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digestive system flashcards
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Card 1
Define digestion and distinguish between its mechanical and chemical forms.
Digestion is the process of breaking down food into forms that cell membranes can absorb. Mechanical digestion breaks down large pieces of food without altering its chemical composition, while chemical digestion uses enzymes to break down food molecules into simpler building blocks.
Card 2
Which of the following is NOT a primary function of the digestive system? A) Ingestion B) Secretion C) Filtration D) Absorption
C) Filtration. The primary functions of the digestive system include ingestion, secretion, propulsion, digestion, absorption, and defecation, but not filtration.
Card 3
What is peristalsis and what role does it play in the digestive system?
Peristalsis refers to the rhythmic contractions of smooth muscle that serve as a form of propulsion in the digestive system. It moves food through the alimentary canal.
Card 4
Name the three pairs of salivary glands and state which gland secretes the largest percentage of total saliva.
The three pairs of salivary glands are the parotid glands, submandibular glands, and sublingual glands. The submandibular gland secretes the largest percentage, accounting for 65-70% of total saliva.
Card 5
How is salivation primarily controlled, and which nervous system division is largely responsible?
Salivation is primarily controlled by the parasympathetic system in a reflex arc. Sensory stimuli communicate to the salivary nucleus in the brainstem, leading to parasympathetic fibers stimulating the salivary glands to release saliva.
Card 6
Which parts of the pharynx are considered part of the alimentary canal, and what is their primary function?
Only the oropharynx and laryngopharynx are part of the alimentary canal. Their primary function is the propulsion of food in the form of swallowing.
Card 7
What is deglutition, and what structures are involved in this process?
Deglutition, or swallowing, is a specialized type of propulsion that pushes a bolus of food from the oral cavity through the pharynx and esophagus to the stomach. It relies on the coordinated action of the tongue, soft palate, pharynx, and esophagus.
Card 8
In which parts of the alimentary canal is motility due to skeletal muscle, as opposed to smooth muscle?
Motility is due to skeletal muscle in the oral cavity, pharynx, superior portion of the esophagus, and the last portion of the large intestine. In the rest of the alimentary canal, motility is the work of smooth muscle.
Card 9
How does the nervous system regulate digestive processes?
The nervous system regulates digestive processes through the Autonomic Nervous System (ANS). The sympathetic system generally inhibits digestive processes, while the parasympathetic system stimulates them.
Card 10
What are gastric pits, and what type of cells are found between them in the stomach mucosa?
Gastric pits are heavy indentations in the stomach mucosa. Between these pits, columnar cells are found, which secrete mucus to protect the stomach cells from its own secretions.
Card 11
Where are gastric glands located, and what two types of cells do they contain based on their secretion destination?
Gastric glands are located at the base of the gastric pits. They contain endocrine cells that secrete hormones into the bloodstream and exocrine cells that secrete gastric juice into the lumen of the stomach.
Card 12
What do mucosal neck cells secrete, and what is the purpose of this secretion?
Mucosal neck cells secrete acidic mucus. This acidic mucus prevents it from neutralizing the acid produced by parietal cells, ensuring the stomach's acidic environment is maintained.
Card 13
Which cells in the gastric glands secrete HCl, and why is this acid important?
Parietal cells secrete HCl. This acid is important because it activates the precursor enzyme pepsinogen into its active form, pepsin.
Card 14
What do chief cells secrete, and what happens to this secretion when it encounters acid?
Chief cells secrete pepsinogen. When pepsinogen encounters acid, it becomes active pepsin, which is a digestive enzyme.
Card 15
What are Diffuse Neuroendocrine System (DNES) cells, and what specific hormone is mentioned as being secreted by G cells, a type of DNES cell?
DNES cells secrete many products similar to neurons and are close to blood vessels. G cells, a type of DNES cell, secrete the hormone gastrin, which stimulates acid production from parietal cells and cell division in the mucosa.
Card 16
What is the most important digestive enzyme in gastric juice, and what does it digest?
Pepsin is by far the most important digestive enzyme in gastric juice. It begins the digestion of nearly all types of protein.
Card 17
Besides pepsin, what other enzymes and factors are found in gastric juice, and what are their functions?
Gastric juice also contains gastric lipase, a fat-splitting enzyme, and intrinsic factor, which is necessary for vitamin B12 absorption in the small intestine.
Card 18
What happens to food in the stomach after mechanical and chemical digestion, and where does it go next?
