p.23
Gastrointestinal Secretions Overview
What does the submucosa of the duodenum contain?
Duodenal glands (Brunner’s glands).
p.25
Digestive Enzymes and Their Functions
What are the main macronutrients involved in digestion?
Starch and disaccharides.
p.4
Salivary Glands and Saliva Composition
Where are the submandibular glands located?
On the floor of the mouth.
p.3
Salivary Glands and Saliva Composition
What types of glands are found in the mucous membrane of the mouth and tongue?
Labial, Buccal, Palatal, and Lingual glands.
p.5
Salivary Glands and Saliva Composition
What is the overall composition of saliva?
99.5% water and 0.5% solutes.
p.12
Digestive Enzymes and Their Functions
What is the role of pepsin in digestion?
To break down proteins into peptides.
p.3
Salivary Glands and Saliva Composition
What are Labial glands?
Salivary glands located in the lips.
p.26
Digestive Enzymes and Their Functions
What is the significance of emulsification in fat digestion?
It breaks down fats into smaller droplets, making them easier to digest.
p.26
Digestive Enzymes and Their Functions
What are triglycerides?
The main form of fat in the diet, composed of glycerol and three fatty acids.
p.14
Digestive Enzymes and Their Functions
How do bicarbonate ions exit the parietal cells?
In exchange for chloride ions (Cl−) via HCO3−–Cl− antiporters.
p.26
Bile Composition and Function
What is the role of bile in fat digestion?
It emulsifies fats, aiding in their digestion and absorption.
p.20
Bile Composition and Function
What are the main components of bile?
Water, bile salts, cholesterol, lecithin, bile pigments, and several ions.
p.10
Stomach Juice and Its Components
What is the function of the muscularis mucosae in the stomach?
It helps in the movement of the mucosa.
p.4
Salivary Glands and Saliva Composition
Where are the parotid glands located?
Inferior and anterior to the ears.
p.3
Salivary Glands and Saliva Composition
What is the primary function of saliva in the mouth?
To keep the mucous membranes moist and to cleanse the mouth and teeth.
p.26
Digestive Enzymes and Their Functions
What are macronutrients?
Nutrients required in large amounts, including carbohydrates, proteins, and fats.
p.11
Stomach Juice and Its Components
What is the pH level of gastric juice?
Typically between 1.5 and 3.5.
p.22
Hormonal Regulation of Digestion
How does CCK affect gastric emptying?
It slows down gastric emptying to allow for better digestion in the small intestine.
p.14
Digestive Enzymes and Their Functions
What does the dissociation of carbonic acid provide for proton pumps?
A ready source of H+ ions.
p.6
Salivary Glands and Saliva Composition
How does mucus function in the mouth?
It lubricates food, allowing it to be moved easily and swallowed.
p.13
Stomach Juice and Its Components
What happens to potassium ions (K+) during the transport process?
They are brought into the cell.
p.6
Salivary Glands and Saliva Composition
What is the role of Immunoglobulin A (IgA) in saliva?
It prevents the attachment of microbes to the epithelium.
p.15
Regulation of Saliva and Gastric Juice Secretion
How does histamine affect HCl secretion?
Histamine acts synergistically, enhancing the effects of acetylcholine and gastrin.
p.1
Gastrointestinal Secretions Overview
What is the focus of Lecture 4 in Human Anatomy and Physiology I?
The Digestive System (Part Two): Gastrointestinal Secretions.
p.28
Intestinal Juice and Its Role
What is the role of goblet cells in the large intestine?
Secretion of mucus to lubricate the passage.
p.28
Intestinal Juice and Its Role
What type of cells make up the epithelium of the intestinal mucosa?
Absorptive cells and goblet cells.
p.8
Regulation of Saliva and Gastric Juice Secretion
What stimulates salivary gland secretions?
The feel and taste of food.
p.3
Salivary Glands and Saliva Composition
What happens to saliva secretion when food enters the mouth?
Secretion of saliva increases to lubricate, dissolve, and begin the chemical breakdown of food.
p.13
Stomach Juice and Its Components
What do parietal cells secrete into the stomach lumen?
