Physiology and Hygiene for Secondary Schools

wal depends the supply of energy. Moreover, there is found to be an actual breaking down of the living material, or protoplasm, in the body. While this does not destroy the cells, a

n the general work of the body. Since these are constantly being lost in one way or another, the

ying on its work. This definition properly includes oxygen, but the term is usually limited to substa

ygen, supply the

aterials for rebu

aid directly or indirectly i

d to be similar in composition and to contain only some five or six kinds of materials that are essentially different. While certain foods may contain only a single one of these, most of the foods are mixtures of two or more. These few common mater

rie

ot

umin

ohyd

a

ral

a

miliar with the different nutrients and t

an abundance of another variety, known as myosin. Cheese consists largely of a kind of proteid, called casein, which is also present in milk, but in a more diluted form. If a mouthful of wheat is chewed for some time, most of it is dissolved and swall

ulphur. Certain ones (the nucleo-proteids from grains) also contain phosphorus. All of

f such a nature chemically that they are readily built into the protoplasm. They are absolutely essential to life, no other nutrients being able to take their place. An a

able to rebuild the tissues. Gelatin, a constituent of soup and obtained from bones and connective tissue by boiling, is the best known of t

y. They are composed of carbon, hydrogen, and oxygen, and are obtained mainly from plants. There are several varieties of carboh

). From these sources it is obtained as food. Glycogen, a substance closely resembling starch, is found in the body of the oyster. It is also formed in the liver and muscles of the higher animals, being prepared from the sugar of the b

potato as they appear under the

ugars (monosaccharides). To the first class belong cane sugar, found in sugar cane and beets, milk sugar, found in sweet milk, and maltose, a kind of sugar which is made from st

all the other sugars, and starch also, are converted before they are finally used in the body. The clo

lants. Butter, the fat of meats, olive oil, and the oil of nuts are the fats of greatest importance as foods. Fats, like the carbohydrates, are composed of carbon, hydrogen, and oxygen. They

e other forms of bodily force. This is perhaps their only purpose.50 Proteids also serve this purpose, but they are not so well adapted to supplying energy as are the carbohydrates and the fats

bones and teeth; and the salts containing iron renew the hemoglobin of the blood. Others perform important functions in the vital processes. The mineral compound of greatest importance perhaps is sodium chloride, or common salt.52 This is a natural constituent of most of our foods, and is also added to food in its preparation for the table. When it is withheld

by all the organs of excretion. Though water does not liberate energy in the body nor build up the tissues in the sense that other foods do, it is as necessary to the maintenance of life as oxygen or proteids. It occurs in all the tissues, and forms about 70 per cent of the entire weight of the body. Its presence is necessary for the interchan

right amounts to supply the body with energy. Much experimenting has been done with a view to determining these proportions, but the results so far are not entirely satisfactory. According to some of the older estimates, a person of average size requires for his daily use five o

eds to be emphasized that proteids, although absolutely necessary, should form but a small part (not over one fifth) of the daily bill of fare. In recognition of this fact is involved a principle of health

nd this excess is oxidized for supplying energy, a strain is thrown upon the organs of excretion, because of the increase in the wastes. Not only is there danger of overworking certain of these organs (the liver and kidneys), but the wastes may linger too long in the body, causing disorder and laying the foundation for disease. On the other hand, if an insuffic

sent in the different materials used as food. This information is supplied by the chemist, who has made extensive analyses for this purpose. Results of such analyses are

ions of different nutrie

the composition of foods can be used to great advantage. Consulting the table on page 126, it is seen that large per cents of proteids are supplied by lean meat, eggs, cheese, beans, peas, peanuts, and oatmeal, while fat is in

The Composition

oteid Fat Carbohydrates Minera

r cent Per cent Per cent Per ce

63.9 36.1 19.5

.9 15.4 35.

40 18.5 20.

1.8 20.5 10.

68.8 31.2 20.2

1.8 38.2 18.3

50.7 15 35

50.3 49.7 16

ed 41.5 58.5 16.7

.1 87.9 .9 82.

1.5 58.8 13.8 4

37.6 18.8 4

27.8 24.4 1

6.2 14.9 10

3 3.6 4 4

5 89 .6 85

m 30.2 69.8 28.3

3 58.7 38.4 6

82.6 17.4 15.8

36.4 21.6 13

1 12.9 6 1.

able

2.5 87.5 11 1

at) 13.1 86.9 11.

1 86.9 6.7 .8

14.6 85.4 6.9

92.4 15.1 7.

85 9.2 3.8 7

7.6 7.4 .4

.7 26.7 1.7

7.4 23.1 2 5

9 21.1 2.1 .

.3 4.7 .8 .

16.8 .2 .4

ted 2 98 ... .

at) 32.3 67.7 8.

