Transcript of 4. Skin and body membranes. DID YOU KNOW?!?: We have a totally “new” epidermis every 25 to 45...
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- 4. Skin and body membranes
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- DID YOU KNOW?!?: We have a totally new epidermis every 25 to 45
days Moles and freckles are seen where melanin is concentrated in
one spot Melanin is the natural sunscreen, but excessive sun
exposure damages skin causing the elastic fibers to clump leathery
skin Excessive sun exposure weakens the immune system You can lose
up to 7L of body water by sweating on a hot day. You have more than
2.5 million sweat glands!
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- Objectives: List the general functions of each membrane type
and give locations Compare tissue makeup of the major membrane
types Describe functions of the integumentary system Recognize and
label skin diagram as; epidermis, dermis, hair follicle, sebaceous
gland, & sweat gland Describe the layers of the epidermis
Describe the function of melanin Recognize the importance of the
rule of nines Summarize the distinctions between skin cancers List
examples of integumentary aging
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- Body membranes Body membranes cover surfaces, line body
cavities, form protective (lubricating) sheets around organs Two
categories Epithelial membranes- Cutaneous, mucous, and serous
Connective tissue membranes- synovial
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- Epithelial membranes are simple organs Cutaneous- skin, its
superficial epidermis is made up of keratinizing stratified
squamous epithelium. A dry membrane that is exposed to air Mucous
(mucosa)- lines all body cavites that open to the exterior such as
those hollow organs of the respiratory, digestive, urinary, and
reproductive tracts. Comprised of stratified squamous ephethelium
(mouth) or simple columnar epithelium (rest of digestive tract).
These are wet or moist mucosa and are surrounded in secretions
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- Serous (serosa)- composed of a layer of simple squamous
epithelium resting on a thin layer of areolar connective tissue.
Lines body cavities that are closed to the exterior (except for the
dorsal body cavity and joint cavities) These membranes occur in
pairs: The parietal layer lines a specific portion of the wall of
the ventral body cavity. It folds in on itself to form the visceral
layer which cover the outside of the organs in that cavity These
layers are separated by a tiny amount of thin, clear fluid, serous
fluid, which allows organs to slide easily across the cavity walls
w/o friction
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- Naming serous membranes depends on LOCATION, LOCATON, LOCATION
Peritoneum- serosa lining the abdominal cavity and covering its
organs Pleura- lining around the lungs Pericardium-lining that
encloses the heart
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- Connective Tissue Membranes Synovial membranes- cushions organs
and structures as they move as a result of skeletal/muscular
movement Found at the ends of the fibrous capsules of joints where
they provide a smooth surface that secretes a lubricating fluid,
synovial fluid, to reduce friction of tendons moving across bone
etc
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- Integumentary covering System (skin, sweat glands, oil glands,
hair, and nails) Functions to protect deeper tissue from:
Mechanical damage detected by cutaneous sensory receptors Chemical
damage prevented by keratinized cells Bacterial damage prevented by
acid secretions of skin UV damage (melanin produced) Thermal damage
detected by thermal receptors Drying out prevented by waterproofing
keratin and glycolipids Aids in temperature regulation Aids in
excretion of urea and uric acid Synthesizes vitamin D from
cholesterols (solar powered)
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- Epidermis- the outer portion is comprised of stratified
squamous epithelium that is capable of keratinizing (becoming hard
and tough) Dermis- the underlying layer mostly made up of dense
connective tissue Blister the result of interstitial fluid getting
in between and separating the dermis from the epidermis (caused by
rubbing)
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- Subcutaneous tissue (hypodermis)- deep below the dermis it is
comprised of adipose tissue. It anchors the skin to the underlying
organs. Acts as a shock absorber and insulator, and is responsible
for curves of the body.
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- Strata of the epidermis From the inside out: Stratum basale-
receives nourishment from dermis via diffusion. Cells constantly
dividing million/day Stratum Spinosum- daughter cells movin on up!
Stratum Granulosum-daughter cells movin on up! Stratum Lucidum
daughter cells that are full of keratin, flat,clear, and dead!
Stratum corneum- skin region that occurs only where the skin is
hairless and extra thick. 20-30 cells thick! Epidermis is avascular
(good thing ) Most epidermal cells are keratinocytes (produce
protein keratin)
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- Melanin- a pigment tht ranges in color from yellow to brown to
black and is produced by melanocytes that are located primarily in
the stratum basale When sunlight stimulates the melanocytes to
produce more of the melanin pigment, tanning occurs. The stratum
basale cells phagocytize (eat) the pigment and it accumulates
within them. Melanin forms a protective pigment umbrella over the
superficial side of their nuclei that shields their genetic
material from the UV damage
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- Dermis = hide This dense fibrous connective tissue layer is
comprised of two parts: Papillary layer- the upper layer dermal
region, uneven with fingerlike projections (dermal papillae) which
indent the epidermis. Contain capillary loops, pain receptors (free
nerve endings), touch receptors ( Meissners corpuscles), produce
ridges of the palms and soles (increase friction) Reticular layer-
deepest skin layer containing blood vessels, sweat and oil glands,
deep pressure receptors (Pacinian corpuscles) Found throughout the
dermis are: phagocytes to destroy bacteria, collagen fibers for
skin toughness and keep skin hydrated, elastic fibers provide the
elasticity of young skin.
