What the Amateur Nurse Should Know - the Blood System, and How the Organs, Tissues, and Cells of the Body are Fed - the Action of the Heart - Blood Corpuscles
It is not only desirable but essential that every woman should know something of the theory and practice of sick nursing. To this end it is not necessary to study in the hospital ward. Very few girls have the time and opportunity for acquiring such valuable experience. But even a " little knowledge " in any subject is better than none at all. The " little knowledge," if it has been acquired in the right way, creates a desire for more.
The woman who begins to take an interest in the art of sick nursing is rarely content with anything short of a useful, living, practical grasp of the subject. At the same time, it is the duty of every woman to learn how to care for the sick. At any time she may be called upon to take charge of a case of illness, and her services are valuable in proportion to what she really knows of the work.
So that in this series of nursing articles we shall deal with all that a nurse ought to know in detail. We shall speak of the care of different ailments and the management of the sick-room. Infectious diseases will be considered in due course, and the disinfection of the patient and the bedroom. The taking of the temperature and pulse, the administration of local remedies and medicines, and the study of signs and symptoms of disease will be taken in turn.
But before a student of nursing can understand the practical care of illness, she must know something of the physiology or functions of the body in health. She can only get an intelligent grasp of invalid feeding and invalid cooking if she has learned the elementary facts concerning the function of digestion.
She must know something of the heart and circulation, of the process of respiration - how fresh air is drawn into the lungs and there gives up its oxygen to the blood. She must have some idea of how the temperature of the body is maintained, and how the brain and nervous system regulate all the vital processes of the body like a vast telegraphic system controlled by one central authority. In a word, she must know something of elementary physiology.
Chief arteries (dark) and veins (light) from the heart throughout the body
The amateur nurse must follow the course of the circulation so that she may have a more intelligent understanding of what the pulse is, what the functions of the blood are, and why pure, rich blood is necessary to health. This diagram shows the course of the blood from the heart to every pan of the body.
Physiology is the science which deals with the functions of the body. Each organ has its definite duty,its share in the life of the individual. When the physiological function of any organ is interfered with, the bodily health of the individual suffers.
Therefore, to have an intelligent and comprehensive grasp of sick nursing, certain physiological facts have to be studied, and we shall deal with these first before taking up the actual practical work of the nurse with reference to the patient.
The blood is that material which nourishes or feeds every organ, every tissue, every cell in the body. All through the tissues - the muscles, the skin, the lungs, liver, stomach, intestines, and other organs, even the bones, there are tiny, invisible or microscopic blood-vessels called the capillaries.
The Latin word capillus means a hair, and these hair-like vessels form a close network of closed tubes filled with blood in every part of the body. The walls are so thin that the gases and some of the fluids of the blood can pass through them into the tissues which they nourish. The blood receives its nouri]shing material from the food we eat, as we shall see later when we study digestion.
How does the blood get to the capillaries ? " The blood system." as it is called, consists of the heart, the arteries, the capillaries, and the veins. The heart pumps the blood with every beat into a large artery called the aorta. The aorta gives off branches to all parts of the body, whichdivideand sub divide like the branches of a
Medical tree until the arteries are so small that they are hair-like in size, when they are called capillaries.
The pure blood passes from the heart through the arteries to the capillaries. There the blood parts with its oxygen and nourishing material to the tissues, and takes up carbonic acid, when it loses its red colour and becomes purple, or ' venous." The capillary arteries open into the little capillary veins, with which they form a communicating network, and these veins gradually get larger and larger as they join other veins from different parts of the body, and pass up the body back to the heart. When this venous blood reaches the heart, it must be purified and made fresh, red, arterial blood again before the heart can send it on through the arteries to nourish the body.
To this end it must be purified by passing through the lungs to get a fresh supply of oxygen, and give up its poisonous carbonic acid.
Imagine the heart as a hollow organ divided into two by a median partition. The right side of the heart contains impure blood coming up from all parts of the body through the veins. The veins open into a chamber of the heart called the right auricle.
