Week 5: The Gastrointestinal System Flashcards
1
Q
The process of _______ occurs when the muscles of the pharynx contract.
a) propulsion
b) mechanical breakdown
c) digestion
d) ingestion
A
a) propulsion
2
Q
Swallowing and peristalsis are examples of this digestive process.
a) defaecation
b) chemical digestion
c) absorption
d) propulsion
A
d) propulsion
3
Q
This is the process of eliminating indigestible substances from the body.
a) defaecation
b) absorption
c) digestion
d) mechanical breakdown
A
a) defaecation
4
Q
There are six major processes of the digestive system beginning with __________.
A
There are six major processes of the digestive system beginning with ingestion.
5
Q
As the foodstuff enters the mouth, __________ begins through the acts of chewing.
A
As the foodstuff enters the mouth, mechanical breakdown begins through the acts of chewing.
6
Q
As the foodstuff enters the mouth, mechanical breakdown begins through the acts of chewing. Then the process of ________ sends the foodstuff through the digestive tract.
A
As the foodstuff enters the mouth, mechanical breakdown begins through the acts of chewing. Then the process of propulsion sends the foodstuff through the digestive tract.
7
Q
In the stomach, further mechanical breakdown is performed by the oblique muscles called ___________.
A
In the stomach, further mechanical breakdown is performed by the oblique muscles called churning.
8
Q
Further mechanical breakdown occurs in the _____________ by segmentation.
A
Further mechanical breakdown occurs in the small intestine by segmentation.
9
Q
____________ is the process that mainly occurs in the small intestine.
A
Absorption is the process that mainly occurs in the small intestine.
10
Q
As the indigestible foodstuff is propelled through the __________, further absorption of water and vitamins occurs and eventually the process of ___________ ends the digestive process.
A
As the indigestible foodstuff is propelled through the large intestine, further absorption of water and vitamins occurs and eventually the process of defaecation ends the digestive process.
11
Q
T/F: There are three layers of the digestive tract.
A
False
There are actually four layers of the digestive tract: mucosa, submucosa, muscularis externa and serosa
12
Q
Which of the following processes occur in the stomach?
a) mechanical breakdown, propulsion, chemical digestion and absorption
b) ingestion, mechanical breakdown, propulsion and defecation
c) mechanical breakdown, chemical digestion, absorption and defecation
d) mechanical breakdown, propulsion, chemical digestion and defecation
A
a) mechanical breakdown, propulsion, chemical digestion and absorption
13
Q
Which of the following is considered an accessory organ of digestion?
a)appendix
b) gall bladder
c) rectum
d) stomach
A
b) gall bladder
14
Q
Which of the following is considered an accessory organ of digestion?
a) liver
b) oesophagus
c) small intestine
d) ascending colon
A
a) liver
15
Q
Which of the following is considered an accessory organ of digestion?
a) pharynx
b) pancreas
c) caecum
d) transverse colon
A
b) pancreas
16
Q
The pancreas produces ____________ that contains __________, these then breakdown all classes of foodstuff.
A
The pancreas produces pancreatic juice that contains enzymes, these then breakdown all classes of foodstuff.
17
Q
The pancreas also produces the hormones __________ and __________ that are involved in metabolism
A
The pancreas also produces the hormones insulin and glucagon that are involved in metabolism
18
Q
The __________ produces ____________ that aids in the digestion of fats. The accessory organ that stores the bile is the ____________
.
A
The liver produces bile that aids in the digestion of fats. The accessory organ that stores the bile is the gallbladder
19
Q
Cellular respiration
a) is the process of producing ATP.
b) is the process of producing glucagon.
c) occurs only in neurons.
d) is the process of synthesising proteins.
A
a) is the process of producing ATP.
20
Q
The catabolic state is
a) also known as the post-absorptive state.
b) also known as the “fed” state.
c) is the state when nutrients are stored for later use.
A
a) also known as the post-absorptive state.
21
Q
Which of the following is not a fate of amino acids
a) stored as fat.
b) used to produce ATP.
c) used to make bile.
A
c) used to make bile.
22
Q
Glycogenesis
a) is the process of forming new glucose from noncarbohydrate molecules.
b) occurs when blood glucose levels decrease.
c) is the production of glycogen.
A
c) is the production of glycogen.
23
Q
Gluconeogenesis
a) is the process of forming glycogen.
b) involves glycogenolysis.
c) is the process of forming new glucose from noncarbohydrate molecules.
A
c) is the process of forming new glucose from noncarbohydrate molecules.
24
Q
Define
Digestive tract
A
A continuous, hollow, muscular tube extending from the mouth to the rectum, involved in the digestion and movement of food. Also known as the gastrointestinal tract or the alimentary canal.
