skin and appendages Histology

Skin & Appendages
Dr. Shahbaz Ahmad PT
DPT[UIPT][UOL]
MS-MSK-PT [UIPT][UOL]*
Lecturer [LIHS][LCPS]

SKIN PHYSIOLOGY
 Protective barrier
 Conservation of fluid,
protein, & electrolyte loss
 Regulation of body
temperature
 Secretory ability
 Vitamin D production
 Sensation
 Appearance and self-image
 Wound healing and
epithelial cell regeneration

SKIN ANATOMY
Two layers:
 Epidermis
 Dermis
Photo from
www.medlineplus.gov

 The epidermis, the outermost layer of skin,
provides a waterproof barrier and creates our
skin tone.
 The dermis, beneath the epidermis, contains
tough connective tissue, hair follicles,
and sweat glands.
 The deeper subcutaneous
tissue (hypodermis) is made of fat
and connective tissue.

ANATOMY OF THE EPIDERMIS
 Avascular layer
 Varies in thickness in
different body areas, thicker
in greater pressure areas
 Fiver layers of the epidermis
Photo from www.wounds1.com

FIVER LAYERS OF THE EPIDERMIS
 Stratum Corneum (waterproof; constantly being shed
 Stratum Lucidium (only found in soles of feet and palms)
 Stratum Granulosum (cells become more flattened)
 Stratum Spinosum (active growing layer)
 Stratum Germinativum (mitotic growth; makes melanin)

EPIDERMIS
 Four types of cells
1. Keratinocytes
2. Melanocytes
3. Langerhans cells
4. Merkel cells

EPIDERMIS
 About 90% of the epidermal cells are
keratinocytes which produce keratin.
 Keratin helps to waterproof and protect the skin
and underlying tissues from heat, light, microbes
and many chemicals.
 Nanoparticles can diffuse and penetrate it.
(Phonophoresis Iontoporesis)

Epidermis
 8% of the epidermal
cells are melanocytes
which produce the
pigment melanin.
 Langerhans cells are
the third cell in the
epidermis, they interact
with helper T cells
(white blood cells) in
immune responses.

EPIDERMIS
 The merkel cell is the fourth type of cell in
the epidermis and is found in the deepest layer
of hairless skin. These cells make contact with
the end of nerve cells and are thought to
function in the sensation of touch.

ANATOMY OF THE DERMIS
• Overall thickness of skin depends
upon thickness of dermis.
• Mainly consists of collagen and
elastic fibers.
• Responsible for tone and texture of
the skin.
• Neurovascular structures and skin
appendages are found in dermis.
• It has two layers:
1.Papillary layer – toward epidermis
2.Reticular layer- toward hypodermis

Layers of dermis
 Papillary layer: loose areolar connective tissue,
finger like projections papillae towards the
epidermis, and contains blood capillaries or
Meissner’s corpuscles.(finger prints)
 Areolar connective tissues hold organs in place and attaches
epithelial tissue to other underlying tissues.

Layers of dermis
 Reticular layer:
 lies under papillary layer.
 Much thicker and composed of dense irregular
connective tissue.
 Collagenous elastic and reticular fibres, gives strength,
elasticity, and extensibility.
Roots of hair, sweat and sebaceous glands, receptors,
nails and blood vessels.


Physiology of the Dermis
 Supports epidermis through tensile strength and
elasticity
 Nourishes epidermis through capillary loops

Reticular layer
• The collagen and elastic fibers are
not randomly oriented but form
regular lines of tension in the skin
called Langer’s lines.
• Skin incisions made parallel to
Langer’s lines heal with the least
scarring.
Papillary layer

Skin appendages
•These are developed as a result of down growth of
the epidermis of skin toward dermis and
hypodermis.
•It includes
1.Hair follicle: give rise to the hair
2.Sebaceous gland
3.Sweat gland
4.Nail

Appendages of the Skin
 Hair
 Produced by hair follicle
which are made of hard
keratinized epithelial cells
 Melanocytes provide
pigment for hair color

Hair Anatomy
 Hair anatomy
 Central medulla
 Cortex surrounds medulla
 Cuticle on outside of cortex
 Most heavily keratinized

Hair cycle
Anangen phase- fast growing phase
Catangen phase- involution phase
Telogen phase- rest phase
Types of hair
1. Laungo hairs
2. Vellus hairs
3. Terminal hairs

Hair Structures
 Associated hair structures
 Hair follicle
 Dermal and epidermal sheath
surround hair root
 Arrector pili muscle
 Smooth muscle
 Pulls hairs upright when cold or
frightened
 Sebaceous gland

Nail structures
 Nail Free edge
 Body is the visible attached portion
 Root of nail embedded in skin
 Cuticle is the proximal nail fold that projects onto the nail body

Sweat and
Its Function
 Composition
 Mostly water
 Salts and vitamin C
 Some metabolic waste (urea and uric acid)
 Fatty acids and proteins (apocrine only)
 Function
 Helps rid body of excess heat
 Excretes waste products
 Acidic nature inhibits bacteria growth
 Odor is from associated bacteria

skin and appendages Histology

More Related Content

What's hot (20)

Similar to skin and appendages Histology (20)

More from Dr. Shahbaz Ahmad PT Chaudhary (14)

Recently uploaded (20)

skin and appendages Histology