Integumentary system Composed of Skin, Hair, Nails
Skin:
Ø Largest
organ.
Ø Thickness 0.2mm
Composed of three layers
A. Epidermis
B. Dermis
C. Hypodermis
The
skin’s colour is created by special cells called melanocytes, which
produce the pigment melanin.
- Melanocytes are located in the epidermis.
Epidermis:
Is
the outermost layer of skin provides a waterproof barrier and creates our skin
tone.
A barrier to infection from environmental pathogens.
Epidermis further divided into 5 layers:
— Stratum corneum
— Stratum lucidum
— Stratum granulosum
— Stratum spinosum
— Stratum basale
Dermis:
Beneath
the epidermis, contains tough connective tissue, consist of
v Hair
follicles
v Sweat glands
v Blood
vessels
v Nerve
endings
The deeper subcutaneous tissue (Hypodermis)
— Is made of
fat and connective tissue.
— It regulates body temperature, acts as an insulator.
Sebaceous (oil) glands:
Secrete the oily, waxy substance called sebum,
Ø Combination
of cholesterol, proteins, fats & salts
Ø Keeps hair
and skin soft & pliable
Ø Inhibits
growth of bacteria & fungi
Ø Sebum waterproofs
and lubricates the skin
Sweat
glands:
A small, coiled, tubular gland that produce sweat
Three types of sweat glands
A. Eccrine
B. Apocrine
C. Apoeccrine
Arrector pili muscles:
Connected to each hair follicle of skin, helps the
hair to erect (Goosebumps).
The function of Skin:
ü Physical
protection
ü Regulation
of body temperature
ü Excretion
ü Nutrition
(synthesis of Vitamin D)
ü Sensation
ü Immune
defence
Nail:
Nail
is a horn-like keratinous plate at the tip of the fingers and toes, made up of keratin.
Consist
of
A. Nail plate
B. Nail fold
C. Nail bed
D. Cuticle
E. Lunula
Hair:
Hair
is made up of Keratin.
Consist of
1. Follicle and
2. Hair shaft