Amazing Kids! Magazine

Sci-Tech Kids – Our Amazing Body

By Ryan Traynor, Editor-in-Chief

The Circulatory System

We like to associate blood with vampires these days, but the blood that truly makes a difference in our life is the one traveling through your circulatory system. Your circulatory system transports food and oxygen throughout your body.  On the way back, it picks up waste products to be removed.  The parts to the system are the heart, blood vessels, and the cells in the blood.  In a single drop of blood there are 5 million red blood cells, 8,000 white blood cells, and 250,000 platelets.   They float in a yellow liquid called plasma.  The red blood cells, when filled with oxygen, make the blood look red.  The average adult has nine pints of blood.

In addition to transporting wastes and materials, the blood helps fight germs, heal wounds, and control body temperature.  It heals wounds by blood clotting.  When you get a minor cut, the blood turns into a gel-like substance.  This keeps more blood from leaking out and germs cannot get in your bloodstream.

Blood travels in blood vessels.  One type is the artery.  Arteries carry oxygen-rich blood to the rest of the body once it is pumped through the heart.  They are thick because they need to withstand the pressure of the heart muscles.  They eventually end in another tube called capillaries.  Capillaries carry both oxygen-poor and oxygen-rich blood.  They are only one cell thick so oxygen and food can easily pass through the needy cells.  Veins take oxygen-poor blood to the heart where it is pumped to the lungs to get oxygenated.  Veins are not as strong as arteries, but stronger than capillaries. In your body you have sixty thousand miles of blood vessels.

The heart never tires. It is a muscular organ that never stops pumping.  The heart has four chambers: the left atrium, right atrium, left ventricle, and right ventricle.  The right side of the heart pumps oxygen-poor blood to the lungs, and the left side pumps oxygen-rich blood to the rest of the body.  There are valves in your heart that make sure the blood does not flow backwards.  The valves opening and closing makes the “heartbeat” sound.  Veins also have valves.  The adult heart pumps seventy times a minute at rest. The average heart pumps four thousand gallons of blood a day.

The circulatory system is essential for life.


The Digestive System

The digestive system breaks down food so your cells can use the nutrients it provides.  The digestive system starts even before you put the food in your mouth!  When you see or smell food you start to salivate.  As you begin to eat the food, many things are happening.  You are mechanically digesting when you grind the food with your teeth.  Also, you are making a special chemical in your salivary glands called ‘amylase’ that breaks down food chemically.  As you start to swallow, a flap called the epiglottis closes over the trachea so it won’t go down the wrong way.  Once you swallow, the nervous system takes over and makes the action involuntary.

After chewing and swallowing, the food enters the esophagus where peristalsis occurs.  Peristalsis is the squeezing motion that occurs in the esophagus.  This allows us to eat or drink when up-side down.  When the food finally reaches the stomach, more digestion occurs.  The stomach churns the food and gastric acid breaks it down with the help of enzymes.  After three hours it becomes a thick liquid.

Then the liquid flows to the small intestine, where more acids (such as pancreatic juice and bile) break down the food.  Pancreatic juice is made of enzymes and bile breaks down fat.  The liver makes bile and the gallbladder stores it.  The pancreas makes pancreatic juice.  After it is digested to its fullest, all the nutrients the body needs are absorbed into the bloodstream so the blood can carry it to all the different body parts.

The leftovers (waste) move on to the large intestine where your body absorbs all the water from the food and leaves the solid waste.  This waste travels to the rectum and is stored there until it is excreted as feces.  Without the digestive system your body would not have enough energy to go through the day.


The Respiratory System

Ever wonder how we breathe? How does that air flow in and out? Our respiratory system does some amazing things. The respiratory system is made up of the lungs and the passageways that lead to them.  The lungs, diaphragm, trachea, bronchi, bronchioles, and alveoli are the parts of this system.  The first step to breathing is inhaling air through your nose and mouth.  Next, the air passes through the larynx, which is also known as the vocal cords, located at the top of the trachea.  When the tension changes in the cords, there is a change in pitch when air passes through them.  Then air flows into the trachea.  The lining of your nose and trachea make a special liquid called mucus.  It warms the air so your lungs won’t freeze.  It also traps dirt and germs in the air.  Tiny hairs called cilia, brush the mucus away from your lungs and to your nose and mouth where it can be sneezed or coughed out.  The average human sneezes at about 100 miles per hour.

The trachea divides into two primary bronchus where each one leads to each lung.  Inside the lung they branch off into secondary and tertiary bronchi, and eventually divide into tubes called bronchioles.  Each bronchiole ends in a cluster of air sacs called alveoli.  They are surrounded by millions of capillaries.  The average adult has 600 million of these air sacs.  The gas exchange takes place in the alveoli.  In the capillaries there is oxygen poor blood that has carbon dioxide in it.  When you breathe in, the alveoli is filled with oxygen, and the oxygen seeps into the blood, and the carbon dioxide goes in the alveoli to be exhaled.

The diaphragm plays an important role in breathing.  When you breathe in, the diaphragm pulls down and the rib muscles pull up and out enlarging the chest cavity, and pulling air in through the nose and mouth.  When you breathe out, the diaphragm moves up and the ribs go down causing the chest cavity to get smaller.  The average adult lung is the size of a football.  Your right lung has three lobes and your left lung has two.

All of these breathing actions happen at the same time.  These are the steps to a living miracle, the respiratory system.


The Excretory System

Bathroom business is not the prettiest (or freshest smelling) picture, but it is undeniably important and operated by the excretory system.  The excretory system consists of four systems including the urinary system, digestive system, respiratory system and the sweat glands.  They help cleanse your body of toxins.

The most important part of the excretory system is the urinary system.  The urinary system is a group of organs, tubes, muscles and nerves that keep the volume of bodily fluids within normal limits.  It consists of the kidneys, ureters, bladder and urethra.  First, blood passes through the kidneys in order to remove wastes.  Then the kidney filters out urea, water and other wastes and makes liquid called ‘urine’. The waste, urea, is produced when food containing protein is digested.  Then the waste product, urea, is formed.  It is carried in the bloodstream to the kidneys.  The kidneys’ filters called ‘nephrons’ filter 440 gallons of blood a day. Then the urine flows to the bladder through the two tubes called ‘ureters’.  Urine is stored in the bladder until it is excreted through the urethra.

Other systems help the urinary system excrete toxins.  The digestive system gets rid of solid waste out of the rectum at the end of the digestive process.  Also, even though the lungs are part of the respiratory system, they play a part in the excretory system.  They excrete carbon dioxide and water.  Finally, the sweat glands help keep normal body temperature, and eliminate urea, water, salt and uric acid.

Did you know that urine is so clean you could (but don’t) drink it?  It is only 5% waste and 95% water. The urinary system is exactly like a car wash.  It makes your body clean.

One comment

  1. Rohan /

    Wow, I love your circulatory system activities!! Thanks for the link-up! See more for kids: