1. Skin and Body Membranes
Chapter 4
Skin and Body Membranes

2. Body Membranes
Cover surfaces, line body cavities, form protective sheets
2 groups – classified according to tissue

3. Epithelial membranes Aka covering and lining membranes
Do contain some connective tissue
Considered simple organs
(1) Cutaneous membrane
– Skin
Dry membrane

4. (2) Mucous membranes (mucosa)
Epithelium on top of lamina propria
Lines any cavity w/ an exterior opening
Wet (moist) membranes
Continuously covered
by secretions
Ex. Respiratory,
digestive, urinary,
reproductive tracts
Adapted for absorption
or secretion

5. (3) Serous membranes (serosa)
Simple squamous epithelium on areolar tissue
Line cavities closed to exterior
Occur in pairs
Parietal layer – wall
of ventral body cavity
Visceral layer –
covers organs in
the cavity

6. Serous fluid – btw layers – secreted by both layers
Allows organs to move w/out friction (heart,stomach)
Name depends
on location
Abdominal
cavity –
peritoneum;
lungs – pleura;
heart - pericardium

7. Connective membranes Aka synovial membranes
Areolar tissue – no epithelial
Line fibrous capsules around joints
Smooth surface
Secrete lubricating fluid

8. Line bursae (small sacs of connective tissue) and tendon sheaths
Cushion organs that move against each other

9. Integumentary System Cutaneous membrane
Aka integument – “covering”
2 layers – epidermis & dermis – usually very close
Burns/friction may cause separation = blister
Functions
Insulates and cushions deeper organs
Regulates body temp – capillaries, sweat glands
Mini excretory system – urea, uric acid, salts, water released w/ sweat
Synthesizes immunity proteins
Synthesizes vitamin D
Contains cutaneous receptors – touch, pressure, temp, pain

10. Epidermis
Avascular
Keratinocytes – majority of cells – produce keratin (tough, protective, waterproofing)
May have up to 5 strata (layers)

11. (1) Stratum basale
Deepest
Best nourished via diffusion
Aka stratum germinativum because they are continually dividing
Daughter cells are pushed upward
Contains melanocytes – produce melanin (pigment)
Sunlight stimulates production
Concentrated in 1 spot = freckles, moles

12. (2) Stratum spinosum (3) Stratum granulosum (4) Stratum lucidum
Dead – unable to get nutrients and oxygen
Occurs in hairless, extra thick areas – palms, soles of feet
(5) Stratum corneum
20-30 cell layers (3/4 of epidermis)
Dead – completely filled w/ keratin
Aka cornified cells (corno = horn)
Rubbed/flakes off and is replaced by lower cells
Cycle days

14. Dermis Hide – leathergoods
Strong, stretchy envelope that holds body together
2 layers
(1) Papillary layer
Upper dermal
Dermal papillae – projections on superior surface
Contain capillary loops which provide nutrients
May have Meissner’s corpuscles – touch receptors
Form ridges - fingerprints

15. (2) Reticular layer
Deepest skin layer
Contains blood vessels, sweat/oil glands, Pacinian corpuscles (pressure receptors)
Both layers contain phagocytes that work to prevent bacteria from going deeper
If blood supply is restricted = cell death = skin ulcers (bed sores)
Ex. Decubitus ulcers – found in bedridden patients

16. Collagen fibers – provide toughness
Attract/bind water – keep skin hydrated
Elastic fibers – give skin elasticity
# of fibers decreases – allows wrinkles
Blood vessels help maintain temp
To release heat – vessels swell
To conserve heat – vessels constrict, may bypass capillaries

17. Hypodermis Subcutaneous tissue – adipose tissue Not part of skin
Acts as an anchor, shock absorber, insulator

18. Skin Color 3 pigments Melanin – yellow, brown, black
Carotene – yellow-orange
Oxygen-rich hemoglobin – red/pink
Emotional stimuli or disease
affect color
Redness (erythema)
Blushing, fever,
inflammation,
allergy

19. Pallor (blanching) – become pale
Anemia, low blood pressure, fear
Jaundice (yellow cast)
Liver disorder – bile deposited in tissues

20. Bruises (hematomas)
Where blood has left vessels and clotted in tissue space
May be vitamin C deficit or hemophilia

21. Cyanosis
Bluish cast due to low oxygen
Common in people with breathing disorders