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- Age process As we age the number of collagen and elastic fibers
decrease, and the subcutaneous tissue loses fat The result: skin
loses elasticity and begins to sag and wrinkle
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- Dermis & temp regulation homeostasis When body temp is
high, the capillaries of the dermis become engorged with heated
blood and the skin becomes reddened and warm. This allows body heat
to radiate from the skin surface If the environment is cool and
body heat must be conserved, blood bypasses the dermis capillaries
temporarily, allowing internal body temperature to stay high
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- Skin color Three pigments and their amounts contribute to skin
color: Melanin (yellow, reddish brown, or black) Carotene
(orange/yellow) Oxygen rich hemoglobin (pigment in red blood cells)
People who produce a lot of melanin have brown-toned skin. In
light-skinned people, the crimson color of the oxygen-rich
hemoglobin in the dermal blood supply flushes through the
transparent cell layers above
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- Redness (erythema)- blushing, fever, hypertension,
inflammation, allergy pallor- pale color due to emotional stress,
anemia, low blood pressure, reduced blood flow Jaundice- abnormal
yellow skin tone due to liver disorders in which excess bile
pigments are absorbed by the blood and deposited Bruises- reveal
sites where blood has clotted in tissue spaces (hematoma) frequent
bruising may indicate a vitamin C deficiency or hemophilia
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- Skin appendages: cutaneous glands, hair, hair follicles, and
nails Cutaneous glands- exocrine glands that release their
secretions to the skin surface via ducts. Two types: Sebaceous
glands Sweat glands
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- Sebaceous glands (oil)- found all over skin (except palms and
soles) secrete sebum. This is a mixture of oily substances and
fragmented cells. Sebum is a lubricant that keeps skin soft, moist,
and prevents hair from becoming brittle. Sebum contains bacteria
killing chemicals. These glands are very active when male sex
hormones are produced in high amounts
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- Sweat glands-sudoriferous glands are widely distributed is skin
~2.5 million /person Two types Eccrine-numerous and everywhere.
They produce sweat- a clear secretion that is primarily water,
salts, vitamin C, metabolic wastes, lactic acid. Has a slightly
acidic pH to prevent bacterial growth. They are supplied with nerve
endings to detect high temperature. Sweating through pores is a
cooling process due to evaporation. Apocrine- found in the axillary
and genital areas. Larger than eccrine glands and ducts empty into
hair follicles. Secretions contain fatty acids and proteins and may
be milky or yellowish in appearance. The secretion is odorless
however as bacteria on the skin use its proteins and fats, it takes
on a musky odor. These glands begin to function at puberty under
the influence of androgens (male sex hormones)
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- Hair and Hair Follicles Functions: Minor protection Shields
eyes Prevents foreign particle from entering respiratory tract
Minimal insulation Hair follicles produce hair. It is formed by the
division of the stratum basale epethial cells in the matrix (growth
zone) of the hair bulb at the inferior end of the follicle. As
daughter cells are pushed further from the growth zone, they become
keratinized and die. Therefore hair is dead cells and is mostly
protein.
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- Small bands of smooth muscle-arrector pili- connect each side
of the hair follicle to the dermal tissue. When these muscles
contract (cold, fear) the hair is pulled upright, dimpling the skin
surface with goose bumps This action allows insulation by trapping
air in the fur Hair pigment is made by melanocytes (yellow, rust,
brown, and black) Hair shaft shape determines hair type and
texture
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- Nail A scale-like modification of the epidermis that
corresponds to the hoof or claw of other animals Comprised of non
living material as the daughter cells produced by the matrix become
heavily keratinized
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- Go to the dermatologist skin disorders resul from: Allergies-
contact dermatitis Bacterial infections-carbuncles, impetigo Viral
infections-cold sores Fungal infections-athletess foot
Autoimmune-psoriasis
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- Burns-1 st, 2 nd, 3 rd, degree (rule of 9s)- volume of fluid
loss is determined by the body surface area that had been burned.
Infection is the cause of death in burn victims. Skin is sterile
for 24 hours after burn but then bacteria infest the decaying skin
matter and thrive. The immune system is suppressed and dehydration,
electrolyte loss and protein loss can contribute to circulatory
shock
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- ABCD Rule for recognizing melanoma
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- Causes of premature gray hair/hair loss Genetics- permanent
Emotional crisis Anxiety Protein-deficient diets Chemotherapy
Radiation Excessive vitamin A Fungal disease (round worm)
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- review Systems in sync pg 125 to understand homeostatic
relationships between the integumentary system and the other body
systems Read summary pg 126-127 Complete all review questions pg
127 Going further/bonus complete at the clinic responses