What is a Promise Ring. A promise ring, sometimes known as a pre-engagement ring, is a simple piece of jewelry that is given as a symbol of a committed, monogamous relationship. In some cases, the promise ring symbolizes purity and a decision to remain celibate until marriage.
Noun. 1. external respiration-the bodily process of inhalation and exhalation; the process of taking in oxygen from inhaled air and releasing carbon dioxide by exhalation. breathing, respiration, ventilation. artificial respiration-an emergency procedure whereby breathing is maintained artificially.
External respiration is the process of exchanging oxygen and carbon dioxide between the air inside the alveoli and the blood in the capillaries of the lungs. Air inside the alveoli contains a higher partial pressure of oxygen compared to the blood in the capillaries.Conversely, blood in the lungs' capillaries contains a higher partial pressure of carbon dioxide compared to the air in the alveoli.ir inside the alveoli contains a higher partial pressure of oxygen compared to the blood in the capillaries. Conversely, blood in the lungs' capillaries contains a higher partial pressure of carbon dioxide compared to the air in the alveoli.