The oxygen required for aerobic respiration is provided to the muscle cells from the air. Describe the events that must take place in a person’s body so that a muscle cell can be provided with molecules of oxygen from the air.
Answers
The cardiovascular or circulatory system is designed to ensure the survival of all cells of the body at every moment and it does this by maintaining the immediate chemical environment of each cell in the body (i.e., the interstitial fluid) at a composition appropriate for that cell's normal function. The term “homeostasis” is used to denote the approximate constancy of the internal environment (Claude Bernard, 1866).
First consider the simple hypothetical case of a single spherical cell suspended in a large (>times the cell volume), well-stirred volume of aqueous medium in equilibrium with room air and containing other nutrients. Oxygen availability is often a limiting factor for cell survival, and it is generally supplied to a cell by passive diffusion. As oxygen molecules diffuse into the cell, they are consumed, so that there is a progressive fall in oxygen concentration from the surface of the cell to the lowest concentration which occurs at the center of the cell. For a spherical cell with a typicaldiffusion coefficient for oxygen (≈10−5 cm2/s) and an oxygen consumption of resting skeletal muscle (≈10−2 ml O2 cm−3 min−1), the critical size (radius) which is just adequately supplied with oxygen from the surrounding medium is about 1 mm. Thus, we find that diffusion puts an upper limit on the size of cells in regard to their need for oxygen.
Answer:
The cardiovascular or circulatory system is designed to ensure the survival of all cells of the body at every moment and it does this by maintaining the immediate chemical environment of each cell in the body (i.e., the interstitial fluid) at a composition appropriate for that cell's normal function. The term “homeostasis” is used to denote the approximate constancy of the internal environment (Claude Bernard, 1866).