digestive system Flashcards
(196 cards)
1
Q
Describe the role of the nervous system in gastrointestinal regulation.
A
The nervous system regulates gastrointestinal functions through the autonomic nervous system and the enteric nervous system, which control GI functions via short and long reflex arcs.
2
Q
How does the endocrine system contribute to gastrointestinal regulation?
A
The endocrine system contributes by secreting hormones from endocrine cells in the stomach and small intestine into the blood, which interact with target cells to change conditions inside the GI tract.
3
Q
Define the phases of gastrointestinal control.
A
The phases of gastrointestinal control include the cephalic phase, gastric phase, and intestinal phase, each involving different regulatory mechanisms.
4
Q
Explain the difference between short and long reflex arcs in the GI tract.
A
Short reflex arcs involve local intrinsic nerve plexus responses to stimuli in the lumen, while long reflex arcs involve the central nervous system in addition to the intrinsic nerve plexus.
5
Q
What is the function of the enteric nervous system in GI regulation?
A
The enteric nervous system controls GI function independently through its submucosal and myenteric plexuses, allowing for local reflexes without external inputs.
6
Q
How do GI hormones affect the gastrointestinal system?
A
GI hormones, secreted in response to specific stimuli, interact with target cells to regulate various functions such as digestion and absorption within the GI tract.
7
Q
Describe the role of sensory receptors in the gastrointestinal system.
A
Sensory receptors in the GI tract detect environmental changes and initiate reflex arcs that help regulate digestive processes.
8
Q
What is the primary goal of gastrointestinal regulation?
A
The primary goal of gastrointestinal regulation is to maximize digestion and absorption of nutrients rather than maintaining homeostasis.
9
Q
Identify the two main systems that control neural pathways in the GI tract.
A
The two main systems that control neural pathways in the GI tract are the enteric nervous system and the central nervous system via the autonomic nervous system.
10
Q
Explain how hormones are secreted in the gastrointestinal system.
A
Hormones in the gastrointestinal system are secreted by endocrine cells in response to specific stimuli and are controlled by the enteric nervous system.
11
Q
How is the Cephalic phase initiated?
A
The Cephalic phase is initiated by stimuli in the head, such as the sight, smell, and taste of food.
11
Q
Describe the three phases of gastrointestinal regulation.
A
The three phases are the Cephalic phase, Gastric phase, and Intestinal phase, each based on the location and contents of the lumen.
12
Q
What role do neural and hormonal pathways play in the Cephalic phase?
A
They control the Cephalic phase, increasing activity in the long reflex arc and stimulating gastric juice secretion and stomach motility.
13
Q
Explain the Gastric phase and its triggers.
A
The Gastric phase is initiated when the bolus reaches the stomach, distending it and activating stretch receptors, along with detecting changes in protein concentration.
14
Q
What is the function of gastrin during the Gastric phase?
A
Gastrin stimulates the secretion of gastric juice and induces peristalsis in the stomach.
15
Q
How does the duodenum influence gastric juice secretion during the Gastric phase?
A
The duodenum reduces gastric juice secretion through a negative feedback loop.
16
Q
What initiates the Intestinal phase?
A
The Intestinal phase is initiated by chyme entering the small intestine.
17
Q
Describe the effects of the Intestinal phase on gastric secretion and motility.
A
The Intestinal phase inhibits gastric juice secretion and reduces motility in the stomach.
18
Q
What substances stimulate enteroendocrine cells during the Intestinal phase?
A
Fatty acids and glucose stimulate enteroendocrine cells during the Intestinal phase.
19
Q
What are the roles of gastric inhibitory peptide, secretin, and cholecystokinin in the Intestinal phase?
A
Gastric inhibitory peptide inhibits gastric secretion, secretin stimulates pancreatic juice secretion, and cholecystokinin stimulates bile secretion.
20
Q
Define the enteric nervous system’s role in gastrointestinal control.
