Which is correct about the contraction sequence of the heart?
A. Contraction begins in the order: right atrium, then right ventricle, then left atrium, then left ventricle.
B. The atria and ventricles begin their contractions at the exact same time, but the atrial contraction only lasts half as long as the ventricle contraction.
C. The contraction and relaxation of all four chambers happen at the same time.
D. The two atria contract at the same time, and as they are relaxing, the two ventricles contract together.
E. The right atrium and ventricle contract at the same time, and as they are relaxing, the left atrium and left ventricle begin to contract.
Answer: D
You might also like to view...
Which of the following is NOT a contribution of the cardiovascular system to other body systems?
a) Blood delivers clotting factors and WBCs that aid in hemostasis when skin is damaged. b) Blood delivers calcium and phosphate ions that are needed for building bone extracellular matrix. c) Blood carries carbon dioxide to body tissues and removes oxygen for use by other organs. d) Blood carries newly absorbed nutrients and water to the liver. e) Blood circulates cells and chemicals that carry out immune functions.
One reason that pregnant women's metabolic rates change is that the placenta secretes
A. human chorionic gonadotropin, which stimulates metabolism of glucose and raises metabolic rate. B. human chorionic thyrotropin, which stimulates the thyroid gland and raises metabolic rate. C. human placental lactogen, which stimulates glycolysis and raises metabolic rate. D. human chorionic somatomammotropin, which inhibits fatty acid metabolism and lowers metabolic rate. E. prolactin, which lowers metabolic rate so that nutrients can be stored in milk.
Every amino acid has a central carbon atom to which all of the followings are attached except
A) a hydrogen atom. B) a phosphate group. C) an amino group. D) a carboxyl group. E) a variable side group labeled as R.
Dendrites
A. are generally long and unbranched. B. conduct action potentials away from the cell body. C. form synapses with the microglia. D. are the input part of the neuron. E. contain the trigger zone.