24
# Define
Digestive system
The system in the body responsible for the breakdown and absorption of food, consisting of the digestive tract and accessory organs.
25
# Define
Accessory organs
Organs that assist in digestion but are not part of the digestive tract itself, including the teeth, tongue, salivary glands, gallbladder, liver, and pancreas.
26
# Define
Small intestine
The portion of the digestive tract where most digestion and nutrient absorption occur, consisting of the duodenum, jejunum, and ileum.
27
# Define
Large intestine
The section of the digestive tract that absorbs water and electrolytes from indigestible food matter, and forms and expels feces. It includes the cecum, colon, and rectum.
28
# Define
Rectum
The final section of the large intestine that stores feces until they are expelled from the body through the anus.
29
# Define
Bolus
A soft, rounded mass of chewed food mixed with saliva, ready to be swallowed.
30
# Define
Peristalsis
A series of rhythmic, wave-like contractions of smooth muscle that move food through the digestive tract.
31
# Define
Mechanical breakdown
Also known as mechanical digestion; the physical process of breaking food into smaller pieces to increase surface area for chemical digestion.
32
# Define
Segmentation
A type of mechanical breakdown in the small intestine, involving rhythmic constrictions that mix and move food back and forth to enhance digestion and absorption.
33
# Define
Chemical digestion
The process by which enzymes break down complex food molecules into simpler forms that can be absorbed by the body.
34
# Define
Glycogen
A polysaccharide that serves as the main storage form of glucose in animal tissues.
35
# Define
Amylases
Enzymes that break down carbohydrates into simpler sugars.
36
# Define
Brush border enzymes
Enzymes located on the surface of the small intestine's epithelial cells that further break down carbohydrates, proteins, and nucleic acids.
37
# Define
Pepsin
An enzyme in the stomach that begins the digestion of proteins into smaller peptides.
38
# Define
Proteases
Enzymes that break down proteins into amino acids.
39
# Define
Emulsification
The process by which bile salts break down large fat globules into smaller droplets, increasing the surface area for fat digestion.
40
# Define
Lipases
Enzymes that break down triglycerides into fatty acids and glycerol.
41
# Define
Nucleases
Enzymes that break down nucleic acids into nucleotides.
42
# Define
Mucosa
The innermost layer of the digestive tract, a moist membrane that lines the lumen and is involved in secreting mucus, digestive enzymes, and hormones, and absorbing nutrients.
43
# Define
Submucosa
The layer of tissue external to the mucosa, containing elastic tissues that allow the digestive tract to stretch and recoil.
44
# Define
Muscularis Externa
The layer surrounding the submucosa, composed of smooth muscle cells responsible for peristalsis, segmentation, and forming sphincters to direct the movement of food.
45
# Define
Serosa
The outermost layer of the digestive tract, providing support to the digestive organ and anchoring it to surrounding structures.
46
# Define
Deglutition
The process of swallowing, where food is pushed to the back of the mouth with the tongue and then involuntarily propelled into the pharynx.
47
# Define
Pyloric Sphincter
A ring of muscle at the end of the stomach that controls the release of stomach contents into the duodenum of the small intestine.
48
# Define
Rugae
Large folds in the lining of the stomach that allow it to expand when full and increase its surface area for digestion.
49
# Define
Chyme
A semi-liquid mixture of partially digested food and gastric juices that is gradually released from the stomach into the duodenum.
50
# Define
Goblet Cells
Cells in the stomach mucosa that produce mucus, forming a protective layer to shield the stomach lining from acidic gastric contents and digestive enzymes.
51
# Define
Gastric Pits
Deep indentations in the stomach mucosa that lead to gastric glands, which secrete various substances necessary for digestion.
52
# Define
Parietal Cells
Cells in the gastric glands that produce hydrochloric acid (HCl), which creates an acidic environment necessary for activating digestive enzymes and digesting food.
53
# Define
Chief Cells
Cells in the gastric glands that produce pepsinogen, an inactive precursor of the enzyme pepsin, which is activated by HCl to aid in protein digestion.
54
# Define
Peptic Ulcers
Sores that develop on the lining of the stomach when the mucus barrier is breached, allowing stomach acid and pepsin to damage the stomach wall.
55
# Define
Duodenum
The first segment of the small intestine, a C-shaped tube that receives bile and pancreatic secretions, and is involved in both mechanical and chemical digestion.
56
# Define
Hepatopancreatic Sphincter
A smooth muscle valve that controls the release of bile and pancreatic secretions into the duodenum.