A
The enteric nervous system, along with the CNS and endocrine system, controls the GI tract.
21
Q
Differentiate between the short reflex arc and long reflex arc in the GI tract.
A
The short reflex arc operates locally within the enteric nervous system, while the long reflex arc involves communication with the central nervous system.
22
Q
Summarize the three phases of gastrointestinal control.
A
The three phases are Cephalic, Gastric, and Intestinal, each responding to different stimuli and regulating digestive processes.
23
Q
Describe the main types of carbohydrates consumed in the diet.
A
The main types of carbohydrates consumed are disaccharides and polysaccharides, which include sucrose, lactose, maltose, starch, glycogen, and cellulose.
24
Define monosaccharides and their role in digestion.
Monosaccharides are the simplest form of carbohydrates that can be absorbed by the body. Disaccharides and polysaccharides must be digested into monosaccharides for absorption.
25
How are disaccharides digested into monosaccharides?
Disaccharides like sucrose, lactose, and maltose are digested by specific enzymes such as sucrase, lactase, and maltase, respectively, into their monosaccharide components.
26
What enzymes are involved in carbohydrate digestion?
Key enzymes involved in carbohydrate digestion include salivary amylase, pancreatic amylase, and brush border enzymes in the small intestine.
27
Explain the process of glucose and galactose absorption in the intestines.
Glucose and galactose are absorbed at the apical membrane of intestinal cells through secondary active transport, cotransported with Na+ via the SGLT symporter.
28
How is fructose absorbed in the intestines?
Fructose is absorbed through facilitated diffusion via the GLUT5 transporter at the apical membrane of intestinal cells.
29
What role does the Na+/K+ pump play in monosaccharide absorption?
The Na+/K+ pump maintains the sodium gradient necessary for the functioning of the SGLT symporter, which drives the absorption of glucose and galactose.
30
Describe the transport mechanisms for monosaccharides at the basolateral membrane.
At the basolateral membrane, glucose, galactose, and fructose are transported out of the intestinal cells via the GLUT2 transporter.
31
What is the significance of the brush border enzymes in carbohydrate digestion?
Brush border enzymes in the small intestine further digest disaccharides and polysaccharides into monosaccharides, facilitating their absorption.
32
Describe the process of fructose absorption in the intestines.
Fructose enters intestinal epithelial cells through the GLUT5 transporter and exits into the bloodstream via the GLUT2 transporter.
33
How are amino acids, dipeptides, and tripeptides absorbed in the intestines?
Amino acids are actively transported into intestinal epithelial cells by cotransport with sodium across the apical membrane, while dipeptides and tripeptides use different carriers.
34
Define the types of proteins that are digested in the gastrointestinal tract.
Proteins that are digested include dietary proteins, secretions into the GI tract lumen, and cell debris from the GI tract cell lining.
35
Explain the role of proteases in protein digestion.
Proteases break down proteins into smaller peptides and amino acids; endopeptidases cleave internal peptide bonds, while exopeptidases cleave terminal peptide bonds.
36
List the pancreatic proteases involved in protein digestion.
The pancreatic proteases involved in protein digestion include trypsin, chymotrypsin, and carboxypeptidase.
37
What is the function of bile salts in lipid digestion?
Bile salts emulsify large fat droplets into smaller droplets, increasing the surface area for lipase action.
38
Describe the process of lipid digestion in the small intestine.
Lipases act on the surface of fat droplets, and bile salts emulsify these droplets to facilitate digestion.
39
How do monoglycerides and fatty acids enter intestinal cells?
Monoglycerides and fatty acids move out of micelles and enter intestinal cells by diffusion.
39
What happens to amino acids after they are absorbed into intestinal epithelial cells?
Once inside the epithelial cell, dipeptides and tripeptides are further broken down by proteases into amino acids, which then cross the basolateral membrane into the blood.
40
Identify the two types of proteases and their functions.
Endopeptidases catalyze the breakdown of internal peptide bonds, producing small peptide fragments, while exopeptidases catalyze the breakdown of terminal peptide bonds, producing amino acids.
