According to the most current model of the plasma membrane,
A. the membrane is a rigid unchanging structure.
B. cholesterol forms the innermost layer of the membrane.
C. phospholipids and cholesterol form a single lipid bilayer.
D. proteins are free to move about within a double layer of phospholipids.
E. the membrane is impermeable to all other molecules.
D
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Once cells in the SA node reach threshold,
A) a heart attack occurs. B) the heart stops beating. C) nothing happens until the AV node is innervated. D) an action potential is triggered.
List 4 items used during a bathing procedure
What will be an ideal response?
Cardiac muscle cells have several similarities with skeletal muscle cells. Which of the following is not a similarity?
A. The cells are each innervated by a nerve ending. B. The cells store calcium ions in the sarcoplasmic reticulum. C. The cells contain sarcomeres. D. The cells become depolarized when sodium ions enter the cytoplasm.
Blood does not enter or leave the ventricles during the period called
A. ejection. B. rapid filling. C. atrial systole. D. isovolumetric contraction. E. active and passive filling.