The Functions of the Tongue

After researching about the muscles in the tongue and the amazing ways in which they work together to move, I wanted to find out more about the functions of the tongue. I believe that this is especially evident in dogs because of the prominent and significant role of the tongue lolling out of a dog’s mouth in a cheerful ‘grin’.

Blood Vessels

Dog’s pant when they are hot because they cannot sweat like humans because of their fur. Therefore the tongue is vital in keeping them cool and ensuring that they cannot overheat. To act this important role, the tongue has a rich supply of blood vessels, and when too hot, these dilate and the tongue swells and expands because of this. This causes the blood vessels to be nearer the surface of the tongue where the heat can be conducted into the colder air around the dog. However, this also means that if punctured when in this state, the tongue will bleed profusely. In order to stop this bleeding,  the dog needs to cool down so that the blood vessels constrict and a blood clot can quickly form due to the many platelets in the many blood vessels.

Taste Buds

The tongue is also vital for tasting. This is because of the taste bud receptors found in small bumps across the tongue, called papillae. Dogs have different areas of the tongue which detect different chemicals with particular sensitivity, which are then interpreted by the brain as different flavours. These are as follows:

Sour – across the top of the tongue

Salt – along the lateral edges and rear of the tongue

Sugar – along the edges and front of the tongue. These respond to a chemical called furaneol which is found in many fruits. Cats do not taste this.

Bitter – the rear of the tongue

Meat – dog’s have a particular sensitivity for chemicals associated with meats and fats. This is found across the top of the tongue.

Water – the tip of the tongue is used to taste water… Why? Dog’s and other carnivores have an ability to taste the chemicals and impurities in water whilst humans cannot. This could be as a result of the salty meats which they are accustomed to eating and therefore the higher levels of water they need to drink.

Although humans have about 9000 taste buds, compared to 1700 in dogs, cats only have about 470.

Salivary Glands

The four major dog salivary glands can be seen on this diagram, these are responsible for making the dog’s mouth wet. They secrete two different types of saliva, mucoid and serous. Their functions are as follows:

Parotid – produce serous saliva which is thin, watery and amylase-rich. This is the only gland which can be examined from the outside of a dog’s mouth.

Mandibular – the acinar cells here are both serous and mucous, therefore this saliva is more viscous and mucous. If these glands are lacerated, they can leak saliva into the surrounding tissue, forming a cyst called a mucocele. This has to be drained.

Sublingual – produce mucous saliva which is very thick and viscous.

Zygomatic – acinar cells consist mainly of mucous secreting cells and only a few serous. They are foun only in carnivores. This is where salivary gland infection can occur and can only treated by removing the gland.

The surface of a dog’s tongue is also covered in tiny salivary glands which contribute to a wet mouth resulting in cooling by evaporation and helping to overcome the problem of sweating.

 

All tongues are amazing pieces of anatomy which have the purpose of carrying out many tasks, vital for function in the body of humans and dogs alike.

 

References:

http://www.petmd.com/dog/general-health/evr_dg_anatomy_of_a_dogs_tongue

http://www.psychologytoday.com/blog/canine-corner/201104/how-good-is-your-dogs-sense-taste

http://flipper.diff.org/app/items/info/367

http://pets.webmd.com/dogs/dog-drooling-salivary-gland-problems

http://en.wikivet.net/Zygomatic_Gland_-_Anatomy_%26_Physiology