When food enters the mouth to be chewed or swallowed, it is either cooled or warmed by the tissue inside the mouth to a more suitable temperature for digestion.
The ears and nose do not have bones inside them. Their inner supports are cartilage which is lighter and more flexible than bone. This is why the nose and ears can be bent.
Red blood cells make approximately 250,000 round trips in the body before returning to the bone marrow, where they were born, to die. Their life cycle is approximately four months.
Unlike other body cells, brain cells cannot regenerate. Once brain cells are damaged they are not replaced.
Humans have two sets of teeth. Twenty "baby teeth" are replaced at around 6-7 years of age with 32 "permanent teeth".
An allergy is your immune system overreacting to substances that are not harmful to other people. True allergies are reactions to substances called allergens.
The weight of skin on an average adult human is around 6 pounds.
A "bursa" is a fluid-filled sac located near a joint that helps muscles and tendons move freely. The shoulder joint has the most bursa, with eight.
Exercise builds much more than the heart. In addition to making the heart more resilient, it also lowers blood pressure, increases the elasticity of blood vessels and increases bone strength by helping bones absorb minerals.
The most common human blood type is O+. About 38 percent of the world population is O+. The rarest is AB-. Only 1 percent of the world is AB-.
The sound made when people moves their fingers rapidly, cracking their knuckles, is the sound of fluid rushing in to fill the space created between the joints.
The hyoid bone is the only bone in the human body that doesn't touch another bone. It is located above the larynx and anchors the tongue muscles.
Human fingernails grow faster than toenails. Both grow faster in the summer than in the winter.
Your stomach doesn't "tell" you when you're hungry. People who have had their stomachs removed still feel hungry. Hunger sensations are controlled by the hypothalamus, a small brain structure that senses what your body's food needs are.
The human skin secretes antibacterial substances as a defense. Most bacteria and spores that land on the skin die quickly.
The ears and nose do not have bones inside them. They are supported by cartilage, which is lighter and more flexible than bone. This is why your nose and ears can bend.
Muscles contract in waves to move the food down the esophagus. This means that food would get to a person's stomach, even if they were standing on their head.
The average person contains about eight ounces of salt, which helps muscles contract, digestion to occur, blood to flow, wounds to heal and fluids to be properly regulated.
Unlike other body cells, brain cells cannot regenerate. Once brain cells are damaged they cannot be replaced.
When your stomach fills with food, a chemical hormone is released into the bloodstream. When this chemical reaches the brain it tells your body to relax. This aids in digestion and is the reason we feel sleepy after a meal.
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