Causes of Chest Pain or Discomfort. We can divide the causes of chest pain into two major categories: those caused by cardiac issues, and those caused by other, non-cardiac issues. Causes of cardiac chest discomfort (pain) Canadian Cardiovascular Society Classification of Angina Class I â Angina occurs only with strenuous exercise. Class III â Angina occurs with mild activity such as climbing 1 fight of stairs or walking level for 1 to 2 blocks. Class IV â Angina occurs with any physical activity and may be present at rest. See also: Types of Angina. Other Cardiac Causes of Chest Pain or Discomfort Acute Pericarditis.
NEPHRIDIA:- In earthworm excretion occurs through nephridium. The excretory system in earth worm is closely associated with its closed circulatory system. Each segment of ea â¦ rthworm consists of a pair of nephridia or in some species cluster of nephridium.he excretory system in earth worm is closely associated with its closed circulatory system. Each segment of ea â¦ rthworm consists of a pair of nephridia or in some species cluster of nephridium.
The bodies of most oligochaetes (earthworms) are divided externally and internally into well-defined segments. Internally, these segments are divided by membranous partitions. Except for the most anterior and posterior segments, all segments are essentially alike. Earthworms burrow through the soil, feeding on decaying leaves and animal debris. As earthworms move through the soil, they both enrich and loosen the soil. It is for this reason that earthworms are valued by gardeners. An acre of good garden soil may contain as many as 50,000 individuals. External Anatomy and Locomotion of the living earthworm Observe the external features of the earthworm. Notice that the body is made up of a number of segments.