Adipose Tissue

What is Adipose Tissue?

The group of cells which have a similar structure and function that acts together to perform the desired function are called tissues. There are four different kinds of tissues in animals, they are: 

  1. Connective tissue

  2. Muscular tissue

  3. Epithelial tissue

  4. Nervous tissue

The connective tissue has two different subclasses, they are loose connective tissue and dense connective tissue. These subclasses can further be divided as follows:

  1. Loose Connective Tissue: 

  • Areolar connective tissue

  • Adipose connective tissue 

  • Reticular connective tissue

  1. Dense Connective Tissue:

  • Dense regular connective tissue

  • Dense irregular connective tissue

  • Elastic 

Adipose Connective Tissue

The specialized type of connective tissue consists of fat or lipid cells called adipocytes. In a healthy person, 20 to 25% of total body weight is composed of fat tissue. The adipose tissue’s main function is to store energy in the form of fat. 


Types of Adipose Tissue:

  1. Based on the location they are present it is divided into two types, they are visceral fat and parietal fat.

  2. Based on the structure it can be divided as, white adipose tissue and brown adipose tissue.

Adipose Tissue Function

Along with the storage of fat cells, these cells help to perform different functions such as:

  • It is a metabolic organ that helps in the regulation of homeostasis.

  • Thermal isolation.

  • Production of a great number of bioactive factors.

  • Acts as an endocrine gland that is responsible for the production of hormones.

  • Helps in cushioning the organs.

Adipose Tissue Location and Structure

The tissue that stores fat in our body is adipose tissue, this fat is distributed all over in two ways, they are:

  1. Parietal fat is also called subcutaneous fat that is found present under the skin.

  2. Visceral fat is found surrounding the internal organs such as eyeballs or kidneys.

The adipose tissue consists of cells and an extracellular matrix. These cells are the most abundant and structural elements that are distributed throughout the small amount of the cellular matrix. The main type of cells that are found are adipocytes. Including this there are other different kinds of cells, are fibroblasts, preadipocytes, capillary endothelial cells, macrophages, and stem cells. These cells are commonly called non-adipocyte cells. The non-adipocytes combine to form a stromal vascular fraction. The adipocytes function is to support and protect the adipose tissue.

The adipocytes and the stromal cells help in the production of the extracellular matrix. The matrix consists of reticular fibres that are connected as a fine network that helps to hold and place the cells. The adipose tissue has a rich supply of blood vessels and unmyelinated nerve fibres.


Adipocytes

Adipocytes are the building blocks of the adipose tissue. They are also known as fat cells or adipose cells. The adipocytes are divided into two types depending on the distribution of two types of adipose tissue.

  • White Adipocytes: It consists of the main cells of the white adipose tissue. The shape can vary from spherical to oval or polyhedral. It consists of a single lipid droplet that pushes the nucleus to the peripheral side of the cell. The cytoplasm is present around the lipid droplet and contains fewer mitochondria

  • Brown Adipocytes: It consists of chief cells of brown adipose tissue. They are very small in size and consist of multiple lipid droplets. These droplets surround the nucleus that is present in the centre. It has numerous mitochondria that are found dispersed among the droplets which give them a brown colour. Golgi apparatus, a small number of ribosomes, and endoplasmic reticulum can also be found in the cytoplasm. 

  • Beige Adipocytes: It is found dispersed in the white fat tissue. A small portion of it can also be found in visceral fat. 

Adipose can perform different functions depending on the location it is present. 

  1. The abdominal fat has a different kind of metabolic function compared to all other fat in the body and it can also influence the inducing of resistance to insulin. 

  2. Parietal fat helps in thermoregulation.

  3. Visceral fat provides cushion-like support to the internal organs by protecting them from mechanical injuries.

The adipose tissue is very crucial for health, it is not only important for the storage of fat cells it also contains plenty of nerve cells and blood vessels that help in the storage and releasing of the energy to the body. The excess of fat content in the body can lead to medical conditions such as obesity and the loss of healthy body fat can lead to a condition called lipodystrophies.

FAQs (Frequently Asked Questions)

1. Define Adipose Tissue. Write the Difference Between White Adipose Tissue and Brown Adipose Tissue.

Ans. The adipose tissue definition is as follows - it is a specialized connective tissue that helps in the storage of fat.

The difference between white adipose tissue and brown adipose tissue is:

White Adipose Tissue

Brown Adipose Tissue

These tissues are located in subcutaneous, intraabdominal, epicardial, and gonadal.

These tissues are located in interscapular, perirenal, cervical, paravertebral and supraclavicular.

These are spherical in shape.

These are elliptical and smaller compared to white adipose.

It consists of a single lipid droplet, few mitochondria, a flattened nucleus, and endoplasmic reticulum.

It consists of multiple lipid droplets, numerous mitochondria, and an oval-shaped nucleus.

They help in the storage of fat.

They help in heat production.

2. What is the Function of Perirenal Fat?

Ans. The adipose capsule of the kidney or the perinephric fat or perirenal fat is a structure found between the renal fascia and renal capsule. It receives blood from the abdominal aorta. It is composed of white adipose tissue. It performs different physiological functions such as the storage of fat and the synthesis of the proinflammatory adipokines.