Digestive System

digestive tract

muscular tube that extends from the oral cavity to the anus

Accessory organs

not part of the digestive tract, but assist in digestion

defecation

elimination of wastes from the body, feces

Peritoneal fluid

produced by the peritoneum, Lubricates surfaces and reduces friction and irritation

Ascites

abdominal swelling due to buildup of peritoneal fluid (Associated with liver disease, kidney disease and heart failure)

mesenteries

double sheets of peritoneal membrane that suspend portions of digestive tract within the peritoneal cavity

Falciform ligament

stabilizes the position of the liver relative to the diaphragm and abdominal wall, marks the path of the fetal umbilical vein

Muscularis mucosae

thin layer of smooth muscle and elastic fibers deep to the lamina propria, Muscle contractions alter the shape of the lumen. Moves epithelial plates and groves.

Peristalsis

waves of muscular contractions that move a bolus along the length of the digestive tract

Uvula

dangling process at the posterior margin of the soft palate that prevents food from entering the pharynx too soon

Frenulum of tongue

thin fold of mucous membrane along inferior midline, which connects the tongue to the floor of the oral cavity

Enamel

hard calcified substance that covers the dentin, covers the crown of a tooth

Parotid glands

Located inferior to the zygomatic arch. Produce serous secretion containing salivary amylase, an enzyme that break down starches. A blockage of the ducts would interfere with carbohydrate digestion in the mouth

Sublingual glands

Covered by the mucous membrane of the floor of the mouth, produce mucus, which acts as a buffer and lubricant

GERD

Resting muscle tone keeps the esophagus closed to

prevent air from entering and backflow of materials

from the stomach (upper and lower esophageal

sphincters) lower esophageal sphincter is too loose allowing

acidic chyme into the esophagus

Buccal phase Deglutition (swallowing)

First phase, Voluntary, Bolus (food) enters oropharynx

Stomach Functions

Temporary storage of ingested food, Denaturation of proteins, Mechanical digestion with muscular contractions, Initiation of protein digestion (questions is function all of the following except)

Ghrelin

This hormone functions to stimulate hunger

Cardia

around the junction with the esophagus, Region of the stomach that the esophagus connects to

Pyloric part

between the body and the duodenum, Empties into the duodenum

Pyloric Part, Fundus, Lesser curvature

Label all red boxes. (Very important)

Gastric pits

shallow depressions that open onto the gastric surface

Parietal cells

Secrete intrinsic factor

Chief cells

Secrete pepsinogen (is converted to pepsin (enzyme that digest

proteins))

Rennin (chymosin)

coagulates milk proteins, Stomachs of newborn infants also produce enzymes

important for the digestion of milk

G cells

produce the hormone gastrin

D cells

release hormone somatostatin (which inhibits release of gastrin)

Cephalic phase

Controlled by the CNS, CNS sensory or cognitive activation stimulates the stomach

Gastric phase

Triggered by food entering into the stomach

Pancreatic juice

alkaline (pH 7.5-8.8) and contains digestive buffers, enzymes, water, and ions. Secretion is triggered by secretin and CCK

Pancreatic juice response to Secretin

Secretes a fluid rich in bicarbonate ion

Pancreatic juice response to CCK

Secretes a fluid rich in enzymes

bile

The liver synthesizes _______. Which contains water, ions, bilirubin, cholesterol and salts. The salts break lipid droplets apart (emulsification) and promote the absorption of lipids

portal hypertension

A blood clot blocking flow through the liver might

cause_________

gallbladder

bile is stored in the _______

cystic duct

_______ from the gallbladder unites with the common hepatic duct to form the bile duct

Cholecystitis

inflammation of the gallbladder

Small intestine

Long, muscular tube, Chemical digestion is completed, 90% of nutrient absorption occurs

Circular fold

permanent, transverse folds in the intestinal lining, Increase the surface area for absorption

Intestinal villi

fingerlike projections of the mucosa, Covered by simple columnar epithelium with

microvilli that form the brush border, Increase the surface area for absorption

Ileum

has no circular folds in its distal portion, Lamina propria contains Peyer's patches

Brush border enzymes

integral membrane proteins on intestinal microvilli

Gastroenteric reflex

stimulates motility and secretion along entire small intestine

Gastroileal reflex

triggers opening of the ileocecal valve and allows materials to pass from the small intestine into the large intestine, Moves some chyme into the colon

Secretin

released when chyme arrives in the duodenum

Gastric inhibitory peptide (GIP)

secreted when lipids and carbohydrates enter the small intestine. Inhibits gastric activity and promotes the release of insulin

1. Stomach

2. Duodenum

3. Jejunum

4. Ileum

5. Cecum

Structure food passes through GI system:

Digestive enzymes

Break molecular bonds in large organic molecules, such as carbohydrates, proteins, lipids, and nucleic acids, in a process called hydrolysis

Bile salts

emulsify lipids

Cecum

pouchlike initial segment, Receives and stores materials arriving from the ileum via the ileocecal valve

Appendix

slender, hollow worm-like structure attached to posteromedial surface of the cecum

Colon

largest segment of large intestine

Haustra

pouches in the wall of the colon that permit expansion and elongation

Teniae coli

longitudinal bands of smooth muscle that run along the outer surface of the colon, deep to the serosa

Transverse colon

Begins at the right hepatic colic flexure and crosses the abdomen from right to left

Descending colon

Proceeds inferiorly from the left splenic colic flexure along the left side of the abdomen to the iliac fossa

Vitamin K, Biotin, Vitamin

Vitamins produced by bacteria in the colon

Organic wastes

Bacteria in the large intestine convert bilirubin to urobilinogens and stercobilinogens. Color of feces due to heme breakdown

Elimination of feces- Defecation reflex

Requires the relaxation of the internal and external anal sphincters