During gas exchange, oxygen and carbon dioxide move between blood, air, and tissues due to partial pressure gradients

Defecation is the process of eliminating solid wastes and undigested foods from the digestive tract

Unlike the production of oocytes, the production of spermatozoa begins at puberty and continues throughout a males life

Unlike spermatogonia, oogonia divide into primary oocytes prior to birth

One of the key functions of the seminal vesicles is to clear urine residues from the penile urethra so it does not harm sensitive sperm during ejaculation

Urine is the filtrate produced and excreted by the urinary system

Carbon monoxide (CO) aids in producing an erection by causing smooth muscles around the penile arteries to relax, thus allowing increased blood flow to the penis

The two most important molecules for good bone health are calcium and vitamin D

Cellular respiration is a catabolic reaction that produces ATP

In vitro, or IVF, is an assisted reproductive technology where eggs are fertilized outside the female body