When you think about glands you probably imagine secretion from the endocrine system. The endocrine system is made up of hormones and glands that send messages around the body, through the blood, to make certain functions happen.
However, glands can also have an exocrine function. Some glands are both endocrine and exocrine such as the pancreas, while some glands are only endocrine or only exocrine.
Keep reading to learn more about what exocrine glands are, the types of exocrine glands that there are, and the various exocrine gland secretions around the body.
What Are Exocrine Glands?
Exocrine glands are glands that secrete substances onto an epithelial surface of the body such as the skin, digestive tract, respiratory tract, and genitourinary tract. A variety of exocrine glands are located all around the body in a work together to keep the body in a balanced state.
Exocrine glands are stimulated by endocrine hormones and also changes in the body status. For example, prolactin signals to the mammary glands to produce milk. On the other hand, if the body recognizes that the temperature is going up it will stimulate the sweat glands to produce sweat to cool the body down.
Types of Exocrine Glands
The function of exocrine glands changes with each type. There are three main types of glands including holocrine glands, merocrine glands, and apocrine glands. The difference between the three is the method of secretion from the glands to the surface.
Holocrine glands release the substance by rupturing the plasma membrane. Merocrine glands secrete the substance directly from the duct to the surface. Apocrine glands release the substance through the ducts.
Sweat Glands
The shimmering sweat that appears on your skin on a hot day must come from somewhere, right? Sweat is also released from an exocrine gland that is found under the surface of the skin. These sweat glands are also called sudoriferous glands and are important for a number of bodily functions.
One thing that sweat is very useful for is controlling body temperature. Sweat is released when your body temperature increases as a mechanism to cool you down. When the sweat evaporates from your skin it causes the body temperature to decrease. This is because evaporation is a cooling process.
So, the next time you are sweating, you can thank your exocrine glands for helping your body to cool itself down instead of sending you into a heat stroke.
Salivary Glands
Salivary glands are another gland that you use on a regular basis. There are actually three main salivary glands including the parotid gland (in the cheek), submandibular glands (in the jaw), and sublingual gland (under the tongue).
Saliva is released when you are eating, when you look at food or feel hungry, and throughout the day. Saliva has two main functions: one is to keep the mouth moist, and the other is to begin the chemical digestion process.
Saliva has enzymes including amylase to break down the molecules in your food so that you can digest them and use it in the body. This is why you may notice that there is more saliva before and during a meal. Throughout your day you also have saliva to keep your mouth moist as well as to improve tasting ability.
Mammary Glands
Mammary glands are in both men and women, however they have a more vital role in women. Mammary glands are responsible for releasing human milk to feed a baby.
Mammary glands are stimulated by oxytocin and prolactin to release and stimulate the production of milk. Memory glands are not usually functional until a woman becomes pregnant or after childbirth.
The mammary glands are made up of various lobes that create and store milk, then ducts carry the milk from the glands to the nipple so that the baby can get the milk.
Ceruminous Glands
Ceruminous glands also known as sebaceous glands are glands that produce sebum or oil. These glands are found on the skin and have several functions in the integumentary system.
One of the most important roles of sebum is to keep the skin moisturized and hydrated. Since it is made of oils it creates a barrier for moisture to enter and exit the skin. Lotions serve a similar purpose to the naturally made oils of our skin.
When washing the skin it is important to use a mild soap that does not strip the natural oils from the skin and to use a moisturizer to reinforce the barrier after washing. Some people have more active sebaceous glands than others, so if you are more oily you may need to wash your skin more often to prevent build-up. A buildup of oils on the skin can lead to acne and other skin issues.
Lacrimal Glands
Lacrimal glands are located in the eyes and are responsible for secreting tears. You are probably most familiar with tears when you or someone else is crying over strong emotions.
The lacrimal glands can be triggered when experiencing intense emotions of happiness, sadness, or other emotions. The lacrimal glands are also regularly creating tears in smaller amounts to keep the eyes hydrated and prevent particles or pathogens from getting into the eye.
As people get older their lacrimal glands tend to produce less amount of tears resulting in dryer eyes. If this occurs you may need artificial tears or eye drops to help supplement you are a lacrimal gland’s output.
Prostate Gland
The prostate gland is a gland unique to the male reproductive system. The prostate gland is located under the bladder near the top of the urethra, or the tube that carries urine from the bladder to the outside.
The role of the prostate is to create seminal fluid that supports the sperm on its journey out of the urethra. It helps to make the sperm swim easier and nourish the sperm as it travels through the urethra and potentially into the vagina.
Because the prostate gland is surrounding the urethra it can cause issues if it becomes too large. As men age it is common to have an enlarged prostate also known as benign prostatic hyperplasia (BPH). If this occurs it can cause urinary dysfunction and make it hard to urinate.
Mucous Glands
You are probably most familiar with the mucus that is created in the nose. But, mucus is actually created throughout the entire digestive system and has many functions. In the nose, mucus is used to trap pathogens and particles such as dust and dirt that could enter the respiratory system. It is a first line of defense to protect your body from infections.
Mucus in the digestive system helps to lubricate the digestive tract and protect the lining of the digestive tract from the harsh acidity. If there is not enough mucus in the digestive tract it could result in breaks in the skin such as ulcers.
There are also mucus glands in the reproductive organs of females. Mucus is released from the vagina and the cervix to lubricate the tract, prevent unwanted pathogens from entering, and prevent the entrance of sperm during certain times of the menstrual cycle. The mucus changes throughout the menstrual cycle to meet the needs of that time.
The Pancreas
The pancreas is most commonly known as an endocrine gland, but it also has exocrine functions as well. The pancreas releases the enzymes trypsin, chymotrypsin, lipase, and amylase. These enzymes help to break down food in the digestive system and release the enzymes through the pancreatic duct. The enzymes are then released into the segment of the intestines called the duodenum.
These enzymes help to break down fats, carbohydrates, and proteins. Without these it would be very difficult for your body to digest the vitamins, nutrients, and minerals that it needs.
The pancreas knows to release these enzymes when the food enters the stomach so it is ready when the food reaches the intestines.
Conclusion
Exocrine glands are located all over the body and are very important in maintaining many functions. From ensuring the digestive tract stays intact, preventing infections in the nose and genitals, to keeping the skin moist and protected.
Also, while apocrine, merocrine, and holocrine glands all function in different ways, they are all exocrine glands at heart and work to meet the same goal.
It is important to recognize the differences between endocrine and exocrine glands to have a better understanding of the body and be able to recognize when things are going right and when they are going wrong.
Resources
Definition of exocrine gland | NCI Dictionary of Cancer Terms