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In respiratory physiology, the ventilation/perfusion ratio (V/Q ratio) is a ratio used to assess the efficiency and adequacy of the ventilation-perfusion coupling and thus the matching of two variables: The V/Q ratio can therefore be defined as the ratio of the amount of air reaching the alveoli per minute to the amount of blood reaching the ...
The V/Q ratio in the apex is roughly 3.3 and 0.63 in the base, which indicates that perfusion is greater than ventilation towards the base, and the ventilation rate is greater than perfusion towards the apex. [3] Towards the base of the lungs, the fluid volume in the pleural cavity increases due to gravity, resulting in greater intrapleural ...
Local venous pressure falls to -5 at the apexes and rises to +15 mmHg at the bases, again for the erect lung. Pulmonary blood pressure is typically in the range 25–10 mmHg with a mean pressure of 15 mmHg. Regional arterial blood pressure is typically in the range 5 mmHg near the apex of the lung to 25 mmHg at the base.
The apex beat (lat. ictus cordis), also called the apical impulse, [ 1 ] is the pulse felt at the point of maximum impulse (PMI), which is the point on the precordium farthest outwards (laterally) and downwards (inferiorly) from the sternum at which the cardiac impulse can be felt. The cardiac impulse is the vibration resulting from the heart ...
The cardiac cycle at the point of beginning a ventricular systole, or contraction: 1) newly oxygenated blood (red arrow) in the left ventricle begins pulsing through the aortic valve to supply all body systems; 2) oxygen-depleted blood (blue arrow) in the right ventricle begins pulsing through the pulmonic (pulmonary) valve en route to the lungs for reoxygenation.
As pressure and stretch decrease, the rate of baroreceptor firing decreases, and the cardiac centers increase sympathetic stimulation and decrease parasympathetic stimulation. [1] There is a similar reflex, called the atrial reflex or Bainbridge reflex, associated with varying rates of blood flow to the atria. Increased venous return stretches ...
The properties of the membrane at a given point along its length determine its characteristic frequency (CF), the frequency at which it is most sensitive to sound vibrations. The basilar membrane is widest (0.42–0.65 mm) and least stiff at the apex of the cochlea, and narrowest (0.08–0.16 mm) and stiffest at the base (near the round and ...
On racing tracks, black stripes of rubber on the tarmac from previous cars often indicate the racing line. In motorsport, the racing line is the optimal path around a race course. [1] In most cases, the line makes use of the entire width of the track to lengthen the radius of a turn: entering at the outside edge, touching the "apex"—a point ...