CARDIOVASCULAR SYSTEM

Heart physiology

Blood pressure

What happen during a heart attack?

RESPIRATORY SYSTEM DISEASES VIDEOS

ASTHMA

How do cigarettes affect the body? - Krishna Sudhir

DIGESTIVE SYSTEM DISORDERS VIDEOS

CONSTIPATION

CAVITIES

HEARTBURN

BALANCED DIET

BALANCED DIET

Healthy eating self-assement

How healthy is your diet?

INTERESTING QUESTIONS ABOUT FOOD AND NUTRITION

How do carbohydrates impact your health? - Richard J. Wood

What is a calorie? - Emma Bryce
What’s the big deal with gluten? - William D. Chey
What would happen if you didn’t drink water? - Mia Nacamulli
How to spot a fad diet - Mia Nacamulli
What is fat? - George Zaidan

Why meat is the best worst thing in the world

Are food preservatives bad for you? - Eleanor Nelsen
The beneficial bacteria that make delicious food - Erez Garty

How the food you eat affects your gut - Shilpa Ravella

RESPIRATORY SYSTEM

How do the lungs work?

After having viewed this video, try to solve these questions

5:10

Oxygen’s surprisingly complex journey through your body - Enda Butler

HUMAN RESPIRATORY SYSTEM ANATOMY AND PHYSIOLOGY

Air typically enters the body through the nostrils of the nose. Small hairs just inside the nostrils may stop some of the unwanted dust and dirt particles found in the air. The air moves from the nostrils into the two nasal cavities of the nose. A wall of cartilage and bone separates the two cavities. The air is heated at this point by warm blood flowing through blood vessels in the nasal cavities. This acts like a radiator. Air taken in through the nose is warmed before going to the lungs. Air can also be brought into the body through the mouth, but here there are fewer opportunities for dust and dirt particles to be removed, and there will not be this warming process. Try this experiment to see the difference in air temperature as it enters the body. Breathe with your mouth closed and through your nose. Then purposely breathe with your mouth as if your nose was stuffed up. The air that you breathe in through the mouth will feel cooler at the back of your throat.

The nose produces a continuous supply of mucus. This mucus, which is replaced every 20 minutes, has two main jobs. One is to add some moisture to the air so that the internal tissues of the respiratory system don’t dry out. The other job is to catch unwanted particles and bacteria from the air. The unwanted particles are caught in the mucus and then billions of small hairlike structures called cilia move the mucus into the esophagus that leads to the stomach. The stomach releases digestive juices that contain hydrochloric acid. This acid destroys the foreign material. Sometimes the particles caught in the mucus of the nasal cavities irritate the nose and causes sneezing. This is an- other way to release unwanted particles from the body.

You can see it is best to breath through the nose because of the warming, filtering, and moistening of the air. From the nose, the air travels into the throat. At one point, the throat leads to two separate paths. One is the esophagus, which is the tube leading to the stomach. The other is the trachea, a tube leading to the lungs. At the top of the trachea is a small flap called the epiglottis. This flap covers the opening to the trachea so that food won’t go into the trachea when you swallow. When we breathe, the flap opens to allow the air to enter the trachea and the rest of the respirAtory system.

Larynx

At the top of the trachea is the larynx, which contains the vocal cords. Two small folds of tissue are stretched across the larynx with a small gap between them. When we talk, the muscles of the larynx tighten the tissue, making the opening smaller. As air from the lungs goes past the open- ing, the vocal cords vibrate, making sounds. The pitch of a sound is determined by the size of the larynx and the length of the vocal cords. Because men have larger larynxes and longer vocal cords, their voices are usually lower than women’s. The shorter vocal cords of a female vibrate faster so the sound has a higher pitch.

You can feel your trachea and find the location of your larynx. With a finger, rub gently on the front of your neck and you will feel a tubelike structure with bumps. This is your trachea or windpipe. What you feel as bumps are actually bands of cartilage that support the trachea. The larynx is made of a piece of cartilage that is larger than the other cartilage in the trachea. On a male, you can easily see this cartilage sticking out. It is referred to as the “Adam’s apple.” Some people think that only males have Adam’s apples, but actually everyone has an Adam’s apple. Only the larynx on a male is larger than a female’s, so the Adam’s apple shows up clearly on males but is not very noticeable on females.

