What Are the Different Types of Organs in the Human Body?

Lauren Romano

There are many different organs in the human body, and there are also a couple of different ways of classifying them. One of the most common and simplest schemes arranges them as external or internal; sometimes they’re also divided by function, such as digestive, respiratory, and blood-related. Some scholars also think in terms of vitality or overarching importance. In these cases, certain organs, the brain and the heart in particular, are called “vital,” whereas others that perform more complementary roles can be labeled “accessory.” This classification system is often harder to work with since the body relies on almost all organs in different ways. It’s often the case that the vitals depend on the accessories to get their jobs done. Additionally, though people can sometimes live without certain organs like the pancreas or the kidney, this is usually only possible with the help of medications and therapies.

Several different organ systems keep the body functioning normally.
Several different organ systems keep the body functioning normally.

External Organs

The most obvious organs in the human body are those that are visible on the outside. Getting a sense of human anatomy usually requires a look at what’s going on inside, either through surgery or diagnostic imaging, but this isn’t the case with those parts that sit externally, either in part or in full.

The heart pumps blood to every part of the body.
The heart pumps blood to every part of the body.

Skin is the largest of the organs in the human body and weighs more than twice as much as the brain. Depending on the person, the average weight of the skin is about 8 pounds (approximately 3.6 kg). It's responsible for protecting the body from a variety of dangers including sunlight and chemicals. The skin is comprised of three layers: the base layer is the subcutis, the middle layer is the dermis, and the outer layer is the epidermis.

The human brain controls all the actions of the body.
The human brain controls all the actions of the body.

Eyes are usually also considered an external organ, though a lot of things happen near the optical nerve, which is inside the face. Humans blink approximately 10,000 times per day, or on average, about 12 times each minute. The eyes start to develop about 26 weeks after conception. It's believed that the eyes focus on 50 things per minute.

The torso houses many of the body's organs.
The torso houses many of the body's organs.

The Reproductive System

In males, the reproductive organs are almost entirely outside of the body. They include the penis and the testicles, which protrude from the body; together these produce and deliver sperm, which are genetic materials essential to conception. The female reproductive system is focused on egg production, fertilization, and gestation, and is made up of the cervix, the uterus, and the ovaries, all of which are internal. They open into the vagina, which is the only part that can be seen externally.

All of the internal organs, like the liver, heart, kidneys and lungs, are vital for the body to work properly.
All of the internal organs, like the liver, heart, kidneys and lungs, are vital for the body to work properly.

Internal Organs

The bulk of the body’s organs reside in the torso, usually in or just beneath the ribcage. One of the main roles of the ribcage is actually to protect these organs from accidental damage or injury. Most of the digestive and respiratory systems are housed here. The stomach, for instance, which is located between the small intestine and esophagus, is responsible for processing food and moving it along to the intestines. The liver, located on the right side of the body under the ribs, is responsible for making bile, processing nutrients from food, and removing toxins from the body. Lungs, which are located in the center of the chest, bring oxygen into the body and remove carbon dioxide. Two kidneys are located in the middle of the back below the rib cage and are responsible for taking water and waste from the blood in order to form urine.

The Heart

The human heart is perhaps the most essential and complex human organ, though again a lot of this depends on perspective. It is responsible for pumping blood to every part of the body through a network of veins and arteries. There are four chambers that make up the heart, two ventricles and two atria, and together the organ is about the size of an adult fist. It’s typically set at an angle, and is located behind the sternum on the left side of the body. In most people it beats about 100,000 times a day, or about 40 million times a year.

The Brain

The brain is another organ that often comes to mind when people think about things that are essential. It is responsible for controlling all the actions of the body and regulating chemical activity, particularly hormonal balance; it is also crucial for things like language processing and communication. It weighs about 3 pounds (1.36 kg). The cerebrum is what makes up 85 percent of its total weight, and the brain as a whole is comprised of about 75 percent water. There aren’t any pain receptors here, though pressures and growths can have serious implications on health and lifestyle in other ways.

The skin is the largest organ in humans.
The skin is the largest organ in humans.

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Discussion Comments


@KoiwiGal - I was always surprised when they classified the skin as an organ, to be honest. When I was a kid I thought organs were basically just the individual bits that did stuff in the body, and that skin and bones and muscles were more like the packaging that just held it all together.

But skin is actually pretty complex stuff. I did a biology paper a few years ago and I can remember being kind of blown away by how many different functions the skin has.

So, anyway, I guess it depends on what your definition of an organ is. The cells in our guts do actually have quite a complex role in our bodies. I'd say they were more complex than even the eye, or possibly anything except the brain.


@browncoat - I don't know if that should be considered to be an organ though. I mean, you can recognize that it is vital to the human body, but oxygen is vital to our survival as well and we don't call the atmosphere an organ.

I guess it does raise the question of at what point we consider a cell to be part of the human body though.


I read an article recently where the author basically said that we have a larger "organ" than skin in our body, and that it's the bacterial ecosystem that lives in our gut. Apparently it has a hundred times more cells than the rest of our body, they are just very small.

And, according to the article, doctors and researchers are realizing more and more often that fixing problems with that ecosystem can fix a lot of different conditions. They had one guy who they basically saved from the symptoms of MS with a fecal transplant.

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