Which of the following statement is CORRECT ?
I. Heart, the mesodermally derived organ, is situated in the thoracic cavity, in between the two lungs , slightly tilted to the left.
II. During joint diastole , tricuspid and bicuspid valves are open and the semilunar values are closed.
III. The first heart sound (lub) is associated with the closure of the tricuspid and biscuspid valves whereas the second heart sound (dub) is associated with the closure of the semilunar valves .
IV. Neural signals through the sympathetic nerves can increases the rate of hearbeat, the strength of ventricular contraction and thereby the cardiac output.

Options

A. I,II , III and IV
B. I,III and IV
C. II, III and IV
D. I,II and III

Answer

To determine which of the statements is correct, we will analyze each statement one by one.

### Step 1: Analyze Statement I
**Statement I:** "Heart, the mesodermally derived organ, is situated in the thoracic cavity, in between the two lungs, slightly tilted to the left."

- The heart is indeed derived from the mesoderm, one of the three primary germ layers in embryonic development.
- The heart is located in the thoracic cavity, between the two lungs, and is slightly tilted to the left.

**Conclusion:** This statement is **correct**.

### Step 2: Analyze Statement II
**Statement II:** "During joint diastole, tricuspid and bicuspid valves are open and the semilunar valves are closed."

- During joint diastole, all four chambers of the heart are in a relaxed state.
- The tricuspid (right side) and bicuspid (mitral, left side) valves are indeed open, allowing blood to flow from the atria to the ventricles.
- The semilunar valves (pulmonary and aortic) are closed during this phase to prevent backflow of blood into the ventricles.

**Conclusion:** This statement is **correct**.

### Step 3: Analyze Statement III
**Statement III:** "The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves whereas the second heart sound (dub) is associated with the closure of the semilunar valves."

- The first heart sound (lub) is produced by the closure of the tricuspid and bicuspid (mitral) valves at the beginning of ventricular contraction (systole).
- The second heart sound (dub) is produced by the closure of the semilunar valves at the end of ventricular contraction.

**Conclusion:** This statement is **correct**.

### Step 4: Analyze Statement IV
**Statement IV:** "Neural signals through the sympathetic nerves can increase the rate of heartbeat, the strength of ventricular contraction and thereby the cardiac output."

- The sympathetic nervous system releases catecholamines (like epinephrine) which increase heart rate and the force of ventricular contractions.
- This results in an increase in cardiac output, which is the volume of blood the heart pumps per minute.

**Conclusion:** This statement is **correct**.

### Final Conclusion
All four statements are correct. Therefore, the correct answer is that **all statements (I, II, III, and IV) are correct**.

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