After the stomach has completed churning and begun mechanical and chemical digestion, the food, now called chyme, is propelled through the pyloric sphincter into the duodenum.
Card 19
Which phase of gastric secretion is mediated by the sight, smell, taste, or thought of food?
The cephalic phase of gastric secretion is mediated by the sight, smell, taste, or thought of food. It prepares the stomach to receive food by increasing H+ ion release.
Card 20
How much of the H+ ion secretion is accounted for by the cephalic phase of gastric secretion?
The cephalic phase accounts for 30-40% of H+ ion secretion.
Card 21
What is the role of the vagus nerve in the cephalic phase of gastric secretion?
During the cephalic phase, the vagus nerve output results in direct stimulation of H+ release, stimulation of gastric secretion, and inhibition of somatostatin secretion, which normally inhibits acid secretion.
Card 22
Which of the following accurately describes the function of the small intestine's extensive blood supply? A) To filter waste products from the blood. B) To rapidly absorb digested nutrients. C) To produce digestive enzymes. D) To store undigested food.
B) To rapidly absorb digested nutrients. The chapter opener highlights that the small intestine's extensive blood supply allows for the rapid absorption of digested nutrients.
Card 23
Why is the secretion of acidic mucus by mucosal neck cells important for stomach function?
The acidic mucus secreted by mucosal neck cells is crucial because it prevents the mucus from neutralizing the acid produced by parietal cells. This maintains the highly acidic environment necessary for pepsin activation and bacterial killing in the stomach.
Card 24
What is the primary difference in the regulation of motility between the superior portion of the esophagus and the rest of the alimentary canal?
The superior portion of the esophagus, along with the oral cavity, pharynx, and last portion of the large intestine, relies on skeletal muscle for motility. The rest of the alimentary canal, however, uses smooth muscle for its motility.
Card 25
Explain the role of the endocrine system in regulating digestive system motility and secretion.
The endocrine system regulates digestive system motility and secretion by secreting hormones. Many of these are paracrines produced by the digestive system itself, particularly in the small intestine and stomach, influencing local digestive processes.
Card 26
What is the primary function of pepsin in gastric juice?
Pepsin is the most important digestive enzyme in gastric juice, responsible for beginning the digestion of nearly all types of protein.
Card 27
Which cells in the gastric mucosa secrete pepsinogen?
Chief cells secrete pepsinogen. When pepsinogen encounters acid, it becomes active pepsin.
Card 28
Define the role of G cells in the stomach.
G cells are a type of Diffuse Neuroendocrine System (DNES) cell that secrete the hormone gastrin. Gastrin, along with histamine, stimulates acid secretion from parietal cells and promotes cell division in the mucosa.
Card 29
What is the function of intrinsic factor, secreted in gastric juice?
Intrinsic factor is necessary for vitamin B12 absorption in the small intestine.
Card 30
Which of the following is NOT a primary function of the stomach? A) Secretion B) Propulsion C) Nutrient absorption D) Digestion
C) Nutrient absorption. While some minor absorption can occur, the bulk of nutrient absorption happens in the small intestine. The stomach's main functions are secretion, propulsion, and digestion.
Card 31
How does the Cephalic Phase prepare the stomach for food?
The Cephalic Phase is mediated by the sight, smell, taste, or thought of food. It prepares the stomach by increasing H+ ion release, stimulating gastric secretion, and inhibiting somatostatin secretion, which accounts for 30-40% of H+ ion secretion.
Card 32
What initiates the Gastric Phase of acid secretion?
The Gastric Phase begins when food enters the stomach. Stimuli include the presence of food in the stomach, which causes vagus and ENS neurons to release Ach, and the presence of partially digested proteins in gastric juice, which stimulates gastrin secretion.
Card 33
Which hormone is triggered by partially digested proteins in the duodenum and reduces acid secretion?
Secretin and GIP (gastric inhibitory peptide) are hormones triggered by partially digested proteins in the duodenum, both of which reduce acid secretion.
Card 34
What is receptive relaxation in the stomach?
Receptive relaxation occurs when food or liquid is swallowed, causing the gastroesophageal sphincter and smooth muscle of the fundus and body of the stomach to relax, allowing the stomach to fill. This is mediated by the medulla and vagus nerve.
Card 35
Distinguish between peristalsis and segmentation in the small intestine.
Peristalsis involves alternating contractions of longitudinal and circular smooth muscle layers to propel chyme towards the cecum. Segmentation, or intestinal churning, involves contractions in the circular layer to produce a squeezing motion for mechanical digestion and mixing chyme with enzymes and bile.
