Author Question: A nursing instructor is explaining the role of calcium in the contraction of the cardiac muscle. The ... (Read 58 times)

abc · **on:** Jul 23, 2018

A nursing instructor is explaining the role of calcium in the contraction of the cardiac muscle. The instructor asks the students to state, in order, the events that allow the cardiac muscle to contract.

Standard Text: Click on the down arrow for each response in the right column and select the correct choice from the list.
Response 1. An action potential occurs.
Response 2. Depolarization occurs.
Response 3. Voltage-gated channels in the sarcolemma open.
Response 4. Ions enter and leave the muscle cell.
Response 5. Muscle contraction occurs.

Question 2

The nurse is teaching a client about the role of calcium in hypertension, and explains that a high concentration of calcium in arterial smooth muscle cells leads to which clinical manifestation?

1. Elevated blood pressure
2. Hypercalcemia
3. Decreased blood pressure
4. Hypocalcemia

prumorgan · **Reply #1 on:** Jul 23, 2018

Answer to Question 1

Correct Answer: 1,2,3,4,5
Rationale 1: An action potential is the first step that must occur for the cardiac muscle to contract.
Rationale 2: Depolarization is the second step that must occur for the cardiac muscle to contract.
Rationale 3: The third step that occurs in the contraction of the cardiac muscle is the opening of the voltage-gated channels in the sarcolemma.
Rationale 4: The fourth step that occurs in the contraction of the cardiac muscle is ions entering and leaving the muscle cell.
Rationale 5: The last step that occurs is the actual contraction of the cardiac muscle.
Global Rationale: An action potential is the first step that must occur for the cardiac muscle to contract. Depolarization is the second step that must occur for the cardiac muscle to contract. The third step that occurs in the contraction of the cardiac muscle is the opening of the voltage-gated channels in the sarcolemma. The fourth step that occurs in the contraction of the cardiac muscle is ions entering and leaving the muscle cell. The last step that occurs is the actual contraction of the cardiac muscle.

Answer to Question 2

Correct Answer: 1
Rationale 1: Blood pressure is increased by the increase in contractility of vascular smooth muscle when intracellular calcium is increased.
Rationale 2: Hypercalcemia is not a consequence of intracellular calcium concentration, although a significant elevation in serum concentration of calcium can increase intracellular calcium.
Rationale 3: Calcium influx into vascular smooth muscle cells increases vasoconstriction and does not decrease blood pressure.
Rationale 4: Hypocalcemia is not a consequence of intracellular calcium concentration, although a significant decrease in serum concentration of calcium can decrease intracellular calcium.
Global Rationale: Blood pressure is increased by the increase in contractility of vascular smooth muscle when intracellular calcium is increased. Hypercalcemia is not a consequence of intracellular calcium concentration, although a significant elevation in serum concentration of calcium can increase intracellular calcium. Calcium influx into vascular smooth muscle cells increases vasoconstriction and does not decrease blood pressure.