41
Explain the role of brush border enzymes in protein digestion.
Brush border enzymes, such as aminopeptidase and enterokinase, further digest peptides into amino acids and activate other proteases.
42
Describe the transport mechanism for amino acids in the intestines.
Amino acids are actively transported into intestinal epithelial cells via cotransport with sodium across the apical membrane.
43
What is the significance of the Golgi apparatus in lipid absorption?
The Golgi apparatus processes and packages lipids into chylomicrons for transport into the lymphatic system.
44
How do bile salts contribute to the recycling process in lipid digestion?
Bile salts are recycled from the intestine back to the liver after aiding in the emulsification of fats.
45
Describe the role of pancreatic lipase and colipase in fat digestion.
Pancreatic lipase and colipase break down fats into monoglycerides and fatty acids, which are then stored in micelles.
46
How are chylomicrons formed and where are they released?
Chylomicrons are formed in the intestinal cells when absorbed fats combine with cholesterol and proteins, and they are released into the lymphatic system.
47
Define micelles in the context of fat digestion.
Micelles are structures that store monoglycerides and fatty acids, allowing for the absorption of fats in the digestive process.
48
Explain the transport mechanism of cholesterol into cells.
Cholesterol is transported into cells by a membrane transporter.
49
Summarize the digestion of carbohydrates.
Carbohydrates are digested into monosaccharides, which are then absorbed into the blood.
50
What are the breakdown products of protein digestion?
Protein breakdown products include amino acids, dipeptides, and tripeptides.
51
How does lipid digestion differ from carbohydrate and protein digestion?
Lipid digestion is complex and requires bile salts to emulsify fat droplets, unlike carbohydrates and proteins which have more straightforward digestion processes.
52
Describe the sections of the large intestine.
The large intestine can be divided into three sections: the Caecum (including the appendix), the Colon, and the Rectum.
53
What are the unique features of the large intestine?
The large intestine has two unique features: Teniae coli, which are three bands of longitudinal smooth muscle in the muscularis externa, and Haustra, which are pocket-like sacs caused by the teniae coli.
54
How is the epithelium of the large intestine adapted?
The epithelium of the large intestine is adapted to absorb ions and water and lacks the folds seen in the small intestine.
55
Define the Crypts of Lieberkühn in the small intestine.
The Crypts of Lieberkühn are pits in the small intestine that contain secretory cells responsible for secreting bicarbonate-rich intestinal juice, known as succus entericus.
56
Describe the surface area of the small intestine.
The small intestine has a huge surface area of approximately 200m², which is increased by deep folds called Plicae circulares and finger-like projections called villi.
57
How do the folds in the small intestine increase surface area?
The folds in the small intestine increase surface area by a factor of 10, allowing for more efficient digestion and absorption.
58
What are the three regions of the small intestine?
The small intestine can be divided into three regions: the Duodenum (0.5m, extending from the pylorus), the Jejunum (1m, where most nutrients are absorbed), and the Ileum (2m, the final portion joining the colon).
59
Recap the components of the upper and lower GI tract.
The upper GI tract includes the Mouth, Pharynx, Oesophagus, and Stomach. The lower GI tract includes the Small Intestine, Large Intestine, Rectum, and Anus.
60
Describe the primary function of the small intestine.
The primary function of the small intestine is digestion and absorption of nutrients.
61
How long is the small intestine?
The small intestine is a coiled, hollow tube approximately 3.5m long.
62
Describe the primary function of the small intestine in digestion.
The small intestine is responsible for chemical digestion and absorption of nutrients, with 80% of absorption occurring here.
63
How does the small intestine facilitate absorption of nutrients?
The small intestine has a large surface area due to villi and microvilli, which enhance nutrient absorption.
64
Define the role of pancreatic juice in the small intestine.
Pancreatic juice is mixed with chyme in the duodenum to aid in the chemical digestion of nutrients.
