Transcript Skin and Body Membranes

Skin and Body Membranes
Chapter 4
What are body membranes?
• Cover surfaces, line cavities, protect
organs
• 2 groups
– Epithelial membranes – cutaneous, mucous,
serous
– Connective Tissue membranes – synovial
membranes
Epithelial Membranes
• Coving and lining membranes
• Do contain epithelial sheet, but all have
connective tissue underneath
• Simple organs
Epithelial Membrane - Cutaneous
• Skin
• Superficial –
keratinizing stratified
squamous epithelium
• Deep (dermis) –
dense connective
tissue
• Exposed to air and
dry membrane
Figure 4.1a
Epithelial Membrane - Mucous
• Epithelium – varies per site, most often stratified
squamous or simple columnar
• Loose connective tissue – called lamina propria
• Lines all body cavities open to exterior
– What?
– Respiratory, Digestive, Urinary, Reproductive
• Wet membranes, bathed in secretions (or urine)
• Adopted for absorption or secretion
• Almost all produce mucus but urinary does not
Epithelial Membranes - Serous
• Superficial - Simple
squamous
• Deep – loose
connective areolar
• Line cavities closed to
exterior (except
dorsal body cavity
and joint cavities)
– What?
Figure 4.1c–d
Epithelial Membranes - Serous
• Come in pairs
– Parietal layer – lines wall of ventral body cavity, folds
over on itself to form, always connected to wall
– Visceral layer – covers outside layer of organ
– Compare to balloon
• Two layers separated by serous fluid – secreted
by both layers, lay very close together
– Why?
• Name of serous membrane based on location
– Peritoneum
– Pleura
– Pericardium
Connective Tissue Membranes
Synovial Membranes
• Areolar connective
tissue
• Line fibrous capsules
surrounding joints
– Smooth surface
– Secrete lubrication
• Lines sacs of
connective tissue of
bursae and tendon
sheaths
Figure 4.2
The Integumentary System
Skin
• Cutaneous Membrane
• Include skin, sweat and oil glands, hair,
and nails
• Mostly protective
Functions
Table 4.1
Functions
• Upper layer contains keratin
– Cornified (hardened) – protect from water loss
• Rich capillary network and sweat glands
– Controlled by nervous system
– Regulate heat loss
• Mini-excretory system
– Urea, water, and salts lost
• Manufac. Proteins imp. to immunity and Vit. D
synthesis
• Cutaneous Sensory Receptors in skin – touch,
pressure, temperature, pain (part of nervous)
Structure of the Skin
• Epidermis – outermost layer
– Stratified squamous able to keratinize
• Dermis – underlying tissue
– Dense connective tissue
• Firmly connected, friction can separate
– Blister – What happens?
• Subcutaneous layer or hypodermis – adipose
tissue
– Not skin, anchors to organs
– Shock absorber, insulator
– Curves of woman
Epidermis
• Up to five layers thick
– You get to learn them all in
2A!!
• Avascular – shaving!
• Most cells keratinocytes
• Bottom layer stratum basale
anchored to dermis by
epidermal cells, receive
nutrients via diffusion from
dermis, millions of new cells
daily, pushed outward
(DEAD)
• You will shed 40lb of skin in
lifetime
Figure 4.3
Melanin
• Pigment – yellow to brown to black
• Produced by melanocytes found in stratum
basale
• Exposed to sun, produce more melanin
• Collected in melanosomes, taken up by
keratinocytes
• Act as umbrella protecting DNA
• Freckles or moles are concentrated
melanin
Herpes Simplex and the sun!
• Sun exposure damages skin
– Depresses immune system
– Develop cold sore more often after sun
bathing
• Overexposure of skin to UV rad. can lead
to skin cancer
– Black individuals seldom have skin cancer
• Power of melanin
Dermis
• Strong, stretchy envelop
that holds you together
• Hide – leather goods
treated dermis
• Dense Connective Tissue
– Papillary layer – upper
– Reticular layer - lower
• Varies in thickness –
feet/hands compared to
eyelids
Figure 4.4
Papillary Layer of Dermis
• Uneven, projections
called dermal papillae
• Contain capillary loops
which nourish epidermis
• Some contain pain and
touch receptors
• Hands and feet – looped
and whorl patterns for
friction and grip
• Determined genetically fingerprints
Figure 4.4
Reticular Layer of Dermis
• Blood vessels, sweat
and oil glands, deep
pressure receptors
• Phagocytes prevent
bacteria
Dermis
• Collagen and elastic fibers
• Collagen – toughness, attract and bind water,
keep skin hydrated
• Elastic – give skin elasticity
• As age both decrease, subcutaneous looses fat,
sag and wrinkle
• Blood vessels to regulated heat
– Hot – hot blood, radiate heat
– Cold – bypass capillaries
• Rich nerve supply – chapter 7
Decubitis Ulcers
• Restriction of blood
supply results in cell
death, possibly skin
ulcers
• Bed sores –
bedridden patients
not turned, pressure
points
• Permanent damage
results in ulceration
Figure 4.5
Quick Quiz
1.
2.
3.
4.
