1. Gut Tube and Digestion Path of Food Liver and Pancreas Esophagus
Stomach
Small intestines
Large intestines
Rectum and anus
Liver and Pancreas
Digestion function
Role in glucose metabolism

2. Path of Food Mouth--chewing Pharynx--conscious swallowing
Esophagusu--transport to stomach
Stomach--mechanical
and chemical breakdown
Small Intestines--
chemical digestion and absorption
Large Intestines--
resorb water, form feces
Rectum---collect and expel feces

3. Esophagus Pharynx to stomach
Smooth muscle (conscious swallowing is in pharynx)
Passes through esophageal hiatus in diaphragm, stomach against inferior diaphragm
Cardiac orifice, with esophageal hiatus guard opening to stomach, prevent regurgitation
GERD--gastroesophageal reflux disease
Sometimes due to hiatal hernia
Lower esophagus becomes ulcerous and precancerous
Treat with antacids and other acid-reducing drugs

5. Stomach STRUCTURE FUNCTION
J-shaped but varies from “steerhorn” (high and horizontal) to vertically elongate (down to pelvis on tall, thin people)
From esophagus (cardiac orifice) to small intestine (pyloric sphincter)
Greater, lesser curvatures
FUNCTION
Mechanical breakdown of food--smooth muscle in wall
Protein breakdown--pepsin secreted by epithelial lining
Acidic conditions--for pepsin to work and to kill bacteria
Absorption of water, ions and some drugs (e.g., aspirin, alcohol)

7. Digestive Tract (adult gut tube) Wall
Internal = Mucosa
Epithelium
Lamina propria
Muscularis mucosae
Middle = Submucosa
CT w/ elastic fibers, nerves, vessels
Outer = Muscularis Externa
Inner circular layer
Outer longitudinal layer

8. Internal Anatomy of Stomach
Mucosa
Rugae: mucosal folds allow expansion
Typical Submucosa
Muscularis externa
Oblique layer
Circular layer
Pyloric sphincter
Longitudinal layer
Serosa
pg 648

9. Small Intestines Duodenum Jejunum Ileum
C-shaped initial piece (5% of total)
Entries for pancreatic, bile ducts
Jejunum
Fan-shaped coil (40% of total) at superior left abdomen
Ileum
Inferior right part of coil
End of appendix at lower right quadrant

10. Location of Duodenum

11. Small Intestine: Modifications for absorption
Length
Increase surface area
Plicae circularis
Transverse ridges of mucosa
Slow movement of chyme
Villi
Move chyme, increase contact
Contain lacteals: remove fat
Microvilli:
Modifications decrease distally
pg 653

12. Large Intestines Frame around rest of gut Teniae coli
Ascending, transverse, descending
Starts at cecum/appendix
Ends at rectum, anal canal
Teniae coli
“ribbons” or strips of muscle along length of colon (three around tube)
Tension in teniae coli forms haustra or sacs
Little continuous movement, but mass peristaltic movement several times daily to force feces towards rectum
Resorption of water from food

14. Rectum + Anal Canal Rectum Anal Canal (more with pelvis)
descends into pelvis
no teniae coli
longitudinal muscle layer complete
rectal valves
Anal Canal (more with pelvis)
passes through levator ani muscle
releases mucus to lubricate feces
Internal anal sphincter
involuntary, smooth m.
External anal sphincter
voluntary, skeletal m.
pg 655

15. Blood supply--ventral branches off of aorta
Celiac a.--to stomach, liver, pancreas, spleen, duodenum
Superior (cranial mesenteric a.--to small intestines and most of colon
Inferior (caudal) mesenteric a.--to descending colon, rectum

16. Innervation of gut Parasympathetic Sympathetic
What nerve?
Where does it run?
Sympathetic
Only thoracic output from spinal cord
Splanchnic nerves from thorax lateral to vertebral bodies bring posteriorly to abdominal cavity and gut
Synapse in celiac and superior mesenteric ganglia
Both Para- and Sympathetic follow aa. out to organs
High level of local control with network of synapses within ganglia and around gut
VAGUS
With aorta

17. Liver STRUCTURE FUNCTION
Large ventral organ of abdominal cavity with multiple lobes (learn them!!)
Sets against inferior surface of diaphragm on left side
Forms as outpocketing of gut--common bile duct is left as connection
Bile duct is two-way street (bile from hepatic duct is stored in gall bladder and later expelled to common bile duct to duodenum)
FUNCTION
Digestion--bile is digestive enzymes plus RBC breakdown product
Removes nutrients and toxins from blood (hepatic portal system brings gut blood directly to liver)
Glucose metabolism (with pancreas--see below)

18. Gallbladder Muscular sac Between right + quadrate liver lobes
Bile is stored + concentrated
Bile: breaks down fats = emulsification
Bile
Produced by liver
Stored in gallbladder
pg 659

19. Bile Ducts Cystic duct Hepatic duct Common Bile duct
carries bile from gallbladder
Hepatic duct
carries bile from liver
Common Bile duct
joins cystic and hepatic
carries bile into duodenum
pg 652

20. Movement of Bile Bile secreted by liver continuously
Hepatopancreatic (Vater) ampulla
common bile + main pancreatic duct meet and enter duodenum
Sphincter of Oddi around it
closed when bile not needed for digestion
Bile then backs up into gallbladder via cystic duct
When needed gallbladder contracts, sphincters open
pg 652

21. Liver: External Features
Diaphragmatic surface
Right lobe (larger)
Left lobe
Falciform ligament between
Fissure between
Visceral surface
Quadrate lobe
Caudate lobe
Both part of left lobe
pg 659

22. Liver: Blood Supply Hepatic Vein Hepatic Artery Hepatic Portal Vein
from inferior vena cava
Hepatic Artery
from abdominal aorta
Hepatic Portal Vein
Carries nutrient-rich blood from stomach + intestines to liver
Portal system = 2 capillary beds!
pg 660

23. Hepatic Portal System--concept
Fig , M&M
Directs blood that has already been through gut capillaries into liver capillaries (or sinusoids)
Allows nutrients and toxins to be removed from blood

24. Hepatic Portal System--anatomy

25. Pancreas STRUCTURE FUNCTION Smaller, diffuse gland
Head in C of duodenum
Tail extends towards spleen
FUNCTION
Digestion--produces most digestive enzymes
Glucose metabolism--Islets of Langerhans make insulin

26. Glucose metabolism
Liver receives blood from intestines (don’t forget hepatic portal system
After meal, in response to insulin from pancreas, glucose stored as complex carbohydrate--glycogen--in liver
Between meals, in response to glucagon from pancreas, glucose is released
Pancreas releases insulin when sugar levels in blood go up
Inadequate or zero insulin production results in hyperglycemia or high blood sugar
Overproduction or over-dosing of insulin results in hypoglycemia or low blood sugar--insulin shock
Diabetes is insufficient production of insulin
Type I--juvenile onset with elimination of Islets of langerhans and zero insulin production
Type II--adult onset with gradual loss of insulin production

27. “How Stuff Works” Diabetes: