Ch. 4 Skin and Body Membranes

Part 1Mrs. Barnes

A&P

Body MembranesTwo Classifications

Epithelial Membranes (3)Connective Membranes (1)

Body MembranesEpithelial Membranes- covering and lining

membranesCutaneous (Skin or Integumentary System)MucousSerous

Epithelial MembranesCutaneous 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 MembranesMucous 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 MembranesSerous 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 exteriorOccur in pairs (Ex. Parietal and _________?)

Balloon and Fist ExampleVisceral 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 MembranesSynovial 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 SystemCutaneous Membrane- just skinIntegumentary 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)

InsulationCushion

Integumentary SystemThe Skin-

Uppermost layer-full of keratin and is cornified (hardened)- prevents water loss from body surface.

Two Layers– EpidermisDermis

Integumentary SystemEpidermis- made of stratified squamous

epithelium. Capable of keratinizing or becominghard and tough

Dermis- made of mostly dense connective tissue.

Epidermis and Dermis are firmly connected What can happen if they separate?

Integumentary SystemSubcutaneous 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

EpidermisComposed of 5 layers (or Strata)

Stratum Basale- Deepest Layer and Most Nourished

Spinosum- 2nd deepestGranulosum- 3rd deepestLucidum Corneum

Epidermis is Avascular- Is this a good thing? Think about when you shave?

British and Spanish Grannies Like CornflakesRemember: Basale = Bottom

EpidermisMost 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).

EpidermisStratum 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.

EpidermisMelanin- 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

EpidermisFreckles and Moles- where there is a

concentrated amount of Melanin

Epidermal Dendritic CellsMerkel Cells

DermisThis is your “hide”- strong, stretchy and binds

your body together. 2 Major Regions:

PapillaryReticular

DermisPapillary Layer

Upper dermal region- p 117Uneven and peglike projections called Dermal

PapillaeContain capillary loops which furnish nutrients to

epidermis. House pain receptors (free nerve endings) and touch

receptors

Fingerprints- Sweat films??

DermisReticular 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?

DermisCollagen and Elastic Fibers found in DermisCollagen 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.

DermisHas 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 __________.

DermisSkin ulcers- Decubitus ulcers- Bed sores p117