During the plateau phase of the action potentials of myocardial contractile cells, which ion(s) is/are crossing the membrane?
A) K+ only
B) Na+only
C) both Na+ and K+
D) Ca2+ only
E) both Ca2+ and K+
E) both Ca2+ and K+
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Indicate whether the statement is true or false
Which of the following situations occurs in electrically excitable cells?
A. Depolarization causes voltage-gated sodium ion channels to open. B. Sodium ion channels are opened by high extracellular calcium levels. C. The sodium-potassium pump moves sodium into the cell. D. When Na+ ion channels open, K+ ion channels close. E. The opening and closing of ligand-gated channels cause depolarization.
Compared to the normal plasma osmolarity, the tubular fluid is ________ as it enters Bowman's space, ________ at the beginning of the loop of Henle, ________ at the tip of the loop, and ________ at the beginning of the distal convoluted tubule
A. isosmotic; hyperosmotic; hyperosmotic; isosmotic B. isosmotic; isosmotic; hypoosmotic; hypoosmotic C. isosmotic; isosmotic; hyperosmotic; hypoosmotic D. isosmotic; isosmotic; hypoosmotic; hyperosmotic E. isosmotic; isosmotic; hyperosmotic; isosmotic
Nerve impulses leading to the brain carry information about cool temperatures on the skin. The nerve fibers sending these signals will most likely belong to which division of the nervous system?
A) sensory (afferent) division B) somatic nervous system C) sympathetic division D) parasympathetic division