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Questions and Answers
What is the primary function of enteropeptidase in digestion?
What is the primary function of enteropeptidase in digestion?
Which enzymes are released by pancreatic secretion to aid in digestion?
Which enzymes are released by pancreatic secretion to aid in digestion?
What type of transport is primarily used for the absorption of monosaccharides?
What type of transport is primarily used for the absorption of monosaccharides?
What is the final route to the bloodstream for carbohydrates and amino acids?
What is the final route to the bloodstream for carbohydrates and amino acids?
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What form do lipids take before entering the bloodstream?
What form do lipids take before entering the bloodstream?
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What role do amino acids play in the body?
What role do amino acids play in the body?
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Which enzyme is released in the stomach and activated by HCl?
Which enzyme is released in the stomach and activated by HCl?
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What triggers the release of the hormone Gastrin in the stomach?
What triggers the release of the hormone Gastrin in the stomach?
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Which enzyme is released by the pancreas in the small intestine?
Which enzyme is released by the pancreas in the small intestine?
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What is the stimulus for the release of CCK in the small intestine?
What is the stimulus for the release of CCK in the small intestine?
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What is the primary hormone released by G cells of the stomach in response to the arrival of food?
What is the primary hormone released by G cells of the stomach in response to the arrival of food?
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Which enzyme is activated by hydrochloric acid (HCl) in the stomach?
Which enzyme is activated by hydrochloric acid (HCl) in the stomach?
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Which of the following enzymes is NOT released from the pancreas into the small intestine?
Which of the following enzymes is NOT released from the pancreas into the small intestine?
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What activates trypsin in the duodenum?
What activates trypsin in the duodenum?
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What type of transport mechanism is primarily used for the absorption of amino acids in the intestinal mucosa?
What type of transport mechanism is primarily used for the absorption of amino acids in the intestinal mucosa?
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What happens to lipids after absorption in the intestines?
What happens to lipids after absorption in the intestines?
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Which pancreatic enzyme specifically digests polypeptides into short peptides?
Which pancreatic enzyme specifically digests polypeptides into short peptides?
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Where do carbohydrates and amino acids enter the bloodstream after absorption?
Where do carbohydrates and amino acids enter the bloodstream after absorption?
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What hormone is released in response to the anticipation or arrival of food in the stomach?
What hormone is released in response to the anticipation or arrival of food in the stomach?
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Which enzyme is activated from pepsinogen in the stomach?
Which enzyme is activated from pepsinogen in the stomach?
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What triggers the release of CCK in the small intestine?
What triggers the release of CCK in the small intestine?
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Which of the following enzymes is NOT released by the pancreas?
Which of the following enzymes is NOT released by the pancreas?
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How are lipids absorbed into the bloodstream?
How are lipids absorbed into the bloodstream?
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What structure do lipids primarily use to travel to the left subclavian vein?
What structure do lipids primarily use to travel to the left subclavian vein?
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What is activated by enteropeptidase in the small intestine?
What is activated by enteropeptidase in the small intestine?
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Which of the following is the end product of lipid digestion that can diffuse into the intestinal mucosa?
Which of the following is the end product of lipid digestion that can diffuse into the intestinal mucosa?
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What is one of the main digestive functions of the liver?
What is one of the main digestive functions of the liver?
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What role do bile salts play in fat digestion?
What role do bile salts play in fat digestion?
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What are micelles primarily made of?
What are micelles primarily made of?
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What role does the gallbladder serve in digestion?
What role does the gallbladder serve in digestion?
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What is produced by hepatocytes in the liver?
What is produced by hepatocytes in the liver?
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Where do chylomicrons transport fat-soluble substances?
Where do chylomicrons transport fat-soluble substances?
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How much bile does the liver secrete roughly per day?
How much bile does the liver secrete roughly per day?
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What are hepatocytes primarily involved in?
What are hepatocytes primarily involved in?
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Which duct connects the liver and duodenum for bile flow?
Which duct connects the liver and duodenum for bile flow?
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How do Kupffer cells relate to liver function?
How do Kupffer cells relate to liver function?
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What is the primary exocrine function of the pancreas?
What is the primary exocrine function of the pancreas?
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What is one role of secretin in the digestive process?
What is one role of secretin in the digestive process?
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Which pancreatic enzyme is specifically responsible for digesting carbohydrates?
Which pancreatic enzyme is specifically responsible for digesting carbohydrates?
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What substance is secreted by the pancreas to neutralize acidic chyme?
What substance is secreted by the pancreas to neutralize acidic chyme?
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How are protein-digesting enzymes released from the pancreas?
How are protein-digesting enzymes released from the pancreas?
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Which cells in the pancreas are responsible for hormone production?
Which cells in the pancreas are responsible for hormone production?
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What is the primary function of bile produced by the liver?
What is the primary function of bile produced by the liver?
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Where do pancreatic juices enter the digestive system?
Where do pancreatic juices enter the digestive system?
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Which of the following substances is NOT produced by the pancreas?
Which of the following substances is NOT produced by the pancreas?
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What type of fluid do pancreatic duct cells secrete?
What type of fluid do pancreatic duct cells secrete?
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Study Notes
Accessory Digestive Organs
- Accessory digestive organs are not part of the alimentary canal
- They secrete digestive enzymes into the canal, aiding in digestion
- Include salivary glands, pancreas, liver, and gallbladder
Pancreas: Location and Secretions
-
Lies behind the stomach, retroperitoneal
-
Exocrine function: Acinar cells secrete pancreatic juice into the duodenum
- Digestive enzymes:
- Pancreatic amylase (carbohydrates)
- Pancreatic lipase (lipids)
- Protein-digesting enzymes (inactive to prevent pancreas damage):
- Trypsinogen → Trypsin
- Chymotrypsinogen → Chymotrypsin
- Procarboxypeptidase → Carboxypeptidase
- Digestive enzymes:
-
Alkaline fluid (NaHCO3) neutralizes acidic chyme from the stomach
Pancreas Histology
- Pancreatic acini: Clusters of exocrine cells producing pancreatic juices.
