Which is correct about joint diastole?
a. Bicuspid and tricuspid valves are open
b. Bicuspid and tricuspid valves are closed
c. Semilunar valves are open
d. Semilunar valves are closed

Options

A. a and c
B. b and d
C. a and d
D. b and c

Answer

To solve the question regarding joint diastole, we need to understand the state of the heart valves during this phase of the cardiac cycle. Let's break it down step by step:

### Step-by-Step Solution:

1. **Understanding Joint Diastole**:
- Joint diastole refers to the phase in the cardiac cycle when both the atria and ventricles are in a relaxed state. This allows for the filling of the heart chambers with blood.

**Hint**: Remember that diastole means relaxation of the heart muscles.

2. **Atrioventricular Valves**:
- During joint diastole, the atrioventricular (AV) valves, which include the bicuspid (mitral) valve and the tricuspid valve, are open. This allows blood to flow from the atria into the ventricles.

**Hint**: Atrioventricular valves open during filling phases to allow blood flow into the ventricles.

3. **Semilunar Valves**:
- In contrast, the semilunar valves (located at the exits of the ventricles into the arteries) are closed during joint diastole. This closure prevents the backflow of blood from the arteries into the ventricles.

**Hint**: Semilunar valves prevent backflow when the heart is relaxed and filling with blood.

4. **Conclusion**:
- Based on the above points, we can conclude that:
- The bicuspid and tricuspid valves are open (Option A).
- The semilunar valves are closed (Option D).

Therefore, the correct answer to the question is that both Option A and Option D are correct.

### Final Answer:
- The correct statements about joint diastole are:
- a. Bicuspid and tricuspid valves are open.
- d. Semilunar valves are closed.