57
# Define
Jejunum
The middle segment of the small intestine, primarily involved in nutrient absorption and digestion.
58
# Define
Ileum
The final segment of the small intestine, ending at the large intestine, where the absorption of nutrients continues.
59
# Define
Circular Folds
Deep, permanent folds in the submucosa and mucosa layers of the small intestine that increase surface area and slow the movement of chyme for enhanced nutrient absorption.
60
# Define
Villi
Finger-like projections of the mucosa in the small intestine that increase surface area for nutrient absorption, containing capillaries and lacteals to transport absorbed nutrients.
61
# Define
Microvilli
Tiny, densely packed projections on the surface of absorptive cells in the small intestine, forming the "brush border," which contains enzymes for the final stages of digestion.
62
# Define
Brush Border
The fuzzy appearance of the microvilli on the surface of absorptive cells, equipped with enzymes that complete the chemical digestion of carbohydrates, proteins, and nucleic acids.
63
# Define
Enterocytes
Cells found in the intestinal crypts that secrete alkaline intestinal juice to neutralize acids and add water to the chyme, aiding in nutrient absorption.
64
# Define
Intestinal Crypts
Indentations in the mucosa between the villi that contain enterocytes and stem cells responsible for secreting intestinal juices and renewing the epithelial lining.
65
# Define
Lacteal
A lymphatic capillary located in the core of the villi that absorbs and transports lipids and other nutrients to the liver.
66
# Define
Ileocecal Valve
A valve located between the ileum of the small intestine and the cecum of the large intestine, preventing the backflow of waste into the small intestine.
67
# Define
Cecum
A pouch-like structure that forms the beginning of the large intestine, located beneath the ileocecal valve.
68
# Define
Vermiform Appendix
A small, tube-like appendage connected to the cecum, containing lymphoid tissue and involved in immune functions.
69
# Define
Colon
The longest part of the large intestine, divided into the ascending colon, transverse colon, descending colon, and sigmoid colon.
70
# Define
Ascending Colon
The portion of the colon that extends upwards from the cecum to the transverse colon.
71
# Define
Transverse Colon
The section of the colon that runs horizontally across the abdomen from the ascending colon to the descending colon.
72
# Define
Descending Colon
The segment of the colon that descends from the transverse colon to the sigmoid colon.
73
# Define
Sigmoid Colon
The S-shaped segment of the colon that connects the descending colon to the rectum.
74
# Define
Teniae Coli
Three bands of longitudinal muscle along the colon that contract to form haustra and move waste through the large intestine.
75
# Define
Haustra
Pouch-like sacs formed by the contraction of the teniae coli in the large intestine.
76
# Define
Internal Sphincter
An involuntary muscle located at the anus, controlled by parasympathetic motor neurons, that maintains closure of the anal canal.
77
# Define
External Sphincter
A voluntary muscle located at the anus, controlled by somatic motor neurons, that can be consciously relaxed to allow defecation.
78
# Define
Mass Movements
Powerful, long contractions in the colon that propel contents toward the rectum and are typically triggered by eating.
79
# Define
Hepatic Artery
A blood vessel that supplies oxygenated blood from the systemic circulation to the liver, constituting approximately 20% of the liver’s blood supply.
80
# Define
Hepatic Portal Vein
A blood vessel that supplies nutrient-rich blood from the digestive tract to the liver, constituting approximately 80% of the liver’s blood supply.
81
# Define
Hepatic Portal System
The system of veins that carries blood from the digestive organs to the liver for processing.
82
# Define
Liver Lobules
The structural and functional units of the liver, each composed of hepatocytes arranged around a central vein, and connected by the portal triad.
83
# Define
Portal Triad
A collection of three vessels at each corner of a liver lobule: an arterial branch of the hepatic artery, a venous branch of the hepatic portal vein, and a bile duct.
84
# Define
Bile Duct
A vessel in the portal triad that collects bile produced by hepatocytes and transports it to the gallbladder.
85
# Define
Liver Sinusoids
Specialized capillaries in the liver with large fenestrations that allow the exchange of large molecules and filtering of blood.
86
# Define
Central Vein
The vein at the center of each liver lobule that collects filtered blood and drains it into the hepatic vein.
87
# Define
Hepatic Vein
The vein that carries blood from the liver to the inferior vena cava, returning it to the systemic circulation.
88
# Define
Bile Canaliculi
Small channels between hepatocytes that collect bile produced by the liver cells and transport it to the bile duct.
89
# Define
Albumin
A plasma protein synthesized by the liver that maintains osmotic pressure, essential for proper fluid distribution between the extracellular fluid (ECF) and intracellular fluid (ICF).
