Download 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
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
•
•
•
•
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
•
•
•
•
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
•
•
•
•
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