construct a model of gas exchange that shows interactions among: air sacs (alveoli) of the lungs, capillaries, artery, vein, red blood cell, and body cell. Include the gases oxygen (O2) and carbon dioxide (CO2), as well as arterial blood and venous blood, in your model. All these structures must be labeled or annotated in your model.

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

i hope this : )

ok yes, but what is the question? as soon as you ask the actual question i will answer it. : )