Hydrogen ions (H+) and chloride ions (Cl−).
p.3
Salivary Glands and Saliva Composition
Where do the small salivary glands open into?
Directly or indirectly via short ducts to the oral cavity.
p.15
Regulation of Saliva and Gastric Juice Secretion
What stimulates HCl secretion by parietal cells?
Acetylcholine (ACh), gastrin, and histamine.
p.24
Intestinal Juice and Its Role
What is the composition of intestinal juice?
A clear yellow fluid containing water, mucus, and is slightly alkaline (pH 7.6).
p.18
Regulation of Saliva and Gastric Juice Secretion
What is the function of the sphincter of the hepatopancreatic ampula?
Also known as the sphincter of Oddi, it regulates the flow of bile and pancreatic juice into the duodenum.
p.27
Intestinal Juice and Its Role
What is absorbed in the large intestine?
Some water, ions, and vitamins.
p.22
Hormonal Regulation of Digestion
What triggers the release of CCK?
The presence of fats and proteins in the small intestine.
p.5
Salivary Glands and Saliva Composition
What type of liquid do the parotid glands secrete?
A watery (serous) liquid containing salivary amylase.
p.29
Gastrointestinal Secretions Overview
What is the primary function of the large intestine?
To absorb water and electrolytes from indigestible food matter.
p.39
Phases of Digestion: Cephalic, Gastric, and Intestinal
What is the significance of partially digested food in digestion?
It is essential for further digestion and nutrient absorption in the intestines.
p.22
Hormonal Regulation of Digestion
What is the primary function of CCK in the small intestine?
To stimulate the release of digestive enzymes from the pancreas and bile from the gallbladder.
p.26
Phases of Digestion: Cephalic, Gastric, and Intestinal
What is the role of the mouth in digestion?
Initiates digestion through mechanical breakdown and saliva secretion.
p.11
Stomach Juice and Its Components
What role does mucus play in the stomach?
It protects the stomach lining from acid and digestive enzymes.
p.16
Digestive Enzymes and Their Functions
What is the function of gastric lipase?
It splits triglycerides into fatty acids and monoglycerides.
p.21
Intestinal Juice and Its Role
What are the three components of the mucosa?
Epithelium, lamina propria, and muscularis mucosae.
p.31
Phases of Digestion: Cephalic, Gastric, and Intestinal
What are the three overlapping phases of digestion?
Cephalic phase, gastric phase, and intestinal phase.
p.33
Regulation of Saliva and Gastric Juice Secretion
What does neural negative feedback regulate during the gastric phase?
The pH of gastric juice and gastric motility.
p.29
Gastrointestinal Secretions Overview
What is the role of the layers in the large intestine?
They help in the contraction and movement of food through the digestive tract.
p.13
Stomach Juice and Its Components
What is the net effect of the secretion from parietal cells?
The secretion of hydrochloric acid (HCl).
p.37
Hormonal Regulation of Digestion
What stimulates the secretion of secretin?
Acidic chyme entering the duodenum.
p.35
Phases of Digestion: Cephalic, Gastric, and Intestinal
What is the effect of reflexes during the intestinal phase?
They have inhibitory effects that slow gastric emptying.
p.13
Stomach Juice and Its Components
How do chloride ions (Cl−) and potassium ions (K+) exit into the lumen?
Through Cl− and K+ channels in the apical membrane.
p.14
Digestive Enzymes and Their Functions
What happens to bicarbonate ions after they exit the parietal cells?
They diffuse into nearby blood capillaries.
p.31
Phases of Digestion: Cephalic, Gastric, and Intestinal
Which parts of the brain are involved in the cephalic phase?
Cerebral cortex, hypothalamus, and brain stem.
p.41
Digestive Enzymes and Their Functions
What are the components of DNA mentioned?
Adenine (A), Inosine (I), Cytosine (C), Guanine (G).
p.23
Gastrointestinal Secretions Overview
What is the function of the alkaline mucus secreted by Brunner’s glands?
