1. Alveoli
   Hypothalamus
2. Duodenum
   None of the above

The hypothalamus is in charge of basic bodily functions. Aside from body temperature, hunger and thirst, it also controls sleep, growth, weight and more. The hypothalamus is small, but important!

1. Glucose
   Bile
2. Oxygen
   Hormones

Bile is a fluid that helps your small intestine digest lipids like cholesterol, fats and fat-soluble vitamins. The fluid, which is sticky and thick, ranges from dark green to yellow-brown in color.

1. It uses acid.
   It cuts up the food.
2. It heats the food.
   None of the above

Your stomach produces a liquid called gastric acid. It's made of sodium chloride, potassium chloride and hydrochloric acid. After this fluid breaks down the food, it moves on to your small intestine.

1. Skin
   Brain
2. Heart
   Stomach

Your heart pumps blood to various parts of the body. This is super important because blood is rich in nutrients and oxygen! So, when your organs get enough blood, they can work properly and stay healthy.

1. Left lung
   Right lung
2. Well, it depends how heavily you're breathing.
   This is a trick question. They're the same size!

Your right lung is slightly bigger than your left lung. This because your heart is on the left side of your body, and it takes up a lot of space. So, your left lung is smaller, which gives the heart more room.

1. Alveoli
   Colon
2. Pancreas
   Ileum

The large intestine is also known as the colon or large bowel. When digested material reaches this organ, existing bacteria breaks it down. This becomes waste, which is eventually excreted as stool.

1. Respiration
   Transpiration
2. Peristalsis
   Lactation

When food and liquid pass through your intestines, the muscles move in a wave-like movement called peristalsis. Your esophagus also uses peristalsis to move food to your stomach.

1. Yes
   No
2. It depends on the person.
   It depends on how it's removed.

Yes, you can live without a spleen! Your spleen, which is like a large lymph node, filters the blood. But if you need to have your spleen removed, the liver and lymph nodes can get the job done.

1. Pituitary gland
   Amygdala
2. Cerebrum
   Brain stem

The amygdala controls your emotional reactions. For example, if you have a fear of spiders, you can thank your amygdala! It tells the rest of your brain that something is a threat.

1. Two
   Four
2. Six
   Eight

The human heart has four chambers. They're called the right atrium, right ventricle, left atrium and left ventricle. Together, these chambers pump blood throughout the body.

1. Heart
   Pancreas
2. Brain
   None of the above

The pancreas is located just behind the stomach. It regulates your levels of blood sugar, which is also known as blood glucose. This organ also secretes digestive enzymes into the small intestine.

1. Helps you breathe in oxygen
   Makes bile to help digestion
2. Filters blood from the digestive tract
   Removes toxins from the body

The liver makes bile, which is stored by the gallbladder. It also filters blood and removes toxins as your body processes food and medicine. But when it comes to taking in oxygen, your lungs are the organs for the job.

1. Cells
   Nephrons
2. Neurons
   Alveoli

Your lungs have approximately 600 million tiny air sacs called alveoli. They're in charge of letting oxygen pass into your blood, which then brings oxygen to different parts of your body.

1. Respiratory
   Skeletal
2. Digestive
   Endocrine

The respiratory system helps you breathe. With every breath, it takes in oxygen and gets rid of carbon dioxide. This is important because your entire body needs oxygen to function.

1. Heart
   Large intestine
2. Stomach
   Brain

From thinking to feeling, your brain controls everything you do and say. It's also responsible for memory, movement and decision making. Luckily, it's protected by a thick skull.

1. Stomach
   Heart
2. Brain
   Kidney

The kidneys are bean-shaped organs that are part of the excretory system. They filter the blood and remove toxins, which eventually become urine. This helps the body maintain fluid balance.

1. Macrophage
   Keratinocyte
2. Nephron
   Gut flora

The microbial community in your intestines is called gut flora or gut microbiota. These "good" bacteria help digestion, control metabolism and work with your immune system to keep you healthy.

