dandruff and oily skin.


  • Death (necrosis) of body tissue caused by a loss of blood supply. 
  • There are two types of gangrene, wet and dry. 
  • Wet gangrene is a bacterial infection of the tissue and the gangrene can spread. 
  • Dry gangrene is absent of infection by bacteria and the gangrene does not spread.

Athlete’s Foot (Tinea Pedis)

A condition of the foot where a fungal disease is present in the skin.

Hives (Urticaria)

  • Red eruptions on the skin that are usually accompanied by excessive itching. 
  • Usually the result of stress or allergic reactions.


  • Skin growths caused by a viral infection in the top layer of the skin.
  • Warts are noncancerous.

Shingles (Herpes Zoster)

  • Inflammation of a nerve that results in blisters on the skin.
  • Caused by the same virus as chickenpox.
  • Symptoms include localized pain, fatigue, or headache.


A mole or a birthmark on the skin.

Common Adverse Skin Reactions

  • Blister
  • Callus
  • Corn
  • Bedsores


  • A pocket of fluid that is located between the two top layers of skin, the epidermis and the dermis.
  • Usual causes are burns and excessive friction resulting from rubbing against an object or the grasping of an object (e.g., the rubbing of the heel of the foot against the back of a tight shoe or using a shovel).


A build-up of the outer layer of skin tissue (stratum corneum) as the body’s way to adapt to frequent, excessive friction.


A small callus on the foot.

Bedsores (Decubitus Ulcer)

May develop on the skin of people who are bedridden for extended periods of time.


  • First Degree
  • Second Degree
  • Third Degree

Burns are lesions affecting the skin as a result of heat or fire, sun exposure, electricity, or chemicals. There are three classifications of burns:

First Degree

A burn that causes redness to only the epidermis (the upper layer of skin).

Second Degree

A burn that causes blisters and involves the deeper layers of the epidermis and also the dermis.

Third Degree

A burn that causes serious damage to all layers of the skin and also to underlying tissues, which may include muscle, bone, and other tissues that lie beneath the skin.

Types of Skin Wounds

  • Abrasion
  • Avulsion
  • Incision
  • Laceration
  • Puncture


An injury that results in the scraping away of a section of skin or mucous membrane.


The type of wound that results in the forcible separation or tearing away of tissue from the body.


A cut into the skin, usually occurring from a sharp object.


A cut or tear to the body tissue in a jagged or irregular pattern.


A small hole in the body tissue when a sharp object has pierced the skin.


  • Hemorrhage
  • Hemarthrosis
  • Hematoma
  • Contusion
  • Ecchymosis


Bleeding to a part of the body.


A hemorrhage occurring in a joint.


A hemorrhage occurring in a muscle or tendon.

Contusion (Bruise)

Slight bleeding under the skin as a result of injury, but in which the skin has not been broken.


The purple discoloration that occurs from a contusion (bruise).


  • Inflammation
  • Swelling
  • Effusion
  • Edema


The body tissue’s response to an injury or medical condition, regardless of the cause. The signs and symptoms of inflammation may include any or all of the following:

  • Swelling
  • An increase of temperature at the site of the injury
  • Redness
  • Pain
  • Loss of function of the affected area

None of these symptoms should ever be ignored.


An accumulation of fluids within the body as a result of disease or injury.


The loss of fluid into a body part.


The swelling that occurs as a result of fluid accumulating in a body part.

Types of Blisters

Blister (Vesicle)

A volume of fluid just beneath the outer layer of the skin, usually resulting in a raised oval or circular shape. Usual causes are burns, sunburns, or friction.

This fluid acts to protect the damaged area, is usually sterile, and comes from a serum that seeps out from the blood vessels that are located in underlying layers of skin.

Never attempt to burst a blister due to damage or injury because it could result in an infection to the area.

Other Causes of Blisters

Certain skin conditions, such as eczema or impetigo, also cause blisters. In other cases, blisters are caused by viral infections such as chickenpox, herpes, and shingles. In these diseases, the blister may contain infectious viruses that can infect other people.

Never attempt to burst a blister due to disease because it could result in an infection to the area and be infectious to other people.

Large Blisters (Bullae)

Blisters that are more than a half-inch in diameter. If the blister worsens or its cause is unexplainable, consult with your physician.

Scar Tissue

  • Hypertrophic Scar Tissue
  • Keloid Scar Tissue
  • Adhesions

Scar Tissue

Any mark that is left on damaged tissue after the regular healing process has occurred. Scar tissue not only occurs on the skin, but on internal wounds as well.

Scar tissue is an inelastic, tough, and fibrous protein collagen, which covers the site of the damage.

The three main types of scars are the following:

Hypertrophic Scar Tissue

A large, unattractive scar that can result from a wound that was infected.

Keloid Scar Tissue

A large, irregularly shaped scar that continues to grow after the wound has healed.


A type of scar tissue that forms between the parts of internal organs that had become separated.

Ear Condition


A condition that causes persistent or intermittent ringing sounds in one or both ears. These sounds may also be described as humming or buzzing.

Hair and Scalp Conditions

  • Alopecia
  • Dandruff


Loss of hair, baldness.


Common dandruff is when the scalp’s outermost layer of skin cells flake off. Washing and brushing the hair keeps this condition under control. Abnormal dandruff is due to skin disease, such as seborrhea and psoriasis.

Cosmetic Surgery

  • Rhinoplasty
  • Mentoplasty
  • Mammoplasty
  • Blepharoplasty
  • Dermabrasion

Cosmetic surgery

Serves to improve a person’s appearance or to correct physical abnormality.


Cosmetic surgery of the nose.


Cosmetic surgery of the chin.


Cosmetic surgery of the breasts.


Cosmetic surgery of the eyelids.


Cosmetic surgery of the skin by removing the surface layers.

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