It neutralizes gastric acid in the chyme.
p.23
Digestive Enzymes and Their Functions
What are brush-border enzymes?
Enzymes located in the microvilli that have local digestive functions.
p.27
Intestinal Juice and Its Role
What processes drive contents of the colon into the rectum?
Haustral churning, peristalsis, and mass peristalsis.
p.11
Stomach Juice and Its Components
What is the primary function of the stomach?
To digest food and mix it with gastric juices.
p.8
Regulation of Saliva and Gastric Juice Secretion
How do chemicals in food affect salivation?
They stimulate receptors in taste buds, sending impulses to salivary nuclei in the brain stem.
p.4
Salivary Glands and Saliva Composition
Where are the sublingual glands located?
Beneath the tongue and superior to the submandibular glands.
p.6
Digestive Enzymes and Their Functions
What are the products of starch breakdown by salivary amylase?
Maltose, maltotriose, and α-dextrin.
p.8
Regulation of Saliva and Gastric Juice Secretion
What happens to saliva secretion after food is swallowed?
Saliva continues to be secreted heavily for some time.
p.3
Salivary Glands and Saliva Composition
What are Buccal glands?
Salivary glands located in the cheeks.
p.10
Stomach Juice and Its Components
What type of cells are G cells and what do they secrete?
G cells are endocrine cells that secrete gastrin.
p.3
Salivary Glands and Saliva Composition
What are Palatal glands?
Salivary glands located in the palate.
p.38
Phases of Digestion: Cephalic, Gastric, and Intestinal
What are the three phases of digestion?
Cephalic, Gastric, and Intestinal.
p.36
Hormonal Regulation of Digestion
What triggers the secretion of Cholecystokinin (CCK)?
Amino acids from partially digested proteins and fatty acids from partially digested triglycerides in the chyme.
p.1
Gastrointestinal Secretions Overview
What is the primary subject of gastrointestinal secretions?
The various fluids and enzymes produced in the digestive system.
p.18
Bile Composition and Function
What is the common bile duct?
A duct that carries bile from the liver and gallbladder to the duodenum.
p.22
Hormonal Regulation of Digestion
Where is CCK produced?
In the cells of the small intestine.
p.12
Stomach Juice and Its Components
What is the function of gastric pepsinogen?
It is a precursor to pepsin, which digests proteins.
p.25
Digestive Enzymes and Their Functions
What are the monosaccharides derived from the digestion of carbohydrates?
Galactose, glucose, and fructose.
p.16
Stomach Juice and Its Components
How are stomach epithelial cells protected from gastric juices?
By a layer of alkaline mucous 1-3 mm thick.
p.5
Salivary Glands and Saliva Composition
What organic substances are present in saliva?
Urea, uric acid, mucus, immunoglobulin A, lysozyme, and salivary amylase.
p.14
Digestive Enzymes and Their Functions
What ions are generated as carbonic acid dissociates?
Bicarbonate ions (HCO3−).
p.15
Regulation of Saliva and Gastric Juice Secretion
What is the role of gastrin in HCl secretion?
Gastrin, secreted by G cells, stimulates parietal cells to secrete more HCl.
p.37
Hormonal Regulation of Digestion
What is the primary function of secretin?
To stimulate the flow of pancreatic juice rich in bicarbonate ions to buffer acidic chyme.
p.35
Phases of Digestion: Cephalic, Gastric, and Intestinal
Why is it important to slow gastric emptying during the intestinal phase?
To prevent the duodenum from being overloaded with more chyme than it can handle.
p.32
Phases of Digestion: Cephalic, Gastric, and Intestinal
What initiates the gastric phase of digestion?
Once food reaches the stomach.
p.14
Hormonal Regulation of Digestion
What is the effect of the 'alkaline tide' after a meal?
It may elevate blood pH slightly and make urine more alkaline.
p.19
Pancreatic Juice and Digestive Enzymes
What does pancreatic juice create for digestive enzymes?
The proper pH for their action in the small intestine.
p.18
Bile Composition and Function
What is the hepatopancreatic ampula?