65
What is the significance of intestinal enzymes in the small intestine?
Intestinal enzymes, synthesized by absorptive cells, help break down nutrients for absorption.
66
Explain the process of motility in the small intestine.
Motility in the small intestine includes segmentation and peristalsis, which help mix and move chyme.
67
Identify the types of cells that secrete hormones in the small intestine.
K cells secrete Gastric inhibitory peptide (GIP), S cells secrete Secretin, and CCK cells secrete Cholecystokinin (CCK).
68
How does the large intestine differ from the small intestine in terms of enzyme secretion?
The large intestine does not secrete digestive enzymes, unlike the small intestine.
69
What are the main functions of the large intestine?
The large intestine concentrates wastes into feces, absorbs water, and stores feces until defecation.
70
Describe the role of the gut microbiome in the large intestine.
The gut microbiome ferments remaining carbohydrates, synthesizes B vitamins and vitamin K, and breaks down bilirubin.
71
What is the significance of the brush border in the small intestine?
The brush border, formed by microvilli, contains digestive enzymes that aid in nutrient breakdown.
72
How is the large intestine anatomically divided?
The large intestine is divided into the ascending colon, transverse colon, descending colon, and sigmoid colon.
73
What is the primary function of the villi in the small intestine?
Villi increase the surface area for absorption of nutrients in the small intestine.
74
Explain the process of mass peristalsis in the large intestine.
Mass peristalsis is a slower movement that helps propel contents through the large intestine.
75
What is the pH level of intestinal juice secreted by intestinal glands?
The pH level of intestinal juice is approximately 7.6.
76
How do goblet cells contribute to the function of the large intestine?
Goblet cells secrete mucus to lubricate the bolus in the large intestine.
77
What is the main function of the lacteal found in the small intestine?
The lacteal absorbs fats and fat-soluble vitamins from the digested food.
78
Describe the structure of the small intestine.
The small intestine is characterised by a large surface area created by plicae, villi, and microvilli.
79
How does the surface area of the small intestine affect its function?
A large surface area provides a large absorptive surface, enhancing nutrient absorption.
80
Define the sections of the large intestine.
The large intestine is divided into three distinct sections.
81
What characterizes the muscularis externa of the large intestine?
The muscularis externa of the large intestine is characterised by additional muscle known as Teniae coli and the presence of Haustra.
82
Explain the role of the gut microbiome in the colon.
The colon is colonised by microbes, forming the gut microbiome, which plays a role in digestion and overall gut health.
83
What is the primary function of the large intestine?
The primary function of the large intestine is to move the bolus to the rectum.
84
Describe the process of defecation.
Defecation occurs when the sigmoid colon empties into the rectum, and both the internal and external anal sphincters relax.
85
How is the rectum involved in the digestive process?
The rectum serves as a temporary storage site for feces before defecation.
85
What structures close the base of the rectum?
The base of the rectum is closed by two sphincters: the internal anal sphincter and the external anal sphincter.
86
Describe the main function of the mouth in the digestive process.
The main function of the mouth is mastication, which involves the mechanical digestion of food.
87
How does saliva contribute to the digestion process in the mouth?
Saliva lubricates food to help with swallowing and contains amylase, which aids in the enzymatic digestion of starch and glycogen.
88
What is the bolus in the context of digestion?
The bolus is the food-saliva mix that is formed in the mouth and propelled into the pharynx by the tongue.
89
Define the pharynx and its role in digestion.
The pharynx is a funnel-shaped opening surrounded by mucous membrane and skeletal muscle, serving as a common passageway for air and food.
90
Explain the function of the epiglottis during swallowing.
The epiglottis prevents food from entering the larynx by directing it into the oesophagus during swallowing.
91
Describe the structure of the oesophagus.
The oesophagus is a muscular tube that descends from the pharynx to the stomach, with the upper third made of skeletal muscle and the lower two-thirds made of smooth muscle.
