Which organ contains circular muscles called sphincters that control the release of urine

Although there are a limited number of amino acids many different types of proteins exist because..

What was dr. willem johan kolff’s first step in using the scientific process to invent the hemodialysis machine? he built the machine and tried it with various patients, collecting data about its effectiveness. when a patient’s kidneys failed, he wondered if it would be possible to perform kidney functions with an external machine. he researched and collected data about numerous patients who exhibited symptoms of kidney failure. he drew conclusions from studies of various symptoms of kidney failure, and drew a design for the ideal external blood-processing machine.

Select three sports that require participants to be highly fit before the beginning a: snowboarding b: skydiving c: rock climbing d: bungee jumping e: free diving f: hiking