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AP Resources - Digestive System

 

Functions of the Digestive System

 

Digestive System Components

 

GI (gastrointestinal tract) ---refers to Digestive System---tubular portion from esophagus---anus

*overtime all parts of DS are referred to as GI

 

Tubular portion

---everything that goes thru from esophagus to anus

----4 distinct layers-----

 

Oral cavity---bounded by lips and cheeks—contains tongue, teeth and salivary glands

-----starting place for __________

 

---Lips---muscle with CT tissue skin---controlled by ________------cheek----_____ muscle—flattens cheek to hold food over teeth

 

-----Tongue----holds food over teeth, primarily attached at root, under the tongue---strip of tissue attaching anterior portion----frenulum----à aids in ________, _______, and _______ also is a sensory organ for taste)

 

--Motor controlled by______ cranial nerve---à ________

 

3 sets of salivary glands and what do they do? What Cranial nerve controls them?

 

Mechanical breakdown—mouth-à chew food-à big to little-à digestion of food---enzymes (amylase, breaks down 5% of ______) ---split chemical bonds

 

Teeth-----32, 16 top and bottom

 

------Palate----separates oral cavity from nasal cavity

 

2 parts 1.

 

2.

----Uvula----most posterior portion of soft palate---rises up during deglutination (swallowing), blocks nasal cavity so food only goes down the esophagus

 

Pharynx--- consists of series of structures that make op throat---

 

-----Larynx---has set of _________ pharyngeal constrictor muscles---take charge of food after chewed

 

Chew---mix with saliva---salivary amylase---back of throat---conscientious control stops

 

Digestive Process---voluntary (deglutination form to ball and push to back of throat) and involuntary phase (pharyngeal constrictor muscles ---take control ----1st set constrict, 2nd set, 3rd set (controlled by___________ cranial nerve)

 

----esophagus—hollow muscular tube---connects ______________to stomach, stratified squamous epithelium—formed in mucosa

 

---submucosa---large amount of mucous secreting glands—secreting into esophagus

 

---Stomach

 

Fundamental differences (compared to the tubular portion of the DS)

 

---Stomach Regions

 

Layers of stomach

 

---3 layers of smooth muscle—

a.

b.

c.

d. ----gastric pits( glands)

e. ---5 different types of epithelium in mucosa---

 

surface mucous cells

 

mucous neck cells

 

parietal cells

 

chief cells

 

G-cell

 

Autonomic enteric nerve plexies in DS---

 

one in sub mucosa

 

one between muscle layers

 

· receive stimulation from_____ cranial nerve- _________

 

3 functions

 

Small intestine----3 parts

 

________-1st portion( right after pyloric sphincter) about 1 ft in length, shortest, c-shape, most activity

 

Variety of modifications to mucosa---to increase volume to surface ratio 3 major modifications

 

i. plicaecircularis—folds in mucosa and submucosa—have finger like projections

 

ii. vili—finger like projections on plicacircularis

 

iii. microvilli—forest on villi

 

**modified surface area absorption increases 22,000ft2**

 

*between these there is loose fibrous CT, arteries, veins, and lacteal to absorb fat**

 

Cells associated with small intestine-----

 

absorptive cell-

 

goblet cells-

 

granular cells-

 

host of endocrine cell-

 

LOOK AT HAND OUT ON GASTRIN_SECRETIN_CCK_ AND GIP

 

Intestinal crypt-

 

Ideal pH of small intestine-

 

pH is kept this way by

 

1.

 

Duodenum==back to two muscle layers—inter circular and outer longitudinal separated by the auerbach plexus

 

Jejunum

 

. Ileum

 

Accessory organs are digestive in nature

 

liver

 

Functions:

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

 

*****THE LIVER DOESN’T PRODUCE DIGESTIVE ENZYMES********

 

Liver superficially

 

________ Major lobes—________ and________

 

----separated by the ________

 

Underside (inferior)

 

--minor lobes

 

****on the right major lobe****

 

__________-stores bile

 

Porta-gate

 

---place where hepatic portal vein enters the liver

 

--hepatic portal vein collects blood from all of the DS—enters liver

 

--branch of the hepatic artery (branch off the celiac trunk—branch off the aorta)

 

--hepatic ducts exit R & L one for each lobe come together and exit porta

 

Porta

 

Inside liver—divided up into a whole bunch of lobules by CT septa

----hepatocytes

 

----hepatic cord

 

Hepatic portal vein

 

Abdominal aorta

 

Superior side of liver

 

Hepatic artery

 

Hepatic portal vein

 

Drain liver

 

Central vein

 

---Spaced all around lobule---portal triads---contain 3 components

 

Circulation of liver

 

Flow of bile

 

Pancreas

 

Pancreatic Enzymes

 

--Pancreas---critical organ will produce death if we don’t have

 

Pancreatic duct-

 

LARGE intestine---

 

1st portion –_________

 

2nd portion---colon

 

----4 parts----

 

a. bend—hepatic flexure or R colic flexure

 

b. splenic flexure or L colic flexure

 

Colon gives rise to rectum_______2 sphincter muscles

 

1.

 

2.

 

3 band like structures______ pouches _________

 

Mesentery

 

Ommentum

 

Lesser ommentum—

 

Greater ommentum-

 

OVER VIEW OF DIGESTION FLOW

 

Chew-à mix with saliva-à salivary amylase-à back of throat-à conscientious control stops--à upper esophopharangeal sphincter relaxes( ring of smooth muscle)-à pharyngeal constrictor muscles constrict-à drop food into esophagus-à upper contracts---peristaltic( sequential contraction of muscualaris externa) moves from upper esophageal to lower esophageal-à lower esophageal( cardiac sphincter) -à opens food drops into stomach---à bolus of food into stomach—mix with digestive enzymes=semi fluid mixture called chyme---( semi fluid mixture of food and digestive enzymes)---à Stomach—lower esophageal (cardiac sphincter) and pyloric sphincter at bottom of stomach churn food with digestive enzymes----à sphincters stay closed-à stomach churns—>mix food-à chyme-à forced thru tonic pyloric sphincter( mostly closed)-à stomach contracts and squirts small amount of chyme into small intestine-----à

Carbohydrate breakdown---à starts in mouth—>salivary amylase—>small intestine---à pancreas will produce pancreatic amylase –>only capable of breaking down to disaccharide level—>border brush enzymes breakdown to final bonds, monosaccharide-à transported to intestinal mucosa--à as food is processed thru sm intestine—>segmental contractions--à peristaltic contractions-à illeocecal sphincter relaxes-à chyme-à into colon thru the illeocecal valveà colon is not interchangeable with large intestine, consists of more than just your colon

 

GOOD LUCK GUYS STUDY HARD AND YOU WILL ALL DO GREAT!!!!!!!!!!!!!!!