Question

Which of the following membranes is not composed of cells? a. serous membrane b. synovial membrane c. cutaneous membrane d. basement membrane e. mucous membrane

Short answer

d. basement membrane

Step-by-step solution

Identify the membranes composed of cells

Enumerate the given options and determine if each one is composed of cells. Most biological membranes, like serous, synovial, cutaneous, and mucous membranes, are composed of cells. They all play roles in covering surfaces and protecting or lining bodily structures.

Consider the basement membrane

The basement membrane is a thin, fibrous, extracellular matrix of tissue that separates the lining of an internal or external body surface from underlying connective tissue. Unlike the other options, it is not composed of cells but rather of collagen and other proteins combined to form a structure for cell attachment.

Conclude which is not composed of cells

Based on the analysis, the basement membrane stands out as the only one that is not made up of cells. It is a non-cellular structure that provides support and anchorage for the epithelial cells above it.

Key concepts

serous membrane

Serous membranes are thin layers of tissue that cover interior body cavities and organs such as the heart, lungs, and abdominal areas. These membranes reduce friction from muscle movements and secrete a lubricating fluid called serous fluid. Serous membranes are composed of two layers: a layer of simple squamous epithelium and a thin layer of connective tissue underneath. This structure is designed to create a smooth, frictionless surface, aiding in the efficient movement of organs.

synovial membrane

The synovial membrane is a specialized connective tissue that lines the inner surface of capsules in synovial joints, such as the knee and elbow joints. It plays a crucial role in producing synovial fluid, which lubricates and nourishes the cartilage covering the bones in the joint. This reduces friction and facilitates smooth movement. Unlike other membranes, the synovial membrane consists of connective tissue only and lacks an epithelial layer.

cutaneous membrane

The cutaneous membrane, commonly known as the skin, is the body's largest organ and first line of defense against environmental hazards. It consists of two main layers: the outer epidermis and the underlying dermis. The epidermis is composed of tightly packed epithelial cells that provide a waterproof barrier. The dermis contains connective tissue, blood vessels, and nerves, providing nourishment and sensation. This structure not only protects but also helps regulate body temperature.

basement membrane

The basement membrane is a thin, dense layer of extracellular matrix that underlies epithelial tissue. Unlike other biological membranes, the basement membrane is not composed of cells but primarily of collagen, laminin, and other proteins. It serves as a scaffold for cell attachment, providing structural support and anchoring epithelial tissue to the underlying connective tissue. This non-cellular membrane is crucial for maintaining tissue architecture and influencing cell behavior.

mucous membrane

Mucous membranes line various cavities in the body, such as the respiratory, digestive, and urogenital tracts. These membranes are involved in secretion and absorption, providing a protective barrier against pathogens. They consist of an epithelial layer overlying a layer of connective tissue. Goblet cells within the epithelium secrete mucus, a sticky fluid that traps dust, microbes, and other particles, preventing them from entering the body and causing harm.