Human Anatomy and Physiology
November 2015

Classification of Body Membranes (Figure 5-1)

Epithelial membranes
 Composed of epithelial tissue and an underlying layer
of connective tissue

Connective tissue membranes
 Composed exclusively of various types of connective
tissue

Epithelial Membranes

Cutaneous membrane
 The skin

Serous membranes
 Simple squamous epithelium on a connective tissue
basement membrane
 Types:
 Parietal – line walls of body cavities
 Visceral – cover organs found in body cavities

Serous membranes
(continued)

Examples
 Pleura – line walls of
thoracic cavity and
cover lungs
 Peritoneum – cover
organs found in body
cavities

Serous membranes (continued)

Diseases
 Pleurisy – inflammation of the serous membranes that
line the chest and cover the lungs
 Peritonitis – inflammation of the serous membranes in
the abdominal cavity

Mucous membranes


Line body surfaces that open directly to the exterior
Produce mucus
 Thick secretion that keeps the membranes soft and
moist

Connective tissue membranes



Do not contain epithelial components
Produce lubricant called synovial fluid
Examples:
 Synovial membranes that line spaces between joints
and lining of bursal sacs.

The Skin

Structure (figure 5-2) -- two
primary layers called
epidermis and dermis

Epidermis




Outermost and thinnest layer
of skin
Composed of several layers of
stratified squamous
epithelium
Stratum basale
(germinativum)
 innermost layer of cells
 Continually reproduces
 New cells move toward
surface
As cells approach surface they
are filled with a tough,
waterproof protein called
keratin and eventually flake
off
 Stratum corneum
 outermost layer of
keratin-filled cells
 Stratum granulosum Pigment-containing layer
 Melanocytes - produce
pigment
 Pigment is called
melanin
 Blisters
 Caused by breakdown
of union between cells
or primary layers of
skin
 Dermal-epidermal
junction - specialized
area between two
primary skin layers

Dermis
 Deeper and thicker
layer composed of
connective tissue
 Upper area of dermis
characterized by
parallel rows of peglike
dermal papillae
 Ridges and grooves in
dermis form pattern
unique to each
individual
(fingerprints)
 Deeper areas of
dermis filled with
network of tough
collagenous and
stretchable elastic
fibers
 Number of elastic
fibers decreases with
age and contributes to
wrinkle formation
 Dermis also contains
nerve endings, muscle
fibers, hair follicles,
sweat and sebaceous
glands, and many
blood vessels

Appendages of the skin
 Hair (figures 5-5 and 5-6)
 Lanugo - soft hair of
fetus and newborn
 hair follicle - epidermal
tubelike structure
required for hair growth
 Hair growth begins from
hair papilla
 Hair root lies hidden in
follicle and visible part of
hair is called the shaft
 Alopecia - hair loss
 Arrector pili - specialized
muscle fiber that
produces “goose
pimples” and causes hair
to stand up straight
 Receptors (figure
5-8)
 Specialized nerve
endings make it
possible for skin
to act as a sense
organ
 Meissner’s
corpuscle - detects
light touch
 Pacinian
corpuscle - detects
pressure
 Nails (figure 5-9)
 Produced by
epidermal cells over
terminal ends of
fingers and toes
 Visible part called
nail body
 Root lies in a groove
and is hidden by
cuticle
 Crescent-shaped area
nearest root called
lunula
 Nail bed may change
color with change in
blood flow
 Skin glands
 Types
 Sweat or sudoriferous
 Sebaceous
 Sweat or sudoriferous
glands
 Types
 Eccrine sweat
glands
 Most numerous,
important, and
widespread
 Produce
perspiration or
sweat which flows
out through pores
on skin surface
 Function throughout
life and assist in
body heat regulation
 Apocrine sweat
glands
 Found primarily in
axilla and around
genitalia
 Secrete a thick milky
secretion different
from eccrine
perspiration
 Breakdown of
secretion by bacteria
produces odor
 Sebaceous glands
 Secrete oil or sebum
for hair and skin
 Level of secretion
increases during
adolescence
 Amount of
secretion regulated
by sex hormones
 Sebum in sebaceous
gland ducts may
darken to form a
blackhead
 Acne vulgaris inflammation of
sebaceous gland
ducts
 Protection - first line of defense
 Against infection by microbes
 Against ultraviolet rays from
sun
 Against harmful chemicals
 Against cuts and tears
 Temperature Regulation
 Skin can release almost 3000
calories of body heat per day
Mechanisms of temperature
regulation
 Regulation of sweat secretion
 Regulation of flow of blood close
to the body surface
 Sense organ activity
 Skin functions as an enormous
sense organ
 Receptors serve as receivers for
the body, keeping it informed of
changes in its environment
 Disorders of the skin
 skin lesions
 Elevated lesions - cast a shadow outside
their edges
 Papule - small, firm raised lesion
 Plaques - large raised lesions
 Vesicle - blister
 Pustule - pus-filled lesion
 Crust - scab
 Wheal (hive) - raised, firm lesion with a
light center

Disorders of the Skin (continued)

Lesions
 Flat lesions - do not cast a shadow
 Macule - flat discolored region
 Depressed lesions - cast a shadow within
their edges
 Excoriation - missing epidermis (such as in a
scratch wound)
 Ulcer - crater like lesion
 Fissure - deep crack or break
 Treatment and recovery
or survival depends on
total area involved and
severity or depth of the
burn
 Estimating body
surface area using the
“rule of nines” (figure
5-11) in adults
 Body divided into 11
areas of 9% each
 Additional 1% of body
surface area around
genitals
 Classification of burns (figure 5-12)
 First-degree (partial-thickness) burns
 Only surface layers of epidermis involved
 Second-degree (partial thickness) burns
 Involved the deep epidermal layers
 Almost always cause injury to the upper level of the
dermis
 Third-degree (full-thickness) burns
 Complete destruction of epidermis and dermis
 May involve underlying muscle and bone
 Lesion is insensitive to pain because of destruction of
nerve endings immediately after injury - intense pain is
soon experienced
 Impetigo - highly contagious staphylococcal infection
 Tinea - fungal infection (mycosis) of the skin; several
forms occur
 Warts - benign neoplasms caused by papilloma virus
 Boils - furuncles; staphylococci infection in hair follicles
 Decubitus ulcers (bedsores) - develop when pressure
slows down blood flow to local areas of the skin
 Urticaria or hives - red lesions caused by fluid loss from
blood vessels
 Scleroderma - disorders of vessels and connective
tissue characterized by hardening of the skin;
 two types: localized and systemic
 Psoriasis - chronic inflammatory condition
accompanied by scaly plaques
 Eczema - common inflammatory condition
characterized by papules, vesicles, and crusts; not a
disease itself but a symptom of an underlying condition
 Three common types
 Squamous cell
carcinoma - most
common type,
characterized by hard
raised tumors
 Basal cell carcinoma characterized by
papules with a central
crater; rarely spreads
 Melanoma - malignancy
in a nevus (mole); the
most serious type
 The most important causative factor in common skin
cancers is exposure to sunlight
 Kaposi’s sarcoma, characterized by purple lesions, is
associated with AIDS and other immune deficiencies.