Transcript Skin and Body Membranes Notes

Guided Notes for
Understanding the Skin
Chapter 4
1. The two major groups of body
membranes are the (1) epithelial
membranes, which include the
cutaneous, mucous, and serous
membranes, and (2) connective
tissue membranes, represented
by synovial membranes.
2. Epithelial membranes are
actually simple organs because
their epithelial sheet is always
combined with an underlying
layer of connective tissue.
3. A mucous membrane is composed of
epithelium resting on a loose
connective tissue membrane. Mucous
membranes line all body cavities that
open to the exterior, such as those of
the hollow organs of the respiratory,
digestive, and urinary systems.
4. The epithelium of the
mucosae is often adapted for
absorption or secretion.
5. A serous membrane is composed of
a layer of simple squamous
epithelium resting on areolar
connective tissue. Serous
membranes line body cavities that
are closed to the exterior. They occur
in pairs.
5. Serous layers are separated by
serous fluid. It allows the organs to
slide easily across the cavity walls
and one another without friction.
6. Synovial membranes are composed
of soft areolar connective tissue and
contain no epithelial cells at all. They
surround joints, where they provide a
smooth surface and secrete a
lubricating fluid.
7. Your skin is also known as a
cutaneous membrane. It is the
major organ of the
integumentary system.
Functions of the Skin
-Protection: cushions deeper organs and protects
the body from damage from outside
elements
-Temperature Regulation: capillary network and
sweat glands disperse heat
-Vitamin D Synthesis: modified cholesterol molecules
are converted to vitamin D by sunlight
-Information Gathering: cutaneous sensory receptors
are a part of the nervous system.
9. The epidermis of the skin is
made up of stratified squamous
epithelium that is capable of
keratinizing, which means
becoming hard and tough.
10. The dermis underlies the
epidermis and is made of dense
connective tissue.
11. The hypodermis, which is
essentially adipose tissue, anchors
the skin to underlying organs. It
serves as a shock absorber and
insulates the deeper tissues from
temperature changes.
12. The epidermis is avascular,
that is, it has no blood supply
of its own.
13. The deepest cell layer of the
epidermis, the stratum basale,
lies closest to the dermis and is
the only layer that receives
nourishment from the dermis.
14. The stratum lucidum is a
flat, clear, dead layer of
epithelial cells that occur only
where the skin is hairless and
extra-thick, such as the palms
of the hands and soles of the
feet.
15. The outer layer of the epidermis
is the stratum corneum. It
contains dead cell fragments, filled
completely with keratin. These
cells are often referred to as
cornified or horny cells.
16. Melanocytes, which are found
mainly in the stratum basale, produce
a pigment called melanin. When skin
is exposed to sunlight, which
stimulates the melanocytes to
produce more of the melanin, tanning
occurs.
17. The papillary layer is the upper
dermal region. It is uneven and has
finger-like projections called dermal
papillae, which indent the epidermis
above. The papillae furnish nutrients
to the epidermis. Papillary patterns
are genetically determined.
18. The reticular layer is the
deepest skin layer. It contains
blood vessels, sweat glands, oil
glands, and deep pressure
receptors called Pacinian
corpuscles.
3 pigments that contribute to skin
tone
1. The amount and kind of melanin in
the epidermis
2. The amount of carotene deposited in
the stratum corneum
3. The amount of oxygen bound to
hemoglobin in the dermal blood
vessels
20. The sebaceous glands, or oil
glands, are found all over the skin,
except on the palms of hands and
soles of feet. Sebaceous glands
produce sebum, which is a mixture of
oily substances and fragmented cells.
It is a lubricant that keeps the skin
soft and moist and prevents the hair
from becoming brittle.
21. Sweat glands are also called
sudoriferous glands. There are
2 types in the body.
22. Eccrine glands produce sweat, a
clear solution that is mostly water,
plus salt, vitamin C, wastes and lactic
acid. Eccrine sweat glands are an
important and highly efficient part of
the body’s heat-regulating
equipment. They secrete sweat when
the external temperature or body
temperature is high.
23. Apocrine glands are confined to the
axillary regions and genital areas.
Their secretions contain fatty acids
and proteins, which can give them an
unpleasant odor. Their precise
function is unknown, but they are
activated during stress.
24. A burn is tissue damage and cell
death caused by intense heat,
electricity, UV radiation, or chemicals.
When the skin is burned, two lifethreatening problems can result.
First, the body loses its supply of
fluids containing proteins and
electrolytes.
Later, infection becomes the most
important threat and is the leading
cause of death in burn victims. After
24 hours, pathogens such as bacteria
and fungi easily invade areas where
the skin has been destroyed.
The 3 Types of Burns
1st: only the epidermis is damged
redness/swelling
usually heals in 2-3 days
2nd: injury to the epidermis and upper region
of the dermis producing very painful
blisters
3rd: destroys the entire skin, appearing white
or blackened.
regeneration is not possible/skin must be
grafted
26. A wart, a neoplasm caused
by a virus, is one example of a
benign skin tumor.
27. The most important risk
factor for skin cancer is
overexposure to UV radiation.
28. Basal cell carcinoma is the least
malignant and most common skin
cancer. The cancer lesions occur
most often on sun-exposed areas of
the face and appear as shiny, domeshaped nodules. They are cured in
99% of the cases where surgery is
involved.
29. Squamous cell carcinoma
appears most often on the
scalp, ears, and dorsal regions
of the hands and neck. It
grows rapidly and metastasizes
to adjacent lymph nodes if not
removed.
30. Malignant melanoma is a
cancer of melanocytes. It
usually appears as a spreading
brown to black patch that
metastasizes rapidly to
surrounding lymph and blood.
ABCD Rule for recognizing
melanoma
A: asymmetry—the 2 sides of the
mole do not match
B: border irregularity—indentations in
a smooth border
C:color—different colors present
D:diameter—larger than 6mm.