1. Oxygen and carbon dioxide
   Oxygen and nitrogen
2. Carbon dioxide and nitrogen
   Nitrogen and argon

During gas exchange, your lungs deliver oxygen to the blood. At the same time, your lungs pull out carbon dioxide from your blood. The carbon dioxide leaves your body when you exhale.

1. Large intestine
   Stomach
2. Brain
   Skin

Your skin is your largest organ! It also grows the fastest. As an organ that protects your body, skin keeps all of your inside parts in place. It also keeps out harmful germs so you can stay healthy.

1. Bile
   Oxygen
2. Blood
   None of the above

Every day, your kidneys filter almost 3 liters of blood about 60 times. As blood passes through, the kidneys pull out waste and excess water, which eventually becomes urine.

1. Lungs
   Stomach
2. Small intestine
   Large intestine

In the small intestine, the duodenum secretes a fluid that neutralizes stomach acid. The jejunum absorbs nutrients into the bloodstream, while the ileum absorbs bile acids, vitamin B12 and other remaining nutrients.

1. Prostate gland
   Pineal gland
2. Adrenal gland
   None of the above

When your brain senses fear, it sends signals to your adrenal glands. These glands release adrenaline, which increase your heart rate and send blood to your muscles. This response helps you get away in the face of danger.

1. Hypothalamus
   Nephrons
2. Epidermis
   Hippocampus

The epidermis is basically a barrier. As the outermost layer, it keeps out harmful germs that can cause infection. The inner layers of the skin are called the dermis and hypodermis.

1. Kidney
   Pancreas
2. Gallbladder
   Small intestine

Nephrons are the filtering units of your kidneys. One kidney has about one million nephrons! They filter your blood and make urine, which is sent to your bladder.

1. Nervous
   Endocrine
2. Reproductive
   Skeletal

The endocrine system consists of glands that produce important hormones. For example, the pineal gland releases melatonin, a hormone that controls your sleep.

1. Small intestine
   Large intestine
2. Lung
   Kidney

When you eat food, most of nutrient absorption takes place in the small intestine. A lot of this happens in the jejunum, the middle section of the small intestine.

1. Lymph nodes
   Nephron
2. Cochlea
   Ovary

Lymph nodes, or lymph glands, are part of the lymphatic system. They support the immune system by filtering foreign substances and cancer cells. You have lymph nodes all throughout your body.

1. Nose
   Eye
2. Skin
   None of the above

Your eyes are organs that respond to light and pressure. When they absorb light, our brain processes the information and forms visual images. Your eyeballs are able to move because of different eye muscles.

1. Uterus
   Ovary
2. Pancreas
   Fallopian tube

Ovaries are female reproductive organs; there's one on each side of the body. Each month, they make an egg for fertilization. The ovaries also release hormones that regulate the menstrual cycle.

1. Nervous
   Digestive
2. Reproductive
   Respiratory

Your nervous system includes your brain, spinal cord and sensory organs (like your skin and eyes). These parts are connected by nerves that send chemical messages in the form of electrical signals.

1. Testicles
   Urethra
2. Fallopian tubes
   Gallbladder

Testicles are two egg-shaped organs that are responsible for making sperm. They also produce testosterone, the primary male sex hormone. Testicles are also known as testes.

1. Spleen
   Pancreas
2. Bladder
   Liver

The bladder stores urine until you go to the bathroom to pee. When it's empty, the bladder is about the size of a grapefruit, but it can stretch if needed.

1. Digestive
   Lymphatic
2. Skeletal
   Respiratory

Thanks to your digestive system, your body can break down food and absorb nutrients. It also turns your food into energy, which is essential for basic bodily functions.

1. Liver
   Heart
2. Stomach
   Pancreas

Cholesterol gets a bad reputation, but you do need some of it to survive. In fact, it's so important that your liver makes it for you! Your small intestine also makes a small amount.

1. Stomach
   Liver
2. Heart
   Large intestine

The liver is a solid organ. However, the stomach, large intestines and heart are like empty bags or tubes. This lets things like food or blood move through.