Question

Buccopharyngeal respiration in frog
a. Is increased when nostrils are closed
b. Stops when there is pulmonary respiration
c. Is increased when it is catching fly
d. Stops when mouth is opened

Answer 1

Hint: Respiration is the process wherein food is oxidized with oxygen to deliver energy to the body to perform different life exercises and CO2 is disposed off from the body during the process.

Complete answer:
In order to answer this question we need to have knowledge about respiration methods of frogs. Frogs are amphibians animals so they can easily adapt themselves in water as well as on land. Due to their adaptability they posses different modes of respiration –

> Cutaneous respiration: By the skin, under water, on land, during hibernation they respire through their skin. Thus cutaneous respiration takes place always.
> Pulmonary respiration: In frogs this occurs when they lead an active life during rains or spring season.
> Buccopharyngeal respiration: The mucosa of buccopharyngeal cavity in frogs is ideally adapted for gaseous exchange. While floating on water surface, or when resting upon land, they respire through the buccopharyngeal cavity. During this process, the mouth, gullet and glottis remain closed, but nares remain open and oxygen is taken up by diffusion or by the contraction and relaxation of the muscles of the buccopharyngeal cavity.

Mechanism of bucco-pharyngeal respiration:
- Bucco-pharynx or buccal cavity
- Contraction of sternohyal muscles
- Lowering of floor of the cavity
- Area of buccal cavity increases
- Air comes inside the buccal cavity through external nares
- Gas exchange occurs
- Petrohyal muscles contracts
- Raising of floor of buccal cavity
- Area of buccal cavity decreases
- Pressure of air contained increases
- Air goes out through external nares.

Therefore, the answer is a, respiration increases when nostrils are closed.

Note:
- Inspiration: The intake of fresh air from atmosphere into the lungs for gaseous exchange. The passage of air from outside into the bucco-pharyngeal cavity is aspiration whereas; when lungs are filled with fresh air it is called pulmonary inspiration.
- Expiration: The process of exhalation of carbon dioxide from lungs back to the bucco-pharyngeal cavity through glottis and to outside is pulmonary expiration.