90
# Define
First-pass Metabolism
The process by which the liver metabolizes drugs and hormones into more water-soluble forms for excretion, occurring after substances are absorbed from the digestive tract.
91
# Define
Fat-Soluble Vitamins
Vitamins A, D, E, K, and B12, which are stored in the liver.
92
# Define
Bile
A yellow-green alkaline solution produced by the liver that aids in digestion by emulsifying fats, making them easier for digestive enzymes to break down.
93
DefineEndocrine Tissue
The part of the pancreas that secretes hormones, including insulin and glucagon, to regulate blood glucose levels.
94
# Define
Exocrine Tissue
The part of the pancreas that produces pancreatic juice, which contains bicarbonate ions and digestive enzymes.
95
# Define
Pancreatic Juice
A fluid produced by the pancreas that contains bicarbonate ions to neutralize acidic chyme and enzymes to digest food.
96
# Define
Anabolism
A type of metabolic reaction that builds larger molecules from smaller ones, such as protein synthesis.
97
# Define
Catabolism
A type of metabolic reaction that breaks down complex structures into simpler ones, such as breaking down glycogen into glucose.
98
# Define
Anabolic (or Absorptive) State
A metabolic state occurring during and up to four hours after eating, when the digestive tract provides nutrients that are used for energy and stored for later use.
99
# Define
Catabolic (or Post-absorptive) State
A metabolic state occurring more than four hours after eating, when the digestive tract is empty and the body breaks down stored nutrients to provide energy.
100
# Define
Glucose Sparing
A process where other cells in the body use fuels other than glucose to make ATP, preserving glucose for neurons.
101
# Define
Cellular Respiration
A biochemical process that extracts energy from nutrients by breaking down chemical bonds in glucose to produce ATP.
102
# Define
Glycolysis
The first step in cellular respiration, where glucose is broken down into pyruvate, producing ATP and NADH.
103
# Define
Glycogenesis
The process of converting excess glucose into glycogen for storage in the liver and skeletal muscles.
104
# Define
Lipogenesis
The process of converting excess glucose or amino acids into triglycerides for storage in adipose tissue.
105
# Define
Glycogenolysis
The process of breaking down glycogen into glucose to maintain blood glucose levels during fasting.
106
# Define
Gluconeogenesis
The creation of new glucose from non-carbohydrate sources, such as glycerol and amino acids, when glycogen stores are depleted.
107
# Define
Lipolysis
The breakdown of triglycerides in adipose tissue into glycerol and fatty acids, which can be used to produce glucose through gluconeogenesis.
108
# What is
The system in the body responsible for the breakdown and absorption of food, consisting of the digestive tract and accessory organs.
Digestive system
109
# What is
A continuous, hollow, muscular tube extending from the mouth to the rectum, involved in the digestion and movement of food. Also known as the gastrointestinal tract or the alimentary canal.
Digestive tract
110
# What is
Organs that assist in digestion but are not part of the digestive tract itself, including the teeth, tongue, salivary glands, gallbladder, liver, and pancreas.
Accessory organs
111
# What is
The portion of the digestive tract where most digestion and nutrient absorption occur, consisting of the duodenum, jejunum, and ileum.
Small intestine
112
# What is
The section of the digestive tract that absorbs water and electrolytes from indigestible food matter, and forms and expels feces. It includes the cecum, colon, and rectum.
Large intestine
113
# What is
The final section of the large intestine that stores feces until they are expelled from the body through the anus.
Rectum
114
# What is
A soft, rounded mass of chewed food mixed with saliva, ready to be swallowed.
Bolus
115
# What is
A series of rhythmic, wave-like contractions of smooth muscle that move food through the digestive tract.
Peristalsis
116
# What is
Also known as mechanical digestion; the physical process of breaking food into smaller pieces to increase surface area for chemical digestion.
Mechanical breakdown
117
# What is
A type of mechanical breakdown in the small intestine, involving rhythmic constrictions that mix and move food back and forth to enhance digestion and absorption.
Segmentation
118
# What is
The process by which enzymes break down complex food molecules into simpler forms that can be absorbed by the body.
Chemical digestion
119
# What is
A polysaccharide that serves as the main storage form of glucose in animal tissues.
Glycogen
120
What isEnzymes that break down carbohydrates into simpler sugars.
Amylases
121
# What is
Enzymes located on the surface of the small intestine's epithelial cells that further break down carbohydrates, proteins, and nucleic acids.
Brush border enzymes
122
# What is
An enzyme in the stomach that begins the digestion of proteins into smaller peptides.
Pepsin
123
# What is
Enzymes that break down proteins into amino acids.