Card 36
What is the role of the ileocecal valve?
The ileocecal valve controls the movement of materials from the ileum into the cecum, preventing the backflow of materials into the small intestine, which is important due to the large number of bacteria in the large intestine.
Card 37
Which segment of the small intestine is the most active site for digestion and absorption?
The Jejunum is the middle portion of the small intestine and is the most active site for digestion and absorption.
Card 38
Name one vitamin produced by bacteria in the large intestine.
Bacteria in the large intestine produce vitamin K, which is necessary for blood clotting.
Card 39
How does fasting affect the Migrating Motor Complex (MMC)?
Fasting activates the Migrating Motor Complex (MMC), which is a cleaning wave that clears bacteria and food debris from the small intestine approximately every 90-120 minutes.
Card 40
What is Gastroesophageal Reflux Disease (GERD)?
GERD occurs when the gastroesophageal sphincter fails to remain closed, allowing acidic chyme from the stomach to regurgitate into the esophagus, leading to symptoms like pain and difficulty swallowing.
Card 41
Which of the following is a common treatment for GERD that blocks histamine receptors? A) Antacids B) Proton pump inhibitors C) H2 blockers D) Surgery
C) H2 blockers. H2 blockers work by blocking histamine receptors, which reduces acid secretion in the stomach to alleviate GERD symptoms.
Card 42
What happens to pepsinogen when it encounters acid?
When pepsinogen encounters acid, it becomes active pepsin, which is the digestive enzyme responsible for protein breakdown.
Card 43
What is the primary purpose of the stomach's churning function?
The stomach's churning function, produced by waves of peristalsis, is to mechanically digest food and propel chyme through the pyloric sphincter into the duodenum, while also pushing the rest back into the stomach for further processing.
Card 44
What effect does caffeine have on gastrin secretion?
Caffeine is one of the stimuli that can trigger gastrin secretion.
Card 45
Which phase of acid secretion accounts for 50-60% of total acid secretion?
The Gastric Phase accounts for 50-60% of total acid secretion, initiated by the presence of food and partially digested proteins in the stomach.
Card 46
What is the enterogastric reflex and what does it do?
The enterogastric reflex is triggered as chyme enters the duodenum, by declining pH and the presence of lipids. It decreases vagal activity and acid secretion, and also triggers the production of hormones like secretin and GIP.
Card 47
Why is it important that the duodenum mixes incoming chyme thoroughly?
The duodenum must mix the incoming chyme thoroughly before it moves to the rest of the small intestine to ensure proper mechanical digestion and mixing with intestinal, pancreatic enzymes, and bile for efficient chemical digestion and absorption.
Card 48
What role do enterocytes play in the small intestine?
Enterocytes, the cells of the small intestine, produce multiple digestive enzymes, hormones, and mucus. They are also responsible for absorbing chemically digested nutrients into the blood or lymph.
Card 49
What is the significance of the major duodenal papilla?
The major duodenal papilla is where secretions from the gallbladder and pancreas enter the small intestine, playing a crucial role in the chemical digestion process.
Card 50
How do bacteria in the large intestine deter the growth of harmful bacteria?
The intestinal flora in the large intestine deter the growth of harmful bacteria by preventing the growth of pathogenic microorganisms, contributing to gut health.
Card 51
What is the primary function of the jejunum in the small intestine?
The jejunum is the most active site for both digestion and absorption of nutrients within the small intestine.
Card 52
Define the term 'ileocecal valve' and state its function.
The ileocecal valve is a sphincter located between the ileum and the cecum. Its function is to control the movement of materials from the small intestine into the large intestine and prevent backflow.
Card 53
How do bacteria in the large intestine contribute to human health?
Intestinal flora produce essential vitamins like vitamin K, metabolize undigested materials such as soluble fiber, deter the growth of harmful bacteria, and stimulate the immune system.
Card 54
Which of the following is NOT a known function of bacteria in the large intestine? A) Produce vitamin K B) Metabolize undigested materials C) Directly absorb water from feces D) Stimulate the immune system
C) Directly absorb water from feces. While bacteria metabolize materials, the large intestine itself is responsible for water absorption, not the bacteria directly performing this function.
Card 55
What is the Migrating Motor Complex (MMC) and when is it activated?
The Migrating Motor Complex (MMC) is a cleaning wave that clears bacteria and food debris from the small intestine. It is activated during fasting, occurring approximately every 90-120 minutes.
Card 56
What is the main purpose of segmentation in the small intestine?
