Homeostasis: The Underappreciated and Far Too Often Ignored Central Organizing Principle of Physiology. By Billman GE in "Frontiers in Physiology", March 10, 2020. (available as Open Access)
A nice and historical review of probably the most important concept in physiology: homeostasis!

Dennis Noble: The music of life. Oxford Univ. Press 2006. As Eric Werner wrote in Science: "Noble presents his case for the systems approach with elegance and simplicity that hides unncessary details ... The book can be recommended to anyone, novice or professional". It also inspired me to sketch the 'levels in physiology' as illustrated in A.1.1.

Bill Bryson: The Body. Doubleday 2019. As usual with Bill Bryson, this book offers a unique exploration, this time of our inner world, how our body functions, what can go wrong and how it then often heals itself. A fantastic and 'unscripted' guide into the wonders of our body.

A.C. Guyton: There are many physiology textbooks, in English and in many other languages, but the most outstanding one certainly has to be the one originally written by A.C. Guyton. First published in 1956, it has been upgraded in many later editions. Unfortunately, Guyton has suddenly passed away in 2003 but his work has fortunately been continued by M.E. Hall and is now available in the 14th edition (2021): "Medical Physiology".

Prabhakar NR. 2019 Nobel Prize in Physiology or Medicine. Physiology 35: 81-83, 2020 (available as Open Access)
See also the bit about living at high altitudes at D.2.4. Anemia and Polycythemia, section H.