Frederick Gymer Parsons, John Gray McKendrick, and Leonard Erskine Hill

“ The systole of the heart may tell back on the liver and cause it to swell, for there are no valves between it and the inferior vena cava. Obstruction in the right heart or pulmonary circulation at once tells back on the liver. The increased respiration which results from muscular exercise greatly furthers the hepatic circulation, while it increases the consumption of food material. Thus exercise relieves the over-fed man. The liver is so vascular and extensile that it may hold one-quarter of the blood in the body. ”

“ The rise of the intrathoracic and intra-abdominal pressures, and the sustained contraction of the skeletal muscles, alike hinder the return of venous blood from the capillaries to the heart, and, owing to this, the face and limbs become congested until the veins stand out as knotted cords. It is obvious that at this stage the total capacity of the vascular system is greatly diminished, and the pressure in all parts of the system is raised. It is during such a muscular effort that a degenerated vessel in the brain is prone to rupture and occasion apoplexy. ”

“ Only the blood of man must be used. The direct giving of blood by connecting the radial artery of a relation to the median vein of a patient has been used as a means of effecting restoration. Blood may be withdrawn from the system slowly to the extent of 4 %, rapidly to the extent of 2 % of the body weight, without lowering the arterial pressure, owing to the compensatory contraction of the arterioles and the rapid absorption of fluid from the tissues into the blood. The withdrawal of the tissue-lymph excites extreme thirst and the great need for water which occurs after severe hemorrhage. ”

“ The pulse is more frequent when one stands than when one sits, or lies down, and this is especially so in states of debility. The taking of food, especially hot food, increases it. By placing tambours on, say, the carotid and radial arteries and recording the two pulses synchronously, it has been found that the pulse occurs later, the further the seat of observation is from the heart. The velocity with which the pulse wave travels down the arteries has been determined thus. ”

“ The hypertrophy may be due to increased work thrown upon the muscle, as in athletics (idiopathic hypertrophy) , or may be compensatory, when the muscle is trying to overcome a circulatory defect, as in valvular stenosis or regurgitation. Hypertrophy, when within physiological limits, is to be considered as a means of adaptation. When occurring in pathological circumstances, it must be regarded as a method, of compensation. Every structure and every function in a healthy body has greater or lesser reserve of energy. ”

“ The cardiac impulse can be recorded by tambour methods of registration, the heart sounds by means of the microphone and capillary electrometer, while the volume and movements of the heart can be studied with the help of the Röntgen rays.
The impulse is caused by the sudden hardening of the muscular mass of the ventricles against the wall of the thorax. It is synchronous with the beginning of systole. The position at which the impulse is felt varies with changing posture of the body, as different parts of the thorax come in turn in contact with the ventricle. ”

“ Malformations.—We are ignorant of the causes which lead to imperfect development of the heart. Many of its malformations are of purely pathological interest, but others, such as deficiencies of the intraventricular septum, non-closure of the foramen ovale, patency of the ductus arteriosus, or malformations of the valves, produce a series of secondary effects resultant on the deficient aeration of the blood and sluggishness of the circulation and of venous congestion. ”

“ If 1000 c.c. of oxygen are absorbed from the air breathed in a minute, and the arterial blood contains 10% more oxygen than the venous, it is clear that 100 × 100 c.c. of blood must have passed through the lungs in that time, and if the heart beat 100 times, the output for each beat would be 100 c.c. From the determinations made on animals the output is calculated for man to be 60–100 c.c. The velocity of the output can be calculated if the volume of the output is known, the duration of the period of output, and the diameter of the aorta. The pressure is measured with a manometer. ”

“ In the cold-blooded animal, such as the turtle, the heart muscle does not become tense rapidly enough to produce a sound (Allen) . This sound is not produced by fluid friction as the blood rushes through the arterial orifices, for the velocity of outflow is too small to produce in this way any noise. Nor is it produced by sudden opening of the semi lunar valves, for these open quietly and without jar at the moment when the intra-ventricular pressure rises above that in the aorta. ”

“ The venous obstruction quickly leads to diminished diastolic filling of the heart, and to such a decreased velocity of blood flow that the effort is terminated by the lack of oxygen in the brain. During any violent exercise, such as running, the skeletal muscles alternately contract and expand, and the full flood of the circulation flows through the locomotor organs. The stroke of the heart is then both more energetic and more frequent, and the blood circulates with increased velocity. ”

“ The blood-making organ, the liver, separates from the blood subtle vapours, the natural spirits, which, carried to the heart, mix with the air introduced by respiration, and thus form the vital spirits; these, in turn carried to the brain, are elaborated into animal spirits, which are distributed to all parts of the body by the nerves. ”

“ The excised heart, properly fed, continues to beat. The heart of a dog continued to work effectively and the animal to keep in health for months after division of all the nerves passing to the heart. The heart, it is true, is controlled and influenced constantly by the nervous system-attuned to the general needs of the body-but this control is not essential to life. ”

“ The muscle-cells of the ventricles are thicker, less -sarcoplasmic and more clearly striated than the auricular muscle, which is more embryonic in structure. The contraction lasts longer in the ventricular than in the auricular muscle, while the automatic rhythm not only persists longer in the auricles, but is of greater frequency, as is clearly seen when the cavities of the heart are divided from each other. The venous orifices of the heart are least sensitive to injury, beat longest after death, and are the first to recover after arrest. ”

“ In tame hutch rabbits, with large patulous abdomens, death may result in from 15 to 30 minutes if the animals are suspended and immobilized in the erect posture, for the circulation through the brain ceases and the heart soon becomes emptied of blood. If, however, the capacious veins of the abdomen be confined by an abdominal bandage, no such result occurs. Man is naturally provided with an efficient abdominal belt, although this in many is rendered toneless by neglect of exercise and gross or indolent living. ”

“ The erythroblasts continue to multiply by karyokinesis in early foetal life, especially in the liver, spleen, bone marrow and lymphatic glands, though later on their formation only occurs in the red bone marrow. In most of the erythroblasts the nucleus soon becomes contracted, and the cell is then known as a normoblast, while ultimately the general view is that the nucleus disappears by extrusion from the cell and the non-nucleated red blood plates or erythrocytes remain. ”

“ The pericardium supports the right heart when the weight of a long column of venous blood suddenly bears upon it, as, for example, when a man stands on his head. The abdominal viscera are slung upwards to the spine, while below they are supported by the pelvic basin and the wall of the abdomen, the muscles of which are arranged so as to act as a natural waist-band. ”

“ A sufficiency of blood to distend it collects within the venous cistern. The arterial system, owin to its elasticity and contractility, empties. If the heart now begin to beat, blood is taken from the venous system and is driven into the arterial system., The arteries receive more blood than can escape through the capillary vessels, and the arterial side of the system becomes distended, until equilibrium is reached, and as much blood escapes into the venous side per unit of time as is delivered by the heart. ”

“ Pressor effects, i.e. those causing increased constriction and rise of arterial pressure, may be produced by stimulating the central end of almost any afferent nerve, and especially that of a cutaneous nerve. Depressor effects are always obtained by stimulating the depressor nerve, and may be obtained by stimulating the afferent nerves under special conditions. That these reflex vaso-motor effects frequently occur is shown by the blush of shame, the blanching of the face by fear, the blanching of the skin by exposure to cold and the flushing which is produced by heat. ”

“ In contradistinction to cross-striated muscle, the structural unit of the heart is not also a functional unit, for the heart-cells are, from the earliest stage of development, joined together by branches into networks and bands so as' to form one functional whole, and hence excitation of any one part leads to the contraction of the whole. ”