The main purpose of segmentation in the small intestine is mechanical digestion and mixing the chyme thoroughly with intestinal, pancreatic enzymes, and bile to facilitate chemical digestion and absorption.
Card 57
Which part of the large intestine is the primary site for water and electrolyte absorption and bacterial activity?
The proximal segment of the large intestine, consisting of the ascending and transverse colon, is the primary site for water and electrolyte absorption and bacterial activity.
Card 58
What is diverticulosis?
Diverticulosis is a condition where parts of the intestinal wall weaken, causing the inner mucosal membrane to protrude through, forming small sacs on the outer intestinal surface where chyme can accumulate and become infected.
Card 59
Name two common symptoms of colorectal cancer.
Common symptoms of colorectal cancer include a change in frequency and consistency of bowel movements, blood in feces, abdominal discomfort and pain, weight loss, fatigue, and unexplained vomiting.
Card 60
How is the defecation reflex initiated?
The defecation reflex is initiated by stretch receptors in the wall of the rectum, which are activated by fecal material. Sensory neurons then transmit impulses to the spinal cord.
Card 61
Why does diarrhea occur?
Diarrhea occurs when the large intestine does not absorb enough water, resulting in watery feces. This can be caused by irritation due to infection or drugs that stimulate the parasympathetic nervous system.
Card 62
What causes constipation?
Constipation is caused by the large intestine absorbing too much water, leading to hard stool. This can be due to factors such as drugs that block acetylcholine.
Card 63
What are acinar cells and what do they secrete?
Acinar cells are found in clusters called acini within the pancreas. They secrete digestive enzymes and other proteins, which are components of pancreatic juice.
Card 64
What makes pancreatic juice alkaline?
Pancreatic juice is made alkaline by the secretion of bicarbonate ions from the duct cells within the pancreas.
Card 65
Which hormone stimulates acinar cells to trigger the release of digestive enzymes from the pancreas?
Cholecystokinin (CCK) is the hormone that acts on acinar cells to trigger the release of digestive enzymes from the pancreas in response to lipids and partially digested proteins in the duodenum.
Card 66
What is the primary digestive function of the liver?
The primary digestive function of the liver is to produce bile, which is essential for the digestion and absorption of lipids.
Card 67
How does the liver contribute to detoxification?
The liver contributes to detoxification by metabolizing drugs and processing various substances ingested through food and drink, thus removing harmful compounds from the blood.
Card 68
What is bilirubin and how is it processed by the liver?
Bilirubin is a waste product from the breakdown of hemoglobin by the spleen. Hepatocytes in the liver secrete bilirubin into bile, and intestinal flora then convert it to urobilinogen and stercobilin for excretion.
Card 69
What is liver cirrhosis and what can cause it?
Liver cirrhosis is a condition resulting from long-term drug or alcohol use, where hepatocytes are damaged. The liver removes toxic substances from the blood, and chronic exposure to toxins can lead to this condition.
Card 70
Which of the following is a function of the liver? A) Producing stomach acid B) Storing glycogen C) Secreting insulin D) Initiating peristalsis in the small intestine
B) Storing glycogen. The liver stores glycogen, iron, and vitamins A, D, and B12 as part of its nutrient metabolism functions.
Card 71
Why is vitamin K, produced by large intestine bacteria, important?
Vitamin K, produced by bacteria in the large intestine, is necessary for blood clotting.
Card 72
During fasting, what happens to the production of digestive enzymes, bile, and stomach acid?
During fasting, the body produces less digestive enzymes, bile, and stomach acid, allowing the gut lining time to recover and reducing inflammation.
Card 73
What is the main purpose of the distal intestine (descending, sigmoid colon, rectum, and anal canal)?
The main purpose of the distal intestine is to store fecal material, although a small amount of water is still absorbed there.
Card 74
How does the parasympathetic nervous system influence the defecation reflex?
During the defecation reflex, parasympathetic neurons cause the smooth muscles in the sigmoid colon and rectum to contract, and the internal anal sphincter to relax, facilitating the passage of feces.
Card 75
Define bilirubin and explain its role in liver excretory function.
Bilirubin is a waste product from the breakdown of hemoglobin by the spleen. Hepatocytes secrete bilirubin into bile, which is then modified by intestinal flora and excreted, primarily as stercobilin.
Card 76
Which hormone stimulates the gallbladder to release bile?
The hormone cholecystokinin (CCK) stimulates the gallbladder to contract and release bile into the cystic duct.