- Pancreatic islets (Islets of Langerhans): Endocrine cells producing hormones insulin and glucagon
Control of Pancreatic Secretions
- Secretin: Carried by blood; stimulates pancreatic duct cells to secrete aqueous NaHCO3 into the duodenum.
- CCK: Carried by blood; stimulates pancreatic acinar cells to secrete digestive enzymes into the duodenum
Liver
- Large organ (~3 lbs), enclosed in the rib cage, inferior to the diaphragm.
- Over 200 functions!
- a) Digestive functions:
- Produces bile for fat digestion
- Detoxifies and processes blood from the digestive system.
- Nutrient storage (blood sugar regulation)
- b) Other main function:
- Plasma protein production (e.g., albumin)
- a) Digestive functions:
Liver Blood Flow
- Blood coming from the digestive system enters the liver through hepatic portal vein
- Blood from hepatic portal veins and hepatic arteries enters sinusoids
- Sinusoids supply hepatocytes
- Hepatocytes produce bile
Bile Salts and Fat Digestion
- Bile salts are a component of bile, essential for fat digestion, but do not contain any enzymes.
- Emulsification: Bile salts physically separate large fat globules into smaller fat droplets suspended in an aqueous solution.
- Increases lipase's surface area to chemically break down fats.
Micelles and Chylomicrons
- Micelles: Water-soluble transport vesicles formed by bile salts (and lecithin).
- Micelles surround lipid-soluble substances like fatty acids, triglycerides, fat-soluble vitamins, and cholesterol, aiding absorption.
- Chylomicrons: Large fat-soluble particles, formed from micelle contents, which move from the small intestine epithelium to lymphatic vessels (lacteals).
Bile Duct System
- Right and left hepatic ducts merge to form the common hepatic duct
- Cystic duct connects the gallbladder to the common bile duct
- Common bile duct and pancreatic duct merge as they enter the duodenum forming the hepatopancreatic ampulla (Ampulla of Vater).
Duodenal (Hepatopancreatic) Ampulla
- Enters lumen of duodenum, releasing bile from the liver and digestive enzymes from the pancreas
Role of CCK
- CCK release in the duodenum causes dilation of the hepatopancreatic sphincter and gallbladder contraction.
- This releases bile into the duodenum through the duodenal ampulla.
Regions of Large Intestine
- Cecum: First sac-like part of the large intestine, with the appendix attached.
- Ascending colon: Travels up the right side of the abdomen.
- Transverse colon: Travels across the abdominal cavity.
- Descending colon: Travels down the left side.
- Sigmoid colon: S-shaped portion, which turns posteriorly into the pelvis.
- Rectum: Anterior to the sacrum and coccyx.
Haustra & Taenia Coli
- Taenia coli: Incomplete longitudinal muscularis externa, forming three thin bands.
- Haustra: Sac-like pouches formed by the bands of taenia coli.
- Haustral contractions: Ring-like contractions at 1 every 30 minutes, aiding in movement.
Large Intestine Bacteria ("Good" Bacteria)
- Bacteria accumulate in the large intestine due to slow motility.
- 500-1000 species estimated in the colon, some beneficial functions:
- Prevent pathogenic bacterial growth
- Breakdown dietary fiber (produces gas)
- Promote motility
- Maintain mucosa
- Synthesize vitamin K (for blood clotting and bone health)
Final Water Absorption in Large Intestines
- Small intestine reabsorbs 7800 mL of water
- Colon reabsorbs 1250 mL of water
- 150 mL of water is lost in feces
Anal Canal
- Anal canal: Last 3 cm of the rectum, opening to the exterior.
- Internal involuntary sphincter: Smooth muscle
- External voluntary sphincter: Skeletal muscle
Defecation Reflex
- Defecation reflex: Rectum wall stretches, internal anal sphincter relaxes.
- Voluntary control of external anal sphincter to release contents
Digestion Summary
- Breaks down physical structure of food
- Disassembles component molecules (e.g., protein to amino acids)
- Molecules released into bloodstream
- Absorbed by cells (for energy or building new molecules)
Carbohydrates Digestion
- Salivary amylase in the oral cavity begins carbohydrate digestion
- Pancreatic alpha-amylase in the small intestine breaks down carbohydrates into disaccharides and trisaccharides
- Brush border enzymes (lactase, maltase, sucrase) break down disaccharides and trisaccharides into monosaccharides, which are absorbed.
Lipids Digestion
- Pancreatic lipase and bile salts break down lipids
- Lipids broken down into monoglycerides and fatty acids
- Monoglycerides and fatty acids absorbed into cells, forming triglycerides
- Triglycerides and other lipids combine to form chylomicrons, which are transported into lymphatic vessels (lacteals).
Proteins Digestion
- Pepsin in the stomach starts protein breakdown
- Pancreatic enzymes (trypsin, chymotrypsin, carboxypeptidase, elastase) break down polypeptides into smaller peptides and amino acids
- Brush border enzyme (dipeptidase) breaks down dipeptides into amino acids
- Amino acids are absorbed into cells.
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Description
This quiz explores the accessory digestive organs, focusing specifically on the pancreas. It covers aspects such as location, secretions, and histology, including the roles of pancreatic acini and islets. Test your knowledge on the functions and characteristics of these vital digestive components.
