Aim to be at your THR for at least 15 to 20 minutes workout time, and ideally 35 to 45 minutes. If you're a beginner, start at 65 percent to 70 percent of your maximum heart rate and gradually increase the intensity.
In respiratory system the lungs are two spongy, cone shaped organs in the thoracic cavity and are separated from each other by the heart and other structures found in the mediastinum.
Deep grooves called fissures divide each lung into lobes. Each lobe receives its own secondary bronchus. Each lung lobe is divided into smaller segments that are supplied by a tertiary bronchus.
<em><u>The segments, in turn are subdivided into small compartments called lobules, which contains, lymphatic vessel, arteriole, venules and also a branch from terminal bronchiole wrapped in elastic connective tissue.</u></em>