92
What are the roles of the upper and lower oesophageal sphincters?
The upper oesophageal sphincter controls the entry of food into the oesophagus, while the lower oesophageal sphincter prevents the acidic contents of the stomach from entering the oesophagus.
93
How is the process of swallowing (deglutination) controlled?
The process of swallowing is controlled by the autonomic nervous system and can be divided into three stages: oral, pharyngeal, and oesophageal.
94
What occurs during the oral phase of swallowing?
During the oral phase, which is a voluntary stage, chewing occurs, saliva is mixed with food, and the food is formed into a bolus by the tongue.
95
What happens to the soft palate during the oral phase of swallowing?
The soft palate closes to prevent nasal aspiration during the oral phase of swallowing.
96
Describe the role of the epiglottis during swallowing.
The epiglottis blocks the trachea to prevent food from entering the airway.
97
How does peristalsis function in the oesophageal phase?
Peristalsis waves move the bolus through the esophagus.
98
Define the function of the gastroesophageal sphincter.
The gastroesophageal sphincter relaxes to allow the bolus to enter the stomach.
99
What is the primary function of the stomach in the digestive system?
The stomach acts as a reservoir for food, mixing it with gastric juice and controlling its release into the small intestine.
100
Describe the structure of the stomach and its sections.
The stomach consists of the fundus, body, and antrum, each serving different functions in digestion.
101
How do gastric pits contribute to digestion?
Gastric pits lead to gastric glands that secrete digestive enzymes and acids essential for breaking down food.
102
What substances are secreted by the chief cells in the stomach?
Chief cells secrete pepsinogen, which is activated to pepsin in the acidic environment.
102
What is the significance of intrinsic factor in gastric juice?
Intrinsic factor is necessary for the absorption of vitamin B12 in the intestines.
103
Explain the role of parietal cells in the stomach.
Parietal cells secrete hydrochloric acid, which lowers pH to aid digestion and kill bacteria.
104
What is chyme and how is it formed?
Chyme is a thick mixture of food and gastric juice produced in the stomach.
105
How does gastric juice protect the stomach lining?
Mucus in gastric juice protects the mucosa from the low pH of the stomach.
106
Describe the function of the pyloric sphincter.
The pyloric sphincter regulates the passage of chyme from the stomach into the small intestine.
107
What role does gastrin play in digestion?
Gastrin stimulates motility in the colon and promotes gastric functions.
108
How does the stomach begin the digestion of proteins and lipids?
The stomach starts to digest proteins and lipids through the action of pepsin and gastric lipase.
109
Summarize the process of deglutination in the upper GI tract.
Deglutination is the process of swallowing that moves the bolus from the mouth to the esophagus.
110
What happens to the bolus in the stomach?
The bolus is mixed with gastric juice to form chyme, which is then prepared for further digestion.
111
Describe the structure of an accessory gland in the digestive system.
Accessory glands are specialized structures that secrete products via ducts into another structure or organ, specifically secreting digestive juices into the lumen of the gastrointestinal tract.
112
Identify the key accessory glands involved in digestion.
The key accessory glands in digestion include the salivary glands, pancreas, and liver.
113
What is a zymogen?
A zymogen is an inactive precursor of an enzyme that requires a biochemical change to become an active enzyme.
113
Explain the function of salivary glands.
Salivary glands secrete saliva, which is composed of 99.5% water and 0.5% solutes, including sodium, potassium, chloride, phosphates, bicarbonate, mucus, and enzymes such as salivary amylase and lysozyme.
114
Describe the anatomy of the pancreas.
The pancreas is divided into exocrine and endocrine portions, with 99% of its cells arranged into acini associated with the pancreatic duct, and 1% arranged in Islets of Langerhans.
115
How do the exocrine and endocrine portions of the pancreas differ in function?
The exocrine portion of the pancreas secretes pancreatic juice, while the endocrine portion secretes hormones.
116
List the main components of saliva.