The blood passes from the right auricle through an opening into a second chamber, the right ventricle, which pumps it on through a large blood-vessel to the lungs. There it receives oxygen and gives up carbonic acid, when it at once loses its purple colour, becomes red, or arterial, blood, and passes back to the left side of the heart.
The " left heart " also consists of two chambers - an auricle and a ventricle. The pure blood reaches the left auricle and passes on to the left ventricle. The left ventricle pumps it into arteries, on to the capillaries, whence the blood flows back by the veins to the right side of the heart. So that the complete circulation of blood is from the left side of the heart, through the arteries, capillaries, veins, to the right side of the heart, from the right side of heart to the lungs, and back once more to the left side of the heart.
The blood always flows in one direction,because the arteries have the power of contracting like the heart, and thus the blood is sent forward with every beat of the heart and every pulsation of the arteries. This pulse wave passes from the heart to the smaller arteries, and can be felt when the arteries come near the surface - for example, at the wrist, or in front of the ankle, or at the temples. The veins do not pulsate, but the blood is kept going in one direction in the veins by valves, which prevent the backward flow of the blood.
The heart beats from sixty to eighty times a minute. First the two auricles contract and then the two ventricles, and the blood flows from the right ventricle to the lungs, and from the left ventricle to the aorta, and on to the arteries.
Between each auricle and each ventricle are valves which prevent any risk of the blood flowing back to the auricles, because, when the ventricles contract, the valves close, and the blood has to flow forwards to the arteries.
Diagram showing the circulation of the blood
The diagram shows the heart as a four'chambered organ, containing two auricles and two ventricles. The pure blood is pumped by the left ventricle through the arteries to the capillaries, where it loses its oxygen and becomes venous. The venous blood returns by the veins to the right auricle, then on to the right ventricle. The right ventricle pumps the venous blood through the lungs, where it is purified (gets a new supply of oxygen). From the lungs it returns to the left auricle, and thence to the left ventricle, which pumps it again throughout the body.
These valves do not stretch across the as they should do when a vein becomes dil as in varicose veins. The result is sometimes fatal haemorrhage if the vein gets punctured or " wears through." The walls of veins are not contractible like arteries, and haemorrhage cannot stop spontaneously.
In a varicose vein haemorrhage is often very alarming for this reason. The vein bleeds at both ends. Blood is being pumped into the vein from the arteries, and that in itself will cause severe haemorrhage. At the same time blood is welling back from the larger veins, because the diseased valves cannot hold the column of blood up. The patient may die in a few minutes from loss of blood unless simple " first aid " measures are taken to stop the haemorrhage.
Blood itself consists of a fluid or plasma, in which large numbers of cells, or corpuscles, are held in sus-pension. There are two kinds of corpuscles - red and white The red give the colour to the blood, because they contain a colouring matter, or pigment, called haemoglobin. They carry the oxygen. The white corpuscles are called phagocytes, or scavengers, because they devour bacteria or germs, eat up dead tissue cells and other waste products.
If it were not for these active phagocytes we should not have a chance in our daily warfare against disease. They form the standing army of the body, and die in protecting us. War is going on all the time between microbes and phagocytes. Here is an example of what takes place when we " catch" a disease - for example, influenza. The microbes first settle in our respiratory tract; the vitality of the tissue cells is not strong enough to resist the infection, to kill the attacking microbes, so they get a hold. Now the phagocytes attack them, the circulation slows in the blood-vessels of that part - that is, there is congestion - then the white blood corpuscles, or phagocytes, become very active. They push their way through the walls of the blood-\ all round, they fall upon the microbes. A certain number of them die in the attack, and these form " pus," or " matter," which is coughed up as expectoration in the case of a lung affection, such as pneumonia or bronchitis.
All the time, although the phagocytes are dying, they are killing or destroying a certain number of microbes, and, unless these are very powerful, the phagocytes are at last victorious, the inflammation subsides and the patient recovers.
The white blood corpuscles behave in the same way when the body is injured.
In the next article we shall consider the physiology of respiration.