Quiz of the Day
The Human Body
Tuesday, 29 September 2026
World Heart Day is 29 Sep — an anatomy quiz on the heart, organs, bones, senses and how the body works
1. How many chambers does the human heart have?
- Two
- Six
- Three
- Four
The human heart has four chambers: two upper atria and two lower ventricles. The right side pumps oxygen-poor blood to the lungs, while the more muscular left side pumps oxygen-rich blood to the rest of the body. This double-loop system keeps oxygenated and deoxygenated blood separate.
2. Which organ is the largest in the human body?
- Brain
- Liver
- Lungs
- Skin
The skin is the body's largest organ, covering roughly 1.5 to 2 square meters in an adult. It acts as a waterproof barrier, regulates temperature, and houses the sense of touch. Among internal organs, the liver is the largest.
3. Approximately how many bones are in the adult human body?
- 106
- 206
- 406
- 306
An adult human skeleton has 206 bones. Babies are born with around 300, but many fuse together as they grow. The smallest bone is the stapes in the ear, and the longest is the femur in the thigh.
4. Which organ is primarily responsible for filtering blood and producing urine?
- Kidneys
- Gallbladder
- Pancreas
- Spleen
The kidneys filter about 180 liters of blood every day, removing waste and excess fluid to form urine. Most people have two kidneys, but a person can live a healthy life with just one. Each kidney contains roughly a million tiny filtering units called nephrons.
5. How many lungs does a human have?
- Three
- Two
- One
- Four
Humans have two lungs, but they are not identical. The left lung is slightly smaller and has only two lobes to make room for the heart, while the right lung has three lobes. Together they hold hundreds of millions of tiny air sacs called alveoli where oxygen enters the blood.
6. Which part of the eye controls how much light enters it?
- Retina
- Lens
- Cornea
- Iris
The iris is the colored ring of muscle that controls the size of the pupil, adjusting how much light enters the eye. In bright light it contracts the pupil, and in dim light it widens it. The retina at the back of the eye is where light is finally converted into nerve signals.
7. What is the main function of red blood cells?
- Carrying oxygen
- Fighting infection
- Clotting wounds
- Producing hormones
Red blood cells carry oxygen from the lungs to the body's tissues using a protein called hemoglobin, which gives blood its red color. A single drop of blood contains millions of them. White blood cells, by contrast, are the ones that fight infection.
8. Which organ produces insulin to regulate blood sugar?
- Pancreas
- Adrenal gland
- Thyroid
- Liver
The pancreas produces insulin, a hormone that helps cells absorb glucose from the blood. When this system fails, the result is diabetes. The pancreas also releases digestive enzymes into the small intestine to help break down food.
9. What is the longest bone in the human body?
- Humerus
- Femur
- Spine
- Tibia
The femur, or thigh bone, is the longest and strongest bone in the human body. It can support many times a person's body weight and typically makes up about a quarter of a person's height. Its ball-shaped head fits into the hip socket to form the hip joint.
10. Which part of the brain is mainly responsible for balance and coordinating movement?
- Cerebellum
- Medulla
- Hippocampus
- Cerebrum
The cerebellum, located at the back and base of the brain, coordinates voluntary movements, balance, and posture. Although it makes up only about 10 percent of the brain's volume, it contains more than half of the brain's neurons. Damage to it can cause clumsy, uncoordinated movement.
11. Roughly how many times does an average adult heart beat per minute at rest?
- 10 to 20
- 60 to 100
- 150 to 200
- 250 to 300
A healthy adult heart at rest typically beats between 60 and 100 times per minute. Well-trained athletes often have resting rates below 60 because their hearts pump more efficiently. Over an average lifetime, the heart beats more than two billion times.
12. In which part of the digestive system is the majority of nutrients absorbed?
- Small intestine
- Large intestine
- Esophagus
- Stomach
Most nutrient absorption happens in the small intestine, which is lined with millions of tiny finger-like projections called villi that vastly increase its surface area. Despite its name, it is around 6 meters long in adults. The large intestine mainly absorbs water and forms waste.
13. Which blood vessel type carries blood away from the heart?
- Capillaries
- Arteries
- Lymph vessels
- Veins
Arteries carry blood away from the heart, while veins return blood to it. The largest artery, the aorta, arches directly out of the heart's left ventricle. Arteries have thick, elastic walls to withstand the high pressure of each heartbeat.
14. The eardrum is part of which sense?
- Taste
- Hearing
- Sight
- Smell
The eardrum, or tympanic membrane, is a thin tissue that vibrates when sound waves hit it, allowing us to hear. These vibrations pass to three tiny bones in the middle ear, the smallest bones in the body. From there the signal reaches the fluid-filled cochlea, which converts it into nerve impulses.
15. Which organ in the digestive system produces bile to help digest fats?
- Kidney
- Liver
- Spleen
- Bladder
The liver produces bile, a fluid that helps break down fats during digestion. Bile is stored and concentrated in the gallbladder before being released into the small intestine. The liver also filters toxins from the blood and can regenerate lost tissue, making it one of the body's most versatile organs.