5.
What are the functions of the body membrane?
Name the body membranes.
Where is the cutaneous membrane found?
Which body systems is the mucous membrane found?
The integumentary system includes the __________,
sweat and _________glands , _______ and
__________.
6. An increased production of _______________ happens
when exposed to the sun.
7. _________________ and ________________
__________ allows our skin to be tough and elastic.
8. What happens when blood supply is restricted to the
skin?
Skin Color
• 3 pigments contribute to skin color
– Melanin – amount and kind in epidermis
– Carotene – deposit in stratum corneum and
subcutaneous tissue, orange-yellow pigment
– Oxygen-rich hemoglobin – in dermal blood
vessels
– Think about variations!
Cyanosis
• Hemoglobin poorly
oxygenated, blood and
skin of Caucasians
appear blue
• Heart failure, breathing
disorders
• In black people, skin does
not appear blue due to
masking melanin –
mucous membranes and
nails
http://meded.ucsd.edu/clinicalimg/upper_cyanosis.htm
Emotions and Skin Color
• Redness (erythema) – embarrassment, fever,
hypertension, inflammation, or allergy
• Pallor (blanching) – emotional stress (fear,
anger), anemia, hypotension, impaired blood
flow
• Jaundice (yellow) – liver disorder excess bile
pigments absorbed by blood, transported and
deposited in tissues
• Bruises – escaped blood has clotted in tissue,
hematomas, deficiency Vit C or hemophilia
Appendages of the Skin
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Cutaneous Glands
Hair and hair follicles
Nails
Arise from epidermis, play role in
homeostasis
Cutaneous Glands
• All exocrine glands – release secretions to
skin surface
• Formed by cells of stratum basale, push
into dermis
• 2 Types
– Sebaceous (oil) glands
– Sweat glands
Cutaneous Glands
Sebaceous Glands
• All over body except hands
and feet
• Most ducts empty into hair
follicle, some to surface of
skin
• Sebum = product
– Oily substances
– Fragmented cells
• Lubricant – soft, moist, hair
not brittle
• Chemicals to kill bacteria
• Become very active when
male hormones produced =
oily skin
Figure 4.6a
Imbalance of Sebaceous Glands
• Whitehead – gland
blocked by sebum
• Blackhead – material
oxidizes and dries
• Acne – active infection of
glands
– Mild or severe, perm.
scaring.
• Seborrhea (cradle cap) –
overactive sebaceous
gland, raised pink lesions
form yellow brown crust
http://www.medical-look.com/Skin_diseases/Acne.html
Cutaneous Glands
Sweat Glands – Sudoriferous Glands
• Widely distributed in skin - +2.5 mil/person
• 2 types
– Eccrine glands – more #’s, all over body
• Produce sweat
• Effective heat regulation
• Nerve endings, stimulate sweat production
– Apocrine glands – Axillary and genital areas
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•
•
•
Larger than eccrine glands
Ducts empty into hair follicle
Puberty, under direction of androgens (♂ hormones)
Activated by nerves during pain, stress, sexual foreplay
Sweat – Eccrine Gland
• Clear secretion
• Mostly water + salts (NaCl),
Vit C, metabolic waste
(urea), lactic acid
• Acidic – pH 4-6, inhibits
bacterial growth
• Reaches surface through
pore
• Pores on face not sweat
pores, but external outlets
of hair follicle
• Excreted when temp. ↑, can
lose up to 7 L of water
Figure 4.6b
Product of Apocrine Gland
• Fatty acids and proteins
in addition to eccrine
secretion
• Milky or yellowish color
• Odorless unless bacteria
on skin use proteins for
growth – musky,
unpleasant odor
• Produced almost
continually
http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/Skin.htm
Hair and Hair Follicles
Hair
• Has lost most of evolutionary purpose
• Some protective features – head, eyes,
nose
Hair
Figure 4.7a
• Produced by hair follicle
• Flexible epithelial
structure
• Shaft – projection out of
skin
• Hair formed from well
nourished stratum basale
epithelial in matrix
(growing)
– As push farther from
growing region, keratinize
and die
– Most of hair shaft dead
cells like epidermis
Figure 4.7c
Hair
Figure 4.7b
• Medulla, Cortex, Cuticle
• Cuticle – single layer of cells
that overlap, shingles
– keeps hair apart, matting
– heavily keratinized – strength,
inner compacted
– Wears out at ends – splint ends
• Melanocytes – hair bulb,
produce hair color, melanin –
yellow, rust, brown, black
Figure 4.8
More Hair
• Different shapes and sizes – eyebrows, head,
body, etc.
