Consists of all parts if Digestive System

3. Mouth
Pharynx
Oesophagus
Stomach
Small intestine
Large intestine
Cloaca
Accessory organs

4.  Esophagus--Return to the stomach and follow it upward,
where it gets smaller is the beginning of the esophagus. The
esophagus is the tube that leads from the frog’s mouth to the
stomach. Open the frog’s mouth and find the esophagus,
poke your probe into it and see where it leads.
 Stomach--Curving from underneath the liver is the
stomach. The stomach is the first major site of chemical
digestion. Frogs swallow their meals whole. Follow the
stomach to where it turns into the small intestine. The pyloric
sphincter valve regulates the exit of food from the stomach
 Pancreas – This glandular organ is located within the curve of
the stomach. On preserved frogs it may not be easy to find, as
the gland breaks down. It secretes insulin, which is needed for
the proper breakdown of sugar.

5.  Small Intestine--Leading from the stomach. The first straight
portion of the small intestine is called the duodenum, the
curled portion is the ileum. A membrane called the
mesentery holds the ileum together. Note the blood vessels
running through the mesentery; they will carry absorbed
nutrients away from the intestine. Absorption of digested
nutrients occurs in the small intestine.
 Large Intestine--As you follow the small intestine down, it will
widen into the large intestine. The large intestine is also
known as the cloaca in the frog. The cloaca is the last stop
before wastes, sperm, or urine exit the frog's body. (The word
"cloaca" means sewer.) Locate the anus.
 Spleen--Return to the folds of the mesentery, this dark red
spherical object serves as a holding area for blood, where
harmful particles can be filtered out for the immune system.

6. The digestive system of a frog starts with the mouth. Mouth helps in
consumption of food. This process is known as ingestion. Frog feeds
on flies or insects. As the teeth’s present in frog is very week they
are not useful to catch the agile prey. Frogs catch their food (such as
insects and flies) with the help of its stick tongue and mixes it with
the saliva. The teeth’s present in the upper jaw are called the
maxillary teeth, it helps in grinding the ingested food before it is
swallowed.
The saliva produced and secreted by the salivary glands helps in
conversion of starch to sugar and adds liquid to the ingested food.
The food mixed with saliva then moves from mouth into the pharynx,
and then into the oesophagus. It pushes the food further into the sac
like structure stomach. This movement is food into the stomach is
known as deglutition or swallowing.

7. Food particles in the stomach mix thoroughly with enzymes and other
fluids due to contraction of smooth muscles present in the stomach.
Peristaltic movement propels the food particles into the digestive tract
and the pyloric sphincter valve is involved in preventing the movement
of food backward from the stomach.
The food which is partially digested in stomach then proceeds in to the
small intestine, where most part of the digestion occurs. It is divisible
into duodenum and ileum. Pancreatic juice is secreted from the
pancreas and bile through the gallbladder from the liver to the small
intestine, which helps in completion of digestion.
Absorption of the digested nutrients in digestive system of a frog occurs in
small intestine. Absorption unabsorbed nutrients and reabsorption of
water takes place in the large intestine. Liquid wastes are in frog is
passed to the urinary bladder, while solids are routed to the cloaca. Both
liquid and solid wastes in frog are expelled out through cloaca which is a
slit that opens out finally in digestive system of a frog.