DIGESTIVE SYSTEM
All living organism require food for energy and
organic matters for growth . food is organic compound and usually of plant or
animal origin . The major components of our food are carbohydrates , proteins
and fats . The process of conversion of complex food substances to simple
absorbable term is called digestion and is carried out by our digestive system
by mechanical and biochemical methods . The organs of the gastrointestinal
tract includes the mouth , pharynx , esophagus ,
stomach , small intestine , large intestine .
a)
Mouth :
The
mouth is formed by cheeks , palates , lips and tongue .
Teeth
:
Teeth
cut , tear and pulnerize food to reduce solids to smaller particles for
swallowing . majority of mammals have two sets of teeth . an adult human has 32
permanent teeth which is of 4 types namely incisors , canine , premolars , and
molars .
Tongue :
Movement
of tongue are important in guiding food within the mouth during chewing and
swallowing . further more the taste buds are located on the tongue .
B
) PHARYNX :
When
food is first swallowed , it passes from mouth into the pharynx , a funnel
shaped tube that extends from the internal nares to the esophagus posteriorly .
It acts as a common passage way for both the digestive system and the
respiratory system .
C
) ESOPHAGUS :
The
esophagus connects the pharynx to the stomach . It is a muscular tube
approximately 25 cm long . In the esophagus , the submucosa contains mucus
secreting submucosal esophageal gland . both submucosal and mucosal gland
secrete mucus for lubrication of esophageal epithelial linning . The esophagus
plays an important role in the chemical digestion of food .
D
) DIAPHRAGM :
The
diaphragm is an important part of the body digestive system . The muscular diaphragm separates the
thoracic cavity from the abdominal cavity where most of the digestive organs
are located . This muscle helps in flexure for the easy passage of digesting
material .
E
) STOMACH :
The
stomach is a major organ of the digestive system . It is a j shaped organ
joined to the esophagus at its upper end and to the duodenum at its lower end .
gastric acid produced in the stomach plays an important role in digestion . It
mainly composed of hydrochloric acid and sodium chloride . The stomach of a new
born baby will only be able to expand to retain about 30ml .
F
) SPLEEN :
The
spleen breaks down both red and white blood cells. A product of digestion is
the pigment bilirubin which is sent to the liver and secreted in the bile .
G
) LIVER :
The
liver is the second largest organ and is an accessory digestive gland which
plays a role in the body metabolism . the liver can detoxify various
metabolites , synthesis protein , and produce biochemical needed for digestion
. The liver also can synthesis glucose .
H
) GALL BLADDER :
The
gall bladder is a hollow part of the biliary tract that sits just beneath the
liver , with the gallbladder body resting in a small depression . It is divided
into fundu , body and neck .
I
) PANCREAS :
The
pancreas is a major part of digestive organ which has both endocrine and
exocrine gland . The endocrine gland secretes insulin when blood glucose is
high . The endocrine part releases glucagon when blood sugar is low . The
pancreas is also the main source of enzymes for digestion of fats and proteins
.
J
) SMALL INTESTINE :
Food
starts to arrive in the small intestine one hour after it is eaten , and after
two hours the stomach has emptied . In the small intestine , the pH becomes
crucial , it needs to be finely balanced in order to activate digestive enzymes
. when the digested food particles are reduced enough in size and composition ,
they can be absorbed by intestinal wall and carried to the bloodstream .
The
last part of the small intestine is the ileum . This also contains villi and
vitamin b12 , bile acids , and any residue nutrients are absorbed here .
K
) LARGE INTESTINE :
It
takes about 12 to 50 hours until it is removed by defecation . The colon mainly
serves as a site for the fragmentation of digestible matter by the gut flora .
The remaining semi solid waste is termed
feces and is removed by the coordinated contractions of the intestinal walls ,
termed peristalsis , which propels the excreta forward to reach the rectum and
exit via defecation from the anus .
The
6 major functions take place in the digestive system they are ,
· Ingestion
· Secretion
· Mixing
and movement
· Digestion
· Absorption
· Excretion
DIGESTIVE DISORDER :
Many diseases and health conditions such as ulcers ,
GERD , IBD and celiac disease .
