Anatomy chapter5

serous membrane

A serous membrane lines body cavities that typically do not open to the external environment. The membrane is composed of a simple squamous epithelium called mesothelium. Serous membranes produce a thin, watery serous fluid, or transudate (tran′sū-dāt; trans = across, sudo = to sweat), which is derived from blood plasma.

organ

An organ is a structure that is composed of two or more tissue types that work together to perform specific, complex functions.

body membranes

Epithelial and connective tissue together form structures called body membranes. Body membranes are formed from an epithelial layer that is bound to an underlying connective tissue. These membranes are designed to line body cavities, cover the viscera, or cover the body's external surface.

synovial membrane

Some joints in the body are lined by a synovial (si-nō′vē-ăl) membrane that is composed of areolar connective tissue covered with a superficial layer of squamous epithelial cells that lack a basement membrane. The epithelial cells secrete a synovial fluid that reduces friction among the moving bone parts and distributes nutrients to the cartilage on the articular surfaces of bone.

cutaneous

The largest body membrane is the cutaneous (kū-tā′nē-ŭs; cutis = skin) membrane, also known as the skin, which covers the external surface of the body. The cutaneous membrane is composed of a keratinized stratified squamous epithelium (called the epidermis) and an underlying layer of connective tissue (called the dermis). Its many functions include protecting internal organs and preventing water loss. This membrane is discussed in greater detail in

Serous membranes are composed of two parts

a parietal layer that lines the inside of the body cavity and a visceral layer that covers the surface of the internal organs. Between these two layers is a serous cavity, which is a potential space into which the serous fluid is secreted. The serous fluid reduces the friction between their opposing surfaces. Examples of serous membranes include part of the pericardium (which is associated with the heart), the pleura (associated with the lungs) and the peritoneum (associated with abdominal organs).

mucous membrane

also called a mucosa (mū-kō′să), lines passageways and compartments that eventually open to the external environment; these include the digestive, respiratory, urinary, and reproductive tracts. Mucous membranes perform absorptive, protective, and secretory functions, or a combination of these functions. A mucous membrane is formed by an epithelium and an underlying connective tissue called the lamina propria. Often, this membrane is covered with a layer of mucus derived from goblet cells, multicellular glands, or both.

four types of body membranes

mucous, serous, cutaneous, and synovial,