A strong immune system is needed in today’s Corona times...Give reason

Your immune system is an intricate, codependent structure of white blood cells, antibodies, complex proteins, networks, and organs. Some parts of the system act as literal barriers, preventing viruses and bacteria from reaching organs like your brain, while others hunt and remove invaders from your body. 

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.