Ito, Joshua Lorenzo
Delos Reyes, Norvin
Ms. Ma. Luisa V. Cuaresma
What is Digestive System?
Digestive System is a group of organs working
together to convert food into energy and
basic nutrients to feed the entire body
William Beaumont (November 21, 1785 – April
25, 1853) was a surgeon in the U.S. Army who
became known as the "Father of
Gastric Physiology” following his research on
> Food doesn't need gravity to get to your
> Stomach doesn't do most of the digestion
> Flatulence gets its smell from bacteria
> Stomach rumbling can happen at any time,
not just when you're hungry
This is also known as Oral Cavity, This is
where you enter food and masticate it.
-Teeth: Cutting and grinding food
-Tongue: Helps for swallowing
-Salivary Glands: Moisten the food
Responsible for the passing of masses of
chewed food from the mouth to esophagus.
Carries swallowed masses of masticated food
along its length.
Acts as the storage tank for food.
Produces bile and its secretion to the small
Used to store and recycle excess bile from
the small intestine.
It secretes digestive enzymes into the small
intestine to complete the chemical digestion
The cavity which collects and stores wastes
from both the colon and kidneys.
Small and Large Intestine
Small- maximize the digestion of food and
absorption of nutrients
Large- absorbs water and contains many
symbiotic bacteria that aid in the breaking
down of wastes to extract some small
amounts of nutrients.
Mouth Chewing Saliva Starches
Esophagus Swallowing None None
Upper muscle in stomach relaxes to let food
enter and lower muscle mixes food with
Small intestine Peristalsis
Liver None Bile acids Fats
This table shows the parts of the digestive process performed by each
digestive organ, including movement of food, type of digestive juice used,
and food particles broken down by that organ.
Food is ingested through the mouth of the fish
using the jaws.
The food then passes through the pharynx (throat)
into the esophagus and into the stomach
Partial digestion takes place here using gastric
juices (including acid and enzymes)
food proceeds to the intestine for more digestion
and absorption into the blood
Between the stomach and the intestine there is
usually a valve called the pyloric valve. Beyond
this valve, a duct from the liver and pancreas
enter the intestine to secrete digestive enzymes
including "pepsin and trypsin" into the food
Mouth and Oral Cavity
The roof of it is formed by a series of skeletal
A tongue that can be used for catching prey
as well as sensory input.
It varies greatly in size and importance
In Anurans, the tongue is attached at the anterior
end of the jaw.
The muscular system of the tongue becomes better
organized with a genioglossus as a protractor and a
hyoglossus as a retractor
Its sense organs are innervated by glossopharyngeal
nerve and its muscles by hypoglossal nerve
The glands of Amphibians are few in number and
are located on the roof of the mouth or on the
In Salamanders, mucous glands are located on the
tongue and a large intermaxillary gland within the
Esophagus and Stomach
The esophagus is short, ciliated, and well-
supplied with mucous glands
The stomach remains simple and straight or
They swallow their prey whole, with some
chewing done in the oral cavities of some
species, so they possess voluminous stomachs.
Intestine and Caeca
Salamanders lack a valve separating the small
intestine from the large intestine.
Tadpoles haves long coiled intestines but Adult
Amphibians have relatively short and simple
digestive tube ranging in length from ½ to 3 ¼
times the body length
Composed of coiled small intestine and a shorter large
intestine, with a simple small colic caecum in between
A cloaca is present
Evolution of teeth
Modern Amphibians (LISSAMPHIBIANS) have fewer
Liver and Gall Bladder
The liver in most amphibians is large with two
lobes. The size of the liver is determined by its vital
function as a glycogen and fat storage unit. from
the liver collect in the gall bladder, and flow into
the small intestine.
Pancreas is present
The mammalian digestive system consists of the
alimentary canal (complete digestive tract) and
various accessory glands that secret digestive
juices into the canal through the ducts. The
food is moved along the tract by the contraction
of smooth muscles in the walls of the canal.
These rhythmic contraction waves are called
peristalsis. The regulation of passage of
material from one chamber to another within
the canal is controlled by ring-like valves called
The accessory glands of the mammalian digestive
tract are three pairs of salivary glands, the
pancreas, the liver, and its storage organ the gall
Mouth: Foodstuffs are broken down mechanically
by chewing and saliva is added as a lubricant.
Pharynx - Out throat is the pharynx which leads
to both the esophagus and the windpipe (
trachea). When a human swallows the top of the
windpipe moves up so that its opening, the
glottis, is blocked by a flap of cartilage called
the epiglottis. This helps to ensure that the
bolus enters the esophagus.
Esophagus: A simple conduit between the mouth
and stomach - important but only marginally
Stomach: Where the real action begins -
chemical digestion of proteins initiated and
foodstuffs reduced to liquid form.
Liver: The center of metabolic activity in the body
- its major role in the digestive process is to
provide bile salts to the small intestine, which are
critical for digestion and absorption of fats.
Pancreas: Important roles as both an endocrine
and exocrine organ - provides a potent mixture of
digestive enzymes to the small intestine which are
critical for digestion of fats, carbohydrates and
Small Intestine: The most exciting place to be in
the entire digestive system - this is where the final
stages of chemical digestion occur and where
almost all nutrients are absorbed.
Large Intestine: Major differences among species
in extent and importance - in all animals water is
absorbed, bacterial fermentation takes place and
feces are formed. In carnivores, that's about the
extent of it, but in herbivores like the horse, the
large intestine is huge and of critical importance
for utilization of cellulose.
Birds has faster and more efficient digestive
system than those of other vertebrate
Their beaks or bills replace the lips and
mouth of mammals and vary in shape.
Their tongue do helps manipulate food for
Food passes through esophagus on its way to
Birds have a two part stomach,
granular portion known as Proventriculus
and the muscular portions known as Gizzard.
Mouth & oral cavity- tetrapods such as
reptiles, typically have longer oral cavities
Teeth- reptiles still have teeth on the vomer,
palatine, & pterygoid bones
Tongue- primary tongue + glandular field (or
tuberculum impar) + lateral lingual swellings
(more hypobranchial muscle)
Tongue mobility- sometimes long and may move
in and out of the oral cavity
Oral glands- some reptiles secrete poison
Pharynx- is the part of the foregut
preceeding the esophagus & includes:
- glottis (slit leading into the larynx)
-openings of auditory (eustachian) tubes
- opening into esophagus
Stomach- increasing specialization (more
differentiated from the esophagus)
Intestine- coiled small intestines & a
relatively short large intestine (that empties
into the cloaca)
Cloaca- chamber at end of digestive tract
that receives the intestine, & urinary &
genital ducts, & opens to the exterior via the