T Physiology of Newborn Infant. Respiration. Two factors to explain its establishment : 1. External irritation, resulting from change of environment (from liquid, with temperature of 990, to air, with temperature of 70°), gives rise to reflex action of all muscles. 2. Maternal supply of oxygen being cut off, there is an accumulation of CO2, and the primary action of this is stimulant to respiratory apparatus. This cause may be operative in utero and determine intra-uterine respiration, with the inspiration of liquor amnii, meconium, mucus, and blood-clots, and a consequent pneumonia. If the membranes are ruptured and there is free access of air to the uterine cavity, there may be a comparatively normal respiration for a while in utero, and the child may even be heard to cry aloud within the womb. Rate of respiration is 44, sinking, after a few months, to 35. 7.3 lbs. Weight. There is a gradual increase, about one-and-a-half pounds before and one pound after the fourth month, for each Accomplished by digestive juices, except the diastatic ferment of the pancreas and salivary secretion. Partially dependent upon bacteria in stomach and intestines. Capacity of Stomach.-Knowledge of this important to avoid over-feeding. The greater the weight the greater the gastric capacity. One one-hundredth of body weight +1 gramme each day (Ssnitkin). One ounce at birth and an increase of one ounce per month up to the sixth month, after which it is somewhat less (Emmet Holt). The time required to digest this amount of food is one to two hours. Position of Stomach.-Its axis is almost longitudinal, which explains frequent regurgitation and vomiting. It is high on left side under the false ribs. This explains presence of air in the stomach. Excretions. (a) Urine.-Always albuminous for first few weeks. Quantity has never been estimated. Always acid. Specific gravity 1003-5. A trace of sugar is often found in breast-fed babies. Voided 6-20 times in 24 hours. Does not always stain diapers, and mistake may thus be made of supposing none to have been voided. (b) Bowels.-Meconium for the first 48 hours. Later, it becomes light yellow, is not formed, is sour and acid. The normal frequency of evacuation is four times in 24 hours. Temperature. Peculiarities are irregularity and height, with the variations above 980. Slight causes will produce great changes. Always hypermetropic. Eyesight. Pulse. 125-160, as shown by heart sounds. Blood. Total bulk to body weight 8 per cent.; six to seven millions red blood-corpuscles to the c. m., which are more spherical and do not tend to form rouleaux. Shadow corpuscles abundant. White blood-corpuscles more numerous, viscid, and deliquescent |