Ch. 4 Skin and Body
Membranes
Part 1
Mrs. Barnes
A&P
Body Membranes
 Two Classifications
 Epithelial Membranes (3)
 Connective Membranes (1)
Body Membranes
 Epithelial Membranes- covering and lining membranes
 Cutaneous (Skin or Integumentary System)
 Mucous
 Serous
Epithelial Membranes
 Cutaneous Membrane- Known as the skin.
 The superficial epidermis is composed of keratinizing
stratified squamous epithelium.
 What does keratinizing mean?
 Unlike the others, this is a dry membrane.
 What does this mean?
Epithelial Membranes
 Mucous Membrane- composed of epithelium resting on
Lamina Propria
 Lines all body cavities that open to the exterior (Ex.
Respiratory, Digestive, Urinary and Reproductive)
 Tissue makeup varies. Mucosa refers only to the
location of the epithelial membranes.
 These are “wet” or moist membranes.
Epithelial Membranes
 Serous Membranes- composed of layer of simple squamous
epithelium resting on a thin layer of areolar connective
tissue.
 Line body cavities that are closed to the exterior
 Occur in pairs (Ex. Parietal and _________?)
 Balloon and Fist Example
 Visceral is touching organ. Parietal on the outside
What is in between the two layers?
Epithelial Membranes
 Membranes surrounding:
 Abdominal cavity- Peritoneum (P and V)
 Lungs- Pleura (P and V)
 Heart- Pericardium (P and V)
Connective Membranes
 Synovial membranes- composed of soft areolar
connective tissue and contain no epithelial cells at all.
 Line the fibrous capsules surrounding joints. Provides a
smooth surface and secrete a lubricating fluid.
Integumentary System
 Cutaneous Membrane- just skin
 Integumentary System includes skin and it’s derivatives
(sweat and oils glands, hair, and nails).
 Integument- means “covering”
Integumentary System
 “Without our skin we would fall prey to bacteria and
perish from water and heat loss”
 Functions of:
 Protection (mechanical, chemical, thermal, UV radiation,
and bacteria)
 Insulation
 Cushion
Integumentary System
 The Skin Uppermost layer-full of keratin and is cornified
(hardened)- prevents water loss from body surface.
Two Layers–
Epidermis
Dermis
Integumentary System
 Epidermis- made of stratified squamous
epithelium. Capable of keratinizing or becoming
hard and tough
 Dermis- made of mostly dense connective tissue.
 Epidermis and Dermis are firmly connected
What can happen if they separate?
Integumentary System
 Subcutaneous tissue (hypodermis)- Deep to the
dermis.
 Essentially adipose tissue.
 Anchors the skin to underlying organs and provides site
for fat storage. Also, a shock absorber and insulator
Epidermis
 Composed of 5 layers (or Strata)





Stratum Basale- Deepest Layer and Most Nourished
Spinosum- 2nd deepest
Granulosum- 3rd deepest
Lucidum
Corneum
 Epidermis is Avascular- Is this a good thing? Think
about when you shave?
British and Spanish Grannies Like Cornflakes
Remember: Basale = Bottom
Epidermis
 Most cells in the epidermis are keratinocytes
What do these cells do?
 All layers are present in Fig. 4.4 except the Stratum
Lucidum. This tissue appears clear and not present in
all skin regions
 Found in hairless and extra thick regions (Ex. Palms of
the hands and soles of the feet).
Epidermis
 Stratum Corneum- Outermost layer
 20-30 cell layers thick but accounts for ¾ of the epidermal
thickness.
 The average person sheds about 40lbs of “flakes” in a
lifetime. This is what the dust mites eat.
 We have a “new” epidermis every 25 to 45 days.
Epidermis
 Melanin- pigment that ranges in colors
 Yellow to Brown to Black
 Produced by spider-shaped cells called Melanocytes
 When the skin is exposed to sun, the melanocytes are
stimulated to produce more melanin pigment
aka tanning occurs
Epidermis
 Freckles and Moles- where there is a concentrated
amount of Melanin
 Epidermal Dendritic Cells
 Merkel Cells
Dermis
 This is your “hide”- strong, stretchy and binds your
body together.
 2 Major Regions:
 Papillary
 Reticular
Dermis
 Papillary Layer
 Upper dermal region- p 117
 Uneven and peglike projections called Dermal Papillae
 Contain capillary loops which furnish nutrients to epidermis.
 House pain receptors (free nerve endings) and touch
receptors
 Fingerprints- Sweat films??
Dermis
 Reticular Layer Deepest skin layer
 Irregularly arranged connective tissue fibers, blood
vessels, sweat and oil glands, and deep pressure
receptors.
 Phagocytes are found here. Why?
 What do Phagocytes do?
Dermis
 Collagen and Elastic Fibers found in Dermis
 Collagen keeps skin tough and attract and bind to
water. This keeps the skin hydrated.
 Elastic fibers give skin its elasticity when we are young.
As we age the number of fibers decrease.
Dermis
 Has lots of blood vessels! Plays a role in maintaining
body temperature.
 When the body temp is high- capillaries _________.
 When the body temp is low- capillaries __________.
Dermis
 Skin ulcers- Decubitus ulcers- Bed sores p117