In birds and mammals, a vestige of the sinus venosus of the fish heart remains as the sinoatrial node, which serves as a(n)
A. inhibitory node.
B. diastole detector.
C. baroreceptor.
D. pacemaker.
E. site of erythropoiesis.
Answer: D
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What is the key concept addressed by the question?
What will be an ideal response?
The figure below illustrates one possible
__________ structure of __________. a. primary; proteins b. primary; carbohydrates c. primary; lipids d. secondary; proteins e. tertiary; proteins
Fish can control buoyancy by:
a. holding air in their lungs. b. expelling air from their lungs. c. swift movements of their opercula. d. adjusting the amount of gas in their swim bladders. e. inflating the chambers of their tracheae.
In response to injury, cell fragments called platelets get activated to induce clotting. Activated platelets release factors that can in turn bind to specific membrane receptors on nearby cells. What type of signaling would this be considered?
A. endocrine B. direct contact C. paracrine D. autocrine E. synaptic