Also known as the ampula of Vater, it is where the bile duct and pancreatic duct meet.
p.6
Salivary Glands and Saliva Composition
What is the primary function of saliva in relation to food?
It provides a medium for dissolving foods so they can be tasted and digestive reactions can begin.
p.10
Stomach Juice and Its Components
What type of cells are responsible for producing mucus in the stomach?
Surface mucous cells and mucous neck cells.
p.8
Regulation of Saliva and Gastric Juice Secretion
Which cranial nerves are involved in stimulating saliva secretion?
Facial (VII) and glossopharyngeal (IX) nerves.
p.4
Salivary Glands and Saliva Composition
Where do the lesser sublingual ducts open?
Into the floor of the mouth in the oral cavity proper.
p.6
Salivary Glands and Saliva Composition
What role do bicarbonate and phosphate ions play in saliva?
They buffer acidic foods, keeping saliva slightly acidic (pH 6.35 - 6.85).
p.8
Regulation of Saliva and Gastric Juice Secretion
What is the role of saliva after swallowing food?
It washes out the mouth and dilutes and buffers irritating chemicals.
p.35
Phases of Digestion: Cephalic, Gastric, and Intestinal
What marks the beginning of the intestinal phase of digestion?
Once food enters the small intestine.
p.19
Pancreatic Juice and Digestive Enzymes
What is the daily production of pancreatic juice?
1.2 to 1.5 liters per day.
p.7
Regulation of Saliva and Gastric Juice Secretion
What type of stimulation promotes continuous saliva secretion?
Parasympathetic stimulation.
p.19
Pancreatic Juice and Digestive Enzymes
What is the pH range of pancreatic juice?
Slightly alkaline (pH 7.1 - 8.2).
p.7
Regulation of Saliva and Gastric Juice Secretion
What is the role of saliva during speech?
It keeps the mucous membranes moist and lubricates the movements of the tongue and lips.
p.31
Phases of Digestion: Cephalic, Gastric, and Intestinal
What do the facial and glossopharyngeal nerves stimulate?
The salivary glands to secrete saliva.
p.28
Intestinal Juice and Its Role
What is the primary function of absorptive cells in the intestinal mucosa?
Water absorption and microvilli function.
p.4
Salivary Glands and Saliva Composition
How do the parotid glands secrete saliva?
Via the parotid duct into the oral cavity.
p.27
Digestive Enzymes and Their Functions
What do bacteria in the large intestine produce?
Some B vitamins and vitamin K.
p.12
Stomach Juice and Its Components
What is the function of HCl in the stomach?
To create an acidic environment for digestion and activate enzymes.
p.29
Gastrointestinal Secretions Overview
What happens to food in the large intestine?
It is processed for water absorption and waste formation.
p.16
Digestive Enzymes and Their Functions
What converts pepsinogen into active pepsin?
Hydrochloric acid or active pepsin molecules.
p.5
Salivary Glands and Saliva Composition
What ions are found in the solutes of saliva?
Sodium, potassium, chloride, bicarbonate, and phosphate.
p.12
Bile Composition and Function
What are triglycerides?
They are a type of fat found in the body, composed of glycerol and three fatty acids.
p.8
Regulation of Saliva and Gastric Juice Secretion
What other stimuli can trigger saliva secretion?
The smell, sight, sound, or thought of food.
p.12
Bile Composition and Function
What are monoglycerides?
They are glycerol molecules bonded to one fatty acid, resulting from the digestion of triglycerides.
p.5
Salivary Glands and Saliva Composition
What is unique about the secretion of the submandibular glands?
They secrete a fluid that contains amylase but is thickened with mucus.
p.17
Pancreatic Juice and Digestive Enzymes
What is the function of the sphincter of the hepatopancreatic ampulla?
Regulates the flow of bile and pancreatic juice.
p.38
Phases of Digestion: Cephalic, Gastric, and Intestinal
What occurs during the cephalic phase of digestion?
The brain prepares the digestive system in response to the sight, smell, or thought of food.
p.38
Phases of Digestion: Cephalic, Gastric, and Intestinal
What happens during the gastric phase of digestion?
