In school, you probably learned that organs are the body's "machines" -- they are active, serving a function, and often complex in structure. This is easy to see when we're talking about the body's "rock star" organs: the brain, heart, lungs, liver and kidneys.
But things are a little more complicated than that. (Aren't they always?) Not everyone can even agree on how many organs the body has. Is it 50? Or even more than 70? To get to that higher number, 78, you have to count all the glands, as well as parts of the body we don't think of as very active or machine-like. Take the bladder, for example. You're probably used to thinking of it as a mere holding tank, but it's classed as an organ. There are some organs you can even do without, like the spleen.
If you're nostalgic for your old health-science class, we've got a quiz for you. We'll provide a picture, and you identify the organ. We'll also provide a hint if you get stuck... which you might, even if you love biology. We get into quite a few of the glands and lesser-known organs.
Are you up to the challenge?
The brain isn't the largest organ, but it's arguably the most important. It regulates the function of all other organs, whether autonomically (heartbeat) or deliberately (breathing).
Yep, the tongue's an organ. A sense organ, to be exact, and one of the body's important "gatekeepers" in terms of food.
The eye is a complex machine. Its diseases are treated by an ophthalmologist (not to be confused with an optometrist, who deals with vision and prescribes glasses or contacts).
The pharnyx is part of the digestive system, located in the throat. Aptly, its name is Greek for "throat."
Many people view the lungs as big balloons, simple in structure. They're actually filled with dense, light structures (alveoli), like a honeycomb.
The stomach is an organ that takes a lot of abuse. We don't appreciate its hard work until we begin to have problems with it, like acid reflux.
The small intestine is responsible for much of the digestive process. It is divided into the ileum, duodenum and jejunum.
What? An organ can be part of another organ? It's true. The duodenum is the first segment of the small intestine, and the first place your food goes after the stomach.
The jejunum comes just after the duodenum in the small intestine. Sidenote: Bonus points if you recognized the other three names as adapted from cryptocurrencies. (Everyone likes an Easter egg once in a while)
The large intestine is virtually the end of the digestive process. Before, well, you know. It removes water from bodily waste before the rest becomes feces.
The liver, along with the kidneys, is the body's detoxification system. Together, they render those expensive "detox programs" largely unnecessary.
The gallbladder stores bile, which is important to the digestive process. Even so, you can have your gallbladder removed without too much inconvenience to your day-to-day life.
The esophagus is the long tract that carries food down to your stomach. Though it might seem like a passive "chute," it actually uses peristaltic contractions to move food along.
The larnyx is responsible for sound production, or more simply, voice. That's why larynx problems hit singers so hard.
How did this tough, essential organ become synonymous with love and passion? We're not sure - it's essentially a big hydraulic pump.
Kidneys are bean-shaped organs that filter and detoxify the blood. They're also among the most commonly donated organs.
The thyroid is a butterfly-shaped gland in your throat. Problems with it are not uncommon, but treatable with hormones.
The pancreas is one of the better-known glands (a gland is an endocrine, or hormone-regulating, organ), thanks to its role in diabetes. When the pancreas does not produce enough insulin from very early in life, that's known as Type I Diabetes, as opposed to Type II, often brought on by excess weight and lack of exercise.
The ovary is a gland. Responsible for far more than fertility, it produces hormones essential to energy and well-being in women.
Far more than a passive storage chamber, the uterus is a reproductive organ. During intercourse, it directs blood flow to the vagina, which is an important part of sexual responsiveness.
Technically, we should call this the "urinary bladder" to differentiate it from the gallbladder. Or the swim bladder, which fish have.
These run from the kidneys down to the bladder. They're also a common site where kidney stones develop. Ouch!
As the name implies, this narrow organ is used in urination. In males, it's also the conduit for semen.
Okay, it's a nerve - but we're including it because the vagus nerve is so powerful in regulation of emotion. It secretes neurotransmitters and can cause, in moments of great stress, fainting or loss of bladder control.
Okay, this is another "not quite an organ." Except it is, when it comes to transplantation - corneas are routinely recovered for re-use, like hearts and kidneys.
The parotid gland secretes saliva, which is important to digestion, as well as general comfort. Vaccination has led to a sharp decrease in infections causing swelling of the parotid glands - commonly known as "mumps."
In healthy men, it's about the size of a walnut. Enlargement tends to occur with age.
The pituitary gland is tiny but mighty. About the size of a pea, it's deep in the base of your brain and regulates the function of many other glands in the body.
The pineal gland, in the brain, produces melatonin, which regulates sleep. However, there's also a lot of pseudoscience about what the pineal gland does - including, supposedly, releasing a large amount of DMT at point of death. Proceed cautiously when analyzing such claims.
You probably know this gland because of the hormone "adrenalin," associated with excitement and stimulation. Technically, we should say "glands," as there's one atop each kidney.
The thymus. along with bone marrow, constitutes the body's immune system. That is, it produces antibodies that attack infectious agents.
Okay, you could say bone marrow is just a "tissue," but it's very biologically active. It creates blood cells, and since white blood cells fight infection, bone marrow is also a key player in the immune system.
As part of the "four humours" theory of medicine, the Greeks thought that an overbalance of spleen fluids cause someone to get angry easily. This is why you'll still sometimes hear the phrase "vent your spleen" for "get something off your chest."
The tonsils, like the spleen, are something that humans can get along without. Some of us grew up hearing, jealously, about all the ice cream patients were allowed to eat post-operation (ice cream being gentle on the throat, the site of the surgery).
The lymphatic system, including the lymph nodes, is part of the body's "acquired" immune system. They filter foreign bodies like cancer cells.
Though we don't always think of it this way, skin is the largest organ. It plays a vital role in protecting the body from pathogens and regulating body temperature.
Stop giggling; this is science! The testis (plural "testes") is the analogue of the female ovary, creating sperm. It's an essential part of the reproductive system.
The Fallopian tubes carry egg cells from the ovaries to the uterus. They are named for an Italian scientist, Gabriele Fallopio, who thought they resembled tubas. (Okay, that's not very dignified!)