Transcript The Alimentary Canal

The Alimentary
Canal
- the one way passageway for
food / nutrients / waste
Human Alimentary Canal
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Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Mouth
• True digestive organ
• physical & chemical
digestion
• Salivary Amylase
breaks carbohydrates
into
disaccharides/maltose
• contains teeth, tongue,
soft & hard palate to
help with physical
digestion
• food is ingested
Salivary Glands
• Accessory Organs
• produce salivary
amylase
– sublingual
– submandibular
– parotids
Pharynx
aka. The throat
• True digestive organ
• no physical or chemical digestion
occurs here
• hooks in with the respiratory system
Esophagus
• True digestive organ
• no physical or chemical
digestion occurs here
• food considered a BOLUS wet ball of chewed food
• PERISTALSIS starts here wavelike contractions of the
tube that moves the foodstuff
along the alimentary canal
Stomach
• Very muscular organ that
participates in both physical &
chemical digestion
• true digestive organ
• lined with thick protective
mucous
• the enzyme pepsinogen
activates in the acid conditions
in the stomach and becomes
pepsin
• pepsin digests the
proteins into groups of 2
amino acids
• cardiac sphincter valve
is at the top and the
pyloric valve is between
the stomach & small
intestine
• the bolus is now
considered chyme
Small Intestine
• True digestive organ
• chemical digestion is completed here
• contains 3 main portions
– duodenum first 10 cm of small intestine
– jejunum
next 2 ½ meters
– ileum
last 4 meters
•the role of the small
intestine is threefold
1. Finish digestion
2. Absorb nutrients
3. Storage
•contains villi for
absorption of nutrients
Small Intestine
Enzyme Action
• Common bile duct hooks into duodenum
• this hooks up to the pancreas and
gallbladder
• pancreatic juice & bile is secreted is
secreted through this
• BILE & bile salts- emulsifies the fat breaks into smaller droplets
• Pancreatic Juice contains:
– sodium bicarbonate / to neutralize the
acid from the stomach
– lipase / breaks fats into fatty acids &
glycerol
– trypsinogen in changed into trypsin in
the si. Environment and digests the
dipeptides into single amino acids
– pancreatic amylase finishes
carbohydrate digestion by breaking
disaccharides into monosacharides
• Increases the surface
area in the small
intestine for the
maximum nutrient
absorption
• monosaccharides &
amino acids are
diffused into the
capillaries 
bloodstream
• fatty acids & glycerol
are absorbed by the
lacteal which hooks into
the lymphatic system
Villi
Pancreas
• Accessory digestive
organ
• produces pancreatic
juice which contains
pancreatic amylase,
sodium bicarbonate,
trypsinogen and
lipase
• located under the
stomach
• LIVER
– produces bile which
breaks up the larger fats
• GALLBLADDER
– stores the bile until
needed
Large Intestine
• True digestive organ, but digestion is all done
by now!!!
• The function is to absorb water & minerals
• at the junction of the
small & large intestine
is the appendix
• there are 5 portions of the large intestine
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ascending colon
transverse colon
descending colon
sigmoid colon
rectum which ends in the anal sphincter
methane in is a normal bi-product and
in combination with e. coli bacteria produce
flatulence
• At this point the waste products are referred
to as feces
• CONSTIPATION - waste sits in large intestine
too long and the stool becomes too hard and
is difficult to evacuate
• DIARRHEA - waste does not sit in the large
intestine long enough and not enough water
is absorbed  producing a watery stool
Hormones of the Digestive System
• GASTRIN – cells of the stomach
secrete into
bloodstream
– triggers cells of
stomach to secrete
hydrochloric acid so
pepsinogen converts
to pepsin
• SECRETIN – when food enters the
small intestine
– secreted by the cells
of si. Into the
bloodstream
– triggers pancreas to
make pancreatic
juice