Anatomy and Physiology Integumentary System Anatomy and Physiology

Four Types of Membranes Serous: lines cavities that do not open to the outside, secretes serous fluid Mucous: lines cavities that open to outside, secretes mucous Synovial: found in joint cavities, secretes synovial fluid Cutaneous: is skin, vital to homeostasis

Layers of Skin Epidermis: outer layer of stratified squamous epithelium Dermis: thicker, contains fibrous connective, epithelial, smooth muscle, nervous tissue, blood Subcutaneous: beneath other two, contains loose connective and adipose

The Epidermis Layers from top to bottom: Stratum corneum Stratum Lucidum Stratum granulosum Stratum basale Basement membrane Page 115 in textbook

The Epidermis No blood vessels in this layer Older cells pushed up away from nourishment, they die and harden Layers of tough dead cells are the stratum corneum

The Epidermis: Functions Shields Holds in water Contains melanocytes in the deepest part of the epidermis Melanocytes produce pigment; some produce more than others

The Connection between layers Basement membrane is the layer of non-living material that anchors the epidermis to the connective tissue of the dermis below.

The Dermis The layer under the epidermis Mostly fibrous connective tissue, with some collagen fibers and elastic fibers Good blood supply Also contains nerves and accessory organs

Accessory Organs Hair: develops from a base called a hair follicle Smooth muscle called the arrector pili muscle is attached to each hair follicle. Causes goosebumps

Accessory Organs Sebaceous Glands: secrete an oily material called sebum Usually attached to a hair follicle

Accessory Organs Sweat Glands: coiled exocrine glands secrete sweat Usually not associated with hair follicles Eccrine: respond to elevated body temp Apocrine: respond to emotion

Subcutaneous Layer Beneath the dermis Consists of loose connective tissue and adipose Insulates and conserves body heat Contains the major blood vessels