Trachea and alveoli

When air enters the trachea, there is another round of mucus found in the lining of this passageway. If dust particles have made it this far, they may be caught in this mucus before moving into the sensitive and delicate lungs. Dust that is trapped by this mucus can be sent back up to the mouth or nose by the movement of small cilia, or a person may cough to remove the mucus and foreign matter.

The trachea branches into two paths before entering the lungs. These branches are called the left and right bronchi. Inside the lungs, the bronchi divide into smaller and smaller branches. At the end of the smallest branches are clusters of hundreds of round sacs called alveoli. They resemble grapes on a vine. The body has about 600 million alveoli. It is here that the exchange of gases takes place. Each alveolus has tiny blood vessels called capillaries running around it. When the oxygen-rich air enters the lungs and travels to the millions of alveoli, the oxygen passes through the cell walls of the alveoli into the capillaries of the circulation system. The blood picks up the oxygen and releases to the alveoli carbon dioxide, the waste product carried from the body’s living cells.

Blood which contains carbon dioxide from the cells of the body will appear blue, while blood rich with fresh oxygen will be red. This exchange must happen quickly, so that is why there are so many of these little exchange sacs. They allow for a greater area for exposure to capillaries. If the material that makes up all the alveoli in your two lungs were spread out flat, it would cover an area the size of a tennis court!

Breathing

A newborn baby takes about 40 breaths each minute. A one-year-old child takes about 24 breaths per minute. An adult takes about 14 breaths per minute. However, during exercise, the rate can increase to over 100 breaths per minute. Adults breathe in about seven to ten liters of air each minute.

It is our brains that control the breathing process. We don’t have to think about breathing, it is automatic. The control center for breathing is found in the brain stem. It uses in- formation from various parts of the body concerning the levels of carbon dioxide and oxygen in the blood. Based on the comparison of carbon dioxide and oxygen levels, the brain sends electrical signals to the diaphragm and chest muscles, which cause us to breathe in and out.

To bring air into our bodies, the diaphragm, which is a bell-shaped sheet of muscle, contracts. This causes it to flatten, creating a larger area in the chest cavity and, as a result, a space of low air pressure. Air rushes in through the nose and trachea to fill the lungs and expand them to fill up some of this low-pressure area. When the diaphragm relaxes, it moves back into its normal bell-shaped position, which causes the chest cavity to shrink and push air out of the lungs. The lungs actually are responding to the change in pressure around them.The diaphragm and muscles of the rib cage are what cause breathing to take place. 

The act of breathing is an automatic operation and requires no thought. If you hold your breath, after a short period of time, you automatically start gasping for breath. Your body needs a constant supply of oxygen. You are breathing while awake and while asleep. During sleeping, the breathing rate slows down because there is not as much of a demand for oxygen. Muscles are at rest and there is less carbon dioxide being produced than during a period of high activity. Breathing during sleep is slower and more relaxed.

Gas Exchange

The respiratory system works with the circulatory system to transport oxygen to the cells and to return carbon dioxide to the lungs for elimination from the body. The heart sends blood that has returned through veins from all over the body into the lungs. This blood is carrying carbon dioxide which it will release into the alveoli. Then oxygen from recently inhaled air will pass through the cell walls of the alveoli and capillaries into the blood. The blood will continue back to the heart, where it receives its push to travel to various parts of the body. As the blood moves into capillaries, it passes by individual living cells, where the gas exchange occurs. Oxygen goes into the cell and carbon dioxide goes into the blood. This exchange takes place in the alveoli and body cells because gases tend to move from areas of concentration into areas of less concentration. What this means is that because the blood entering the lung is carrying carbon dioxide and there are lower amounts of that gas in the alveoli, the gas moves through the capillary and alveoli cell walls and into the area of lower concentration. The same thing happens to the oxygen in the alveoli as it moves into the blood stream. This also accounts for the passage of gases from the capillaries into the cells and from the cells into the capillaries.

The respiratory system is very important to our survival. Being deprived of oxygen for just a few minutes can mean great damage to the body. After a few minutes of lack of oxygen, the brain begins to suffer. If a lack of oxygen persists, death can soon follow. We can survive for days without food or water, but if deprived of oxygen, we can only survive for a few minutes.

REVISE

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FOOD LABELLING AND PRESERVATION

Food labelling worksheet

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