Unit -7
Dermatology
Dermatology
 The medical specialty that studies the anatomy and
physiology of the integumentary system and uses
diagnostic tests, medical and surgical procedures, and
drugs to treat integumentary diseases.
Figure 7-1 Integumentary system
Anatomy and Physiology
• The integumentary system consists of the skin
(epidermis and dermis), sebaceous glands, hair, and
nails.
• Protects the body and is the first line of defense
against invading microorganisms
• Includes the sense of touch
Anatomy of the Integumentary
System
• Skin consists of two different layers:
 The epidermis is categorized as epithelial tissue and
covers the external surface of the body.
 The epidermis also includes the mucous membranes
that line the walls of internal cavities that connect to the
outside of the body.
 The dermis is categorized as connective tissue.
Anatomy of the Integumentary
System (con't)
• Epidermis
 This is the thin, outermost layer of the skin.
 It contains cells that have no nuclei and are filled with
keratin, a hard, fibrous protein.
 These cells form a protective layer, but they are dead
cells, so they are constantly being shed or sloughed off
in the process known as exfoliation.
Anatomy of the Integumentary
System (con't)
• Epidermis (con't)
 The deepest part (basal layer) of the epidermis is
composed of living cells that are constantly dividing and
being forced to the surface (exfoliation).
 Does not contain any blood vessels; it receives nutrients
and oxygen from the blood vessels in the dermis
Anatomy of the Integumentary
System (con't)
• Epidermis (con't)
 Contains melanocytes, pigment cells that produce
melanin, a dark brown or black pigment that absorbs
ultraviolet light from the sun to protect the DNA in skin
cells from undergoing genetic mutations
Figure 7-2 Epidermis and dermis
Anatomy of the Integumentary
System (con't)
• Dermis
 A thicker layer beneath the epidermis
 Contains collagen fibers (firm, white protein) and
elastin fibers (elastic, yellow protein)
 Contains arteries, veins, and neurons (nerve cells), as
well as hair follicles, sebaceous glands, and sweat glands
 A dermatome is a specific area on the skin that sends
sensory information to the spinal cord.
Anatomy of the Integumentary
System (con't)
• Sebaceous and Sweat Glands
 Sebaceous glands are a type of exocrine gland in the
dermis that secrete sebum through a duct into a hair
follicle.
 Also known as oil glands.
 Sweat glands are also exocrine glands.
 Sweat contains water, sodium, and small amounts of
body waste (urea, ammonia, creatinine).
Anatomy of the Integumentary
System (con't)
• Sebaceous and Sweat Glands (con't)
 Sweat glands help to regulate the body temperature.
 The process of sweating and the sweat itself are both
known as perspiration.
 The sweat glands are also known as the sudoriferous
glands.
Anatomy of the Integumentary
System (con't)
• Hair
 Covers most of the body
 Additional facial, axillary, and pubic hairs appear during
puberty.
 Forms in a hair follicle in the dermis
Anatomy of the Integumentary
System (con't)
• Hair (con't)
 Melanocytes give color to the hair.
 Hair cells are filled with keratin, which makes the hair
shaft strong.
 Usually, the hair lies flat on the surface of the skin, but
when the skin is cold, a tiny erector muscle at the base of
the hair follicle contracts and causes the hair to stand up
(piloerection).
Xie Qiuping
Hair Length = 18’ 5.54”
Tran Van Hay
Hair Length = 20’ 3.6”
Anatomy of the Integumentary
System (con't)
• Nails
 Cover and protect the distal ends of the fingers and toes
 Each nail consists of a nail plate, nail bed, cuticle,
lunula, and nail root.
Figure 7-4 Nail
Anatomy of the Integumentary
System (con't)
• Subcutaneous Tissue
 A loose, connective tissue directly beneath the dermis of
the skin
 Composed of adipose tissue or fat that contains
lipocytes (fat-storing cells)
 Provides a layer of insulation to conserve internal body
heat
Anatomy of the Integumentary
System (con't)
• Subcutaneous Tissue (con't)
 Can be thin or as thick as several inches
 Subcutaneous layer also acts as a cushion to protect the
bones and internal organs
Physiology of an Allergic
Reaction
 An allergy or allergic reaction is a hypersensitivity
response to certain types of antigens known as
allergens.
 Allergens include cells from plant and animal sources
(foods, pollens, molds, animal dander), as well as dust,
chemicals, and drugs.
Physiology of an Allergic
Reaction (con't)
 The basis of all allergic reactions is the release of
histamine from basophils in the blood and mast cells
in the connective tissue.
 A local reaction occurs when an allergen touches the
skin or mucous membranes of a hypersensitive
individual
 Anaphylaxis is a severe systemic allergic reaction that
can be life-treatening
 Epi-pen
Figure 7-5 Edema
Figure 7-6 Types of skin lesions.
Figure 7-7 Necrosis and pallo
Meyer/Custom Medical Stock Photo, Inc.
Figure 7-9 Second-degree burn of the hand
Logical Images, Inc.
Figure 7-11 Decubitus ulcer
Custom Medical Stock Photo, Inc.
Figure 7-12 Laceration
Gill/Custom Medical Stock Photo, Inc.
Figure 7-13 Shingles
Gill/Custom Medical Stock Photo, Inc.
Figure 7-14 Tinea pedis
SPL/Photo Researchers, Inc.
Figure 7-16 Hemangioma
Custom Medical Stock Photo, Inc.
Figure 7-20 Malignant melanoma
ISM/Phototake, Inc.
Figure 7-21 Kaposi’s sarcoma
Zeva Oelbaum/Peter Arnold, Inc.
Figure 7-22 Psoriasis
NMSB/Custom Medical Stock Photo, Inc.
Table 7-1 Comparison of Acne Vulgaris and Acne Rosacea
Figure 7-26 Allergy skin testing
SIU/Photo Researchers, Inc.
Figure 7-27 Botox injection
Suzanne Dunn/The Image Works
Figure 7-30 Liposuction
James King-Holmes/D. Mercer/Photo Researchers, Inc.
Figure 7-31 Skin grafts
Courtesy Martin R. Eichelberger, M.D., Children’s National Medical Center, Washington, DC
Figure 7-32 Subcutaneous injection