Associate Professor:
Dina A.A. Hassan
-Associative professor in pharmacology
-Pharmacology department
-College of Pharmacy
-Sattam Ben Abdulaziz University ,
Al Kharge
Email : da.Hassan@sau.edu.sa.
dinallam5@gmail.com
INTEGUMENTARY SYSTEM

Dr Dina Allam Hassan
OBJECTIVES
At the end of this lecture , you should be able to:
-Define and enumerate the structure of the Integumentary
system
-Describe layers of the skin in details and function of each layer.
-Define and locate hypodermal layer and its related functions .
-Discuss the structure and function of hair follicles, nail , sweet
and sebaceous glans ( which are collectively called Skin
Appendages).
The Integumentary System
Integumentary system is the skin and the organs derived
from it (hair, glands, nails)
It is also one of the largest organs
◦ Largest sense organ in the body Integument is skin
STRUCTURE OF THE SKIN:
Two distinct regions
◦ Epidermis
◦ Dermis
◦ A fatty layer (hypodermis) lies deep to it
Skin Appendages
Derived from epidermis but extend into
dermis
 Include

 Hair and hair follicles
 Sebaceous (oil) glands
 Sweat glands
 Nails
Functions of Skin
Protection
◦ Cushions and insulates and is waterproof
◦ Protects from chemicals, heat, cold, bacteria
◦ Screens UV
Synthesizes of vitamin D with UV
Regulates body heat
Prevents unnecessary water loss
Sensory reception (nerve endings)
Structure of the skin
Histologically the skin is formed of two distinct
regions:
1- Epidermis
2- Dermis
N.B: A fatty layer (hypodermis) lies deep
to it
Epidermis and
Dermis
◦Epidermis is avascular (no blood vessels)
◦Dermis is highly vascular (has blood vessels)
◦Epidermis receives nourishment from dermis
◦Cells far away from nourishment die
1-Epidermis
Four types of cells
◦ Keratinocytes – produce keratin (tough fibrous protein) Keratinized stratified
squamous epithelium
◦ Melanocytes - make dark skin pigment melanin
◦ Merkel cells – associated with sensory nerve endings
◦ Langerhans cells – macrophage-like dendritic cells
Layers of keratinocytes(from deep to superficial)
◦ Stratum basale or germinativum – single row of cells attached to dermis; youngest
cells and actively divide by mitosis to form new cells which forms the more
superficial layers
◦ Stratum spinosum or spinous layer – spine is artifactual; it contains tonofilaments
(bundles of protein) resist tension
◦ Stratum granulosum or granular layer – layers of flattened keratinocytes producing
keratin (hair and nails made of it also)
◦ Stratum lucidum or clear layer-(present only on thick skin as palms and soles)
◦ Stratum corneum or horny layer –it is a dead layer that appears as flat membrane
filled with keratin. (cells dead, many layers thick)
FUNCTION OF KERATINOCYES :
Cell renewal and formation of keratin.
2- Dermis
See next picture
1)This layer locates deeper to dermis
2)It is formed of strong connective tissue
3)It is rich supply in nerves and blood vessels.
4)This layer is formed of two layers (see next slides)
◦ Papillary layer that includes dermal papillae and formed of
areolar connective tissue that rich in connective tissue
cells(fibroblast, macrophages, mast cells) .
◦ Reticular layer – “reticulum” under the papillary layer and
formed of networks of collagen and reticular fibers. That is
why it is called reticular layer
FUNCTION OF DERMIS :
It has a critical role in temperature regulation (rich in blood
vessels)
*Dermis layers
*Dermal papillae
*
*
Hypodermis
* It is also called :
1-“Hypodermis” = that means below the skin
2-“Subcutaneous” = that means below the skin
3- “superficial fascia” “fascia” (Latin) =in anatomy it means
sheet of connective tissue
Structure of hypodermis:
It is formed of fatty tissue
FUNCTIONS OF HYPODERMIS :
* it is formed of fatty tissue which stores fat
* it anchors skin to the underlying structure
Skin color
Three skin pigments
◦ Melanin: the most important
◦ Carotene: from carrots
◦ Hemoglobin: the pink of light skin
Melanin in granules passes from melanocytes (same
number in all races) to keratinocytes in stratum basale
◦ Digested by lysosomes
◦ Variations in color
◦ Function of melanin : Protection from UV light vs
vitamin D?
Nails
1- It is formed of hard keratin
2- it grows from nail matrix
Hair and hair follicles: complex
1- Hair and hair follicles are derived from epidermis
and dermis
2- usually they are present everywhere except palms,
soles, nipples, parts of genitalia
*
Hair bulb:
epithelial cells
surrounding
papilla
Hair papilla
is connective
tissue________________
Functions of hair:
◦ Warmth – less in human than other mammals
◦ Sense light touch of the skin
◦ Protection - Especially in the scalp
Parts hair:
◦ Root imbedded in skin
◦ Shaft projecting above skin surface
Make up of hair – hard keratin
Three concentric layers
◦ Medulla (core)
◦ Cortex (surrounds medulla)
◦ Cuticle (single layers, overlapping)
Types of hair
◦ Vellus: fine, short hairs
◦ Intermediate hairs
◦ Terminal: longer, courser hair
Hair growth: averages 2 mm/week
◦ Active: growing
◦ Resting phase
◦ shed
Hair loss:
◦ Thinning – age related
◦ Male pattern baldness
Hair color:
◦ Increase mount of melanin for black or brown colour;
◦ Distinct form of melanin for red colour
◦ White: decreased melanin and air bubbles in the medulla
Sebaceous (oil) Glands
These glands usually connected to
hair follicles
They are present in entire skin of the
body(thin skin) except palms and
soles (thick skin).
FUNCTION :
- Produce sebum
- Sebum is an Oily material that
lubricates hair.
Sweat Glands
- These glands present in the entire thin skin surface except nipples and
part of external genitalia
- In humans sweet gland are efficient ( but in animals only mammals
have efficient sweet glands )
FUNCTION:
1- Produce sweet in response to stress as well as heat
2- Prevent overheating
Use the following vocabulary to label the diagram: hair shaft,
oil (sebaceous)gland, fat cells, erector pili muscle, blood vessels, nerve
endings, epidermis, dermis, epithelial cells, hair follicle, sweat gland,
connective tissue