THE INTEGUMENTARY SYSTEM

Integumentary System

Integumentary system - consists of the skin, hair, and nails

Main Functions of Integumentary System

1. protection
2. temperature regulation
3. sensory reception

A. Skin – is the largest organ of the body

- an average adult human body has about 16,718.4 cm² or 1.67 m² of skin. It has a thickness of 0.05 – 3 mm or 0.0197 – 0.1182 inch

- surface area of 1.4 to 1.9 square meters

Functions of Skin

1. It prevents inner tissues from completely drying up.
2. Protects the body from bacteria, fungi, and mechanical injury
3. Helps rid the body waste products.
4. Regulates body temperature
5. Senses changes in its environment

Parts of the Skin

1. Epidermis – the outermost protective tissue of the skin

- it produces melanin which protects skin from sunlight.

- this is the top layer of skin and the one you can actually see. It protects your body from invasion and infection and helps to seal in moisture. It's built up of several layers of living cells which are then topped by sheets of dead cells. It's constantly growing, with new cells being produced at its base. They quickly die, and are pushed up to the surface by the arrival of new ones, These dead cells eventually flake away, which means that every new layer of skin is another chance to have a soft, glowing complexion.

- the epidermis is responsible for your coloring, as it holds the skin's pigment. It ranges in thickness from l/20-th of an inch on the palms and soles, to 1/200-th of an inch on the face. 

·  Melanin – the dark pigment of the skin present in the dermis

·  Keratin – a protein that makes skin tough and waterproof by preventing fluids and certain substances from passing through the skin

2. Dermis – the innermost layer of the skin

- the only layer of the skin which contains blood vessels

- it houses the sweat glands, sebaceous glands and hair follicles

- sensations of touch, temperature, and pain originate in nerve cells within the dermis

- also contains tiny muscle called arrector pili that are attached to hair follicles (goose bumps)

- the dermis is the layer that lies underneath the epidermis, and it is composed entirely of living cells. It consists of bundles of tough fibers which give your skin its elasticity, firmness and strength. There are also blood vessels, which feed vital nutrients to these areas.

- the most important function of dermis is respiration. The countless tiny blood vessels, or capillaries end here in finely-drawn networks, from where they feed the outer skin layer. Dermis also determines the tone of the skin.

3. Hypodermis or Subcutaneous Tissue – located beneath the dermis

- a layer of connective tissue made mostly of fat

- acts as a shock absorber, provides additional insulation to help conserve body heat, and stores energy

B. Hair – it is made up of epithelial tissues

- an average human head contains about 100,000 hair strands

- the primary function of hair is for protection, it guards the scalp from injury and sun’s rays

- eyebrows and eyelashes protect the eyes from foreign particles

- hair in the nostrils and external ear canal protects these structures from insects and dusts

- the color of hair, like the color of skin, comes from melanin. Melanin is made in the hair root. The hair of older people turns gray because the root stops making melanin.

- the shape of the hair shaft gives you straight or curly hair. A round shaft makes straight hair. An oval-shaped shaft makes wavy hair. A comma-shaped shaft makes curly hair.

Parts of Hair

1. Hair Shaft – it protects above the surface of the skin

- it is composed of keratin

2. Hair Root – it is the portion below the surface that penetrates deep into the dermis
3. Hair Follicle – it is the portion of the skin which produces and supports the hair

- where hairs are manufactured

 

Two Kinds Of Glands

1. Sweat Glands – are distributed throughout the skin except on the nails, beds of the fingers and toes, margins of the lips, and eardrums

- are numerous in the skin of the palms and soles

- found in abundance in the armpits and forehead

- there are millions of them and their main function is to regulate your body temperature. When sweat evaporates on the skin's surface, the temperature of your skin drops.

2. Sebaceous Glands

- are tiny organs which usually open into hair follicles on the surface of your skin. They produce an oily secretion, called sebum, which is your skin's natural lubricant. 

- the sebaceous glands are most concentrated on the scalp and face - particularly around the nose, cheeks, chin and forehead, which is why these are usually the most oily areas of your skin. 

· Sebum – a mixture of fats, cholesterol, proteins, and inorganic salts

- keep the hair from drying and becoming brittle

C. Nails – the grow out of the dermis from special cells which divide rapidly to produce new fingernail cells

-  are dead cells which have keratin

- protect the ends of the fingers from injury, help us grasp small objects, and      enable us to   scratch.

- fingernails typically grow 1 mm (0.04 in) per week. Toenails generally grow more slowly.

• Free Edge - the is the end of the nail plate that is shaped during Manicure & Pedicure 
• Hyponichium - this is the portion of skin at the end of the finger underneath the free edge, where the nail plate separates from the skin.
• Nail Grooves - these are the grooves on the skin at the sides of the free edge, and the nail follows the line as it grows.
• Nail Plate - this is the visible portion of the nail that sits on top of the nail bed. It is made by Keratinisation; the change of living cells to hard, dead cells, and it consists of carbon, hydrogen, oxygen, sulfur and nitrogen.
• Nail Walls - these are the folds of skin where the nail is still attached.
• Nail Bed - this is the part of the finger underneath the nail plate.
• Lunula - this is the moon shaped point where the matrix and nail bed meet.
• Cuticle - this is the overlapping skin surrounding the nail. Its job is to protect the matrix from invading bacteria and physical damage.
• Matrix - this is where the nail is made. It is the only living part of the nail, and contains nerves and blood vessels so that cell reproduction can occur.

Some Common Skin Problems

1. pimples                            5. hives                                  9. boils

2. blackheads                      6. eczema                             10. freckles

3. cold sores                        7. impetigo                            11. warts

4. psoriasis                          8. acne                                  12. moles