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Difference Between Glands and Organs

A gland is always an organ. Therefore, it is important to know the specific features of glands that are useful to distinguish those from other organs. Since, glands support all other organs and organ systems to function according to the requirement, there should be a high demand to know the particulars of glands. This article discusses the differences of glands from other organs.


According to the definition for the term gland, it could be either a specialized cell, or a group of cells, or an organ of endothelial origin, which secretes substances into the blood stream or removes selected materials from blood or body. In simple terms, a gland produces and release substances that can be a hormone, an enzyme, or any other secretion. Glands are of two types, known as endocrine glands and exocrine glands. Endocrine glands release substances directly into the bloodstream, while exocrine glands release substances to the exterior or into cavities inside the body. Endocrine glands do not have a duct system, but exocrine glands do have a duct system through which the substances are excreted. These duct systems could be either simple or complex. Sweat glands are simple exocrine glands while salivary glands, mammary glands, liver, and pancreas are examples for complex exocrine glands. According to the secretory product, the exocrine glands are of three sub categories known as Serous, Mucous, and Sebaceous glands. Endocrine glands on the other hand are ductless organs and mostly secrete hormones into bloodstream and hormones travel through circulation into the target organs. Pituitary, thyroid, testes, and ovaries are some of the typical endocrine glands secreting very important hormones to sustain the life.


The organ is a group of organized tissues to perform a specific function or a group of functions. Usually, organs are made up of more than one cell type. In addition, the main two types of tissues participating to form an organ are main tissue and sporadic tissue. Depending on the organ, the type of main tissue differs; myocardium is the main tissue in the heart while blood, nervous, and connective tissues are the components of sporadic tissue. The largest organ of the mammals is the skin, which in humans has more than two square metres of area. Animals have developed with many types of organs to perform different functions. Organs in association with each other form organ systems. Reproductive, circulatory, nervous, endocrine, digestive, muscular, skeletal, excretory, and lymphatic systems are the main body organ systems functioning in a body. However, organs are not only found among animals, but also in plants; for example, flowers of plants are reproductive organs of trees. Organs make use of the building blocks of life to form body systems. Organs do not have to have a specific shape, but could be of any shape or size.

What is the difference between Gland and Organ?

• Gland is a specialized cell or group of cells synthesize and excrete substances. However, organ is a group of organized tissues performing specific or group of functions.

• Gland always secretes substances but not all the organs secrete substances.

• Gland is always a tubelike structure but organ is not always in that nature. Ex: liver is a dense organ but stomach is a hollow organ.

• Gland is technically a collection of cells, which are of the same type. However, many other organs have different types of cells.

• The functionally related organs perform functions together as a unit called organ systems, which involves in homeostasis, but glands alone do not function together always.

• An animal cannot live without vital organ but, if the essential substances are provided externally, the animal can live without that particular gland.

• Normally most of the organs are larger and complex compared to glands.

What Is A Circadian Rhythm?

Circadian rhythms describe regular events that happen to all humans, plants and animals on a daily basis. We are far from understanding all of them and their effects on our health but we know that there are processes that happen in all of us on a roughly 24 hour cycle influenced by various cues from our environment. The influence of these rhythms can change sleep and wake cycles, release various hormones, influence body temperature and regulate other important bodily functions. While we all have circadian rhythms there are some differences in the length of the cycles which helps to explain why some of us are “night owls” and others are “morning people”. There also appears to be a genetic component to our rhythms which explains why some lifestyle habits such as staying up late appear to run in families.

The image below shows many of the circadian rhythms:


From the image we can see regular changes in melatonin secretion, body temperature, vascular changes and bowel changes among others. For example, melatonin secretion starts around 9pm and ceases around 7:30am with our period of deepest sleep at 2am. This sets in place a natural sleep cycle for us as humans. For those of us who work late hours or third shift we are in direct contention with this natural cycle and this may lead to issues with sleep or other aspects of our health.

We also see that our lowest body temperature is at 4:30am and our highest is at 7pm. This natural temperature variation allows for many processes in our body to function correctly, yet our temperature controlled environments may not always cater to allowing these functions to completely take place. This, again, is another example of possible disruptions.

Learn more about Circadian Rhythm