Food enters the stomach, triggering the release of gastric juices for digestion.
p.38
Phases of Digestion: Cephalic, Gastric, and Intestinal
What is the focus of the intestinal phase of digestion?
The digestion and absorption of nutrients in the small intestine.
p.34
Hormonal Regulation of Digestion
What effect does gastrin have on gastric glands?
It stimulates them to secrete large amounts of gastric juice.
p.19
Pancreatic Juice and Digestive Enzymes
Name two enzymes contained in pancreatic juice.
Pancreatic amylase and Trypsin.
p.20
Bile Composition and Function
What do bile salts aid in after lipid digestion?
The absorption of lipids.
p.24
Intestinal Juice and Its Role
What happens to absorptive cells in the small intestine?
They slough off into the lumen, break apart, and release enzymes that help digest nutrients in the chyme.
p.10
Stomach Juice and Its Components
What is the lamina propria?
A layer of connective tissue in the stomach mucosa.
p.3
Salivary Glands and Saliva Composition
What are Lingual glands?
Salivary glands located in the tongue.
p.37
Hormonal Regulation of Digestion
How does secretin affect gastric juice secretion?
It inhibits the secretion of gastric juice.
p.34
Hormonal Regulation of Digestion
Where is gastrin released from?
The G cells of the gastric glands.
p.24
Intestinal Juice and Its Role
What is the role of pancreatic and intestinal juices together?
They provide a liquid medium that aids the absorption of substances from chyme in the small intestine.
p.36
Hormonal Regulation of Digestion
How does Cholecystokinin (CCK) affect the gall bladder?
Causes contraction of the gall bladder wall, squeezing stored bile into the cystic duct.
p.20
Bile Composition and Function
How do small lipid globules affect the digestion of triglycerides?
They present a large surface area for pancreatic lipase to act more rapidly.
p.34
Hormonal Regulation of Digestion
How does gastrin affect the lower esophageal sphincter?
It strengthens its contraction to prevent reflux.
p.21
Hormonal Regulation of Digestion
What do K cells secrete?
Glucose-dependent insulinotropic peptide (GIP).
p.34
Hormonal Regulation of Digestion
What is the effect of gastrin on stomach motility?
It increases motility of the stomach.
p.2
Regulation of Saliva and Gastric Juice Secretion
What regulates the secretion of gastric juice?
Nervous and hormonal signals.
p.2
Salivary Glands and Saliva Composition
What are the three types of salivary glands?
Parotid, sublingual, and submandibular glands.
p.24
Intestinal Juice and Its Role
What contributes to the alkaline pH of intestinal juice?
High concentration of bicarbonate ions (HCO3−).
p.37
Hormonal Regulation of Digestion
What role does secretin play in the pancreas?
It promotes normal growth and maintenance of the pancreas.
p.37
Hormonal Regulation of Digestion
What is the function of vasoactive intestinal polypeptide (VIP)?
It stimulates secretion of ions and water by the intestines and inhibits gastric acid secretion.
p.17
Pancreatic Juice and Digestive Enzymes
What are some components of pancreatic juice?
Sodium bicarbonate, pancreatic amylase, trypsin, chymotrypsin, carboxypeptidase, elastase, pancreatic lipase, ribonuclease, and deoxyribonuclease.
p.24
Digestive Enzymes and Their Functions
What are the protein-digesting enzymes found in the small intestine?
Aminopeptidase and dipeptidase.
p.2
Bile Composition and Function
What are the main components of bile?
Bile salts, cholesterol, lecithin, bile pigments, and bilirubin.
p.36
Hormonal Regulation of Digestion
How does Cholecystokinin (CCK) interact with secretin?
Enhances the effects of secretin.
p.31
Phases of Digestion: Cephalic, Gastric, and Intestinal
What activates the neural centers in the cephalic phase?
The smell, sight, thought, or initial taste of food.
p.21
Digestive Enzymes and Their Functions
What is the function of absorptive cells in the small intestine?
They release enzymes that digest food and contain microvilli to absorb nutrients.
p.6
Salivary Glands and Saliva Composition
What is the function of lysozyme in saliva?
