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.
Earthworms breathe through their moist skin. Gas exchange takes  place directly there.   The Earthworm's body has to stay moist & slimy because  it allows oxygen to be dâ¦iffused from air through the skin. This  allows the worm breath because they do not have lungs.   They do not breathe as we do- they take in oxygen directly through  their skin, and give off carbon dioxide the same way.   They use their skin [integument] to support the process of gaseous  exchange known as transpiration.   Through their pores.