Human Anatomy

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Optical illusions work because humans have binocular vision, which allows people to see different objects with each eye and sometimes the images do not merge properly. The brain must also interpret the signals correctly. Persistence of vision can also make optical illusions work.

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  • How long does it take for water to get to the bladder?

    Q: How long does it take for water to get to the bladder?

    A: On average, it takes the human body approximately two to three hours to excrete a liter of water through the bladder. This is dependent on several factors, including the absorption of water, the components in the water, if dehydration is present, the time of day and the general health of the person.
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  • What is the hardest tissue in the body?

    Q: What is the hardest tissue in the body?

    A: According to WebMD, the hardest tissue in the human body is tooth enamel. Tooth enamel is the thin, hard, white covering that protects the dentin of the teeth.
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  • Do eyes grow after birth?

    Q: Do eyes grow after birth?

    A: According to the Chicago College of Medicine, eyes do continue to grow after birth. A newborn's eyes are about 75 percent the size they are going to be when fully grown.
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  • What does it mean when your nose itches?

    Q: What does it mean when your nose itches?

    A: An itchy nose may indicate allergies, most notably to animals, including cats, dogs, birds, seasonal allergies like hay fever, food, or the start of the common cold. It may also be the result of dry skin.
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  • What is the function of the heartstrings?

    Q: What is the function of the heartstrings?

    A: The function of the heartstrings is that of an information transmitter. The information transmitted is the increase and decrease of tension from the papillary muscles to the three valve cusps of the right atrioventricular (AV) valve. This information causes the valve cusps to open and close.
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  • Where is the navel located on the human body?

    Q: Where is the navel located on the human body?

    A: The navel is located on the front of the body, roughly half way up the abdomen. There is a great variety in navel size and shape among humans.
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  • What are sensory skills?

    Q: What are sensory skills?

    A: Sensory skills are the act of seeing, smelling, touching, tasting and hearing to better engage in daily activities. According to the Public Broadcasting Service, sensory skills are vital to a child's development and help people of all ages perceive their surroundings.
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  • What is located where the nose and mouth come together?

    Q: What is located where the nose and mouth come together?

    A: According to Medline Plus, the body feature located between the nose and mouth is called the "philtrum." It consists of a groove in the skin and muscle. It can be wide, narrow, short, long, deep or shallow based on genetic background.
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  • At what age does a girl stop growing?

    Q: At what age does a girl stop growing?

    A: On average, girls reach their final adult height and stop growing by age 14 or 15, though this figure skews either younger or older depending on when puberty begins. Most girls experience a growth spurt between ages 10 to14, and a female's rate of growth peaks around two years after puberty begins, which is usually around age 12.
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  • Are attached earlobes dominant or recessive?

    Q: Are attached earlobes dominant or recessive?

    A: Attached earlobes are considered to be recessive. Free earlobes are a dominant trait. This means that far more people have earlobes that are unattached.
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  • What causes flushed cheeks?

    Q: What causes flushed cheeks?

    A: According to the National Health Service of the U.K., flushed cheeks, or "blushing," is a result of the involuntary nervous system responding to stress or embarrassment. Your face muscles relax, which allows your face's blood vessels to expand and take in more blood, causing the reddish hue of blushing.
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  • Why is the sense of touch important?

    Q: Why is the sense of touch important?

    A: The sense of touch is important because it allows animals to derive information about their surroundings when the other senses are not appropriate. Some animals rely on the sense of touch more than others do. Typically, animals with a very poor sense of sight develop an exquisite sense of touch.
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  • What is the average heart rate for my age?

    Q: What is the average heart rate for my age?

    A: Normal heart rate varies based upon age and activity level. A resting heart rate is typically above 60 beats per minute. It changes as an individual ages. The Mayo Clinic explains that a well-trained athlete often has a lower resting heart rate, closer to 40 beats per minute.
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  • When does your head stop growing?

    Q: When does your head stop growing?

    A: The human head never stops growing and changing, according to findings reported by Duke Magazine. While most bones stop growing following puberty, CT scans conducted on 100 men and women demonstrated that the bones of the skull continue to grow and change throughout a person's lifetime.
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  • What is the fastest healing part of the body?

    Q: What is the fastest healing part of the body?

    A: The fastest healing part of the body is the tongue. This is due to the rich supply of blood the tongue receives, making it able to heal twice as fast as any other part of the body. This includes taste buds, which is why someone can burn taste buds eating hot food and later be able to taste perfectly fine because the taste buds have quickly healed.
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  • At what age does your head stop growing?

    Q: At what age does your head stop growing?

    A: Duke Magazine reports that the bones in the head continue to grow throughout a person's lifetime. The cheekbones move backward and the forehead moves forward as a person ages. The facial bones also seem to tilt forward as a person gets older.
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  • Why does asparagus make your pee smell?

    Q: Why does asparagus make your pee smell?

    A: Asparagus pee (for lack of a better term) is a centuries-old problem, and scientists still aren't sure what causes its unique odor. Adding to the uncertainty is a strange phenomenon: a portion of the population either doesn't produce the smell or can't smell it at all.
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  • What is the function of the hammer in the ear?

    Q: What is the function of the hammer in the ear?

    A: The hammer in the ear, also called the malleus, transmits sound vibration to the anvil from the eardrum. The hammer and the anvil, also called the incus, are two of three very small, linked and movable bones in the ear. The other is the stirrup or stapes. Together, these three bones transmit sounds through the inner ear. InnerBody states that "the small bones create fluid membrane waves by converting compression sound waves from the eardrum."
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  • What is the largest vein in the human body?

    Q: What is the largest vein in the human body?

    A: The two largest veins in the human body are the superior and inferior vena cavae. These veins, which are roughly the same size, are the final conduits for deoxygenated blood before it is returned to the heart.
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  • How much food does the average person eat in a day?

    Q: How much food does the average person eat in a day?

    A: An average person eats about 2000 calories a day, according to a study conducted by the University of Westminster's Human Performance Laboratory. The six women studied consumed between 1770 to 2600 calories a day, as published in the Mirror.
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  • When do men stop growing?

    Q: When do men stop growing?

    A: Most males have reached their full height by age 16, but their muscles still grow. Much of the height increase comes from a growth spurt between ages 12 and 16. During this period, boys often add as many as 12 inches. They also put on weight, and this gain typically ranges from 15 to 65 pounds.
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