Glands definition biology

Exocrine Glands

Exocrine glands are the glands of external secretion. These are those that secrete substances on the body surface through a duct. Salivary glands, mammary glands, sweat glands, are some of the exocrine glands.

Structure Of The Exocrine Glands

The structure of the exocrine glands is divided into two parts:

The ductal portion is tubular in shape. It is a single, thick, cuboidal cell wall that helps in the movement of the secretion. The duct may be branched or unbranched. It can also be found as a simple coiled structure.

The glandular portion is responsible for the production of the secreted substance. It is a circular or elongated cluster of cells. The cells found in the glandular portion depend upon the substance secreted. For eg; serous cells secrete proteins, mucous cells secrete fluids.

Functions Of Exocrine Glands

Types of Exocrine Glands

The exocrine glands are of three types:

Holocrine Glands

These are released by the rupture of the plasma membrane. Produced in the cytoplasm of the cell, these destroy the cells and secrete the product in the lumen.

Merocrine/Eccrine Glands

The substance is secreted directly into the duct through the cellular channels. There is no rupturing of cell wall involved.

Apocrine Glands

They bud off a part of their cellular cytoplasm and membrane and release the substance into the ductal system.

Examples of Exocrine Glands

  • Lacrimal Glands– include tear ducts near each eye.
  • Pancreas– Secretes pancreatic juice along with the digestive enzymes into the stomach.
  • Salivary Glands- secretes saliva along with digestive enzymes.
  • Liver- secretes bile that contains salts and digestive substances.
  • Mammary Glands- secrete breast milk.
  • Eccrine Sweat Glands- release salty water through perspiration.

For more information on Exocrine Glands and related topics visit BYJU’S website or refer the BYJU’S app.

Important Questions

Q.1. What are exocrine glands?

A.1. Exocrine glands are cellular structures or organs that secrete substances external to the body through a ductal system.

Q.2. Which gland has both exocrine and endocrine functions?

A.2. The pancreatic gland has both exocrine and endocrine functions.

Q.3. What are the three types of exocrine glands?

A.3. The three types of exocrine glands are:

Q.4. Where are exocrine glands found in the body?

A.4. The exocrine glands are located in the intestinal wall, gastrointestinal tract, or outside such as salivary glands, liver, pancreas, etc. They secrete water, ions, and mucins in the digestive tract.

Q.5. Name the largest exocrine gland.

A.5. Pancreas is the largest exocrine gland which is 99% exocrine and 1% endocrine.

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