Loose Connective Tissue (Areolar Tissue)

Study Notes

Connective Tissue

Loose connective tissue (areolar tissue) is the most widely distributed connective tissue type in the vertebrate body.
It consists of various cells, including fibroblasts, macrophages, mast cells, leukocytes, and fat cells.
All three types of fibers are found in this tissue, which are loosely arranged and wavy in nature.
This tissue binds epithelia and the underlying tissue, holding organs in place.
It is found under the skin and throughout the body.

Fibrous Connective Tissue (Dense Connective Tissue)

This tissue is densely packed with collagen fibers.
The matrix is relatively reduced and contains fewer cells (fibrocytes).
It is found in tendons (attaching muscle to bones) and ligaments (connecting bones and joints) where tensile strength is required.

Adipose Tissue

This tissue is packed with adipose cells, each containing a large fat droplet.
It is a specialized type of loose connective tissue that pads and insulates the body and stores fuel as fat molecules.
It is found under the skin, where it acts as a thermal insulator and energy store.

Blood Tissue

This tissue is a specialized connective tissue where the matrix is not secreted by the cells and fibers are formed only during blood clotting process.
The extracellular matrix of the blood is liquid, known as plasma.
Plasma contains salts, water, and dissolved proteins.
Red blood cells (transport respiratory gases), white blood cells (defense), and platelets (blood clotting) are suspended in the blood plasma.
Main functions of blood tissues include transport of materials, protection, and osmoregulation.

Cartilage

This tissue consists of a matrix composed of chondroitin sulphate, a rubbery protein-carbohydrate complex.
Collagen fibers and chondrocytes are embedded in the matrix.
Chondrocytes secrete chondroitin sulphate and collagen fibers.
This tissue provides support and flexibility in places such as the trachea, intervertebral discs.

Bone

It is a mineralized connective tissue.
The matrix consists of collagen fibers and inorganic salts, such as calcium, magnesium, and phosphate ions.
Cells are osteoblasts (bone-forming cells) and osteocytes (mature bone cells that maintain bone tissue).
Osteocytes are enclosed within lacunae.
The mammalian hard bone has repeating units called osteons.
Each osteon has a concentric layer of mineralized materials.
At the center of the osteon is a central canal containing blood vessels and nerves.
This tissue forms the endoskeleton of most vertebrates and provides support and strength to the body.

Muscle Tissue

Muscle tissue is responsible for movement.
The cells in the muscle tissue are composed of actin and myosin proteins.
This tissue is able to contract and relax.
There are three basic types of muscle tissues found in the vertebrate animal body: smooth muscle, skeletal muscle, and cardiac muscle tissues.

Smooth Muscle Tissue

The cells of the smooth muscle tissue are spindle-shaped and uninucleated.
Cells lack striations.
This tissue is responsible for involuntary body functions (e.g., churning of stomach, constriction of arteries).
It is found in the digestive tract, urinary bladder, arteries, and other internal organs.

Description

Learn about the most widely distributed connective tissue in the vertebrate body, known as areolar tissue. Explore the types of cells and fibers found in this tissue, and understand its role in binding epithelia and holding organs in place.