EYES
Your eyes are about 1 inch across and weigh about 0.25 ounce.
The human eye can differentiate approximately 10 million different colors.
Our eyes remain the same size throughout life, whereas our nose and ears never stop growing.
The human eye blinks an average of 4,200,000 times a year. This means if you were given a nickel for every time you blinked you would make $210,000 annually.
Eyes are made up of over 2 million working parts.
Each individual eye contains 107 million cells and all are light sensitive
Your eye is the fastest muscle in your body. Hence, the phrase: “In the blink of an eye.”
The world’s most common eye color is brown.
The night vision of tigers is six times better than that of humans.
Ommetaphobia is the fear of eyes.
Pirates wore earrings because they believed it improved their eyesight.
NOSE
Human noses can have a wide array of shapes and sizes due to genetics and injuries.
Men generally have large nose than women.
The two openings in the nose care called nostrils, or napes.
They lead to two nasal cavities that are separated by the septum, a wall of cartilage.
Inside the face is an intricate system of canals and pockets of air called sinus cavities.
Sinus cavities span all the way to the back of the skull, right above the oral cavity, within the cheekbones and between the eyes and brow.
The nose is lined with fine, hair-like projections known as cilia.
The nose also plays a role in hearing.
The nasopharynx is flanked on either side by eustachian tubes. These tubes connect the nasopharynx to the middle ear.
The nasopharynx fills the middle ear with air, equalizing air pressure in the ear with the atmosphere around it, which is an important part of hearing properly.
A runny nose is caused by the production of mucus in the nose.
The production of mucus can be triggered by anything that irritates or inflames the nose, such as allergies, a cold, the flu or dust.
EAR
The ear has three main parts: external ear, middle ear and inner ear.
The external ear, also called the auricle or pinna, is the loop of cartilage and skin that is attached to the outside of the head.
It works much like a megaphone. Sound waves are funneled through the external ear and piped into the external auditory canal.
The Eustachian tube, or pharyngotympanic tube, equalizes air pressure in the middle ear with the air pressure in the atmosphere. This process helps humans retain their balance.
The eardrum, also known as the tympanic membrane, is a thin membrane that separates the outer ear from the middle ear. It vibrates in response to sound waves and transmits these vibrations to the ossicles.
The inner ear is a complex structure responsible for converting sound vibrations into electrical signals that can be interpreted by the brain.
It contains the cochlea, a spiral-shaped organ filled with fluid and hair cells that detect sound vibrations.
The inner ear is also crucial for balance and spatial orientation.
It contains the vestibular system, which consists of three semicircular canals and otolithic organs. These structures help detect changes in head position and movement.
The middle ear is a small air-filled space behind the eardrum.
It contains three tiny bones called the ossicles: the malleus (hammer), incus (anvil), and stapes (stirrup). These bones amplify and transmit sound vibrations from the eardrum to the inner ear.
The outer ear consists of the visible part called the pinna and the ear canal. Its main function is to collect sound waves and direct them towards the eardrum.
MOUTH
Tooth enamel is the strongest substance in the entire body! This makes it perfect for protecting teeth against cavities!
Tooth decay is actually classified as an infectious disease because it is caused by a specific strain of bacteria that can be shared between people.
The average person produces just over 100,00 gallons of saliva in their lifetime.
The first toothbrush was actually called a “chewstick.” Chewsticks were made by chewing on one end of a small branch until it became soft and fibrous. Surprisingly enough, chewsticks were effective at cleaning teeth of debris.
Saliva actually helps fight cavities and keep tooth enamel strong by washing away sugary and acidic food debris.
The human tongue is as unique as a fingerprint, and no two tongues are alike.
Toothpaste was once made out of crushed seashells, salt, pulverized dried bread, and sometimes crushed bones! Ancient toothpaste was often flavored with mint, juniper and other herbs.
The inside of the mouth heals faster than any other part of the body. This is because the cells in the mouth regenerate quickly due to the high amount of blood vessels present.
Breathing through the mouth instead of the nose can lead to dry mouth, bad breath, and other oral health problems. It can also affect facial development in children if it persists over time.
The shape and size of the mouth influence speech patterns. This is why people from different regions or with different native languages may have distinct accents or pronunciations.
LUNGS
Our lungs fuel us with oxygen, the body's life-sustaining gas.
They breathe in air, then extract the oxygen and pass it into the bloodstream, where it's rushed off to the tissues and organs that require it to function.
When we exhale, we produce carbon dioxide as a byproduct. Without this vital exchange, our cells would quickly die and leave the body to suffocate.
Our two lungs are made up of a complex latticework of tubes, which are suspended, on either side of the heart, inside the chest cavity on a framework of elastic fibers.
Air is drawn in via the mouth and the nose, the latter acting as an air filter by trapping dust particles on its hairs.
The air is warmed up before passing down the windpipe, where it's divided at the bottom between two airways called bronchi that lead to either lung.
Within the lungs, the mucus-lined bronchi split like the branches of a tree into tens of thousands of ever smaller tubes (bronchioles), which connect to tiny sacs called alveoli.
The alveolli are where the crucial gas exchange takes place. The air sacs are surrounded by a dense network of minute blood vessels, or capillaries, which connect to the heart.
The rate at which we breathe is controlled by the brain, which is quick to sense changes in gas concentrations.
The actual job of breathing is done mainly by the diaphragm, the sheet of muscles between the chest and abdomen.
