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SKIN AND BODY MEMBRANES: The Integumentary
System 
Saturday, 16 October 2021  9:22 pm 

The Integumentary System 
 
• Keeps water and precious molecules in the body 
• Pliable and tough 
 
 

Functions: 
 

Desiccation  

Contains a water-resisting glycolipids
and keratin (prevents drying out) 

Body Heat loss  

Activate sweat glands and allow blood
to flush into the skin capillary beds
(heat radiate from skin surface) 

Heat Retention  

Not allowing blood to flush into skin
capillary beds 

Excrete UREA /URIC
Acid 
 

 Through PERSPIRATION 

Synthesizes Vitamin D  

Modified molecules in skin converts to
Vitamin D by sunlight (Epidermal cells
produce cholecalciferol (Vitamin D3) 

 
 
Body Membranes COVERS the surface
...
Epithelial Membrane 
 
○ Cutaneous  Membrane (Skin/Integumentary System) 
• Superficial epidermis 
• Keratinizing STRATIFIED SQUAMOUS EPITHELIUM 
• DERMIS - made up of dense (FIBROUS) connective tissues
...
Stratified squamous epithelium - MOUTH and ESOPHAGUS 
ii
...
Parietal layer – Lines a specific portion of the wall of the ventral body cavity
...
Visceral layer – covers the outside of the organ in a cavity
...
 
• Allows the organ to slide easily across the cavity wall and one another without FRICTION
...
Connective Tissue Membrane 
○ Synovial (Joint Cavities) 
 

 
 
DAMAGES IN THE INTEGUMENTARY SYSTEM: 

 
Mechanical Damage -  Bumps and Cuts 
• Contains keratin that toughens the cell 
• Has pressure receptors which alerts the nervous system 
 
Chemical Damage - Acids and Bases 
• Impermeable keratinized cell or pain receptors 
 
Thermal Damage - Heat and Cold 
• Has heat and cold receptors 
 
Ultraviolet Damage -  Contains Melanin (Melanocytes) as protection against UV rays
...
Burn or Friction may cause the to separate allowing interstitial fluid
to accumulate in the cavity between layer (Blister) 

 

Hypodermis  
•
•
•
•

SUBCUTANEOUS tissue / Adipose 
Not part of the skin – but it anchors the skin to UNDERLYING organs 
 Shock absorber / Insulates deeper tissue 
 Responsible for the CURVES 

 
 
 

Epidermis 
○ Made up of STRATIFIED SQUAMOUS EPITHELIUM 
○ Capable of KERATINIZING (HARD and TOUGH) 
Contains ridges and ducts
...
 
• Ducts of eccrine sweat glands empty onto the surface of the skin
...
 

 

Represented by FLAT membranous sacs filled with keratin 

 

“Overcoat” of the body that provides protection
...
 
 

Stratum Lucidum 

Not present in all skin regions 

 

Occurs where skin is hairless and extra thick (Palms of hand/Sole of

feet) 
 

Accumulating keratin secretes water repellant glycolipid in to cellular
space 

 

Died – inadequate nutrients and oxygen (distant from the dermis) 
 

Stratum Granulosum 

Cells are flattened 

 

Full of KERATIN / KERATOHYLIN (Dense granules) 

 

ORGANELLES are deteriorate 
 

Stratum Spinosum 

Cells contain thick bundles of intermediate filaments made of prekeratin 

 

Cells shirks until cytoskeleton sticks out  

 

Contains Langerhans cell – IMMUNE RESPONSE 
 

Stratum
Germinativum  

Stem Cells are constantly dividing 

 

Forms a strong bond between the EPIDERMIS and DERMIS 
Avascular - no blood supply 
Keratin -  fibrous protein that makes the tough protective layer 
Keratinocytes – cells of the epidermis 
 
Epidermal Dendritic Cells are important in alerting and activating immune system cell 
(bacteria/viral invasion) 
 
Merkel Cells  
• Seen in Epidermal – Dermal Junction 
• Associated with SENSORY NERVE ending 
• Merkel Disc - Serves as touch receptors 

Melanin 
• A pigment  that ranges in color from yellow to brown to black 
• Function: Protect from sun damage 
 
Melanocytes 
Specialized spider shaped cells 
• Produces Melanin 
• Found in the STRATUM BASALE 
 
Melanosomes 
Membrane-bound granules where MELANIN 
accumulates 

Dermis  

 

 
○ STRONG and STRETCHY envelop that binds the body together 
○ Rich in blood supply 

Papillary Layer 

Upper dermal region 

 

• Has PEG like projection from superior surface (Dermal papillae 

 

• Capillary loops – furnish nutrients to the epidermis 
 

Reticular Layer 

Lower dermal region 

 

• Contains irregular arranged connective tissues fibers, blood 
vessels, sweat, oil glands and deep pressure receptors 
(lamellar corpuscles) 

 

• Phagocytes are abundant and collagen (toughness and binds
water) and ELASTIC FIBERS 

