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Still Digesting
Pharynx, esophagus, stomach, pancreas,
and liver
Pharynx
 Connects nasal and oral cavities to larynx
and esophagus
 3 Parts – you do not need to know def. of
each
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Nasopharynx – w/ nasal cavity provides
passage for breathing
Oropharynx – posterior to soft palate, inferior
to nasal cavity; passage for food from mouth,
and air to/from nasal cavity
Laryngopharynx – inferior to oropharynx,
passage to esophagus
Friday Writing Reflection
 On a sheet of paper to be turned in in Bin C
at the end of the period, please write 100150 words on the following prompt:
 Who are 2 people that you admire? Choose 1
adult (20+ years old) and 1 high school
student.


Why? What qualities do they embody?
How do they stand out from the rest of their
peers?
Epiglottis
 Directs food down into esophagus while
preventing food/liquids from entering
larynx/trachea
 Will get confused if you try to do too many
things at once…thus you choke
 Epiglottis Animation
 Swallowing Animation
Esophagus
 Straight collapsible tube, 25cm long
 Passageway for food from pharynx to
stomach
 Connects to stomach at cardiac sphincter
(thickened wall of circular smooth muscle)
Stomach
 Capacity 1 liter
 4 regions

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Cardiac – near esophagus
Fundic – temporary storage area
Body – main portion
Pyloric – end of stomach  pyloric canal

Ends in pyloric sphincter which controls gastric
emptying
Gastric Secretion
 Gastric juice – products of mucous cells,
chief cells, and parietal cells

Those 3 cells make up the gastric glands
Gastric Secretion cont.
Component
Source
Function
Pepsinogen
Chief cells from gastric
gland
Inactive form of pepsin
Pepsin
Formed when pepsinogen
reacts with acid
Protein splitting enzyme
that digests nearly all
types of dietary protein
Hydrochloric Acid (HCl)
Parietal cells from gastric
gland
Acid environment for
conversion of pepsinogen
to pepsin
Mucus
Goblet cells and mucous
glands
Provides viscous, alkaline
protective layer on the
inside stomach wall
Intrinsic factor
Parietal cells of the gastric Aids in Vitamin B12
glands
absorption
Regulation of Gastric Secretions
 Juice produced continuously; rate varies  controlled
neurally and hormonally
 Parasympathetic impulses on vagus nerve
stimulate stomach cells to release gastrin

Gastrin – peptide hormone that increases secretory
activity of gastric glands
 Sympathetic impulses in small intestine trigger
release of cholecystokinin

Cholecystokinin – hormone that decreases gastric
motility as small intestine fills with food
 Note: the stomach does not absorb nutrients…only
alcohol and some lipid soluble drugs
Moving out of the Stomach
 Chyme – semifluid paste of food particles
and gastric juice

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Moves into the duodenum (first portion of
small intestine)
Pancreas, liver, and gallbladder then add their
secretions
Secretin and cholecystokinin – hormones
secreted by duodenum to initialize pancreatic
secretions
Pancreas
 Secretes digestive juice  pancreatic juice
 Pancreatic duct extends the length of the pancreas
and connects to the duodenum
 Pancreatic juice

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Pancreatic amylase – enzyme that breaks down
carbs
Pancreatic lipase – enzyme that breaks down lipids
into fatty acids and glycerol
Nucleases – enzymes that break down nucleic acids
into nucleotides
Sodium bicarbonate – chemical released to
neutralize acid
Pancreas cont.
 Protein splitting enzymes:

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Trypsin, chymotrypsin, and
carboxypeptidase
Split bonds between amino acids in proteins
Released in inactive forms
Activated in small intestine by other enzymes

Ex. Trypsinogen is turned into trypsin by
enterokinase (produced by SI)
Liver
 Located in upper quadrant of abdominal
cavity just inferior to diaphragm
 Reddish, brown well supplied w/ blood
vessels
 Hepatic cells produce bile

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Bile contains several ingredients the most
important being bile salts
Bile salts break fat globules into smaller
droplets  emulsification
Lipases are then able to break them down
 Bile moves through hepatic ducts
Gallbladder
 Stores bile produced by the liver
 Cystic duct connects to the common
hepatic duct to form the common bile duct
 Be able to label these ducts on a diagram
of the liver/gallbladder