HEART
The average heart is the size of an adult fist.
Your heart will beat about 115,000 times each day.
The beating sound your heart makes is caused by the opening and closing of its valves.
Each day, your heart pumps about 2,000 gallons of blood.
If you were to stretch out your blood vessel system, it would extend over 60,000 miles.
The human heart weighs less than one pound, but a man’s heart is typically two ounces heavier than a woman’s.
A woman’s heart beats slightly faster than a man’s.
There is such a thing as a broken heart. Symptoms are similar to a heart attack but the cause is usually stress and not heart disease.
Laughing is good for your heart. It reduces stress and gives a boost to your immune system.
The first successful human heart transplant was performed by Dr. Christiaan Barnard in South Africa in 1967. Since then, heart transplant surgery has become more common, offering a second chance at life for many patients with end-stage heart disease.
STOMACH
The stomach is a J-shaped organ located in the upper abdomen, situated between the esophagus and the small intestine.
The stomach secretes hydrochloric acid, which plays a crucial role in breaking down food and killing bacteria that enter the digestive system.
Apart from hydrochloric acid, the stomach also secretes various enzymes and mucus to aid in digestion. These gastric juices help break down food into smaller particles for absorption.
The stomach has a remarkable ability to stretch. It can expand to accommodate large meals, and its capacity can vary from person to person.
The esophagus, the stomach undergoes peristalsis, which is the rhythmic contraction and relaxation of muscles that helps move food along the digestive tract.
One of the primary functions of the stomach is to continue the digestion process that begins in the mouth. It mixes food with gastric juices and churns it into a semi-liquid substance called chyme.
The stomach has a protective lining that prevents its own tissues from being damaged by the acidic environment. However, certain conditions like gastritis or ulcers can disrupt this lining.
After food is sufficiently digested in the stomach, it is gradually released into the small intestine in a controlled manner. This process is called gastric emptying.
The stomach also produces hormones such as ghrelin, which signals hunger to the brain, and gastrin, which regulates acid secretion.
While the stomach is highly acidic, some bacteria like Helicobacter pylori have adapted to survive in this harsh environment. H. pylori is associated with gastritis and peptic ulcers.
While the stomach primarily aids in digestion, it also plays a role in the absorption of certain substances like alcohol and certain medications.
The stomach contains sensory receptors that can detect the presence of food, stretch, and chemical composition, sending signals to the brain to regulate appetite and digestion.
KIDNEY
The kidneys are vital organs responsible for filtering waste products, excess ions, and water from the blood to form urine. They play a crucial role in maintaining the body's overall fluid balance and electrolyte levels.
Each day, the kidneys filter about 120 to 150 quarts of blood to produce about 1 to 2 quarts of urine, depending on factors such as hydration and diet.
Kidneys help regulate blood pressure by controlling the volume of blood and the concentration of sodium and potassium ions in the bloodstream.
The kidneys produce several important hormones, including erythropoietin, which stimulates red blood cell production, and renin, which helps regulate blood pressure.
They also play a crucial role in maintaining the body's acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate ions.
Kidneys are involved in the regulation of calcium levels in the blood by activating vitamin D, which helps in the absorption of calcium from the intestines.
Each kidney is about the size of a fist and is located on either side of the spine, just below the rib cage.
Internally, the kidney is divided into two main regions: the outer renal cortex and the inner renal medulla. The nephrons, the functional units of the kidney, are located in the renal cortex and extend into the renal medulla.
The kidneys have a unique ability to regulate their own blood flow to ensure adequate filtration. They can constrict or dilate the blood vessels leading into and out of the kidney to maintain a consistent blood flow.
Kidney failure, or renal failure, occurs when the kidneys are no longer able to function adequately. This can lead to a buildup of waste products and toxins in the body, which can be life-threatening if left untreated.
HUMAN BRAIN
The human brain consists of about 86 billion neurons, each connected to thousands of other neurons, forming an intricate network of communication.
It's estimated that the human brain has a processing power of about 1 exaFLOP, which is equivalent to a billion billion calculations per second.
Although the brain only represents about 2% of the body's weight, it consumes about 20% of the body's energy.
The brain itself does not have pain receptors, so it doesn't feel pain. However, the surrounding tissues and structures do.
The brain exhibits a remarkable ability to reorganize itself by forming new connections between neurons throughout life. This phenomenon is known as neuroplasticity.
The brain generates electrical impulses that can be detected by electroencephalography (EEG) machines. These electrical activities vary depending on the state of consciousness.
While the exact purpose of dreaming is still debated, it's believed that dreaming helps consolidate memories, process emotions, and may even aid in problem-solving.
The human brain has an immense capacity for storing memories. It's estimated that the brain's memory storage capacity could be equivalent to 2.5 petabytes, which is roughly equivalent to 3 million hours of TV shows.
The speed at which neurons transmit information in the brain can reach up to 268 miles per hour (431 kilometers per hour).
The human brain continues to develop well into a person's 20s. The prefrontal cortex, responsible for decision-making and impulse control, is one of the last areas to fully mature.
Mirror neurons are a type of neuron that fires both when an individual performs an action and when they observe someone else performing the same action. They are believed to play a role in empathy, imitation, and understanding others' intentions.
The brain is divided into two hemispheres, with each hemisphere specializing in certain functions. For example, the left hemisphere is typically associated with language and logical processing, while the right hemisphere is more involved in spatial awareness and creativity.
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