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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, and sweat glands are some of the exocrine glands.

Structure Of The Exocrine Glands

  1. Ductal portion: The ductal portion is tubular. 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.
  2. Glandular portion: 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

  • Regulate body temperature
  • Lubrication
  • Lactation
  • Helps in digestion
  • Helps in reproduction

Types of Exocrine Glands
They are three types:

  1. 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.
  2. Merocrine/Eccrine Glands: The substance is secreted directly into the duct through the cellular channels. There is no rupturing of the cell wall involved.
  3. Apocrine Glands: They bud off a part of their cellular cytoplasm and membrane and release the substance into the ductal system.

Examples:

  • 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.
  • The liver: It secretes bile that contains salts and digestive substances.
  • Mammary Glands: secrete breast milk.
  • Eccrine Sweat Glands: release salty water through perspiration.

Difference Between Endocrine and Exocrine Glands

Comparision

Endocrine Glands

Exocrine Glands

Definition

Glands that do not possess any ducts are called endocrine glands; their secretions called hormones, are transported by the blood.

Glands possessing ducts to help to transport their secretions in the place of their action are called exocrine glands.

Examples

Thyroid, pituitary, hypothalamus, and adrenal glands

Esophageal glands, Liver, sebaceous glands, tear-producing glands, mammary glands, and salivary glands.

Nature of Secretions

These secrete hormones which are chemical substances in the body.

These secrete digestive juices and other excretory products like sweat.