Exocrine System

Your exocrine system includes a series of glands all over your body. These glands secrete substances that help your organs function, including sweat, breast milk, mucus and oil. Your exocrine system is different from your endocrine system, in that it secretes these substances through ducts. Conditions that affect your exocrine system include cancer, inflammation and hair loss.

Overview

What is the exocrine system?

Your exocrine system consists of glands all over your body that carry out many functions. It’s part of your autonomic nervous system, which controls involuntary actions supporting your well-being.

Glands are tiny organs that secrete substances that trigger certain biologic processes. For example, your salivary glands produce saliva to keep your mouth moist.

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What is the difference between the endocrine and exocrine systems?

  • Your endocrine system: Endocrine glands secrete hormones and release them directly into your bloodstream. Your bloodstream then delivers hormones to target tissues.
  • Your exocrine system: Exocrine glands secrete substances into ducts, which carry the substances onto the surface of target tissues.

What areas of the body do the exocrine glands support?

Exocrine glands control specific functions in your:

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Function

What is the function of the exocrine system?

Exocrine system glands take on a variety of functions.

  • Mammary glands produce milk.
  • Mucinous glands produce mucus to line and protect delicate tissue.
  • Sebaceous glands produce an oily substance on the surface of your hair and skin.
  • Serous glands produce watery substances, such as sweat and saliva.

What are the functions of the exocrine system glands?

Exocrine system glands serve many essential functions based on their location:

Breasts

  • Mammary glands, which are modified serous glands, support breastfeeding (chestfeeding). They produce milk that nourishes babies and boosts their immune systems.

Mouth

  • Serous glands produce saliva in many areas of your mouth. Saliva lubricates and protects your mouth and throat. It also initiates the digestive process by breaking down carbohydrates.
  • Mucinous glands are also present in your mouth and play a role in lubricating the substances you swallow.

Pancreas

Your pancreas functions as both an exocrine and endocrine gland.

  • As an exocrine gland, it releases substances that neutralize stomach acid. It also secretes digestive enzymes that break down proteins, fats and carbohydrates.
  • As an endocrine gland, your pancreas secretes hormones, insulin and glucagon, that regulate blood sugar levels.

Skin and hair

  • Serous glands help you sweat. There are two types of sweat glands. Eccrine sweat glands are in nearly every area of your skin’s surface. Apocrine sweat glands secrete a fatty substance that slows evaporation so sweat keeps you cooler longer.
  • Sebaceous glands secrete oil that produces moisture to protect your skin and hair.

Small intestine

  • Mucosal glands, known as Brunner’s glands, release a substance that protects your small intestine from stomach acid. It also activates enzymes that break down sugars in food and absorbs nutrients.
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Anatomy

What is the anatomy of the exocrine system?

The anatomy of exocrine system glands includes:

  • Acinus: Tiny sacs containing cells of exocrine system secretions that the duct hasn’t yet released. An acinus may house many different types of cells depending on the type of secretion the duct is responsible for.
  • Duct: Passageway that transports cell secretions to the inner surfaces of organs throughout your body.

Conditions and Disorders

What conditions and disorders affect the exocrine system?

Exocrine system diseases and disorders include:

Mammary gland conditions

Pancreas gland conditions

Salivary gland conditions

Skin gland conditions

Small intestine conditions

  • Rare, noncancerous tumors, including Brunner’s gland hamartoma and Brunner’s gland adenoma.

Care

How do I care for my exocrine system?

Taking good care of yourself is one of the best ways to keep your exocrine system healthy.

You can do this by:

  • Staying physically active.
  • Eating a diet that’s high in protein, fruits and vegetables, but low in saturated fats and processed foods.
  • Drinking plenty of water.
  • Limiting alcohol consumption.
  • Quitting smoking if you use tobacco.
  • Seeing your healthcare provider for regular check-ups.
  • Staying current with screenings, including mammograms for breast cancer.

A note from Cleveland Clinic

Your exocrine system includes glands all over your body. They secrete oil, mucus, saliva and milk that aid in organ function. Various conditions can affect your exocrine system, including tumors, inflammation and blockages. Taking good care of yourself can lower the risk of experiencing these issues.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 05/06/2022.

Learn more about our editorial process.

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