Page 11, O2 Uptake, Exercise & Cor. Circ., Dr. D. Penney

Blood Flow:

Blood flow can also be expressed on a tissue weight specific basis (Figure 3.06). The kidneys being small organs, have very high specific flow, not because of a very high metabolic rate but because of the kidneys' essential service function to the body - osmoregulation and the formation of urine.

The specific blood flow of resting skeletal muscle is very low, since 35-45% of body mass is muscle. It increases 10-20 fold during maximal activity, increasing most in those muscles which are working. Resting myocardial flow rate is equal to that of active skeletal muscle, and may increase 4-5 fold at high cardiac work loads.

Skin specific flow rate, low at rest, can also increase many-fold, as during the cutaneous vaso- and venodilatation involved in heat-dumping. In salivary gland and gastrointestinal tract, specific blood flow increases sharply during and immediately following food ingestion.