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- 2 nd deepest Granulosum- 3 rd 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 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