Download Digestive System Organs

Digestive System
Anatomy and Physiology
BIO 169
Turk
Digestive System
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Alimentary canal
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gastrointestinal (GI) tract
mouth, pharynx, esophagus,
stomach, small intestine,
and large intestine
accessory digestive organs
include
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teeth, tongue, gallbladder,
salivary glands, liver, and
pancreas
Digestive Processes
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Ingestion
Propulsion
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Mechanical digestion
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swallowing is followed by
peristalsis
chewing, mixing food with saliva,
churning, and segmentation
Chemical digestion
Absorption
Defecation
Digestive Processes
chemoreceptors and mechanoreceptors
 parasympathetic enhances secretory activities
and mobility
 sympathetic inhibits
digestive activity
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Digestive System Organs
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visceral peritoneum
parietal peritoneum
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peritoneal cavity
Mesentery
all digestive organs have four tunics
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Mucosa
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secretes mucus, digestive enzymes, and hormones
absorbs end products of digestion
protects against pathogens
Digestive System Organs
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Submucosa
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Muscularis Externa (aka muscularis)
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connective tissue with blood vessels, lymph vessels,
lymph nodes, and nerve fibers
responsible for segmentation and peristalsis
Serosa
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visceral peritoneum
adventitia
Digestive System Organs
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Mouth and Associated Organs
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oral cavity or buccal cavity
lined with stratified squmaous epithelium
Palate
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hard anterior and soft posterior
Tongue
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lingual frenulum
Filiform, fungiform, circumvallate
sulcus terminalis
Digestive System Organs
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Mouth and Associated Organs
cont.
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salivary glands
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bolus
parotid, submandibular, sublingual
serous cells
mucous cells
Amylase, mucin, lysozyme, and IgA
Digestive System Organs
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Mouth and Associated Organs cont.
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Teeth
Mastication
deciduous teeth (baby teeth or milk teeth)
Incisors, canines, bicuspids (premolars), and molars
Crown is enamel covered
dentin
pulp
Gingivitis and periodontitis
Digestive System Organs
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Pharynx
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oropharynx than laryngopharynx
inner longitudinal muscles
outer pharyngeal constrictor muscles
Esophagus
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cardiac (gastroesophageal) sphincter
Heartburn - hiatus hernia
Digestive System Organs
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Esophagus cont.
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Swallowing
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buccal phase
involuntary pharyngeal-esophageal phase
tongue blocks reentry into the mouth
soft palate closes off the nasopharynx
larynx rises so the epiglottis covers the respiratory
passages
peristalsis
Digestive System Organs
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Stomach
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where protein digestion begins
chyme (a creamy paste)
rugae (folds)
pyloric region is inferior and funnel shaped
Digestive System Organs
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Stomach cont.
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gastric pits lead to gastric glands that produce
gastric juices
parietal (oxyntic) cells
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secrete hydrochloric acid and intrinsic factor
chief (zymogenic) cells
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produce pepsinogen (inactive form of pepsin)
Digestive System Organs
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Stomach cont.
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mucosal barrier of bicarbonate-rich mucus
gastric ulcers
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pepsin is the enzyme involved in protein digestion
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hypersecretion of hydrochloric acid
hyposecretion of mucus
Helicobacter pylori
children also have rennin
alcohol and aspirin
Digestive System Organs
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Stomach cont.
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Gastrin
cephalic (reflex) phase
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triggered by sight, smell, taste, or
thought of food
gastric phase
intestinal phase
emetic center of the medulla
Digestive System Organs
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Small Intestine and Associated Structures
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pyloric sphincter to ileocecal valve
duodenum curves around the head of the pancreas
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hepatopancreatic ampulla
Jejunum
ileum
Digestive System Organs
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Small Intestine and Associated Structures cont.
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plicae circulares (circular folds)
Villi
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simple columnar absorptive cells
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Lacteal
Microvilli
brush border enzymes
goblet cells and enteroendocrine cells
duodenal glands secrete an alkaline mucus to
neutralize the stomach acid entering
Digestive System Organs
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Liver
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Bile in the common hepatic duct goes to the
duodenum
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fuses with the cystic duct that drains the gallbladder to
make the bile duct
liver sinusoids are very leaky capillaries
Kupffer cell (hepatic macrophages)
process nutrients – store fat soluble vitamins – help
with detoxification of the blood
Digestive System Organs
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Liver
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Hepatitis
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HVB, HVC, HVD
HVA
Cirrhosis
bile contains bile salts, bile pigment, cholesterol,
natural fats, phospholipids, and electrolytes
bile salts emulsify fats to facilitate fat and
cholesterol absorption
bilirubin
Digestive System Organs
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Gallbladder
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stores bile not immediately needed and
concentrates it
cholecystokinin (CCK)
gallstones
Digestive System Organs
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Pancreas
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main pancreatic duct fuses with the bile duct
acini – clusters of secretory cells surrounding ducts
pancreatic islets (islets of Langerhans) which
release insulin and glucagon
pancreatic juice is alkaline
Digestive System Organs
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Large Intestine
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ileocecal valve to the anus
absorb water from food residue and eliminate it as
feces
teniae coli
Haustra
Cecum with veriform appendix
Digestive System Organs
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Large Intestine
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Ascending colon
transerse colon
descending colon
sigmoid colon
Rectum
anal canal to the anus
involuntary internal anal sphincter
voluntary external anal sphincter
Digestive System Organs
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Large Intestine
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simple columnar epithelium
stratified squamous epithelium
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anal sinuses
haustral contraction
mass movements
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gastrocolic reflex
defecation reflex
Digestion
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Hydrolysis
Carbohydrates – monosaccharides
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Proteins - amino acids
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pepsin – works best in acidic conditions
Lipids (fats)
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digestion begins in the mouth (salivary amylase)
pancreatic amylase in the small intestine
lipases are relased by the pancrease
Nucleic Acids - nucleotides
Absorption
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active transport
absorption of iron and calcium occur in the
duodenum
95% of water is absorbed by the small intestine
by osmosis