• Oval hair shaft – smooth, wavy
• Flat, ribbonlike – curly or kinky
• Round shaft – straight and course
• Found all over body except hands, feet, lips,
nipples
• Among fastest growing tissue
• Hormones account for development of hairy
regions – scalp, public, axillary
Hair Follicle
• Epidermal sheath –
inner, epithelial
tissue, forms hair
• Dermal sheath –
outer, dermal
connective tissue,
supplies blood to ES
and supports
• Papilla provides blood
supply to hair bulb
Hair Follicle
• Hair follicle slanted
• Arrector pili muscle
– Connects hair follicle
to dermal tissue
– Muscles contract, hair
stands, dimpling of
skin
– Keeps animals warm
in winter, added layer
of warmed air
– Not useful to humans
Nails
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Modification of epidermis, like hoof or claw
Free edge, body, root
Nail fold or cuticle
Stratum basale – nail bed, thickened proximal area is nail matrix
(growth), cells heavily keratinized and dead
• Colorless, look pink due to blood supply
• Lunula – white crescent
Figure 4.9
Homeostatic Imbalances of Skin
• When something goes wrong, very visible
• Most diseases caused by allergies,
bacterial, viral, or fungal infections
• More damaging are burn and cancers
Infections and Allergies
Athlete’s Foot
• Itchy, red, peeling
skin
• Fungal infection
• Tinea pedis
• Can affect other
areas of skin
• Ringworm
http://www.squidoo.com/natural-cure-for-athletes-foot-x
Infections and Allergies
Boils and Carbuncles
http://www.mayoclinic.com/health/medical/IM01272
• Inflammation of hair
follicles and
sebaceous glands
• Carbuncles – boils
caused by bacterial
infections like
Staphylococcus
aureus
http://www.dshs.state.tx.us/idcu/health/antibiotic_resistance/mrsa/picpage.asp
Infections and Allergies
Cold Sores
• Fluid filled blisters
• Herpes simplex virus
• Localized to
cutaneous nerve
where dormant until
stress, fever, UV
radiation
• Lips or oral mucosa
http://www.stanford.edu/group/virus/herpes/2000/herpes2000v1.html
Infections and Allergies
Contact Dermatitis
• Itching, redness,
swelling, eventual
blistering
• Exposure to
chemicals that elicit
allergic rxn
• Poison ivy
http://mmcenters.discoveryhospital.com/shared/enc/img_htm/Derm-12.htm
Infections and Allergies
Impetigo
• Pink, water filled, raised
lesions
• Normally around nose
and mouth
• Develop yellow crust than
rupture
• Caused by
staphylococcus infection
• Common in elementary
school aged children
http://www.impetigodoctor.com/impetigo-photo.htm
Infections and Allergies
Psoriasis
http://www.psoriasite.com/
• Chronic condition
• Overproduction of skin
cells
• Reddened epidermal
lesions covered with dry,
silvery scales
• Itch, burn, crack, bleed
• Autoimmune disorder
• Trauma, stress, hormonal
changes, infections
Importance of skin
• Skin only paper towel thick, when
damaged affects all organs systems
– Metabolism accelerates or impaired
– Immune system changes
– Cardiovascular system may fail
Burns
• Burn – tissue damage and cell death by intense
heat, electricity, UV radiation, chemical
• 2 life threatening problems result from burns
– 1) Loss of supply of fluids containing proteins and
electrolytes that seep from burns
• Dehydration and electrolyte imbalance follow – shut down of
kidneys and circulatory shock
– 2) Infections – leading cause of death
• Burned skin sterile for 24 hours
• Pathogens – bacteria and fungus multiply in nutrient rich dead
tissue
• Immune system suppressed
Burns - Classification
• First degree burns – only epidermis damaged,
red, swollen, sunburn
• Second degree burns – epidermis and upper
region of dermis, red, painful, blisters, no
permanent scars if prevent infection
– Both 1 and 2 partial-thickness burns
• Third degree burns – full thickness burn, destroy
entire thickness of skin
– Appears blanched or blackened, nerves destroyed so
area not painful
– Regeneration not possible, grafting to cover tissue
When are burns critical?
• Over 25% of body has second degree
burns
• Over 10% of body has third degree burns
• Third degree burns on face, hands or feet
– Face dangerous why?
Skin Cancer
• 1 in 5 Americans
• Basal Cell Carcinoma
– Least malignant and most
common
– Cell of stratum basale
• Do not form keratin, no
boundary between dermis
and epidermis
– Usually on sun exposed area
– Slow-growing
– 99% cure rate when surgically
removed
Figure 4.12
Skin Cancer
• Squamous Cell Carcinoma
– Cells of stratum spinosum
• Scaly, reddened papule to
shallow ulcer with firm raised
border
• Scalp, ears, dorsum of hands,
lower lip
• Grows rapidly, metastasizes to
lymph nodes if not removed
• Sun induced
• Surgical removal and/or
radiation therapy
Skin Cancer
• Malignant Melanoma
– Cancer of melanocytes
– 5% of skin cancers, incidence
increasing and often deadly
– Melanoma begin wherever
pigment, most spontaneous, but
some from moles
– Damaged DNA in skin cell,
spreading brown to black patch
– Metastasizes rapidly to lymph
and blood vessels
– 50% chance survival, based on
detection
ABCD Rule
• A – asymmetry – the two sides of
pigmented spot don’t match
• B – border irregularity – borders of lesion
not smooth, exhibit indentations
• C – Color – spot contains different colors,
blacks, browns, tans, blues, reds
• D – Diameter – larger than 6 mm in
diameter
The End