The main components of saliva include water, sodium, potassium, chloride, phosphates, bicarbonate, mucus, salivary amylase, and lysozyme.
117
What role do accessory glands play in the digestive system?
Accessory glands secrete digestive juices that aid in the digestion of food within the gastrointestinal tract.
118
Define the term 'accessory glands' in the context of the digestive system.
Accessory glands are specialized structures that secrete digestive products into the gastrointestinal tract to assist in digestion.
119
Describe the role of pancreatic juice in digestion.
Pancreatic juice is rich in bicarbonate, which helps neutralize stomach acid, and contains pro-enzymes called zymogens, including pancreatic amylase, lipase, and proteases like trypsin, chymotrypsin, and carboxypeptidase.
120
Define zymogens and their function.
Zymogens are inactive forms of digestive enzymes that enable safe storage and transport. They become activated by enteropeptidases on the surface of enterocytes.
121
How are zymogens activated in the digestive system?
Zymogens are activated by enteropeptidases, which are enzymes located on the surface of enterocytes in the intestinal lining.
122
Explain the functions of the liver as an accessory gland.
The liver has a wide variety of functions, including the secretion of bile, processing nutrients, removal of old red blood cells, elimination of waste products, and the catabolism of hemoglobin, which generates bilirubin.
123
Describe the anatomy of the liver in relation to bile production.
Hepatocytes in the liver absorb materials for bile from sinusoids, and bile is secreted into bile canaliculi on the opposite side of the cell, which then flow into the bile duct and onto the common hepatic duct.
124
What is the structure and function of the biliary system?
The biliary system consists of the liver, which synthesizes bile; the gallbladder, which stores and concentrates bile; and associated ducts that transport bile to the duodenum.
125
Identify the termination point of the common bile duct.
The common bile duct terminates at the Ampulla of Vater, which is the junction between the common bile duct and the pancreatic duct.
126
How is the flow of bile and pancreatic juice regulated?
The flow of bile and pancreatic juice is controlled by the sphincter located at the Ampulla of Vater.
127
Describe the role of accessory glands in the digestive system.
Accessory glands, such as the salivary glands, pancreas, and liver, secrete products into organs to aid in digestion.
128
Define acini in the context of accessory glands.
Acini are small, sac-like structures within accessory glands that produce and secrete digestive substances.
129
How do salivary glands contribute to digestion?
Salivary glands produce saliva, which contains enzymes that begin the breakdown of food in the mouth.
130
Explain the function of the pancreas as an accessory gland.
The pancreas secretes digestive enzymes and bicarbonate into the small intestine to aid in digestion and neutralize stomach acid.
131
What is the significance of the liver in the digestive system?
The liver produces bile, which is essential for the emulsification and digestion of fats.
132
Identify the three main accessory glands in the digestive system.
The three main accessory glands are the salivary glands, pancreas, and liver.
133
How do accessory glands support the digestive process?
Accessory glands support digestion by secreting enzymes and other substances that facilitate the breakdown and absorption of nutrients.
134
Describe the layers of the GI tract wall.
The GI tract wall consists of four distinct layers: Mucosa, Submucosa, Muscularis Externa, and Serosa.
135
Define the function of the Mucosa in the GI tract.
The Mucosa serves three major functions: secretion of mucus, absorption of digestive products, and protection against infectious disease.
136
How does the Submucosa support the GI tract?
The Submucosa is made of connective tissue that supports the mucosa and contains blood vessels, lymphatic vessels, and nerves.
137
What is the role of the Muscularis Externa in the GI tract?
The Muscularis Externa is a smooth muscle layer responsible for the motility of the GI tract, facilitating the movement of contents.
138
Identify the three major classes of cells found in the Mucosa.
The three major classes of cells in the Mucosa are absorptive cells, exocrine cells (like goblet cells), and endocrine cells (like G cells).
138
Explain the structure of the Mucosa.
The Mucosa is the innermost layer of the GI tract, consisting of a mucous membrane, lamina propria, and muscularis mucosae.
