Secretion of human chorionic gonadotropin [HCG] only occur during pregnancy in the placenta. The concentration of this hormone increase rapidly during the first three months of pregnancy; the amount in the blood stream doubles every two to three days as the development of the placenta and embryo progress. The hormone reaches its maximum concentration peak around the sixth week of pregnancy and after this, its concentration decline.
The organ is the LUNGS.
The lungs excrete carbon dioxide and water vapour through metabolism.
The lungs are used for breathing in humans, through the lungs we take in oxygen which is carried by the blood to all the part of the body and we exhale carbon dioxide which is a waste product generated as a result of the reactions that occur in the body.
Endoplasmic Reticulum. -- Transport System.
Golgi Apparatus -- Delivery System.
Lysosomes - Intracellular Digestion Centers.
Ribosomes - Sites of Protein Synthesis.
ENERGY RELATED ORGANELLES.
Cytoskeleton - Support System.
Related to Movement.