Endocrine glands secrete hormones into the bloodstream, while exocrine glands secrete substances, such as sweat or enzymes, into organs or onto the surface of the body.
The two main types of glands in the body are exocrine and endocrine glands. A gland is an organ that produces a substance, such as hormones, digestive enzymes, or saliva.
Endocrine glands secrete hormones directly into the bloodstream, while exocrine glands secrete other substances through a duct, either into the body or onto its surface.
This article looks at the differences between endocrine and exocrine glands, gives examples of each gland within the body, and discusses problems relating to endocrine and exocrine glands.
Endocrine glands release hormones directly into the bloodstream
Exocrine glands release substances, such as sweat or tears, through ducts to the surface of the body or an internal organ.
The following table shows some similarities and differences between endocrine and exocrine glands.
| Endocrine glands | Exocrine glands |
|---|---|
| do not have any ducts | have ducts that release substances |
| only secrete hormones | secrete various substances, including sweat, sebum, enzymes, and mucus |
| secrete hormones directly into the bloodstream | secrete substances into an organ or onto the surface of the body |
Endocrine glands form the endocrine system and include the following:
- Pituitary gland: The pituitary gland sits at the base of the brain and produces hormones for various functions, such as growth and metabolism.
- Hypothalamus: The hypothalamus is part of the brain that produces hormones. The hypothalamus and the pituitary gland regulate the rest of the endocrine system.
- Thyroid gland: The thyroid gland produces thyroid hormones, which help support various functions in the body.
- Adrenal glands: The two adrenal glands sit above the kidneys. The adrenal glands help control functions such as heart rate and blood pressure.
- Pancreas: The pancreas is an organ in the abdomen that creates hormones to support digestion and normal blood sugar levels.
- Ovaries: The ovaries form part of the female reproductive system and create estrogen and progesterone.
- Testicles: The testicles form part of the male reproductive system and produce sperm and testosterone.
Exocrine glands
- Salivary glands: Salivary glands in the mouth produce saliva, which helps with digestion as well as lubrication and protection of the mouth and throat.
- Sebaceous glands: Sebaceous glands on the skin secrete oil, or sebum, which helps lubricate and protect the skin.
- Sweat glands: Sweat glands on the skin release sweat to help control body temperature.
- Mammary glands: The mammary glands in the breasts produce milk for chest or breastfeeding.
- Pancreas: The pancreas releases digestive enzymes into the small intestine to help support digestion.
- Stomach glands: Exocrine glands in the stomach release digestive enzymes to help break down food, regulate stomach pH levels, and support the absorption of nutrients.
- Brunner glands: Brunner glands are in the duodenum, which is the first section of the small intestine. The Brunner glands secrete mucus to protect the small intestine from stomach acid.
Certain common health problems can occur due to issues with the endocrine or exocrine glands. Problems relating to the exocrine glands
- Acne: Acne is a condition relating to the sebaceous glands. Excess sebum production can block pores and cause inflammation, leading to acne.
- Sjögren disease: Sjögren disease is an autoimmune condition in which the lacrimal, or tear, glands and the salivary glands do not function properly. This causes excessive dryness of the eyes and mouth.
- Cystic fibrosis: Cystic fibrosis is a genetic disorder in which a faulty protein affects exocrine glands that produce sweat, mucus, and digestive enzymes. With cystic fibrosis, these substances are much thicker than usual, which causes problems with organs throughout the body.
Problems affecting the endocrine glands can
- Thyroid disease: Hyperthyroidism can occur if the thyroid gland produces excess thyroid hormones, whereas hypothyroidism can occur if the gland does not produce enough thyroid hormone.
- Polycystic ovary syndrome (PCOS): PCOS occurs due to a hormonal imbalance that can cause symptoms such as irregular menstrual cycles, excess hair growth due to androgens, and abnormal growths on the ovaries.
- Adrenal insufficiency: Adrenal insufficiency, such as Addison’s disease, occurs if the adrenal glands cannot produce enough hormones, such as cortisol and aldosterone.
This section answers some frequently asked questions about endocrine and exocrine glands.
What organs are both endocrine and exocrine?
The liver and the pancreas are both endocrine and exocrine glands.
Endocrine functions of the liver
As an endocrine gland, the pancreas
As an exocrine gland, the pancreas secretes digestive enzymes into the small intestine to help break down and digest food.
Are sweat glands endocrine or exocrine?
Sweat glands are exocrine glands. They secrete water to the surface of the skin
What are the three types of exocrine glands?
Three examples of exocrine glands are:
- salivary glands, which produce saliva to protect and lubricate the mouth and throat and help digest food
- lacrimal glands, or tear glands, which produce tears to lubricate and protect the surface of the eyes
- sebaceous glands, which produce sebum, an oily substance that helps retain moisture in the skin
Endocrine and exocrine glands help control many important functions throughout the body.
Endocrine glands release hormones into the bloodstream and include the pituitary and thyroid glands.
Exocrine glands release substances, such as sebum, sweat, and digestive enzymes, through a duct to an organ or the surface of the body. Exocrine glands include salivary and sweat glands.