90.8 25.8 24

95.2 21 17.3

) 2.5 97.5 16.6

d should, be simple in itself and, at the same time, differ sufficiently from the meal preceding and the one following to give the necessary variety in the course of the day. The bill of fa

ould be promptly rejected. Not only do fresh meats, fruits, and vegetables need careful inspection, but canned and preserved goods as well. If canned foods are imperfectly sealed or if not thoroughly cooked in the canni

e largest field for adulterations, although it is possible to adulterate nearly all of the leading articles of food. A long step in the prevention of food and drug adulteration was taken in this country by the passage of the P

early all oxidized, yielding energy as does fat or sugar. If no harmful effects attended the use of alcohol, it might on this account be classed as a food. But alcohol is known to be harmful to the body. When used in large quantities, it injures nearly all of the tissues, and when taken habitually, even in small doses, it leads to the formation of the alcohol habit which is now recognized and treated

ncreasing or diminishing the action of the different organs. In disease where this balance is already disturbed, they may be administered for their counteractive effects, but always under the advice and direction of a physician. Knowing the nat

OF DI

e lymph, and for the purposes which they finally serve. The first of these changes is preparatory to the entrance of the nutrients and is known as digestion. The organs which bring about this change, called dige

in the lungs, although surrounded by the body, are still outside of what is called the body proper. To gain entrance into the body proper, a substance must pass through the

o the walls of blood or lymph vessels. Only liquid materials can make this passage. It is necessary, therefore, to reduce to the

he action of certain liquids, called solvents. Through the action of the solvent the minute particles of the solid separate from each other and disappear from view. (Shown in dropping salt in water.) At the same time they mix

, one of dissolving. The liquid employed as the digestive solvent is water. The different nutrien

sufficient amount of this liquid. The majority of the nutrients, however, are insoluble in water and are unaffected by it when acting alone. Fats, starch, and most of the proteids do not dissolve in water. Be

62). (See Practical Work.) It seems at first thought that the acid dissolves the limestone, but this is not the case. The acid produces a chemical change in the limestone (calcium carbonate) and converts it i

ater containing acid, suggesting the dou

e all of them have water for their most abundant constituent, there are dissolved in the water small amounts of active chemical agents. It is the work of these agents to convert the insoluble nutrients into substances that are soluble in wa

reference to the changes which they undergo during diges

e action. Water and solutions of simple foods in water belong to th

des[pg 133] common salt and sugar. These require

se have first to be changed into soluble

mpounds have all the qualities of foods and are suitable for introduction into the body. Substances known as drugs, which may be used as medicines in disease, should be avoided in health. Before foods can be passed into the body proper,

the cells make necessary the introdu

purposes are ser

rient? Name the

rials? From what sour

inds of carbohydrates. Why are proteids called nitrogeno

be carried on without

rate are found in wheat flour, oatmeal, rice, b

bread, and butter; to one consisting of potatoes, rice, bread, a

general plan

is not a simple process like t

TICA

enable the pupil to identify most of the elements present in

in lead pencils. Show that the charred wood and the coal will burn. Recal

. Hold a cold piece of glass over the flame and observe the deposit of moisture. Hydrogen in burning forms water. Extinguish the flame by covering the top of the tube with a piece of cardboard. Now let the escaping gas collect in a tumbler inverted over the tube. Af

he cork on water and have ready a glass fruit jar holding not more than a quart. Ignite the phosphorus with a hot wire and invert the jar over it, pushing the mouth below the surface of the water. The phosphorus uniting with the oxygen fills the jar with white fumes of phosphoric oxide. These soon dissolve in the water, leaving a clear gas above. This is nitrogen. Pl

eriments (page 114) showin

a piece as large as a pea in a teaspoonful of carbon disulphide in a test tube, pour this on a piece of porous paper, and lay the paper on an iron support. When the carbon disulphide evaporates the phosphorus takes

Impure sulphur may have an odor and a taste.) Burn a little sulphur in an iron spoo

chloride, and ferric oxide or iron rust. Sodium. Drop a piece of the metal on water and observe results. Sodium decomposes water. It has to be kept under some liquid, such as kerosene, which contains no oxygen. (It should not be

g what elements make up the different nutrients is by heatin

that water condenses on the sides of the tube and that a black, charred mass remains behind. The black mass consists mainly of carbon. The water is compo

to the room. First hold in the escaping gases a wet strip of red litmus paper. This will be turned blue, showing ammonia (NH3) to be escaping. Next hold in the mouth of the tube a strip of a paper wet with a solution of lead nitrate. This is turned black or brown on account of hydrogen sulphide(H2S) which is bein

d by holding it in a clear, hot flame, and observe the ash that

resent it turns yellow and partly dissolves in the acid, forming a yellow solution. Let cool and then add ammonia. The yellow solid an

dine. (Prepare by dissolving a crystal of iodine in 25 cubic centimeters (1/20 pint) of a solution of potassium iodide in water and add water to this until it is a light amber color.) The starch solution is turned blue, (b) Cut with a razo

recipitate which first forms is redissolved and a clear blue liquid obtained. Heat the upper portion of the liquid slowly to near the boiling point. A little below the boiling point the blue color disappears and a

r olive oil. Also show the presence of fat in peanuts by crushing them in a mortar and rubbing the powder on thin paper. If the substance to be tested contains but l

n (proteid) hardens, or coagulates, observe that the quantity of clear liquid increases. This is due to the withdrawal of water from the albumin by the alcoh

salt has not been changed chemically. Now add a little powdered limestone to the water and stir as before. Observe that the limestone does not dissolve. Then add some hydro

g