Unit II, Chapter-1-Integumentary System. As per PCI Syllabus. HAP-I, Integumentary system Structure and functions of skin

1. BP101T. Human Anatomy And Physiology-I
(Theory)
Unit-II
1. INTEGUMENTARY SYSTEM
Represented By,
Mr. Audumbar Mali.
(Assistant Professor)
Sahyadri College of Pharmacy
Methwade

2. THE SKIN
• It is outer covering of body.
• In humans, it is the largest organ of
integumentary system.
• It helps to maintain a constant body
temperature, protects the body and provide
sensory information.
• Dermatology: It is the branch of medical
science that deals with the diagnosis and
treatment of skin disorders.

3. STRUCTURE OF SKIN
• The skin is the cutaneous (related to skin)
membrane covers the external surface of
the body.
• It is the largest organ of the body in both
surface area and weight.
• The thickness of skin ranges from 0.5mm on
the eyelids to 4.00 mm on the feet.
• The skin is composed of 2 layers
1. Epidermis
2. Dermis

4. Fig.: Structure of Skin

5. EPIDERMIS
• It is the outermost layer of skin.
• It is composed of keratinized stratified
squamous epithelium.
• It consists of principal types of cells
a) Keratinocytes
b) Melanocytes
c) Langerhans cells
d) Markel cell

6. CELLS OF EPIDERMIS
Keratinocytes:
• About 90% of epidermal cells are keratinocytes
• Keratin is a tough, fibrous protein that helps to
protect the skin and underlying tissues from heat,
microbes and chemicals.
Melanocytes:
• About 8% of the epidermal cells are melanocytes and
produce pigment melanin.
• Melanin is the yellow red or brown black pigment
that contribute the skin color and absorb damaging
UV light.

7. CELLS OF EPIDERMIS
Langerhan’s cells:
• They arise from red bone marrow and migrate to the
epidermis & contribute a small fraction of the epidermal
cells.
• They participate in immune responses mounted against
microbes.
Markel cells:
• These are the least numerous epidermal cells.
• They are located in the deepest layer of epidermis.
• These cells are very close to the nerve endings that receive
the sensation of touch and may be involved in touch. The
cells also contain substances that may act as hormones.

8. CELLS OF EPIDERMIS

9. LAYERS OF EPIDERMIS
• Epidermis is composed of 5 layers:
1. Stratum corneum
2. Stratum lucidum
3. Stratum granulosum
4. Stratum Spinosum
5. Stratum basale (innermostlayer)

10. LAYERS OF EPIDERMIS

11. LAYERS OF EPIDERMIS
1. Stratum corneum:
• It is the outermost layer of epidermis.
• Made up of 25-30 layers of flat, dead cells,
completely filled with keratin.
• Between the cells are lipids from smaller granules,
making it water repellant barrier.
• It is effective barrier against light, heat, bacteria,
water and many chemicals.

12. LAYERS OF EPIDERMIS
2. Stratum Lucidum:
• It lies below the stratum corneum.
• It consist of 3-5 layers of clear, flat, dead cells lacking
granules and nuclei.
• The cells of stratum lucidum are also filled with
keratin.
• It is present only in skin of fingerprints, palms, and
soles.

13. LAYERS OF EPIDERMIS
3. Stratum granulosum:
• In the middle of the epidermis is the stratum
granulosum.
• It consist of 3-5 layers of flattened keratinocytes.
• Cell contain the protein keratohyaline, which
converts tonofilaments into keratin and smaller
granules, which release a lipid rich, water repellant
secretions.

14. LAYERS OF EPIDERMIS
4. Stratum Spinosum:
• Superfacial to stratum basale.
• It consist of 8-10 layers of keratinocytes fits closely
together.
• It include projections of melanocytes and
langerhans cells.

15. LAYERS OF EPIDERMIS
5. Stratum Basale:
• It is the deepest layer of the epidermis.
• It is composed of single layer of cuboidal or
columnor keratinocytes.
• Stem cells undergo cell division to produce new
keratinocytes.

