A thin-walled, triangular chamber attached dorsally to heart of frog is known as

Options

A. a.Truncus arteriosus
B. b.Sinus venosus
C. c.Atrium
D. d.Ventricle

Answer

To answer the question "A thin-walled, triangular chamber attached dorsally to the heart of a frog is known as," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Frog's Heart**:
- The heart of a frog consists of three main chambers: two atria (auricles) and one ventricle. Additionally, there are two other chambers associated with the heart.

2. **Identify the Additional Chambers**:
- The two additional chambers are the **sinus venosus** and the **truncus arteriosus**.
- The sinus venosus is located dorsally (on the back side) of the heart, while the truncus arteriosus is located ventrally (on the front side).

3. **Examine the Characteristics of Sinus Venosus**:
- The sinus venosus is described as a thin-walled, triangular chamber.
- It is responsible for collecting deoxygenated blood from the body through the major veins (superior and inferior vena cavae) and transferring it into the right atrium.

4. **Confirm the Location and Function**:
- The sinus venosus collects deoxygenated blood and is indeed a triangular chamber attached dorsally to the heart.
- In contrast, the truncus arteriosus is involved in supplying oxygenated blood to the body and is not triangular in shape.

5. **Conclusion**:
- Based on the characteristics and location described, the correct answer to the question is **sinus venosus**.

### Final Answer:
The thin-walled, triangular chamber attached dorsally to the heart of a frog is known as **sinus venosus**.

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