Covering and Lining Membranes
• Information found in Chapter 4 and 5
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Covering and Lining Membranes
• Composed of at least two primary tissue
types
– An epithelium bound to underlying connective
tissue proper
– Are simple organs
• Three types
– Cutaneous membranes
– Mucous membranes
– Serous membranes
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Figure 4.11a Classes of membranes.
Cutaneous membrane
The cutaneous membrane
(the skin) covers the body surface.
Cutaneous
membrane (skin)
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Figure 4.11b Classes of membranes.
Mucous membranes
Mucous membranes line body
cavities that are open to the
exterior.
Mucosa of
nasal cavity
Mucosa of
mouth
Esophagus
lining
Mucosa of
lung bronchi
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Figure 4.11c Classes of membranes.
Serous membranes
Serous membranes line body cavities that are
closed to the exterior.
Parietal
pleura
Visceral
pleura
Visceral
Parietal
pericardium pericardium
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Parietal
peritoneum
Visceral
peritoneum
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Figure 5.1 Skin structure.
Hair shaft
Dermal papillae
Epidermis
Subpapillary
plexus
Papillary
layer
Sweat pore
Appendages of
skin
Eccrine sweat gland
Arrector pili muscle
Sebaceous (oil)
gland
Hair follicle
Hair root
Dermis Reticular
layer
Hypodermis
(subcutaneous
tissue; not part
of skin)
Nervous structures
Sensory nerve fiber
with free nerve endings
Lamellar corpuscle
Hair follicle receptor
(root hair plexus)
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Cutaneous plexus
Adipose tissue
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Skin Color
• Three pigments contribute to skin color
– Melanin
• Only pigment made in skin
– Carotene
– Hemoglobin
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Melanin
• Two forms
– Reddish-yellow to brownish-black
• Color differences due to amount and form
• Produced in melanocytes
– Same relative number in all people
• Migrates to keratinocytes to form "pigment
shields" for nuclei
• Freckles and pigmented moles
– Local accumulations of melanin
• Sun exposure stimulates melanin production
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Carotene and Hemoglobin
• Carotene
– Yellow to orange pigment
• Most obvious in palms and soles
– Accumulates in stratum corneum and
hypodermis
– Can be converted to vitamin a for vision and
epidermal health
• Yellowish-tinge of some asians – carotene
and melanin variations
• Hemoglobin
– Pinkish hue of fair skin
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Skin Color in Diagnosis
• Cyanosis
– Blue skin color - low oxygenation of hemoglobin
• Erythema (redness)
– Fever, hypertension, inflammation, allergy
• Pallor (blanching)
– Anemia, low blood pressure, fear, anger
• Jaundice (yellow cast)
– Liver disorder
• Bronzing
– Inadequate steroid hormones in addison's disease
• Bruises
– Clotted blood beneath skin
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Skin Cancer
• Most skin tumors are benign (not cancerous)
and do not metastasize (spread)
• Risk factors
– Overexposure to UV radiation
– Frequent irritation of skin
• Some skin lotions contain enzymes that can
repair damaged DNA
• Three major types of skin cancer
– Basal cell carcinoma
– Squamous cell carcinoma
– Melanoma
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Basal Cell Carcinoma
• Least malignant; most common
• Stratum basale cells proliferate and slowly
invade dermis and hypodermis
• Cured by surgical excision in 99% of
cases
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Basil Cell Carcinoma
Basal cell skin
cancers are
common after
age 40,
especially in
fair-skinned
people
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Squamous Cell Carcinoma
• Second most common type
• Involves keratinocytes of stratum
spinosum
• Usually scaly reddened papule on scalp,
ears, lower lip, and hands
• Does metastasize
• Good prognosis if treated by radiation
therapy or removed surgically
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Squamous Cell Carcinoma
Squamous
cell cancers
are more
common in
fair-skinned
people who
are older
than 50
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Melanoma
• Cancer of melanocytes
• Most dangerous
– Highly metastatic and resistant to chemotherapy
• Treated by wide surgical excision accompanied
by immunotherapy
• Chance of survival is poor if the lesion is over 4
mm thick
• Key to survival is early detection – ABCDE rule
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Melanoma – A = Asymmetrical Shape
Asymmetrical skin growths, in
which one part is different from
the other, may indicate
melanoma. Here, the left side of
the mole is dark and a little
raised, whereas the right side is
lighter in color and flat.
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Melanoma – B = Border
B: Irregular border
Melanomas tend to have borders
that are vaguely defined.
Growths with irregular, notched
or scalloped borders need to be
examined by a doctor.
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Melanoma – C = Color
C: Changes in color
Multiple colors or uneven
distribution of color may
indicate cancer. Generally,
growths that are a uniform
color are noncancerous
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Melanoma – D = Diameter
D: Diameter
A skin growth's large size may
be an indication of cancer. A
rapid increase in size over
weeks or months may
indicate cancer. Have your
doctor check out any growth
larger than the diameter of a
pencil eraser (6 millimeters).
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Melanoma – E = Evolving
The mole shown here does not fit
into any of the other criteria for
removal — size, shape, color or
pattern. But watch moles like these
closely for changes, due to the
small amount of color irregularity.
Look for changes over time, such
as a mole that grows in size or that
changes color or shape. Moles may
also evolve to develop new signs
and symptoms, such as new
itchiness or bleeding.
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Mole vs Melanoma
Mole
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Burns
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Burns
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Burns
• Tissue damage caused by heat, electricity,
radiation, certain chemicals
– Denatures proteins
– Kills cells
• Immediate threat:
– Dehydration and electrolyte imbalance
• Leads to renal shutdown and circulatory shock
• To evaluate burns
– Rule of nines
– Used to estimate volume of fluid loss
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Figure 5.9 Estimating the extent and severity of burns using the rule of nines.
Totals
41/2%
Anterior and posterior
head and neck, 9%
Anterior and posterior
upper limbs, 18%
41/2% Anterior 41/2%
trunk,
18%
9%
9%
Anterior and posterior
trunk, 36%
(Perineum, 1%)
Anterior and posterior
lower limbs, 36%
100%
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Burns Classified by Severity
• Partial-thickness burns
– First degree
– Second degree
• Full-thickness burns
– Third degree
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Figure 5.10 Partial thickness and full thickness burns.
1st-degree burn
3rd-degree burn
2nd-degree burn
Skin bearing partial thickness
burn (1st- and 2nd-degree burns)
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Skin bearing full thickness
burn (3rd-degree burn)
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Severity and Treatment of Burns
• Critical if
• Treatment includes
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