16. THE DERMIS
• Second deeper layer of the skin is dermis.
• It is composed of mainly connective tissue.
• Blood vessels, nerves, glands and hair follicle are
embedded in the dermis tissue.
• The dermis can be divided into:
1. Papillary region
2. Reticular region

17. THE DERMIS
• The papillary region makes up to
the 1/5th thickness of total layer.
• It consist of areolar connective
tissue containing fine elastic fibers.
• Its surface area is greatly
increased by small, fingerlike
structure called as dermal
papillae.

18. THE DERMIS
• The reticular region which is attached to the
subcutaneous layer, consists of dense irregular tissue
containing fibroblast, bundles of collagen and some
elastic fibers.
• A few adipose cells, hair follicles, nerves, sebaceous
(oil) glands and sweat glands are present in the
reticular region.
• The combination of collagen and elastic fibers in the
reticular region provides the skin with strength,
extensibility and elasticity.

19. ACCESSORY STRUCTURE OF
THE SKIN
• The accessory structure of the skin
includes
1. Hairs: Protects the body.
2. Skin glands: Regulate body temperature
3. Nails: Protects the body

20. HAIRS (PILI)
Hair:- Anatomy:
- composed of dead columns of keratinized cells.
- shaft: is the superficial portion of hair.
- root: below the surface in the dermis.
• Shaft and root are composed of three layers: inner
medulla, middle cortex and outer cuticle.
• Inner medulla has 2-3 rows of polyhedral cells
where pigment is located.
• Cortex is major portion of shaft.
• Cuticle is scaly and heavily keratinized (shingles).

21. HAIR

22. HAIR
• Cuticle of the hair:
• Surrounding the root hair is the hair follicle which is made up of
external root sheath and internal root sheath .
• Together these are referred as epithelial root sheath.
• The dense dermis surrounding the hair follicle is called as dermal
root sheath.
• The base of each hair follicle is called as dermal root sheath.
• The base of each hair follicle is an anion shaped structure
called bulb.
• The bulb contains nipple structure called as papilla of
the hair contains many blood vessels that nourish the
growing hair follicle.

23. HAIR
• Cuticle of the hair:

24. SKIN GLANDS
Glands:
Two types of glands exist in the integument.
- Sebaceous glands (oil glands)
- Sudoriferous glands (sweat glands)
Sebaceous glands: (oil or holocrine glands)
- connected to hair follicle
- not found on palms and soles of feet
- secretes sebum (fats, cholesterol and
proteins
- keep hair from drying out, keeps skin moist
- whiteheads, blackheads and acne

25. SKIN GLANDS

26. SKIN GLANDS
• Whitehead: When the trapped sebum and
bacteria stay below the skin surface, a
whitehead is formed.

27. SKIN GLANDS
• Blackhead: A blackhead occurs when the trapped
sebum and bacteria partially open to the surface and
turn black due to melanin, the skin's pigment.
Blackheads can last for a long time because the
contents very slowly drain to the surface.

28. SKIN GLANDS
Sudoriferous glands: ( Sweat gland)
exocrine glands
- millions located throughout the skin
- It has two types:
1. Eccrine sweat gland
2. Apocrine sweat gland

29. SKIN GLANDS
Eccarine :more common (merocrine)
- originate in subQ layer
- duct empties on skin surface
- palms and soles of feet
- sweat is watery (99% H20)
- sweating regulated by
-sympathetic nervous system

30. SKIN GLANDS
- Apocrine: axillary and pubic region
- duct empties onto hair follicle
- viscous fluid
- causes body odor (“b-o “) when
bacteria break it down

31. SKIN GLANDS
Ceruminous glands: located in ear only
- modified apocrine glands
- originate in Sub Q layer
- ducts open onto EAM.
- produces cerumen (ear wax) : brown
sticky substance that prevents foreign
material from entering.

32. References:
1. Presentation on Introduction To Human
Anatomy & Physiology,
By Mr. Abhay Shripad Joshi.
2. Human Anatomy and Physiology-I,
By Dr. Mahesh Prasad, Dr. Antesh Kumar
Jha, Mr. Ritesh Kumar Srivastav, Nirali
Prakashan, As per PCI Syllabus.
Page No. 2.1 to 1.4.
3. www.google.com.

33. THANK YOU