Jenny, a healthy young woman, had a battery of tests during a physical for a new job. Her RBC count was at the higher end of the normal range at that time, but four weeks later it was substantially elevated beyond that. When asked if any circumstances had changed in her life, she admitted to taking up smoking. How might her new habit explain her higher RBC count?

Smoke-induced oxidative stress limited the oxygen-carrying capacity of the previous red blood cells

Explanation:

The red blood cell (RBC) contains hemoglobin which helps in the transport of oxygen. However, the Jane's smoking must have induced oxidative stress to the cells of her body including RBC, thus compromising it's oxygen-carrying capacity.

Hence Jane's body increased RBC count in order to maintain oxygen supply to all cells of her body.

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what is a measurement of the earth’s history divided into time periods?

> fossil record <

sedimentary rock

> geologic time scale <

radioactive elements