1. Artificial respiration can be given with no equipment. A method of artificial respiration which has now found favour is known as «mouth-to-mouth respiration». The principle of this method is as follows: air from the resuscitator's lungs is breathed into the patient's lungs. The patient's nostrils should be closed by the resuscitator's hand and the patient's head should be held back. The resuscitator must also guard against the use of excessive force: this might propel sea water or vomit back into the patient's lungs.
2. Food is one of the sources of the raw materials that cells must obtain from the external environment, but it is not always in a form that cells can use. Food is taken in at the mouth and broken down by physical and chemical means. Then it can pass through the walls of the alimentary canal into the blood. Substances that cannot be used by the cells are regarded as waste materials. The accumulation of these substances will upset the fine balance which must be maintained between chemical substances in the internal environment.
3. Heart attack is diagnosed most readily by means of an electrocardiograph. This machine records patterns of electrical activity of the heart and can detect changes in activity that are associated specifically with heart attack. In many hospitals heartattack victims are routinely admitted to coronary care units. In these units the electrical rhythm of the heart is monitored continuously, and arrhythmias (abnormal rhythms) can be treated promptly. In case of low heartbeat rate, a temporary pacemaker may help. The pacemaker is inserted into a vein and moved to the right ventricle. There its electrical impulses stimulate the heart and it beats more quickly.