Arteries 

Veins 

Nerves 

Cutaneous plexus is a
Venous plexus - capillary return deep Nerve fibers skin control: 
network of arteries along the
to the papillary plexus 
• Blood flow 
reticular layer 
• Gland secretions 
 
• Sensory receptors 
Papillary plexus is a capillary
network from small arteries in
papillary layer 

Hypodermis 

 
The subcutaneous layer or hypodermis: 
• Lies below the integument 
• Stabilizes the skin 
• Allows separate movement 
 
 The subcutaneous layer is: 
• Made of elastic areolar and adipose tissues 
• Connected to the reticular layer of integument by connective tissue fibers 
 
Subcutaneous layer: 
• Has few capillaries and no vital organs 
• Site of subcutaneous injections using hypodermic needles 
 
 
Adipose Tissue 
 
Deposits of subcutaneous fat: 
○ have distribution pattern determined by hormones 
○ are reduced by cosmetic liposuction 

The skin life cycle takes 15-30 for a  cell to move from stratum germinosum to stratum
corneum
...
Amount and kind of MELANIN 
○ Yellow, Reddish Brown or Black 
○ Caucasian – LESS Melanin 
 
2
...
Amount of OXYGEN-RICH Hemoglobin 
○ Pigment of red blood cell found in the dermal blood vessel 
○ Crimson color of skin 
 
The signs of certain diseases: 
 
REDNESS
AND
ERYTHEMA 

PALLOR /
BLANCHING 

Embarrassmen Emotional
t (Blushing) 
stress
(Fear/anger) 
Fever 

JAUNDICE
(Yellow
Cast) 

BRUISES or  SKIN
Loss of
BLACK and DARKENI skin color 
WHITE
NG 
MARKS 

Liver
Impaired
Disorder
circulation 
(excess BILE
pigments) 

Impaired blood  

Hematoma 

Addison’s
disease 

Vitiligo 

 

 

flow / ANEMIA 
Hypertension 

 

 

 

 

 

Inflammation 

 

 

 

 

 

Allergy 

 

 

 

 

 

 
 
Skin Appendage: 
 
• Arises form the epidermis 
• Unique role in maintaining Homeostasis 
 
a
...
 
 
1
...
  
• Duct empty into a hair follicle or Directly in to the skin 
SEBUM is a mixture of oil substance and fragmented cell 
•  lubricant (keep skin soft and moist) 
•  Contains chemical that kills BACTERIA 
• Lubricate the hair 
• Control bacteria 
 
2
...
Found on DERMIS
...
5 million per person 
• HEAT REGULATING apparatus 
 
Two types: 
1
...
Apocrine gland 
FUNCTION: activated by nerve fibers during PAIN and STRESS / During sexual
foreplay 
 
• Found in the Axillary (Armpit) / Genital area 
• Larger than eccrine glands 
• Ducts empty in to the HAIR FOLLICLE 
• Secretion Contains: 
• Milky / Yellowish color 
• Secretion is ODORLESS 
• Fatty Acids 
• Proteins 
• High during PUBERTY (Androgen) 
 
b
...
Guarding the head 
b
...
Protect the respiratory tract/foreign objects 
d
...
 
• Found in all locations of the body except: 
• Palms 
• Soles of feet 
• Lips 
• Nipples 

 

• The Hair Follicle 
○ Is located deep in dermis 
○ Is wrapped in a dense connective-tissue sheath (Dermal sheath) 
○ Base is surrounded by sensory nerves (root hair plexus) 
 
• Produced by a hair follicle (flexible epithelial structure) 
• ROOT – part of the hair is enclosed 
• Lower part of the hair 
• attached to the integument 
 
• SHAFT – projecting surface at the scalp/ skin 
• upper part of the hair 
• not attached to the integument 
• Arrector Pili 
• “Raiser of hair” or “Goose bump” 
• Involuntary smooth muscle 
• Causes hairs to stand up 
 
 
• Hair is formed by division of a well-nourished stratum basale epithelial cells in the MATRIX
(Growth zone) of the hair bulb
...
As hair is produced, the
medulla contains the flexible soft keratin 
• CORTEX 
• Enclosed by the CUTICLE (layer of cells)
...
  
• CUTICLE 
• Most keratinized region
...
  
 
 
 

 

• Hair Gowth Cycle 
• Growing hair: 
• is firmly attached tomatrix 
 
• Club hair: 
• is not growing 
• is attached to an inactive follicle 
a
...
FREE EDGE 
2
...
ROOT (Embedded on skin) 
• Nail Folds – Border of nail overlapped by skin fold 
• Cuticle – Edge of the thick proximal nail fold
...
 

•
•
•
•
•
•

Nail matrix – responsible for nail growth
...
 
Eponychium – Skin (living tissue)attached to the nail plate 
Hyponychium – Skin just under the free edge of the nail 
Proximal nail folds – wedge of thickened skin at the base of the nail

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