The Dogs Digestive System

1.0 Introduction

The similarities and differences between the dog and the lizards’ digestive and reproductive systems are explored within this essay.

2.0 The dog’s digestive system

The dogs’ digestive system mainly consists of 15 different parts. These are the oral cavity, oesophagus, diaphragm, stomach, liver, gall bladder, pancreas, duodenum, jejunum and ileum, transverse colon, ascending colon, descending colon, caecum, anal canal and the rectum (Aspinall and Cappello, 2009). Each of these play an important role in the dogs’ digestive system.

Starting at the oral cavity where food is taken in, it can also be known as the mouth or buccal cavity. It contains the teeth, tongue and salivary glands and its functions are prehension which is

It has three functions which are to act as a food reserve, to break down food further whilst mixing it with digestive juices and to start protein digestion (Aspinall and Cappello, 2009). There are gastric pits within the gastric mucosa that produce hydrochloric acid, mucus and pepsin. The process of breaking down and mixing the food with digestive juices takes approximately two hours using the muscles to contract and mix the contents of the stomach. Once this is complete, chyme is produced which moves into the duodenum (Dallas, 2012).

The small intestine a narrow tube and can be up to three and a half times the dogs body length. It is the main site of enzymic digestion, it receives the acidic chyme from the stomach and it absorbs the digested food product (Aspinall and Cappello, 2009).

The large intestine is a wider but shorter tube compared to the small intestine and is divided up into three sections. These are the caecum which is a pocket like blind end that joins the ileum in the intestine (Boden, 2007). The caecum is small in the dog as vegetation does not make up a large amount of its diet. The colon is spilt up into the ascending colon, transverse colon and the descending colon. Typically their function is to absorb water from the ingesta and also pushes forward faeces to the rectum (Dallas,

In its buccal cavity the lizard has well developed teeth, the amount of teeth the lizard has depends on the species of lizard. For example the green iguana has 19 to 29 on their lower jaw and 20 to 30 on the upper jaw (Jacobson, 2003). The most common tooth type in lizards is pleurodon dentition, these are very loose because they are not in sockets. Some lizards also shed their teeth and replace them throughout their lives (Fraser and Girling, 2011). Most insect eating lizards do not chew their food, they ingest it as a whole whereas herbivorous lizards tear and chew up the vegetation before ingesting it (Grenard, 1998). The lizard has a jacobson organ in the roof of their mouth, this assists with the lizards ability to taste the environment (Aspinall and Cappello,