Ch 4 integumentary system

Ch. 4 Skin and Body Membranes
http://www.udel.edu/biology/Wags/histopage/colorpage/cin/cin.htm
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Essential Question:
How is skin considered a body system?
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Body membranes:
• cover surfaces
• line body cavities
• protective sheets around organs
2 types:
• epithelial
• connective
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Epithelial Membranes:
(do have connective tissue underneath)
• Cutaneous = skin
keratinizing stratified squamous epithelium
underlying dermis = dense fibrous connective tissue
dry membrane
http://dictionary.reference.com/illus/illustration.html/ahd4/skin/skin
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Mucous Membranes (mucosa):
• epithelium on loose connective tissue called lamina propia
• lines all body cavities open to exterior
respiratory, digestive, urinary, reproductive
• cell make­up varies
stratified squamous ­ mouth, esophagus
simple columnar ­ digestive tract
• wet membranes
• adapted for absorption, secretion
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Serous membranes (serosa):
• simple squamous epithelium on aerolar tissue
• line body cavities closed to exterior
• occur in pairs
parietal­ lines wall of ventral cavity
visceral ­ covers outside of organs
between layers = serous fluid ­ secreted by the membranes (prevents friction)
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Serous membrane names depending on where found:
• peritoneum ­ abdominal cavity
• pleura ­ lungs
• pericardium ­ heart
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Synovial membranes:
• soft aerolar tissue, no epithelium
• line fibrous capsules surrounding joints
• secrete lubricating fluid
• line bursae (small sacs) and tendon sheaths (tube­
like) ­ cushion during muscle activity
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Skin
aka: integumentary system
(What kind of membrane?)
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Functions:
• Protection
mechanical damage
chemical damage
bacterial damage
ultraviolet damage
thermal damage
desiccation (drying out)
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• heat maintenance
to lose heat ­ activates sweat glands
to retain heat ­ capillaries constrict
goosebumps ­ arrector pili ­ makes hair stand up to try and trap heat
subcutaneous layer = fat = insulation
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• Excretion
lose urea and uric acid via sweat glands
• synthesis of Vitamin D
modified cholesterol molecules converted to vitamin D by sunlight
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• other functions:
nervous system receptors found here
pain
temperature
pressure
light touch
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Structure: Epidermis
top layers
Dermis
bottom layers
subcutaneous
fat
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Epidermis:
stratified squamous epithelium
keratinizing
5 zone layers = strata
avascular
cells = keratinocytes = produce keratin
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Layers from the inside out (deep to superficial):
• Stratum Basale
aka. stratum germinativum
­ actively mitotic (dividing), millions daily
­daughter cells pushed upwards
­close to dermis
­only epidermal cells that receive nourishment
­melanocytes found here ­ produce melanin = color of skin
­sun exposure= more melanin production
­cells phagocytize the pigment, protects DNA
­freckles, moles = concentrated areas of melanin
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albinism= lack of melanin pigment
­missing enzyme that changes tyrosine into melanin
­genetic problem
Vitilago ­ skin condition that causes loss of pigment in skin
­melanocytes are destroyed
­2­4 million Americans
­cause ­ unknown, but may be genetic, immunological or neurological
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• Stratum Spinosum
= "spiny layer"
­8­10 layers thick
­irregular shaped cells
­cells in this layer starts synthesis of keratin, lots of RNA present
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• Stratum granulosum
­granular layer
­keritinization happens here ­ cell replaces cytoplasm with keratin (protein)
­waterproofs the cell
­3­5 layers thick
­top layer, cells start to die
­lysosomes release digestive enzymes
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• Stratum Lucidum
­clear layer
­3­5 layers thick
­lose this layer as we age
­found in soles of feet, palms of hands
­made of dead cells
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• Stratum Corneum
­outermost layer of skin
­20­30 layers thick
­stratified squamous keratinizing epithelial
­dead cells, no nutrients
­shed skin every 25­45 days
­hyperkeratosis = callous
­cause = friction
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Layers of Dermis:
• Papillary Layer
­upper dermal region
dermal papillae ­ make the ridges for your fingerprints, genetic
­contains capillaries ­ nutrients ­house pain receptors = Meissner's corpuscles
­made of dense fibrous connective tissue
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• Reticular layer
­makes up 80% of dermis
­made of collagen and elastin fibers
­contain blood vessels ­ nutrients, temp. regulation
­sweat and oil glands located here
­nerves located here
­pressure receptors ­ Pacinian corpuscles
­phagocytes here ­ kill bacteria
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Hematoma = bruise
capillaries break and bleed into surrounding
tissue
http://www.answers.com/topic/hematoma
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Decubitis ulcer = bed sore
­weight of body puts pressure on skin over bones
­restricts blood supply, cells die, small cracks form
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Stretch marks
­breaking apart of dense tissue ­ scar like
­cause rapid weight gain, pregnancy
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blisters
­separation of epidermis from dermis
­causes: friction, heat, chemicals
http://health.allrefer.com/health/burns­burn­blister­close­up.html
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underneath dermis = subcutaneous tissue = Fat
­adipose tissue
­insulation
­protection
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Skin color