Card 77
What are gallstones primarily composed of?
Gallstones are hard lumps primarily composed of calcium salts and cholesterol that can form in the gallbladder.
Card 78
Where does the chemical digestion of carbohydrates begin?
Chemical digestion of carbohydrates begins in the mouth with the help of salivary amylase, which breaks down polysaccharides into shorter oligosaccharides.
Card 79
What is lactose intolerance?
Lactose intolerance is a condition where individuals lack the enzyme lactase, making them unable to digest the milk sugar lactose.
Card 80
Where does the chemical digestion of proteins begin?
Chemical digestion of proteins begins in the stomach, where they encounter the enzyme pepsin.
Card 81
What is the role of pepsin in protein digestion?
Pepsin, activated from pepsinogen at a pH of 2, catalyzes reactions that digest about 10-15% of ingested proteins in the stomach.
Card 82
How do bile salts aid in lipid digestion?
Bile salts mix with lipids, physically breaking up large lipid globules into smaller ones, a process called emulsification, which increases surface area for enzymatic digestion.
Card 83
How is water absorbed in the alimentary canal?
Water is absorbed exclusively by osmosis in the alimentary canal, primarily in the small intestine and significantly in the large intestine.
Card 84
Which chemical is essential for the absorption of Vitamin B12?
Intrinsic factor, produced by the parietal cells of the stomach, is essential for Vitamin B12 to be absorbed in the ileum.
Card 85
What condition can result from a deficiency of Vitamin B12 due to a lack of intrinsic factor?
A deficiency of Vitamin B12 due to a lack of intrinsic factor can lead to pernicious anemia and nervous system problems.
Card 86
Which cells secrete bicarbonate ions to make pancreatic juice alkaline?
The duct cells of the pancreas secrete bicarbonate ions, which make pancreatic juice alkaline.
Card 87
What is the function of cholecystokinin (CCK) in pancreatic secretion?
CCK, produced by duodenal DNES cells in response to lipids and partially digested proteins, acts on acinar cells to trigger the release of digestive enzymes from the pancreas.
Card 88
How does secretin influence pancreatic secretion?
Secretin, released by duodenal cells in response to acid and lipids in the duodenum, is another stimulatory hormone for pancreatic secretion.
Card 89
What are some other functions of the liver besides producing bile?
Other functions of the liver include nutrient metabolism, detoxification of drugs and substances, storage of glycogen, iron, and vitamins A, D, and B12, and excretion of bilirubin.
Card 90
What is liver cirrhosis?
Liver cirrhosis is a condition where hepatocytes, overtaxed with detoxification, die and are replaced with scar tissue, often due to long-term drug or alcohol use.
Card 91
Which enzymes complete oligosaccharide digestion on the brush border of the small intestine?
Oligosaccharide digestion is completed by enzymes on the brush border of the small intestine, including lactase, maltase, and sucrase.
Card 92
How are fat-soluble vitamins absorbed?
Fat-soluble vitamins are packaged into micelles with fats and other lipids and are absorbed along with them.
Card 93
What is the role of pancreatic amylase?
Pancreatic amylase, produced by the small intestine, further breaks down carbohydrates into smaller oligosaccharides.
Card 94
Which of the following hormones is released by duodenal cells in response to acid and lipids in the duodenum? A. Cholecystokinin (CCK) B. Gastrin C. Secretin D. Insulin
C. Secretin. Secretin is released by duodenal cells in response to acid and lipids, stimulating pancreatic secretion.
Card 95
The main digestive function of the liver is to produce: A. Pepsin B. Amylase C. Bile D. Intrinsic factor
C. Bile. The liver's main digestive function is to produce bile, which is crucial for lipid digestion and absorption.
Card 96
Which of these is NOT a function of the liver? A. Nutrient metabolism B. Production of intrinsic factor C. Detoxification D. Storage of glycogen
B. Production of intrinsic factor. Intrinsic factor is produced by the parietal cells of the stomach, not the liver.
Card 97
Gallstones are typically formed from: A. Protein and water B. Calcium salts and cholesterol C. Glucose and vitamins D. Bile salts and enzymes
B. Calcium salts and cholesterol. Gallstones are hard lumps primarily composed of calcium salts and cholesterol.
Card 98
The process of physically breaking up large lipid globules into smaller ones is called: A. Hydrolysis B. Emulsification C. Absorption D. Detoxification
B. Emulsification. Emulsification is the physical breakdown of large lipid globules by bile salts, increasing surface area for enzymatic digestion.
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