Digestive System of Vertebrates
Digestive System is one of the largest
organ systems in the body. It is responsible for
processing ingested food and liquids. The cells
of the body all require a wide array of chemicals
to support their metabolic activities, from organic
nutrients used as fuel to the water that sustains
life at the cellular level. The digestive system not
only effectively chemically reduces the
compounds in food into their fundamental
building blocks, but also acts to retain water and
excrete undigested materials. Vertebrates have evolved more complex digestive
systems to adapt to their dietary needs. Some animals have a single stomach, while
others have multi-chambered stomachs. Birds have developed a digestive system
adapted to eating un-masticated (un-chewed) food.
Structure & Functions of Digestive System
Digestive system is a uniquely constructed
system and its job is turning food into nutrients and
energy needed to survive. And when it’s done with
that,
it handily packages solid waste, or stool, for disposal.
The functions of the digestive system can be
summarized as follows: ingestion (eat food), digestion
(breakdown of food), absorption (extraction of
nutrients
from the food), and defecation (removal of waste
products). The main organs that make up the digestive
systems (in order of their function) are the mouth, esophagus, stomach, small
intestine, large intestine, rectum and anus. Helping them along the way are the
pancreas, gallbladder and liver.
Mouth is the beginning of the digestive tract. The salivary glands get active as a
food is seen and smelled. Before eating, the food is chewed into pieces that are more
, easily digested. The saliva mixes with the food to begin to break it down into a form the
body can absorb and use. When swallowing, the tongue
passes the food into the throat and into the esophagus. But first a ring-like muscle at
the bottom of the esophagus, called the lower esophageal sphincter, has to relax to let
the food in. The sphincter then contracts and prevents the contents of the stomach
from flowing back into the esophagus.
Esophagus is located in the throat near the trachea (windpipe), it receives food
from the mouth when swallowing. The epiglottis is a small flap that folds over the
windpipe when swallowing to prevent choking (when food goes into your windpipe). A
series of muscular contractions within the esophagus called peristalsis delivers food to
the stomach.
Stomach is a hollow organ, or "container," that holds food while it is being mixed
with stomach enzymes. These enzymes continue the process of breaking down food
into a usable form. Cells in the lining of the stomach secrete a strong acid and
powerful enzymes that are responsible for the breakdown process. When the contents
of the stomach are processed enough, they’re released into the small intestine.
Small Intestine is made up of three segments -- the duodenum, jejunum, and
ileum. The duodenum is the first segment of the small intestine. It’s largely responsible
for the continuous breaking-down process. The jejunum and ileum lower in the
intestine are mainly responsible for absorption of nutrients into the bloodstream.
Contents of the small intestine start out semi-solid, and end in a liquid form after
passing through the organ. Water, bile, enzymes and mucus contribute to the change
in consistency. Once the nutrients have been absorbed and the leftover-food residue
liquid has passed through the small intestine, it then moves on to the large intestine, or
colon.
Pancreas secretes digestive enzymes into the duodenum that break down
protein, fats and carbohydrates. The pancreas also makes insulin, passing it directly
into the bloodstream. Insulin is the chief hormone in your body for metabolizing sugar.
Liver processes the nutrients absorbed from the small intestine. Bile from the
liver secreted into the small intestine also plays an important role in digesting fat and
some vitamins.
Gallbladder stores and concentrates bile from the liver, and then releases it into
the duodenum in the small intestine to help absorb and digest fats.
Digestive System is one of the largest
organ systems in the body. It is responsible for
processing ingested food and liquids. The cells
of the body all require a wide array of chemicals
to support their metabolic activities, from organic
nutrients used as fuel to the water that sustains
life at the cellular level. The digestive system not
only effectively chemically reduces the
compounds in food into their fundamental
building blocks, but also acts to retain water and
excrete undigested materials. Vertebrates have evolved more complex digestive
systems to adapt to their dietary needs. Some animals have a single stomach, while
others have multi-chambered stomachs. Birds have developed a digestive system
adapted to eating un-masticated (un-chewed) food.
Structure & Functions of Digestive System
Digestive system is a uniquely constructed
system and its job is turning food into nutrients and
energy needed to survive. And when it’s done with
that,
it handily packages solid waste, or stool, for disposal.
The functions of the digestive system can be
summarized as follows: ingestion (eat food), digestion
(breakdown of food), absorption (extraction of
nutrients
from the food), and defecation (removal of waste
products). The main organs that make up the digestive
systems (in order of their function) are the mouth, esophagus, stomach, small
intestine, large intestine, rectum and anus. Helping them along the way are the
pancreas, gallbladder and liver.
Mouth is the beginning of the digestive tract. The salivary glands get active as a
food is seen and smelled. Before eating, the food is chewed into pieces that are more
, easily digested. The saliva mixes with the food to begin to break it down into a form the
body can absorb and use. When swallowing, the tongue
passes the food into the throat and into the esophagus. But first a ring-like muscle at
the bottom of the esophagus, called the lower esophageal sphincter, has to relax to let
the food in. The sphincter then contracts and prevents the contents of the stomach
from flowing back into the esophagus.
Esophagus is located in the throat near the trachea (windpipe), it receives food
from the mouth when swallowing. The epiglottis is a small flap that folds over the
windpipe when swallowing to prevent choking (when food goes into your windpipe). A
series of muscular contractions within the esophagus called peristalsis delivers food to
the stomach.
Stomach is a hollow organ, or "container," that holds food while it is being mixed
with stomach enzymes. These enzymes continue the process of breaking down food
into a usable form. Cells in the lining of the stomach secrete a strong acid and
powerful enzymes that are responsible for the breakdown process. When the contents
of the stomach are processed enough, they’re released into the small intestine.
Small Intestine is made up of three segments -- the duodenum, jejunum, and
ileum. The duodenum is the first segment of the small intestine. It’s largely responsible
for the continuous breaking-down process. The jejunum and ileum lower in the
intestine are mainly responsible for absorption of nutrients into the bloodstream.
Contents of the small intestine start out semi-solid, and end in a liquid form after
passing through the organ. Water, bile, enzymes and mucus contribute to the change
in consistency. Once the nutrients have been absorbed and the leftover-food residue
liquid has passed through the small intestine, it then moves on to the large intestine, or
colon.
Pancreas secretes digestive enzymes into the duodenum that break down
protein, fats and carbohydrates. The pancreas also makes insulin, passing it directly
into the bloodstream. Insulin is the chief hormone in your body for metabolizing sugar.
Liver processes the nutrients absorbed from the small intestine. Bile from the
liver secreted into the small intestine also plays an important role in digesting fat and
some vitamins.
Gallbladder stores and concentrates bile from the liver, and then releases it into
the duodenum in the small intestine to help absorb and digest fats.