• melanin ­ brownish pigment
­epidermis
• carotene ­ orange pigment
­carrots
­ stratum corneum, subcutaneous tissue
• hemoglobin ­ pink color
­emotions
­heat
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Skin disorders that affect skin color
• cyanosis ­ lack of oxygen to skin
­turns blue
­ex. emphysema
• jaundice ­ yellow color to skin
­indicates a liver problem
­bilirubin pigments released by liver and colors skin, normally get broken down
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• pallor ­
­lack of blood (hemoglobin)
­cause ­ anemia, scared, before passing out
• bronzing ­ metallic sheen
­cause­ hypofunction of adrenal cortex
• erythema ­ redness
­due to emotional stimuli, fever, allergies
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Skin appendages:
• Glands ­ exocrine ­ made from stratum basale
1. sebaceous glands = oil glands
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­ all over skin, except palms and soles
­ducts empty into hair follicle, some to surface
­sebum = oily substance and fragmented cells
­lubricant
­has chemicals that kill bacteria
­become very active during puberty ­ male sex hormones
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­ whitehead = pimple
­blocked sebaceous gland
­blackhead = whitehead that has oxidized
­acne = infection of sebaceous
glands
http://www.acneguide.ca/basics/images/acne_7.html
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­seborrhea= "cradle cap"
­cause ­ overactive sebaceous glands in infants
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2. sweat glands = sudoriferous glands
A. eccrine glands
­produce sweat (water, salts, vit C, metabolic wastes ­ urea, ammonia, lactic acid
­pH = 4­6
­inhibits bacterial growth
­pores
­regulate body temp
­secrete sweat if high body temp
­hot day ­ lose up to 7 liters of water
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B. Apocrine sweat glands
­associated wtih axillary and genital areas
­larger than eccrine glands
­ducts empty into hair follicles
­secrete fatty acids and proteins, water, salts, etc.
(odorless)
­milky to yellowish color
­bacteria on skin use secretions for nutrients
­causes odor (BO)
­begin functioning at puberty due to androgens (male hormones)
­no heat regulation
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• Hair
function:
• guard head against bumps
• shields eyes
• keep debris out of respiratory passages
• evolution
­insulation
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hair follicle
flexible structure
root
part in follicle
shaft
part projecting
from scalp
formed by stratum basale
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­hair made in inferior follicle, pushes out and dies
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hair has three parts:
medulla
cortex ­ pigmented
cuticle ­ scale­like
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follicle ­ ­epidermal sheath
­forms hair
­dermal sheath
­supplies blood
­reinforces
arrector pili
­muscle
­pulls hair upright
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Nail = scale like modification of epidermis
free edge, body, root (under skin), nail folds, cuticle
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nail bed­ under nail, stratum basale here
nail matrix­where nail growth occurs
­keratinized
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Lunula = white crescent of nail
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Skin Imbalances
1. Athlete's foot (tinea pedis)
­fungal infection
http://foot­cure.com/
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2. Boils and Carbuncles
­inflammation of hair follicles and sebaceous glands
­carbuncles = many boils together, Staphylococcus aureus
http://www.healthline.com/galeimage?contentId=gem_01_00251&id=gem_01_img0117
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3. cold sores (fever blisters)
­cause ­ herpes simplex in nerve
­activated by emotions, fever, UV light
­usually on lips, mouth
http://www.eurodrugspharmacy.com/coldsoreimages.htm
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4. contact dermatitis
­cause ­ exposure to chemicals, ex. poison ivy
­allergic response
http://www.livestrong.com/image/611­contact­dermatitis/1133­Dermatitis­contact/
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5. impetigo
­pink, water­filled lesions, develop yellow crust
­cause ­ Staphylococcus infection
­common in elementary school children
http://dermnetnz.org/bacterial/impetigo­imgs.html
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6. Psoriasis
­chronic condition
­reddened epidermal lesions, with dry silvery scales
­unknown cause,
may be genetic
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Burns
= tissue damage and death due to intense heat, electricity, UV radiation & chemicals
Immediate life threatening problems:
dehydration ­ wound seeps liquids
infection ­ pathogens ­ bacteria & fungi
­burned skin is sterile for 24 hours
­leading cause of death in burn victims
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To determine how much of body is burned:
The Rule of the Nines
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Classification of Burns:
• 1st degree ­ only epidermis damaged
­red & swollen
­not serious, heal in 2­3 days
­ex. mild sunburn
­partial thickness burn
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• 2nd degree burn
­injury to epidermis and upper region of dermis
­red and painful
­blisters appear (separation of epidermis from dermis)
­regeneration of tissue, no scars if not infected
­partial thickness burn
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• 3rd degree burn
­entire thickness of skin burned
­full thickness burn ­ can be down to bone
­appears gray­white or black
­nerve endings destroyed ­ not painful initially
­no regeneration, need skin grafting
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skin graft
http://www.nlm.nih.gov/medlineplus/ency/imagepages/19083.htm
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1st degree
2nd degree
3rd degree
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Burns considered critical if:
1. over 25 % of body with 2nd degree burns
2. Over 10% of body with 3rd degree burns
3. 3rd degree burns on face, hands or feet.
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