THE INTEGUMENTARY SYSTEM:

SKIN

HAIR

NAILS

GLANDS

IS THE MOST VISIBLE ORGAN SYSTEM OF HUMAN BODY

FUNCTIONS

        •          PROTECTIVE BARRIER

•          REGULATOR OF BODY TEMPERATURE

•          SYNTHESIS OF VITAMIN D

•          SENSORY RECEPTOR

•          SOTRAGE OF NUTRIENTS

•          EXCRETION ( glands )

SKIN

CONSISTS OF TWO LAYERS:

AN OUTER MULTILAYERED EPIDERMIS AND A DEEPER DERMIS

EPIDERMIS

•          IS THE OUTERMOST LAYER OF EPITHELIAL TISSUE

•          IN PALMS AND SOLES SKIN HAS FIVE LAYERS ( THICK SKIN )

•          IN THE REST OF THE BODY HAS FOUR LAYERS ( THIN SKIN )

LAYERS OF THE EPIDERMIS

•          STRATUM GERMINATIVE ( BASALE )

•          STRATUM SPINOSUM

•          STRATUM GRANULOSUM

•          STRATUM LUCIDUM ( in thick skin )

•          STRATUM CORNEUM

STRATUM GERMINATIVE

•          INNERMOST EPIDERMAL LAYER

•          FORMS EPIDERMAL RIDGES

•          HAS BASAL CELLS, MERKEL CELLS AND MELANOCYTES

STRATUM SPINOSUM

•          CONSISTS OF 8-10 LAYERS OF KERATOCYTES

•          HAS LANGERHANS CELLS

•          CELLS INTERCONNECTED BY DESMOSOMES

STRATUM GRANULOSUM

•          CALLED GRAINY LAYER

•          3-4 LAYERS OF CELLS

•          IN THIS STRATUM THE CELLS STOP DIVIDING, AND BEGIN MAKE KERATIN AND KERATOHYALIN

STRATUM LUCIDUM

•          A THIN TRANSPARENT LAYER OF CELLS.

•          LIES BETWEEN STRATUM GRANULOSUM AND STRATUM CORNEUM ( only in thick skin )

•          KERATOHYALIN IS CONVERTED IN ELEIDIN WHICH BECOMES KERATIN

STRATUM CORNEUM

•          15-30 LAYERS OF KERATINIZED CELLS ( flattened, dead cells )

•          IS THE EXPOSED SURFACE OF SKIN

•          CELLS ARE CONSTANTLY BEING SHED AND REPLACED BY NEW CELLS

DERMIS

•          IS A THICKER LAYER OF CONNECTIVE TISSUE BENEATH THE EPIDERMIS

•          DERMIS TOLERATES LIMITED STRETCHING, BECAUSE OF THE FIBERS OF COLLAGEN AND ELASTIN

•          HIGHLY VASCULAR ( provides most of nourishment to epidermis

DERMIS IS DIVIDED INTO TWO REGIONS:

THE PAPILLARY LAYER AND THE RETICULAR LAYER

PAPILLARY LAYER

•          OUTER PORTION OF DERMIS

•          CONTAIN THE DERMAL PAPILAE

•          CONTAIN THE CAPILLARIES FOR BLOOD SUPPLY

•          CONTAINS AREOLAR TISSUE

RETICULAR LAYER

•          DEEPER PORTION OF DERMIS

•          CONTAINS MORE COLLAGENOUS FIBERS THAN PAPILLARY LAYER          ( responsible for strenght of the skin )

•          CONTAINS DENSE IRREGULAR CONNECTIVE TISSUE

SUBCUTANEOUS LAYER (  HYPODERMIS  )

•          LIES BENEATH THE DERMIS

•          IT CONSISTS OF LOOSE CONNECTIVE TISSUE, NERVES, AND BLOOD VESSELS, ADIPOSE TISSUE.

•          PROVIDE ATTACHMENT FOR THE SKIN TO UNDERLYING STRUCTURES

ACCESORY STRUCTURES OF THE SKIN:

GLANDS

HAIR

NAILS

HAIR

•          IS COMPOSED OF CORNIFIED THREADS OF CELLS THAT DEVELOP FROM THE EPIDERMIS

•          ITS FUNCTION IS PROTECTION

•          WE HAVE VELLUS HAIRS ( body ) AND TERMINAL HAIRS (eyebrows, eyelashes)

STRUCTURE OF HAIR

•          HAIRS CONSISTS OF EPITHELIAL CELLS ARRANGED IN THREE LAYERS. FROM THE INSIDE OUT OF A HAIR SHAFT, THESE ARE:

1. MEDULLA ( soft keratin )
2. CORTEX ( hard keratin )
3. CUTICLE ( hard keratin )

THE HAIR SHAFT PROTRUDES FROM THE SKIN, THE HAIR ROOT IS EMBEDDED BENEATH THE SKIN, AND THE ENTIRE STRUCTURE IS ENCLOSED WITH A

HAIR FOLLICLE

GLANDS

SKIN HAS TWO TYPES OF EXOCRINE GLANDS

SEBACEOUS GLANDS AND SWEAT ( sudoriferous ) GLANDS

SEBACEOUS GLANDS

•          DISCHARGE A WAXY, OILY SECRETION ( SEBUM ) INTO HAIR FOLLICLES AND OUT ONTO THE SKIN SURFACE  ( sebaceous follicles )

•          THE MAJOR FUNCTION IS LUBRICATION AND PROTECTION OF KERATIN

SWEAT GLANDS

WE HAVE TWO TYPES OF  SWEAT GLANDS:

APOCRINE SWEAT GLANDS AND MEROCRINE SWEAT GLANDS

APOCRINE SWEAT GLANDS

•          LOCATED IN ARMPITS, NIPPLES, GROIN.

•          SECRETE THEIR PRODUCTS INTO HAIR FOLLICLES.

•          BECOME ACTIVE AT PUBERTY

•          ODOROUS SECRETION

MEROCRINE SWEAT GLANDS

•          ARE MORE NUMEROUS AND WIDELY DISTRIBUTED THAN APOCRINES

•          PALMS AND SOLES HAS THE HIGHEST NUMBER

•          ARE NOT ASSOCIATED WITH HAIR FOLLICLES

•          SECRETE SWEAT COINTAING WATER AND ELECTROLYTES

NAILS

•          ARE MODIFICATION OF THE EPIDERMIS

•          ARE COMPOSED OF HARD KERATIN

•          PROTECT THE TIPS OF THE FINGER TOES