 INTEGUMENTARY 1.

Keratinocytes
-makes up keratin = fibrous protein
SYSTEM that makes epidermis tough/ protective,
and an acidic substance that kills
foreign microorganisms
I. INTRODUCTION
-predominant in epidermis
-Remarkable organ (has all the four types of
-keratohyalin = requirement for
tissues)
keratin formation
-Largest organ
2. Melanocytes
-Adult skin = 15-20% of total body weight
-makes melanin = responsible for
-Composed of 2 kinds of tissue
skin coloration, protective pigment
-Epidermis and Dermis are firmly connected, but
umbrella, prevents damaging effects of
separate (when rubbed/burned = blisters)
UV rays
II. SKIN 3. Langerhans Cells
A. LAYERS -protective function
a. EPIDERMIS b. DERMIS
-Outer -Inner
-Epithelial (Stratified squamous -Connective Tissue Layer
epithelium) -True layer of the skin
-Keratinized -Has collagen (toughness) and elastic
-Avascular (elasticity when young) fibers
-Has few nerve endings/ sensory receptors -Key cell type: Fibroblast
-Thinner than dermis -Vascularized
-LAYERS OF THICK SKIN: -Has nerve endings
1. Stratum Corneum -Strong, stretchy envelope, helps hold
-Keratinized outermost layer body together
-Has very thin squamous cells (dead -Has capillaries (oxygenation and
cells), its protoplasm changes to keratin nourishment) and lymph nodes (protection,
-Flaked off periodically phagocytic mechanism)
(desquamation) -Has cutaneous glands, hair follicles and
-Exposure = melanocytes some nerve and muscle cells
2. Stratum Lucidum -Thickest of skin layers
-Protective layer -LAYERS:
-Clear, transparent 1. Papillary Layer
-Has few layers of dead cells with -Superficial Layer
eleiden (blocks water loss/ -Has fingerlike protrusions;
penetration), later transforms to keratin Dermal Papillae:
-Absent in thin skin, present in thick -Has tactile corpuscles
skin (soles and palms) (Meissner’s corpuscles) and pain
3. Stratum Granulosum receptors (free nerve endings)
-Has 2 to 3 layers of squamous cells -Has capillary loops that furnish
with irregularly shaped keratohyalin nutrients to epidermis
granules 2. Reticular Layer
-Might be missing in some sections -Deepest Layer
of thin skin -Has blood vessels
Stratum Germinativum: -Has sweat and oil glands
4. Stratum Spinosum -Has deep pressure receptors
-8 to 10 layers of irregularly shaped (Pacinian corpuscles)
cells -Has fibrous and elastic tissues, taht
5. Stratum Basale interlace between occupied adipose
-simple columnar epithelium tissues
-undergo mitosis -Has phagocytes
-has melanocytes
-Total thickness = 0.5 to 1mm -HYPODERMIS
-3 TYPES OF CELLS: -Subcutaneous Tissue
 -Deep in the dermis/ beneath skin -Found everywhere
-Contains Areolar and Adipose -most abundant in axillae, palms, soles
-Serves as shock absorber and forehead
-Insulates deeper tissues from extreme -has single tube with coiled end in
temperature subcutaneous tissue
-opens into surface by a pore
 SKIN COLOR: (pigments contributing to skin -secretes eccrine/sweat
color) -Salt (NaCl)
1. Melanin -Organic constituents; urea, uric
-yellow, reddish brown, or black acid, ammonia, lactic acid,
2. Carotene ascorbic acid
-yellow-orange -Inorganic Constituents
-deposited in stratum corneum and -pure sweat = very dilute and
hypodermis neutral
3. Hemoglobin -Perspiration (sweating) Purpose:
-in RBC found in dermis -Primary: to eliminate heat
-Secondary: eliminate excess water and
B. FUNCTIONS mineral salts
1. Protection -2 TYPES:
a. Insulates and cushions deep organs (from A. Eccrine Sweat Glands
mechanical, chemical, thermal damages, ultraviolet -more numerous
rad and bacteria) -all over the body
b. Keratin prevents water loss from the body -highly efficient for heat regulation
surface -has nerve endings
2. Regulates heat loss (because of rich capillary B. Appocrine Sweat Glands
network and sweat glands) -largely confined to axillary and
3. Mini Excretory System that eliminates urea, genitals
salts and water (when sweating) -empty into the hair follicles
4. Synthesizes vitamin D and proteins important for -minimal role in thermoregulation
immunity -secretion has fatty acids and
5. Sense Organ (Has cutaneous sensory receptors proteins
sensitive to touch, pressure, temperature and pain) -odoriferous glands
B. NAILS
III. SKIN APPENDAGES -clear and horny cells of epidermis
A. CUTANEOUS GLANDS -forms solid continuous plates on dorsal
1. Sebaceous Glands/ Oil Glands surface of terminal phalanges.
-Exocrine Glands with secretory and -stratum basale extends beneath the nail bed
excretory part (hair, sometimes on skin -all nail cells are produced by matrix
surface) -nail cells become heavily keratinized and
-occurs everywhere except palms and die
soles -PARTS:
-abundant in scalp and face, numerous in -Free edge, Nail body and Nail root
apertures of nose, external ears, mouth and -Nail fold, Cuticle
anus -Nail matrix = nail growth
-secretes sebum/oil C. HAIRS
-contains soap, fats, -all over body except palms and soles,
cholesterol, albuminous terminal phalanges, parts of ext genetalia,
materials, remnants of nipples and lips
epithelial cells and inorganic -develops from hair follicles
salts -hormones = growth of hair
-protects hairs from
becoming brittle
-keeps skin soft and pliable

2. Sweat Glands
 -hair is formed by division of well-
nourished stratum basale cells in matrix
(growth zone) of hair bulb (inferior end of hair
follicle)
-PROTECTIVE FUNCTIONS:
-guards head against bumps (hair)
-shields eyes (eyelashes)
-helps keep particles out of respiratory
tract (nasal hairs)
-PARTS:
-Hair shaft (surfaces from scalp)
-Hair root (enclosed in hair follicles)

 ARRECTORES PILORUM
-Small bands of smooth muscle LANGERHANS
cells that connect each side
of the hair follicle to the
dermal tissue.
-When these muscles
contract (as when we are
cold or frightened), the hair
is pulled upright, dimpling
the skin surface with “goose
bumps.”

KERATINOCYTE
MELANOCYTE