Digestive System Flashcards
What is the order & pathway of the digestive system ?
- Oral cavity (mouth)
- Pharynx
- Esophagus
- Stomach
- Small intestine
- Large intestine
- Rectum
* Salivary glands, pancreas, liver, & gallbladder aid in this process
A collection of 1 hundred million neurons that govern the function of the gastrointestinal system is known as ?
Enteric nervous system
*Peristalsis triggered = rhythmic contractions of the gut
The process of mechanical digestion is known as ?
Mastication (chewing)
What are the different components & functions of saliva ?
Salivary amylase (Ptyalin): hydrolyzes starch into smaller sugars
Lipase: catalyzes hydrolysis of lipids
*Tongue forms bolus
What are the 3 components of the pharynx ?
- Nasopharynx: behind nasal cavity
- Oropharynx: back of the mouth
- Laryngopharynx: above vocal cords
How is food prevented from entering the larynx when passing through the pharynx ?
By the epiglottis
The rhythmic contraction of smooth muscle that propels food forward toward the stomach is called what ?
Peristalsis
*Reverse process = emesis (vomiting) 🤮
What constitutes the upper esophageal sphincter ?
The muscles of the oropharynx (initiate swallowing)
What constitutes the lower esophageal sphincter (cardiac sphincter) ?
Muscular ring that relaxes & allows passage of the bolus
What are the 4 main anatomical divisions of the stomach ?
- Fundus + body: contain mostly gastric glands
2. Antrum + pylorus: contain mostly pyloric glands
The functions of gastric glands mainly consist of ?
Respond to signals from vagus nerve of parasympathetic NS
What are the 3 different cell types of the gastric glands ?
Mucosal: produce bicarbonate-rich mucus that protects the muscular wall from harsh acidic & proteolytic environment
Chief: secrete pepsinogen (zymogen of pepsin)
Parietal: as HCL, cleave pepsinogen into pepsin (digest proteins by cleaving peptide bonds); also secrete intrinsic factor (glycoprotein involved in absorption of B12)
What does pyloric glands contain ?
G cells: secrete gastrin (induces parietal cells to secrete more HCl & signal for stomach to contract)
The digestion of solid food in the stomach results in an acidic semifluid mixture known as ?
Chyme
Enzymes present on the surface of the duodenum that function to break down dimers & trimers of biomolecules into absorbable monomers is known as ?
Brush-border enzymes
What are the different types of peptidases & what are their functions ?
Aminopeptidases: cleave N-terminus from peptides
Dipeptidase: cleaves peptide bonds of dipeptides to free amino acids
Enteropeptidase: critical for activation of trypsinogen to trypsin (pancreatic protease)
Which peptide hormone causes for pancreatic enzymes to be released into the duodenum ?
Secretin
*Enterogastrone: slows motility through digestive tract
Cholecystokinin (CCK) is secreted in response to chyme in the duodenum. This peptide hormone then stimulates the secretion of bile & pancreatic juices. What are the functions of bile & pancreatic juices ?
- It is composed of bile salts, pigments, & cholesterol
- Bile salts are derived from cholesterol & play an important role in mechanical digestion of fats & chemical digestion of lipids; emulsify (mixes) fats & cholesterols into micelles (aggregates)
- complex mixture of several enzymes in a bicarbonate-rich alkaline solution
- aids in neutralizing chyme & providing ideal environment for digestion enzymes
The exocrine cells that produce pancreatic juices & compose the bulk of the pancreas & produce pancreatic enzymes is known as ?
Acinar cells
*Secrete products into major & minor duodenal papillae (empty intp duodenum)
What connects the liver with both the small intestine & gallbladder ?
Bile ducts
The liver takes up excess sugar to create what ?
Glycogen:: storage form of glucose
*Also stores fats as triacylglycerols
What is the major pigment of bile ?
Bilirubin: byproduct of the breakdown of hemoglobin
What does the small intestine consist of ?
- Duodenum: primarily involved in digestion
2. Jejunum + Ileum: primarily involved in absorption of nutrients
What are the 4 fat-soluble vitamins ?
A, K, E, D
*Everything else = water soluble
The large intestine is primarily involved in ?
H2O absorption
What are the components of the large intestine ?
Cecum: accepts fluid from small intestine through ileocecal valve & is site of attachment of appendix
Colon: absorb H2O & salts from undigested material; concentrates remaining material to form feces
Rectum: anus (internal & external sphincters)
Which enzyme is responsible for the hydrolysis of the C-terminal on peptide bonds, aiding in the digestion of proteins ?
Carboxypeptidases
Which enzyme cleaves the peptide bond @ the N-terminal, & aids in the digestion of proteins ?
Chymotrypsin
Which hormone (enzyme) causes for contraction of the gallbladder ?
Cholecystokinin
Which enzyme activates pancreatic digestive enzymes ?
Enteropeptidase
What enzymes do each region of the digestive system produce ?
Mouth: amylase, lipase
Stomach: Pepsin
Pancreas: Trypsin, chymotrypsin, carboxypeptidases A & B, amylase, lipase
Gallbladder: Bile micelles
Small intestine: dipeptidases, aminopeptidases, sucrase, lactase, maltase, isomaltase
Which enzyme produced in the duodenum activates trypsin ?
Enterokinase
What facilitates fat absorption in the small intestine by breaking down large fat droplets ?
Bile (in liver)
