Question | Answer |
What are the main functions of the Digestive System? | -Take in food
-Break it down into nutrient molecules
-Absorb molecules into the blood stream
-Rid body of any indigestible remains |
What are the six essential activities involved in the processing of food? | 1.Ingestion
2.Propulsion
3.Mechanical Breakdown
4.Digestion
5.Absorption
6.Defecation |
Define Ingestion | Eating |
Define Propulsion | Movement of food through the alimentary canal, which includes:
-Swallowing
-Peristalsis: Major means of propulsion of food that involves alternating waves of contraction and relaxation |
Define Mechanical Breakdown | includes chewing, mixing food with saliva, churning food in stomach, and segmentation. |
Define segmentation | Local constriction of intestine that mixes food with digestive juices |
Define Digestion | series of catabolic steps that involves enzymes that break down complex food molecules into chemical building blocks |
Define Absorption | passage of digested fragments from lumen of GI tract into blood or lymph |
Define Defecation | elimination of indigestible substances via anus in form of feces |
Define Peritoneum | serous membranes of abdominal cavity that consists of:
-Visceral Peritoneum
-Parietal Peritoneum |
Define Visceral Peritoneum | membrane on external surface of most digestive organs |
Define Parietal Peritoneum | membrane that lines body wall |
Define Peritoneal cavity | Fluid-filled space between two peritoneums |
What is the function of the Peritoneal Cavity? | Fluid lubricates mobile organs |
Define Mesentery | double layer of peritoneum; layers are fused back to back |
Where is mesentery located in the abdominal cavity? | Extends from body wall to digestive organs |
What are the functions of mesentery? | -Provides routes for blood vessels, lymphatics, and nerves
-Holds organs in place and also stores fat |
What are Intraperitoneal (peritoneal) organs? | organs that are located within the peritoneum |
What are Retroperitoneal organs? | located outside, or posterior to, the peritoneum
-Includes most of pancreas, duodenum, and parts of large intestine (also the kidneys) |
Define Peritonitis | Inflammation of peritoneum |
What are some of the causes of peritonitis? | Can be caused by piercing abdominal wound, perforating ulcer, or ruptured appendix |
What helps localize the infection in a patient with peritonitis? | Peritoneal coverings stick together, which helps localize infection |
When does peritonitis become lethal and dangerous? | When is becomes widespread |
What is the treatment of peritonitis? | debris removal and megadoses of antibiotics |
All digestive organs have the same four layers or tunics. What are the layers? | 1.Mucosa
2.Submucosa
3.Muscularis externa
4.Serosa |
What is the Splanchnic circulation ? | Arteries that branch off aorta to serve digestive organs:
-Hepatic, splenic, and left gastric arteries
-Inferior and superior mesenteric arteries |
What are the functions of the hepatic portal circulation? | -Drains nutrient-rich blood from digestive organs
-Delivers blood to liver for processing |
What is the enteric nervous system? | The GI tracts own nervous system.
-Also called the gut brain
-Contains more neurons than spinal cord |
What is the gut brain made of? | Enteric neurons that communicate extensively with each other
-Major nerve supply to GI tract wall that controls motility |
Enteric neurons make up bulk of two main interconnecting intrinsic nerve plexuses: | Submucosal nerve plexus
Myenteric nerve plexus |
What is the function of the submucosal nerve plexus? | Regulates glands and smooth muscle in mucosa |