What mechanisms assist venous return to the heart?
What will be an ideal response?
Blood pressure in venules and medium-sized veins is too low to oppose the force of gravity, and therefore, blood can backflow, unless opposed by special mechanisms, such as one -way valves, which act to compartmentalize the blood within the veins, dividing the weight between the compartments. Movement of skeletal muscles in the region acts to squeeze the blood toward the heart, segment by segment.
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Which of the following are not present prior to birth?
A) Pulmonary arterial resistance is high. B) Pulmonary vessels are collapsed. C) Rib cage is compressed. D) Alveoli are expanded. E) Lungs and airways contain only a small amount of fluid.
What type of fluid is cerebrospinal fluid?
a. transcellular b. lymph c. intracellular d. extracellular e. interstitial
Tay-Sachs disease is caused by a genetic defect that causes accumulation of wastes and other molecules within cells. For this to occur, the genetic defect must affect the activity of ________ enzymes.
A. mitochondrial B. lysosomal C. ribosomal D. centrosomal
Noninsulin-dependent diabetes mellitus results when
a. excessive secretion of insulin triggers hypoglycemia. b. somatostatin is able to compensate for the deficiency of insulin. c. insulin is secreted but target cells lack receptors for it. d. glucagon is able to compensate for the deficiency of insulin. e. insulin binds to its target cells but the cAMP second-messenger system fails to work.