Transcript Ahmad ata

Integumentary System
(Skin)
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OBJECTIVES:
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2.
3.
4.
5.
Name the layers of the skin, describe the structure
(tissues) of each, and name a general function of each.
Discuss the four cell types present in the epidermis..
Explain the protective role of keratin, and in turn, the
epidermis.
Name the pigment responsible for skin and hair color,
and explain how people of different races (i.e. and skin
color) differ in regards to it, and the cell that produces
it.
List some factors that promote the production of
melanin.
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OBJECTIVES:
7. Describe the structure and function of the
subcutaneous layer.
8. Describe the general structure of a hair follicle
and identify two other structures that are
always associated with them.
9. Distinguish between merocrine (eccrine) and
apocrine sweat glands in terms of structure,
secretion content and odor, activation, and
major body locations.
10. Describe the structure, function, secretion, and
location of sebaceous glands.
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Discuss
the many functions of skin.
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Introduction
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The integumentary system consists of a
major organ, skin, and many epidermal
derivatives (accessory organs), which
include hair follicles, sebaceous glands,
sweat glands, and nails.
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The skin is the largest organ in the body and
serves as variety of important function in
maintaining health and protect from injury
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Integumentary System Includes:
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Skin (cutaneous membrane)
Subcutaneous tissue below the
skin
Accessory Structures
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Sweat glands
Sebaceous or oil glands
Hair
Nails
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Layers Of The Skin
1.
Epidermis – outer
a. composed of stratified squamous
epithelium
2.
3.
Dermis – inner
subcutaneous layer
The fat content of these layers varies with
the state of nutrition, in obese
individuals may exceed 10 cm in
thickness.
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THE SKIN
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Thin and thick skin
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Most of the body surface is covered by skin
that is classified as thin.
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Skin covering the palms of the hand, soles of
the feet are classified as thick.
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Cell Types
Epidermis
1. Keratinocyte the most important cell in
the epidermis become filled with a tough
fibrous protien called keratin.
 They make up more than 90% of the
epidermal cells
2. Melanocyte contribute color to the skin
and serve to decrease the amount of
ultraviolet light that can penetrate into
deeper layers of the skin.
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Cell Types:
3. Langerhans cell : it plays limited role in
immunological reaction that effect the
skin and may serve defense mechanism
for the body.
4. Merkel cells - combines with disclike
sensory nerve endings to make Merkel’s
discs
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Cell Types:
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2) Dermis
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It is some time called true skin , it is
composed of a thin papillary and thicker
reticular layer.
It may exceed 4mm on the soles and
palms .
At various level in the dermis , there are
muscle fibers, sweet gland, hair follicles
and many blood vessels.
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Skin color
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The basic determinant of skin color is the
quantity of melanin deposit in the cell.
Only melanocytes have ability to convert
amino acid tyrosine in to melanin pigments
through tyrosinase enzyme.
If the melanocytes cannot formed melanin this
condition called albinism
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albinism
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Vitiligo - partial or complete loss of melanin in an
area
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Factors effect on skin color
Heredity: four to six genes control the amount of
melanin formed by melanocytes.
2. Prolonged exposure to sunlight Increase melanin
production.
3. Adenocorticotropic hormones.
4. Age
Modify by:
1. Volume blood in skin capillaries.
2. Unoxygenated hemoglobin.
1.
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Functions of the skin
1) Protection:
 A) from micro organism.
 B) from dehydration.
 C) from ultraviolet.
 D) mechanical trauma.
 E) pain
 F) heat and cold
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Functions of the skin
2) sensation: the widespread of the millions
of different somatic sensory receptors that
detect stimuli.
3) Excretion by regulating the volume and
chemical content of sweat.
4) Vitamin D production .
5) Immunity (langerhan’s cell).
6) Regulation of body temperature.
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Accessory Structures of the Skin
Hair:
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1.
2.
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Hair is composed of column of dead keratinized.
Its consists of shaft and root.
Hair covers the whole body part but its
distribution, color, texture, differ according to:
Location.
Age .
Gender.
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1) Hair:
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Hair color is determined by the amount and type
of melanin present.
Melanocytes become less active with age. Gray
hair is a mixture of pigmented and nonpigmented hairs.
Red hair results from a a modified type of
melanin that contains iron.
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Alopecia is the term for hair loss.
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Hair
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Each hair follicle has an associated bundle
of smooth muscle, the arrector pili
muscle..
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2) Nail :
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Nails made of keratin.
Parts of nail:
Nail root.
Nail body.
Nail bed.
The lunula is part of the matrix that can be
seen thru the nail body.
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Parts of Nail
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Glands of the Skin
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A) sweet gland are simple coiled tubular glands.
They are divided into two principal types:
1) Apocrine glands are found mainly in the skin
of the armpits, of the genital areas and of the
areola of the breasts. Their secretary portion can
be located in the dermis or in the hypodermis.
Their excretory ducts open into hair follicles.
Their secretion is more viscous than that of the
eccrine glands. They start secreting at puberty.
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Glands of the Skin
2) Eccrine glands are the most common. Their
secretory portion can be located in the dermis or
in the hypodermis. They produce sweat, a
watery mixture of salts, antibodies and
metabolic wastes.
Functions in maintaining body temperature,
eliminating wastes, and immunity
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Glands of the Skin
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Oil (sebaceous)
Secretes sebum containing fat, salt, cholesterol
and protein
b. Most are connected to hair follicles, some
open directly onto the surface – lips.
Function - keeps hair from drying, forms a
protective film to prevent excess water
evaporation, inhibits bacterial growth
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Glands of the Skin
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Ceruminous (wax) - in external
auditory meatus; secretes cerumen
(wax) which prevents the entrance of
foreign bodies.
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Please review chapter 6 page 160
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