On a person's hand, there are 300,000-500,000 genetically distinct bacteria at one time. Wendy regularly puts hand santitizer on because she is nervous about getting sick. The hand sanitizer kills 99% of these bacteria, but aout 3000-5000 bacteria are left that are genetically resistant to the hand sanitizer. Why

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

synapse nervous system