139
What is the primary function of the muscularis mucosae?
The primary function of the muscularis mucosae is to mix the contents of the lumen.
140
Describe the significance of the lamina propria in the Mucosa.
The lamina propria is connective tissue beneath the epithelial lining that contains small blood vessels, lymphatic vessels, and nerves.
141
How does the structure of the Mucosa vary between different organs?
The structure of the Mucosa is highly specialized in each organ, with modifications in surface shape to increase surface area for different functions.
142
What protective role does the Mucosa play in the GI tract?
The Mucosa protects against infectious disease by acting as a barrier between the contents of the GI tract and the internal environment.
143
Describe the structure and function of the mucosa in the small intestine.
The mucosa in the small intestine has a thinner layer compared to other parts of the GI tract and contains a large number of villi that extend the surface area for absorption.
144
Define the role of the submucosa in the gastrointestinal tract.
The submucosa is a thick layer of connective tissue that provides elasticity and distensibility to the organs of the GI tract, containing large blood vessels, lymphatic vessels, and the submucosal plexus.
145
How does the muscularis externa contribute to gastrointestinal motility?
The muscularis externa consists of two layers of smooth muscle: an inner layer of circular muscle and an outer layer of longitudinal muscle, which work together in coordinated contractions to propel contents through the lumen in a process called peristalsis.
146
Explain the significance of the serosa in the gastrointestinal wall.
The serosa is the outermost layer of the GI wall, providing strength through its inner layer of connective tissue and allowing movement through its outer layer of epithelial tissue called the mesothelium.
147
What is the enteric nervous system and its components?
The enteric nervous system is a complex system of nerves throughout the GI tract, composed of two major intrinsic nerve plexuses: the submucosal plexus in the submucosa and the myenteric plexus in the muscularis externa.
148
Describe the function of the myenteric plexus.
The myenteric plexus is part of the enteric nervous system and coordinates the contractions of the muscularis externa to facilitate peristalsis.
149
What are Peyer's patches and where are they located?
Peyer's patches are lymphoid tissues located in the mucosa of the small intestine, playing a role in immune surveillance.
150
How do the layers of the muscularis externa interact during digestion?
The inner circular muscle layer constricts to mix and propel contents, while the outer longitudinal muscle layer shortens the segment of the GI tract, working together to facilitate the movement of food.
151
Define the role of the submucosal plexus.
The submucosal plexus regulates the activity of glands in the epithelium and smooth muscle, contributing to the control of digestive processes.
152
What is the function of villi in the small intestine?
Villi increase the surface area of the small intestine, enhancing nutrient absorption.
153
Describe the role of the myenteric nerve plexus in the gastrointestinal tract.
The myenteric nerve plexus is the major nerve supply that controls gastrointestinal tract motility.
154
Define the Enteric Nervous System and its function.
The Enteric Nervous System is a part of the autonomic nervous system that controls motility in the GI tract through local reflex arcs, allowing the GI to function autonomously.
155
How is motility in the gastrointestinal tract primarily controlled?
Motility is primarily controlled by the muscularis externa.
156
Explain the two main processes of gastrointestinal motility.
The two main processes of gastrointestinal motility are segmentation and peristalsis.
157
Describe the process of segmentation in the small intestine.
Segmentation promotes mixing of the contents in the small intestine by contracting circular muscles in alternate segments, causing the chyme to move back and forth.
158
What is chyme and its role in the digestive process?
Chyme is a liquid solution of digestive juices in the small intestine that is mixed during segmentation.
159
What happens to chyme during peristalsis as water is absorbed?
As water is absorbed from the chyme during peristalsis, it forms a bolus.
160
How do circular and longitudinal muscles work together during peristalsis?
During peristalsis, circular muscles contract to restrict the lumen's diameter while longitudinal muscles contract to shorten the GI tract, facilitating the propulsion of contents.
161
Describe the function of the muscularis mucosae in segmentation.