It kills bacteria, but not in large enough quantities to eliminate all oral bacteria.
p.2
Salivary Glands and Saliva Composition
What are the main components of saliva?
Water, electrolytes, mucus, enzymes, and antibacterial compounds.
p.21
Digestive Enzymes and Their Functions
What is the role of Paneth cells in the small intestine?
They secrete lysozyme, capable of phagocytosis, and may regulate the microbial population.
p.7
Regulation of Saliva and Gastric Juice Secretion
What occurs when the body becomes dehydrated regarding saliva secretion?
The salivary glands stop secreting saliva to conserve water.
p.36
Hormonal Regulation of Digestion
What role does Cholecystokinin (CCK) play in satiety?
Produces a feeling of fullness by acting on the hypothalamus.
p.20
Bile Composition and Function
Where does bile flow between meals?
Into the gall bladder for storage.
p.20
Bile Composition and Function
What closes off the entrance to the duodenum, allowing bile to be stored?
The sphincter of the hepatopancreatic ampulla.
p.36
Hormonal Regulation of Digestion
What is one of the growth-related effects of Cholecystokinin (CCK)?
Promotes normal growth and maintenance of the pancreas.
p.19
Pancreatic Juice and Digestive Enzymes
What is the function of the trypsin inhibitor?
It blocks the enzymatic activity of any trypsin formed accidentally.
p.2
Phases of Digestion: Cephalic, Gastric, and Intestinal
What are the three phases of digestion?
Cephalic phase, gastric phase, and intestinal phase.
p.19
Pancreatic Juice and Digestive Enzymes
What does trypsin act on to produce other enzymes?
Chymotrypsinogen, procarboxypeptidase, and proelastase.
p.19
Pancreatic Juice and Digestive Enzymes
What role does pancreatic juice play in relation to gastric juice?
It buffers acidic gastric juice in chyme.
p.36
Hormonal Regulation of Digestion
What is one of the primary functions of Cholecystokinin (CCK)?
Stimulates secretion of pancreatic juice.
p.35
Phases of Digestion: Cephalic, Gastric, and Intestinal
What triggers the enterogastric reflex?
Distension of the duodenum by the presence of chyme.
p.24
Digestive Enzymes and Their Functions
Where are brush border enzymes synthesized?
By the absorptive cells and inserted in the plasma membrane of the microvilli.
p.37
Hormonal Regulation of Digestion
What does gastrin-releasing peptide do?
It stimulates the release of gastrin.
p.21
Hormonal Regulation of Digestion
What is the function of CCK cells?
They secrete cholecystokinin (CCK).
p.31
Phases of Digestion: Cephalic, Gastric, and Intestinal
What is the purpose of the cephalic phase of digestion?
To prepare the mouth and stomach for food that is about to be eaten.
p.2
Intestinal Juice and Its Role
What does intestinal juice contain?
Bicarbonate ions, brush border enzymes, carbohydrate-digesting enzymes, protein-digesting enzymes, and nucleotide-digesting enzymes.
p.34
Hormonal Regulation of Digestion
What is the role of the negative feedback mechanism involving gastrin?
It helps maintain an optimal low pH for pepsin function, killing microbes, and denaturing proteins.
p.32
Phases of Digestion: Cephalic, Gastric, and Intestinal
What happens during gastric emptying?
A small quantity of chyme is released into the duodenum.
p.35
Phases of Digestion: Cephalic, Gastric, and Intestinal
What does the intestinal phase promote?
The continued digestion of foods that have reached the small intestine.
p.32
Regulation of Saliva and Gastric Juice Secretion
What regulates the gastric phase of digestion?
Neural and hormonal mechanisms.
p.15
Regulation of Saliva and Gastric Juice Secretion
How do H2 receptors differ from H1 receptors?
H2 receptors mediate different responses than H1 receptors, which are involved in allergic responses.
p.34
Hormonal Regulation of Digestion
What stimuli trigger the release of gastrin?
