Muscle complete lecture

1. Integumentary System
Unit VII
Ikramullah
Wiqarullah

2. Objectives
At the end of this lecture, the students will be able to:
a. Define key terms
b. Discuss epithelial membrane and its types
c. Describe the structure of epidermis and dermis
d. Briefly discuss the structure & function of skin
derivatives as:
e. Sweat gland
f. Sebaceous gland
g. Hair and Nail
h. Identify the functions of skin

3. Key Terms
• Integumentary (in= inward; tegere= to cover) system: is
composed of skin and its derivatives (hair, nails, glands).
• Dermatology: is the medical specialty that deals with the
diagnosis and treatment of integumentary system disorder.
• Skin is the largest organ of the body.
– About 1 to 4 mm thick
– 2 square meters; 10-11 lbs.
– Largest sense organ in the body.
Organs are two or more tissues which together perform
a specialized function.
• Keratinization: The process of accumulation of
keratin into keratinocytes.

4. Functions of Skin
1. Regulation of body temperature
o Cellular metabolism produces heat as a waste product.
– High temperature
• Dilate surface blood vessels
• Sweating
– Low temperature
• Surface vessels constrict
• shivering

5. 2. Protection
physical abrasion
dehydration
ultraviolet radiation
3. Sensation
tactile
thermal
pain

6. 4. Excretion
Skin excretes some waste materials like
salts, CO2 , ammonia, urea, and water
5. Absorption
fat-soluble vitamins
O2 and CO2
Organic solvents like acetone
Salts of heavy metals (i.e, (lead) Pb, Hg)
6. Immunity/ Resistance
7. Blood Reservoir
8-10 % in a resting adult
8. Synthesis of vitamin D
UV light
helps in the absorption of calcium

7. Anatomy of the Skin
Two layers of skin
• Epidermis
• Dermis
Subcutaneous layer or hypodermis (no skin
layer)

8. Skin Layers cont…
• Epidermis is composed of keratinized stratified
squamous epithelium. 100 to 600 micrometer thick
It contains:
• Keratinocytes—90 % that produce keratin protein to
protect skin and underlying tissues.
• Melanocytes—8% of the epidermal cells that
produce melanin (brown-black pigment) to absorb uv
light.
• Langerhans cells—Macrophages that help immune
system
• Markel cells—contact with sensory neurons to detect
touch sensation. Also called tactile cells.

13. Epidermis Layers
• Stratum basale (stratum germinativum)
– The deepest layer
– Single layer of cuboidal to columnar cells
– Germinative layer that produces keratinocytes

14. Stratum Spinosum
–Consists of 8-10 layers of keratinocytes
–They are so named because they give out
extensions which present spiny appearance.

16. Epidermis Layers cont…
• Stratum granulosum
–2-5 layers of flat keratinocytes
–Keratinization begins here
–A dark pigment Keratohyalin granules are found
–Glycolipid produced here to waterproof the skin

18. • Stratum lucidum (lucid = clear)
– More apparent in thick skin
– 3-5 layers of clear cells
– The cells have no more nuclei and organelles
– Eleidin (an intermediate stage of keratin) is produced
• Stratum corneum (corneum means horny)
– Up to 30 layers of dead keratinized cells
– Keratin is waterproof
• Basal cells to surface – take about 30-40 days

19. Dermis
• Connective tissue layer
• Composed of collagen and elastic fibers, nerves, blood
vessels, muscle fibers, adipose cells, hair follicles, glands
and nail roots.
• Smooth muscle fibers, the arrector pili, associated with
hair follicles make the hairs stand erect in response to cold
or fear causing “goose bumps”
• Two Layers of Dermis are:
 Papillary layer
– Areolar connective tissue having collagen and elastic fib
– The upward fingerlike extensions that project into the
undersurface of the epidermis form dermal papillae
– Dermal papillae shape fingerprints

20. Reticular (net) layer
– Deeper layer
– Attached to the subcutaneous layer
– Dense irregular connective tissue with collagen
and elastic fibers
– Hair follicles
– Sebaceous (oil) glands
– Usually sweat glands

21. Hypodermis
• Attaches the reticular layer to the underlying
structures
• Loose connective tissue and adipose tissue
• Major blood vessels

22. Accessory organs or epidermal derivatives
• Hair
– Epidermal growths that function in protection
– Divided into shaft, root, and folllicle
– Sebaceous glands, arrector pili muscle, and hair
root plexus (dendrites) are associated with hair.
Clinical terms
• Hirsutism
• Alopecia

24. Nails
• Plates of highly packed, keratinized cells
• Protection, scratching, & manipulation
• Formed by cells in nail bed called the matrix ( in
area of lunula)
• Elongate 1 mm / week
• Eponychium

27. Skin Glands
• Sebaceous (oil) glands
– Usually connected to hair follicles.
– Secretes sebum.
– Sebum contains fats, cholesterol, proteins, and salts.
– Prevents excessive evaporation.
– Moistens hair and waterproofs skin.
Clinical connection
• Acne

28. Sweat (sudoriferous) glands—2 types
– Eccrine sweat glands
• Also called merocrine sweat glands
• Simple coiled tubular exocrine glands
• The ducts open on the surface of the skin
• Mostly found on forehead, palms, and soles but not
on the lips.
• The eccrine sweat contains water, salt (Na+, Cl-) ,
urea, amino acids, glucose, and lactic acid.
• Function is to cool the body
• Emotional sweating in response to fear or
embarrassment.
• Eccrine starts function soon after birth

29. Apocrine sweat glands
• Simple coiled tubular exocrine glands
• Found mainly in the skin of the axilla, groin, areola
of the breast, and bearded region of the face.
• The secretory ducts open into the hair follicles.
• Apocrine sweat is relatively viscous
• It contains the same components as eccrine plus fatty
acids and proteins
• Odorless
• Odor occurs when broken down by bacteria
• Apocrine starts function at puberty.

31. • Ceruminous glands
– Modified sudoriferous glands in the external ear
– Secrete cerumen (ear wax)
• Mammary glands
– Secrete milk

32. Some Skin Markings
• Freckles—flat patch as a result of the aggregation of
melanocytes
• Mole—elevated patch as a result of aggregation of
melanocytes
• Friction ridges—marking on the fingertips that leave
oily and sweaty fingerprints on surfaces we touch.
• Palmer creases—lines on the palms formed after birth
by repeated closing of the hands.
• Flexion creases—lines formed on the wrist and elbow

33. Skin Color with Clinical connection
• Melanocytes synthesize melanin from the amino acid
tyrosine in the presence of an enzyme tyrosinase by
an organelle called melanosome.
• Dark-skinned individuals have more melanin in the
epidermis as compared to that of the light-skinned.
• Albinism is the inherited inability to produce
melanin by melanocytes because of inability to
synthesize tyrosinase.
• Vitiligo is an autoimmune disorder characterized by
the partial or complete loss of melanocytes from
patches of skin producing white spots.

34. • Jaundice (jaund=yellow) is the build up of
yellow pigment bilirubin in the skin.
• Cyanosis (cyano=blue) is the condition in which
the blood is not picking up adequate oxygen.
• Pallor or paleness of skin occurs in usually in
anemia
• Erythema (eryth=red) is caused by engorgement
of capillaries in dermis due to skin injury,
infection, etc.
• Bruise or contusion is a superficial injury of the
skin which results in bluish color of it.

35. Any Question
References
Tortora, Gerard J., and Sandra Reynolds Grabowski. 1996. Principles of anatomy and
physiology. New York, NY: HarperCollins College.