The Gastrointestinal System

These flashcards cover key terms and definitions related to the gastrointestinal system as outlined in the lecture notes.

Primary function is to transfer nutrients, water, and electrolytes from ingested food into the body’s internal environment.

Digestive System

is secreted by the liver, breaks fats down into small particles,

• Actively secreted by liver and actively diverted to gallbladder between meals

• Stored and concentrated in gallbladder

bile

• Only enzyme secreted throughout entire digestive system that can digest fat 

• Pancreatic lipase

• Action mixes chyme with digestive juices throughout small intestine lumen and exposes chyme to all absorptive surfaces of small intestine mucosa

• Segmentation

pancteartic enzymes (Proteolytic enzymes)

• Trypsin

• Chymotrypsin

• Carboxypeptidase

break down proteins. 

Proteolytic enzymes

Converts polysaccharides into disaccharides

Pancreatic amylase

does the pancrease help digest carbs, fats, and proteins?

yes

secretes bicarbonate buffer to help neutralize the chyme in the small intestine, and it secretes enzymes that help digest all 3 major macromolecules:

pancrease

stimulated by presence of fat and protein in the duodenum which causes the pancreas to release lipase, which breaks down lipids (fats) and enzymes that can help break down proteins (proteolytic enzymes). 

CCK

stimulated by the presence of protein in the duodenum and stimulates chief and parietal cells to secrete more HCl. 

gastrin

stimulated by acidic chyme in the duodenum and stimulates (tells) the pancreas to release bicarbonate buffer.

Secretin

Keeps entrance closed to prevent large volumes of air from entering esophagus and stomach during breathing (think a circle)

Pharyngoesophageal sphincter

Prevents reflux of gastric contents by keeping your stomach contents inside your stomach.

Gastroesophageal sphincter

Muscular contractions that mix and move forward the contents of the digestive tract.

Motility

Push contents forward through the digestive tract.

Propulsive movements

Mixes food with digestive juices and facilitate absorption by exposing intestinal contents to absorbing surfaces of digestive tract

Mixing movements

Consist of water, electrolytes, and specific organic constituents released into the digestive tract lumen

Secretions

Biochemical breakdown of complex foods into smaller, absorbable units.

Digestion

The process by which complex molecules are broken down into absorbable units.

Enzymatic hydrolysis through digestion

Transfer of small units from digestive tract lumen into the blood.

Absorption

Innermost layer of the digestive tract lining the luminal surface and  is folded up extensively because this increases the surface area for nutrients to be absorbed. (think of a mop)

Mucosa

Thick layer of connective tissue providing elasticity to the digestive tract.

Submucosa

Major smooth muscle coat of the digestive tube responsible for motility.

Muscularis externa

secretes fluid for lubrication, prevents friction between digestive organs and surrounding viscera, Supports digestive organs in proper place while allowing them freedom for mixing and propulsive movements

Serosa

_________ is produced by the tongue and breaks long chain fats into smaller pieces

Lingual lipase

what food is called once you chew it and swallow it. 

bolus

Enzyme that converts polysaccharides into disaccharides.

Pancreatic amylase

• Store ingested food until it can be emptied into small intestine

• Secretes hydrochloric acid (HCl) and enzymes that begin protein digestion

• Mixing movements convert pulverized food to chyme

function of stomach

 food mixed with HCl in the stomach

Chyme

______ begins the digestion of carbohydrates.

Salivary amylase

• Involves receptive relaxation

  • Enhances stomach’s ability to accommodate the extra volume of food with little rise in stomach pressure

  • Triggered by act of eating

  • Mediated by vagus nerve

filling

Takes place in antrum of stomach

mixing

factors in the duodenum ____  emptying of the stomach into the duodenum:

prevent

Amount of chyme in stomach that influences the strength of contraction

this will PROMOTE emptying of the stomach into the duodenum. 

Factors in stomach

protects stomach lining from other secretions

Alkaline mucus

begins protein digestion when activated

Pepsinogen

activates pepsinogen, breaks down connective tissue, kills microorganisms

HCL

Substance that facilitates the absorption of Vitamin B12.

Intrinsic factor

factors in the dudonem that prevents emptying into the dudonom

ph, hypertonicity, fat, distension

Hormone that stimulates the release of bile and pancreatic enzymes.

Cholecystokinin (CCK)

Wave-like muscle contractions that move food through the digestive tract.

Peristalsis

Method of motility in the small intestine involving ring-like contractions.

Segmentation

Band of smooth muscle in the large intestine aiding in motility.

Taeniae coli

Initiated when stretch receptors in the rectal wall are stimulated by distension.

Defecation reflex

Include salivary glands, exocrine pancreas, liver, and gallbladder.

Accessory digestive organs

Occurs primarily in the small intestine, transferring water from the digestive tract into blood.

Water absorption

Vitamins are absorbed in conjunction with dietary fats, primarily in the small intestine.

Vitamin absorption

Include organs that contribute to digestion but are not part of the digestive tract itself.

Accessory organs of digestion

Stores and concentrates bile produced by the liver.

Gallbladder

Secretion of ___ in the stomach and other enzymes in the stomach that negin protein digestion

Hydrochloric acid (HCl)

Include pepsinogen, HCl, and intrinsic factor among others.

Gastric secretions

Derivatives of cholesterol that aid in fat digestion and absorption.

Bile salts

Organs that assist in digestion but are not part of the alimentary canal.

Accessory organs

Fairly straight muscular tube connecting the pharynx to the stomach.

Esophagus

A circular muscle at the bottom of the stomach that serves as a barrier between the stomach and the upper part of the small intestine, contracting to keep chyme from leaving the stomach and entering the small intestine too quickly. 

Pyloric sphincter

Microscopic finger-like projections of the intestinal mucosa that increase surface area for absorption.

Villi

First part of the large intestine, receiving material from the ileum.

Cecum

Part of the large intestine that extracts moisture and forms feces.

Colon

Enzyme secreted by the pancreas that digests fats into fatty acids and glycerol.

Pancreatic lipase

Include cephalic, gastric, and intestinal phases affecting gastric juices.

Gastric secretion phases

Include propulsive and mixing movements for food processing.

Motility functions

Accomplished through folding of the mucosa to increase absorption efficiency.

Absorptive area expansion

Biochemical catalysts that expedite the digestion of food.

Digestive enzymes

Neutralizes stomach acid in the small intestine.

Bicarbonate buffers

Simple sugars resulting from carbohydrate digestion.

Monosaccharides

waste moves through the large intestine too quickly, and not enough water is removed. 

This is what causes diarrhea. 

Massive contractions that move contents toward the rectum.

Mass movements in large intestine

Enhances digestive health and aids in regular bowel movements.

Dietary fiber roles