Distension of the stomach, partially digested proteins, high pH, caffeine, and acetylcholine.
p.31
Phases of Digestion: Cephalic, Gastric, and Intestinal
What does the vagus nerve stimulate during the cephalic phase?
The gastric glands to secrete gastric juice.
p.36
Hormonal Regulation of Digestion
How does Cholecystokinin (CCK) influence gastric emptying?
Slows gastric emptying by promoting contraction of the pyloric sphincter.
p.37
Hormonal Regulation of Digestion
What is the function of somatostatin?
It inhibits gastrin release.
p.7
Regulation of Saliva and Gastric Juice Secretion
What effect does drinking have on the body?
It restores homeostasis of body water and moistens the mouth.
p.7
Regulation of Saliva and Gastric Juice Secretion
What happens to most components of saliva after swallowing?
They are reabsorbed to prevent fluid loss.
p.5
Salivary Glands and Saliva Composition
What is the characteristic of the fluid secreted by the sublingual glands?
It is much thicker and contributes only a small amount of salivary amylase.
p.7
Regulation of Saliva and Gastric Juice Secretion
What effect does sympathetic stimulation have on saliva secretion?
It dominates during stress, resulting in dryness of the mouth.
p.7
Regulation of Saliva and Gastric Juice Secretion
How does dryness in the mouth relate to thirst?
It contributes to the sensation of thirst.
p.2
Pancreatic Juice and Digestive Enzymes
What are the main enzymes found in pancreatic juice?
Pancreatic amylase, trypsin, chymotrypsin, carboxypeptidase, elastase, pancreatic lipase, ribonuclease, and deoxyribonuclease.
p.37
Hormonal Regulation of Digestion
How do some of these hormones act in the body?
Some act as local hormones (paracrines), while others are secreted into the blood or the lumen of the GI tract.
p.32
Regulation of Saliva and Gastric Juice Secretion
What suppresses the secretion of gastric juice?
Decrease in pH of stomach chyme and less distended stomach walls.
p.31
Phases of Digestion: Cephalic, Gastric, and Intestinal
Which nerves are activated during the cephalic phase?
Facial (VII), glossopharyngeal (IX), and vagus (X) nerves.
p.20
Bile Composition and Function
What is the role of bile salts in digestion?
Emulsification of large lipid globules into small lipid globules.
p.32
Regulation of Saliva and Gastric Juice Secretion
What do chemoreceptors in the stomach detect?
pH increase due to proteins buffering stomach acid.
p.32
Regulation of Saliva and Gastric Juice Secretion
What is the role of the submucosal plexus during the gastric phase?
It activates parasympathetic and enteric neurons.
p.24
Digestive Enzymes and Their Functions
What types of enzymes digest nucleotides?
Nucleosidases and phosphatases.
p.35
Neural Regulation of Digestion
What role do stretch receptors in the duodenal wall play?
They send nerve impulses to the medulla oblongata to inhibit parasympathetic stimulation and stimulate sympathetic nerves to the stomach.
p.19
Pancreatic Juice and Digestive Enzymes
In what form is trypsin secreted?
In an inactive form called trypsinogen.
p.34
Hormonal Regulation of Digestion
What does gastrin do to the pyloric sphincter?
It relaxes the pyloric sphincter, promoting gastric emptying.
p.36
Hormonal Regulation of Digestion
What effect does Cholecystokinin (CCK) have on the sphincter of Oddi?
Causes relaxation, allowing pancreatic juice and bile to flow into the duodenum.
p.24
Digestive Enzymes and Their Functions
What types of enzymes are involved in carbohydrate digestion?
α-dextrinase, maltase, sucrase, and lactase.
p.35
Neural Regulation of Digestion
What is the result of the enterogastric reflex on gastric motility?
Gastric motility is inhibited and there is an increase in the contraction of the pyloric sphincter, decreasing gastric emptying.
p.32
Gastrointestinal Secretions Overview
What do nerve impulses from stretch and chemoreceptors cause?
Waves of peristalsis and stimulation of gastric juice flow.
p.32
Gastrointestinal Secretions Overview
What is the result of peristaltic waves in the stomach?
They mix food with gastric juice.