The muscularis mucosae supports segmentation by providing rhythmic contractions that aid in mixing the chyme.
162
Describe the purpose of the digestive system.
The digestive system is needed to break down nutrients that are too large to enter the bloodstream or cells directly, allowing for their absorption.
163
Identify the four digestive processes.
The four digestive processes are ingestion, mechanical processing, digestion, and absorption.
164
Explain the role of mechanical processing in digestion.
Mechanical processing involves the mechanical breakdown of food to increase its surface area for more efficient digestion.
165
List the major organs of the gastrointestinal (GI) tract.
The major organs of the GI tract include the mouth, esophagus, stomach, small intestine, large intestine, and anus.
166
Define catabolism in the context of cellular metabolism.
Catabolism is the process of breaking down complex molecules to release energy, often resulting in the production of ATP.
167
What is the significance of enzymes in digestion?
Enzymes facilitate the chemical breakdown of complex macromolecules into absorbable units during digestion.
168
How does the digestive system contribute to defense against pathogens?
The digestive system helps remove pathogens found in food, playing a crucial role in the body's defense mechanisms.
169
Describe the process of absorption in digestion.
Absorption is the active and passive transfer of digested products into the bloodstream or cells for use by the body.
170
What are the three types of processes involved in digestion?
The three types of processes involved in digestion are mechanical, chemical, and enzymatic processes.
171
Explain the difference between catabolism and anabolism.
Catabolism involves breaking down molecules to release energy, while anabolism involves building new molecules from smaller units.
172
What are the components of fats that are absorbed during digestion?
Fats are broken down into monoglycerides, glycerol, and fatty acids for absorption.
173
Describe the role of the gastrointestinal (GI) tract in nutrient absorption.
The GI tract is responsible for the digestion and absorption of nutrients, allowing the body to utilize the food consumed.
174
Identify the types of carbohydrates involved in digestion.
The types of carbohydrates include polysaccharides, disaccharides, and monosaccharides.
175
What is the function of excretion in the digestive system?
Excretion involves the removal of undigested macromolecules from the body.
176
How does the digestive system facilitate the intake of food and water?
The digestive system facilitates ingestion, which is the intake of food and water necessary for nourishment.
177
Describe the role of secretion in the digestive system.
Secretion involves the release of digestive fluids into the GI tract to aid in the process of digestion.
178
Define motility in the context of the digestive system.
Motility refers to the muscle contractions that mix and move the contents of the gastrointestinal tract.
179
How is the digestive system organized?
The digestive system is divided into two main parts: the gastrointestinal tract (GI tract) and accessory glands.
180
List the components of the gastrointestinal tract.
The GI tract includes the mouth, pharynx, oesophagus, stomach, small intestine, large intestine, rectum, and anus.
181
What are the two parts of the GI tract?
The GI tract is subdivided into the upper GI tract and the lower GI tract.
182
Identify the sections of the small intestine.
The small intestine consists of the duodenum, jejunum, and ileum.
183
Explain the importance of digestion.
Digestion is necessary because we consume large macromolecules that cannot be absorbed directly; it breaks them down into smaller components.
184
What processes are involved in digestion?
The four digestive processes are digestion, absorption, secretion, and motility.
185
Describe the function of accessory glands in the digestive system.
Accessory glands, such as the liver, pancreas, and gall bladder, support digestion by secreting enzymes directly into the GI tract.
186
How is the GI tract structured?
The GI tract is a long, hollow tube with a central lumen.
187
What is the function of the hepatic portal vein?
The hepatic portal vein carries products from the GI tract to the liver for processing.
188
Identify the main sections of the stomach.
The stomach is divided into the fundus, body, and antrum.
189
What is the significance of mechanical, chemical, and enzymatic digestion?
These types of digestion work together to break down macromolecules into absorbable units.
190
What is the role of the rectum and anus in the digestive system?
The rectum and anus are involved in the elimination of waste from the body.
