Digestive System

You are what you eatOh my!!!!

A. Overview of structure

1. Esophagus2. ???3. Stomach4. Liver5. Pyloric valve6. Pancreas7. Duodenum8. Jejunum9. Ileum10. Ileocecal valve-

appendix11. colon

B. Mouth

1. Different types of teeth2. Functions of tongue3. Uvula4. Salivary glands5. Salivary amylase6. Food bolus7. Mechanical digestion8. Deglutition

http://www.youtube.com/watch?v=wqMCzuIiPaM

C. Esophagus

1. 10” long2. Stratified squamous

epithelium3. Hiatal hernia4. GERD5. Peristalsis of bolus6. http://

www.youtube.com/watch?v=Q-n_Q0qKXzg

D. Stomach

1. Cardiac region2. Fundus3. Body4. Pyloric region5. Pyloric sphincter6. Rugae-full can hold 4 liters7. Storage tank8. Mechanical breakdown9.

http://www.youtube.com/watch?v=hpS5kMn_B0I&feature=related

9. Gastric pits

a. Produce gastric juiceb. Intrinsic factor-needed for

absorption of vit B c. Chief cells-pepsinogend. Parietal cells-HCle. Mucous neck cellsf. Enteroendocrine cells-D

and G cells produce hormones

g. rennin

10. Stomach physiology

a. Pepsinogen to pepsinb. Pepsin proteolyticc. Rennind. No other chemical digestione. Very little absorptionf. Aspirin and alcohol

11. Gastric motility

a. Peristalsis begins upper halfb. Increases in forcec. 3 ml or less squirts throughd. Rest is refluxed back into stomache. http://www.youtube.com/watch?v=hpS5kMn_B0If. http://www.youtube.com/watch?

v=o18UycWRsaA&feature=related

E. Small intestine

1. 7-13 feet2. Suspended by

mesentery3. Duodenum “twelve

finger widths”-5%4. Jejunum “empty”-40%5. Ileum “twisted

intestine”-60%6. Ileocecal valve7. Major digestive

structure

8. Structures adapted to increase surface area

a. Plicae circularisb. Microvillic. Villid. Lacteal-

lymphatic capillary

e. Modifications decrease in significance toward ileum

f. Peyer’s patches increase in number

9. Duodenuma. Shortest segment-

interesting featuresb. Pancreas opens herec. Bile enters from liverd. Brunner’s glands in tunica

submucosa-alkaline mucous

e. Crypts of Lieberkuhn-intestinal juice relatively enzyme poor but release lysozyme-antibacterial enzyme

10. Movements in small intestine

a. Modified peristalsisb. Peristalsis starts in duodenumc. Starts strong and dies downd. Next peristaltic wave starts further downe. Moves food a little further onf. Second type of muscular activityg. Segmentation http://www.youtube.com/watch?

v=GdNtRom-Pvsh. Kind of like making meatloafi. Random contractions superimposed upon peristaltic waves

11. Food breakdown via action of pancreas

a. Carbo and protein digestion already begunb. No fats digestedc. 3-6 hoursd. Endocrine functione. Pancreatic juices

-huge amount of digestive enzymes-pancreatic amylase-trypsin, chymotrypsin digest proteins-lipases-rich supply of bicarbonate

12. Liver-huge number of functions

a. Most important digestive function production of bile

b. Fat emulsifierc. Stored in gall bladderd. Large droplets scattered into

smalle. Increases surface area for

digestionf. Also improves fat and

cholesterol absorptiong. Excretion of bilirubinh. 500-1000 ml per day

13. Gall bladder

a. About size of kiwi fruitb. Stores bilec. Concentrates biled. Gall stones

F. Large intestine-a.k.a. colon

1. 5 feet but larger in diameter

2. Extends from3. Parts4. Appendix5. Longitudinal

muscle not continuous-three bands

6. haustra

7. Functions of large intestine

a. Few nutrients-remains for 12-24 hoursb. No digestive enzymesc. Resident bacteria

-many different species-sometimes described as the forgotten organ-evolved in a mutualistic relationship-metabolize remaining nutrients-make vitamin K and B complex-keep out harmful species

d. Dry residual materiale. Lubricate material for defecation

8. Propulsion of Residue and defecation

a. Haustral contractionsb. Mass movementsc. Sphincter muscles

9. Imbalances

a. Diverticulosisb. Diverticulitisc. Diarrhead. Constipation