ANATOMY – INTEGUMENTARY SYSTEM … to the session on

ANATOMY – INTEGUMENTARY SYSTEMANATOMY – INTEGUMENTARY SYSTEM

… to the session on

From T. MADHAVAN, M.Sc., M.L.I.S., M.Ed., M.Phil., P.G.D.C.A., Lecturer in Zoology..

This power presentation optimized for the students who aspires for medical studies

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INTEGUMENTARY SYSTEMINTEGUMENTARY SYSTEM

The skin is the largest organ in the body: 12-15% of body weight, with a surface area

of 1-2 meters.

Skin is continuous with, but structurally distinct from mucous membranes that line the mouth,

anus, urethra, and vagina.



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Anatomy

- Epidermis

- Dermis

- Hypodermis

Thin skin & Thick skin

Skin color

Skin Derivatives

- Hair

- Nails

- Skin glands

Functions



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Comprises two distinct layers occur in the skin: the dermis and epidermis, both layers rests

over the hypodermis

Hypodermis It attaches the skin to the underlying bones and muscles. It supplies the blood vessels and nerve to the skin

Epidermis is made up of Stratified squamous epithelium. Keratinocyte is the basic cells of epidermis, which contain keratin, a fibrous protein. Melanocytes produce the pigment melanin, and are also in the inner layer of the epidermis.

Dermis is a connective tissue layer under the epidermis, and contains fibroplasts, adipose cells, nerve endings, sensory receptors, capillaries, and macrophages.

SKIN or INTEGUMENT



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As new cells formed in the deepest layers of epidermis, the older cells are pushed to the surface which will protect the inner new cells. Gradually the surface cells are getting filled with Keratin. This process is called keratinization.

During the keratinization epidermis divided into 5 distinct regions or strata.

They are theStratum basale

Stratum spinosumStratum granulosum

Stratum lucidium

Stratum corneum



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Stratum basale is in the deeper region of epidermis consists of singler layer of columnar cells. Keratinization begins in this region.

Stratum spinosum lies over the stratum basale. It has 8 – 10 layers of polygonal cells.

Stratum granulosum is the middle layer of the epidermis. It has 3-5 layers of flat cells.

Stratum lucidium is the next upper layer of the straum granulosum. It is a thin Zone having several of dead cells.

Stratum corneum is the upper most layer of the epidermis having more than 20 layers of dead cells. These cells get filled with keratin. They are said to be cornified. These cornified cells are surrounded by a hard protective envelope.



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Dermis layer of the skin

Dermis provides the structural strength to

the skin.

It accomodates nerve endings, hair follicles, smooth muscles and

glands.

It is divided into 2 layers, namely the superficial

papillary layer (has papillary projections) and the deeper

reticular layer (major layer of the dermis, dense in nature

continuous with the hypodermis)



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The skin or integument rests on layers of cells

called Hypodermis

The Hypodermis attaches the skin to the underlying

bones and muscles.

It supplies blood vessels and

nerves to the skin

Hypodermis Layer of the Skin



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Thin skin & Thick Skin

In the thin skin each layer inturn has few layers of cells.

Ther are only has 1 or 2 layers of cells in Stratum granulosum

The general body surface has thin skin.

In the thick skin all 5 layers are visible.

Stratum corneum contains numerous cells.

Thick skin is formed in the soles of feet, palms of hands, tips of fingers.

CALLUS: The regions of skin subjected to constant friction or pressure are thickened to form the callus. The callus has several layers of cells in stratum corneum



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Skin ColorSkin Color

The thickness of the stratum corneum and blood circulation can also cause the skin color.

Hormones and exposure to light can also alter the skin color. Normally skin color is caused by the Melanin pigments.

Melanin pigments provide color to skin, hair, and eye.

Melanin is produced by melanocytes.

Production of melanin is herditary.



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Hair has a root and a shaft.

Shaft projects above the skin.

Root remains below the surface.

The base of the root has hair bulb.

shaft and the most of the root are formed of dead keratinized epithelial cells

arranged in 3 concentric layers called the medulla, cortex and cuticle.

Central axis of the hair is formed of the medulla.

Skin derivatives: Hair



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Muscle cells found associated with hair follices are called Arrector Pili.

Cotraction of these muscles cause `goose flesh` making the hairs to ‘stand on end’



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HAIR GROWTH is due to addition of cells at the base of hair root.

The hair growth stops at specific stages.

After a resting period , New hair replaces old hair.

Hairs on the head grow for a period of 3 years and rest for 1-2 years.

HAIR COLOR may vary with the amount and types of melanin present in the skin.

During old age decrease in melanin causes White hair.

Grey hair has a mixture of faded, unfaded and white hairs.




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Skin derivatives: NailsEach Nail is made up of 2 parts.

They are Nail root & the Nail body.

The Nail body is the visible part.

The Nail root covered by the skin.

The proximal and Lateral edges of the nail are covered by the nail fold.

The Nail is found placed on the Nail matrix and nail bed.

Lunula, a small white regionat the base of nail contains nail matrix.

The free edge of the Nail body is the Hyponchium.

The stratum corneum of the nail fold grows on to the nail body as the Eponchium.

The nails grow at an average rate of 0.5-1.2 mm per day



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Glands of the Integumentary System

The Skin has

- Sebacious glands

- Sweat glands

- Apocrine glands

The modified form of sweat glands are

- Mammary glands &

- Ceruminous glands

The most common type of Sweat glands on the skin are Merocrine glands. They open directly on to the skin through seat pores. Numerous Sweat glands are

found in the palms of the hands and soles of the feet.



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Glands of the Integumentary System



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INTEGUMENTARY SYSTEMINTEGUMENTARY SYSTEM

- covers the outside of the body- detects stimuli such as touch, pain and temperature

- prevents the entry of infectious agents- protects internal structures- produces Vitamin D- reduces water loss- regulates body temperature- removes excess salts through perspiration

FUNCTIONS OF THE SKIN



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