Gizzard

A gizzard meaning is defined as a specialized part of the stomach that is used to store food and churn them into small particles. A gizzard can also be known as the modified grinding part of the digestive system. This organ is majorly seen in birds. It helps the birds to crush the grains they eat.

Structure of Gizzard

The gizzard is not present in all the animals. It is majorly present in birds. It helps in the process of digestion in birds.

It is a muscular structure and is very thickly walled. There are three layers of muscle tissue forming the wall of the Gizzard. The muscular structure ensures the churning of the food. It is located on the hind side of the stomach. The anatomical positioning is defined in between the saclike crop and the intestine of the organism. The gizzard in birds is mainly responsible for churning all the stones and pebbles they consume with the grains. These stones are also referred to as gastroliths. An additional protective layer is also present in the gizzard, called Kolin. Kolin is primarily made up of protein that is about 90% of the total constituent, the rest 10% is made of lipids and fatty acids.

Gizzard Function

The function of the organ is to mediate the churning of the food in animals that lack the process of mastication in the buccal cavity. For example, a bird's gizzard is located on the hind side of the stomach, when a bird engulfs a food particle it gets temporarily stored in the crop of the bird. Then the food passes through the proventriculus which is also known as the glandular stomach or the true stomach. This is the site of enzymatic digestion after this semi-digested food passes to the gizzard, where the bolus (food particle) undergoes mechanical mastication. The food then again enters the glandular stomach for complete digestion.

There are slight differences in the series of the passage of food as some animals lack stomachs. An example of such an organism is an earthworm. An earthworm performs its complete digestion in its gizzard. An important point to understand here is that gizzard is only present in the animals that lack teeth, there is no human gizzard, and gizzards are absent in evolutionarily developed vertebrates.

Conclusion

Digestion is one of the most important life processes in organisms. In some organisms such as birds, those lack teeth, a specialized organ known as the gizzard is present. This is present in their stomach. The gizzard helps to churn the food. Sometimes it also helps in digesting the small stones and pebbles that the birds eat with their grains.