How does a frog breathe? How they breathe underwater? And more to know!

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What are the breathing and respiratory organs of frog?

The breathing and respiratory organs of frog includes: their lungs, skin, the buccal cavity lining.

Gills are present at least during their early stages of development. As the tadpole larva of the frog matures, the gills are absorbed by the body and replaces with its buccal cavity lining.

A pair of lungs of frogs can only be seen during their adult stages with which they can only do a part of their breathing and respiration.

Their pair of lungs are really very simple and help them breathe when on land or when their face is above the water.

Skin is the most important organ of a frog’s body. Their skin is thin and allows the exchange of carbon dioxide and oxygen in and out of the body of a frog. Thus, helping in overall respiration.

The outer skin surface always remains wet with mucus secretions and this helps the frog to breathe and respire easily with the exchange of the required gases.

Moreover, inside the mouth of the frog, there is the lining of the buccal cavity that can also help the frog to exchange the oxygen and carbon dioxide gas very easily by diffusion.


The location of the buccal cavity lining was the spot where the gills were present during the tadpole stage of the frog.

How does a frog breathe?

Frogs breathe by means of gills during their tadpole larval stages, and by lungs, skin, and buccal cavity lining when they have become adults.

Their lungs are not fully developed and only helps them to breathe when only on land.

They take the air in through their nostrils down into their lungs which helps diffuse the air and exchange the gases between the blood capillaries and the lung tissue.

Because a frog’s lungs don’t inflate and collapse on their own, they are considered poorly developed compared to those of other vertebrates. In fact, the lungs of a frog are not their main method of respiration.

Their skin is usually naked and often plays an important part in respiration. The skin is slippery, smooth, moist, and lacking in the external protective scales or hairs.

Their skin is composed of very thin membranous tissues along with mucus glands. The mucus glands keep the outer skin smooth and moist all of the time.

The moist skin allows gases to pass through, helping the frog to breathe. To keep the skin working well, frogs must stay clean and moist.

Simply when the frog undergoes summer sleep (aestivation) and winter sleep (hibernation), the skin is their only organ for respiration.

On the other hand, the thin membranous tissues in their skin are quite permeable to water and contain a large network of blood vessels.

The thin membranous skin allows the respiratory gases to readily diffuse directly down their gradients between the blood vessels and the surroundings when either on land or when in water.

The lining of the buccal cavity is also lined with blood capillaries and remains moist by mucus. Through the buccal cavity lining as well the exchange of gases can take place.

How do frog respire after breathing? What’s their physiology of respiration?

There’s a difference between respiration and breathing. Breathing is actually a biological process of inhaling and exhaling of the gases between the body surface and the environment.

Whereas, Respiration, on the other hand, is a chemical process that takes place in the cell. This involves the production of energy typically with the intake of oxygen and the release of carbon dioxide from the oxidation of complex organic substances.

The Red Blood Cells (RBCs) of frog’s blood contain a respiratory pigment called the haemoglobin to which the respiratory gases Oxygen and Carbon dioxide can combine temporarily only in high partial pressure.

In the respiratory surfaces of the body like skin, lung surface, buccal cavity lining the Oxygen in the air is found in higher concentration due to which it combines with haemoglobin of the blood to form oxyhaemoglobin.

Now the oxygen is easily transported by blood to the different tissues of the body where it dissociates due to the less concentrations of oxygen in the tissues and cells, and thus, gives up its oxygen to the tissues.

Now, the resultant Carbon dioxide formed due to a series of chemical reactions that want to come out of the tissue and cell is in high concentration, therefore it passes into the blood and binds with haemoglobin.

Haemoglobin can bind to four molecules of carbon dioxide. Thus, one haemoglobin molecule can transport four carbon dioxide molecules.

Carbon dioxide taken by the blood is passed out from the respiratory surface of the frog, where they are released. And, the molecule changes back to the oxyhaemoglobin form.

The role of Oxygen is to release energy from the absorbed food by oxidizing it in the cell and then release the energy along with Carbon dioxide.

How does a frog breathe underwater?

A frog uses its moist skin to breathe underwater. They don’t use their lungs to breathe underwater, or else if their lungs fill with water, they can drown very easily.

The respiration through their skin surface is also termed as cutaneous respiration. The skin is the largest organ with a large surface area to use for cutaneous respiration.

They use their skin to absorb dissolved oxygen into their skin when underwater, and remove carbon dioxide out through their skin that gets dissolved in the water. All this happens by simple diffusion-based on gradient concentration.

If the concentration of oxygen in the skin region is low then the surrounding water, then dissolved oxygen in the water gets escaped into the body of the frog through the skin surface.

Now since the skin is composed of thin membranous tissue that is quite permeable to water and contains a large network of blood vessels. The oxygen easily gets diffuses to the blood and gets transported to the whole body.

The released Carbon dioxide from the cells is now carried via the blood in the blood vessels to the outer skin surface.

Here, on the skin surface, as the concentration of carbon dioxide is greater than the outer surrounding water, therefore the carbon dioxide in the cells gets released and gets dissolved into the open water.

Since frogs are small, and their cold-blooded bodies don’t need a lot of energy to stay alive, they don’t require a lot of oxygen as well.

So, this allows frogs to survive in environments with less oxygen, and also in conditions like in water with dissolved oxygen.

How does a frog breathe on land?

On land, frog uses their wet and moist skin, their buccal cavity lining, and also a pair of their lungs to breathe.

Their skin not only serves as an organ of respiration while in water, but also as an organ of respiration when outside of water. However, the skin doesn’t remain that much active as it was while inside the water.

When the frog is out of the water, mucus glands in the skin keep the frog moist, which helps them absorb dissolved oxygen from the air.

They also use their buccal cavity lining which is rich in blood capillaries and always remains moist with mucus covering. This type of respiration is called buccal respiration.

The buccal respiration occurs by lowering and raising the floor of the buccal cavity, during the course of which the air is being constantly sucked into the buccal cavity and is drawn out through the external and internal nostrils.

They also can use their lungs only when in the air that is when on land. Respiration on land in air with the help of the lungs is called pulmonary respiration.

The oxygenated air that enters through the nostrils gets into the mouth by inspiration. The air enters and leaves the mouth towards the lungs only through the respiratory tract that connects the two lungs together, one at each end-branch of the tract.

In the surface of the lungs there are cells that are connected with very thin blood vessels between which the exchange of gases takes place.

The deoxygenated air that comes out of the lungs gets into the mouth through the respiratory tract by expiration.

To eliminate the carbon dioxide out from the lungs the nostrils are opened and the floor of the mouth moved up pushing the air out of the nostrils.

How do tadpoles breathe?

Tadpoles are the aquatic larval stage of frog and toads. They have a big head and a long tail and they 101% don’t look like frogs.

The only stage in the life of a frog where you can find gills is the tadpole stage. Tadpoles are born with gills, just like a fish, so that they can breathe underwater.

Later on, as tadpoles grow into an adult frog, these gills disappear and get absorbed into the skin surface, as other respiratory organs have well developed in the adults. That’s why adults don’t have gills.

Tadpoles have tiny external gill flaps that extract oxygen from water as it passes over them. Tadpoles exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills.

In very simple words, tadpoles open their mouths as they swim and take in water. As the mouth closes, the water gets transferred to the gills and eventually out through it.

Each filament of the tadpole’s gills contains a minute capillary network that provides a large surface area for exchanging oxygen and carbon dioxide.

This capillary network takes the oxygen from the water where it enters the bloodstream through the process of diffusion.

Tadpoles can also rise to the surface and take oxygen from the air and fill it in their mouth.

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