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CHAPTER TEN

THE RESPIRATORY, EXCRETORY AND DIGESTIVE SYSTEMS

THE RESPIRATORY SYSTEM

Of all the needs of the human body, oxygen is the most important. Humans beings may live for days without food or water; adequate sleep may be postponed night after night without apparent effect. But to go without air in which oxygen is contained is utterly impossible. The normal functioning of all the tissue cells of the body is dependent upon oxygen, hence the absolute need of a continual supply. Circulating blood is brought in contact with air in the lungs where it is supplied with oxygen and gives up carbon dioxide. Circulating through the body the blood comes in contact with the cells in the tissues where it gives up oxygen and takes up carbon dioxide.

This exchange of gases is known as Respiration. Respiration depends upon the proper functioning of certain organs of the body which are grouped together and called the Respiratory System.

ORGANS OF THE RESPIRATORY SYSTEM

1. Nose
2. Pharynx
e. Larynx
4. Trachea
5. Bronchial Tubes
6. Lungs

The lungs are the chief organs of the respiratory system, for it is in the lungs that oxygen is extracted from the air and supplied to the blood, while carbon dioxide is taken from the blood and discharged from the body.

The nose, pharynx, larynx, trachea and bronchial tubes are the organs through which air is taken into the lungs by the process known as INSPIRATION and expelled from the lungs by EXPIRATION. The combined act of inspiration and expiration is known as BREATHING.

It is estimated that the normal rate of respiration for an adult is sixteen to eighteen per minute. The rate is higher in children and lower in old age. Excitement, emotion, muscular activity, etc., have a tendency to increase the rate of respiration just as

TEXT BOOK OF BEAUTY CULTURE

they do the heart beat, for the one is affected by the action of the other.
About one pint of air flows in and out of the lungs with each normal respiration.

THE DIAPHRAGM, or dome-shaped fibrous-muscular partition between the chest and the stomach, is known as the principal muscle of inspiration. Air is taken into the lungs by the contraction of the muscles of the diaphragm and as they recoil, or return to their natural position air is expelled from the body. The nerve center of respiration is located in the Medulla Oblongota. Respiration then, is involuntary muscular activity, except when directed by the sensory nerves through reflex stimulation.

Correct Breathing of clean air of the proper humidity, (water content) is highly important to one who would be healthy and comfortable. Science has found that fresh air is one of the best factors to promote proper functioning of the heat-regulating mechanism of the body and thus insure body comfort, beauty and health. Under normal conditions every one should breathe through the nose, with the mouth closed, because the nose warms the air in the coldest weather before it reaches the lungs and acts as a filter against the passage of dust and other foreign matter which might be inhaled. Deep, or abdominal breathing is the most beneficial respiration because it brings into the lungs about 5% of fresh oxygen and expels about the same quantity of carbon dioxide. Light, chest, or Costal Breathing restricts the diaphragm in its functional activity and hampers respiration, hence the wearing of tight fitting clothing is to be avoided.

PHARYNX- A muscular membraneous pouch located back of the nose and mouth with seven different openings two of which lead to the nose, two to the Eustachian tubes which are the tubes leading to the ears; the Esophagus which leads to the stomach; and the larynx leading to the lungs and the mouth.

LARYNX- Organ of the voice. Located between the trachea and the base of the tongue. It is composed of a series of cartilage the most important of which are the Thyroid, Cricoid, Epiglottis and the Two Arytenoids. Stretched across the larynx are fibrous, elastic ligaments covered with mucous membrane known as the Vocal Cords, so termed because they function in the production of the human voice. The opening between the vocal cords is called the Glottis.