A & P I Note Home Page



Integumentary System

Skin cross section

I). Functions of the Integumentary System

A). Protection

1). Chemical Barrier

2). Physical Barrier

3). Biological Barrier

B).   Body Temperature Regulation

1).  The body rids itself of excess heat through the skin.

2). If body temperature rises (external environment hot), blood vessels dilate causing the sweat glands to release sweat.

3). If body temperature lowers (external temperature cold) the blood vessels constrict to prevent heat loss.


body temperature regulations

When the skin needs to CONServe heat, the
blood vessels of the skin
When the skin is COld, the blood
vessels of the skin

C). Cutaneous Sensation

D). Metabolic Function

E). Blood Reservoir

F). Excretion

II). Regions or Layers of the skin


  squamous epithelial tissue


  reticular connective tissue


  adipose connective tissue


layers of skin



A). Epidermis

1). Keratinized stratified squamous epithelium

 A  tough outer barrier of dead cells

The epidermis is not vascularized

Nutrients are diffused from the dermal layer.

The epidermis has extensive innervation

2). Types of cells

i). Keratinocytes

ii). Melanocytes

iii). Merkel cells

iv). Langerhans’ cells

3). Layers of the Epidermis

i). Stratum Basale

ii). Stratum Spinosum

iii). Stratum Granulosum

iv). Stratum Lucidum

v). Stratum Corneum


layers of the epidermis





Bob's Shaving Grandma's Love Child. 

Layers of the epidermis-bottom to top






B). Dermis

1).  Reticular tissue with tough collagen fibers

2).  Richly supplied with nerve fibers, blood vessels, and lymphatic vessels.

3).  At joints the dermal layer folds to allow for joint flexibility.

4).  Stretch marks occur because of tearing of the dermal layer.

5).  Wrinkles are caused by the break down of the collagen fibers of the dermal layer

6).  Fingerprints

C). Hypodermis

III). Skin Color: Pigments

A). Melanin

Sun exposure causes an increase in melanin concentration.


Protect the nucleus (DNA)  from UV radiation

B). Carotene

  Yellow to orange pigment from bilirubin (from the breakdown of red blood cells) which is released as bile

C). Hemoglobin

IV). Structures of the skin

A). Sweat Glands

1). Eccrine Glands

2). Apocrine Glands

3). Ceruminous Glands

4). Mammary Glands

B). Sebaceous (Oil) Glands

Whiteheads: blocked sebaceous glands.

Blackheads: blockages dries and darkens.

Acne: inflammation of the sebaceous gland.

skin glands



meorcrine gland

apocrine gland

holocrine gland

merocrine glands

(eccrine glands)

apocrine gland



(sebaceous glands)


C). Cutaneous Sensory Receptors

exteroceptors:  receive stimulus outside body.




Missner’s Corpuscles

light touch

upper layer;

Merkel Discs

light touch

upper layer

Pacinian receptors

strong impact

deeper dermis

Root Hair plexus

wind blowing

hair follicle

Bare Nerve Ending

Painful stimuli

cold, hot, etc

through the skin

V). Skin Cancer

A). Basal Cell Carcinoma

B). Squamous Cell Carcinoma

C). Melanoma

VI). Burns

A). Rule of 9

B). Problems associated with burns:

bulletloss of body fluids and proteins and electrolytes.
bulletextra calories for cellular repair

C). Levels of burns

1). First-degree burns

2). Second-degree burns

3). Third-degree burn


rule of 9