Proteases
124
# What is
The process by which bile salts break down large fat globules into smaller droplets, increasing the surface area for fat digestion.
Emulsification
125
# What is
Enzymes that break down triglycerides into fatty acids and glycerol.
Lipases
126
# What is
Enzymes that break down nucleic acids into nucleotides.
Nucleases
127
# What is
The innermost layer of the digestive tract, a moist membrane that lines the lumen and is involved in secreting mucus, digestive enzymes, and hormones, and absorbing nutrients.
Mucosa
128
# What is
The layer of tissue external to the mucosa, containing elastic tissues that allow the digestive tract to stretch and recoil.
Submucosa
129
# What is
The layer surrounding the submucosa, composed of smooth muscle cells responsible for peristalsis, segmentation, and forming sphincters to direct the movement of food.
Muscularis Externa
130
# What is
The outermost layer of the digestive tract, providing support to the digestive organ and anchoring it to surrounding structures.
Serosa
131
# What is
The process of swallowing, where food is pushed to the back of the mouth with the tongue and then involuntarily propelled into the pharynx.
Deglutition
132
# What is
A ring of muscle at the end of the stomach that controls the release of stomach contents into the duodenum of the small intestine.
Pyloric Sphincter
133
# What is
Large folds in the lining of the stomach that allow it to expand when full and increase its surface area for digestion.
Rugae
134
# What is
A semi-liquid mixture of partially digested food and gastric juices that is gradually released from the stomach into the duodenum.
Chyme
135
# What is
Cells in the stomach mucosa that produce mucus, forming a protective layer to shield the stomach lining from acidic gastric contents and digestive enzymes.
Goblet Cells
136
# What is
Deep indentations in the stomach mucosa that lead to gastric glands, which secrete various substances necessary for digestion.
Gastric Pits
137
# What is
Cells in the gastric glands that produce hydrochloric acid (HCl), which creates an acidic environment necessary for activating digestive enzymes and digesting food.
Parietal Cells
138
# What is
Cells in the gastric glands that produce pepsinogen, an inactive precursor of the enzyme pepsin, which is activated by HCl to aid in protein digestion.
Chief Cells
139
# What is
Sores that develop on the lining of the stomach when the mucus barrier is breached, allowing stomach acid and pepsin to damage the stomach wall.
Peptic Ulcers
140
# What is
The first segment of the small intestine, a C-shaped tube that receives bile and pancreatic secretions, and is involved in both mechanical and chemical digestion.
Duodenum
141
# What is
A smooth muscle valve that controls the release of bile and pancreatic secretions into the duodenum.
Hepatopancreatic Sphincter
142
# What is
The middle segment of the small intestine, primarily involved in nutrient absorption and digestion.
Jejunum
143
# What is
The final segment of the small intestine, ending at the large intestine, where the absorption of nutrients continues.
Ileum
144
# What is
Deep, permanent folds in the submucosa and mucosa layers of the small intestine that increase surface area and slow the movement of chyme for enhanced nutrient absorption.
Circular Folds
145
# What is
Finger-like projections of the mucosa in the small intestine that increase surface area for nutrient absorption, containing capillaries and lacteals to transport absorbed nutrients.
Villi
146
# What is
Tiny, densely packed projections on the surface of absorptive cells in the small intestine, forming the "brush border," which contains enzymes for the final stages of digestion.
Microvilli
147
# What is
The fuzzy appearance of the microvilli on the surface of absorptive cells, equipped with enzymes that complete the chemical digestion of carbohydrates, proteins, and nucleic acids.
Brush Border
148
# What is
Cells found in the intestinal crypts that secrete alkaline intestinal juice to neutralize acids and add water to the chyme, aiding in nutrient absorption.
Enterocytes
149
# What is
Indentations in the mucosa between the villi that contain enterocytes and stem cells responsible for secreting intestinal juices and renewing the epithelial lining.
Intestinal Crypts
150
# What is
A lymphatic capillary located in the core of the villi that absorbs and transports lipids and other nutrients to the liver.
Lacteal
151
# What is
A valve located between the ileum of the small intestine and the cecum of the large intestine, preventing the backflow of waste into the small intestine.
Ileocecal Valve
152
# What is
A pouch-like structure that forms the beginning of the large intestine, located beneath the ileocecal valve.
Cecum
153
# What is
A small, tube-like appendage connected to the cecum, containing lymphoid tissue and involved in immune functions.
Vermiform Appendix
154
# What is
The longest part of the large intestine, divided into the ascending colon, transverse colon, descending colon, and sigmoid colon.
Colon
155
# What is
The portion of the colon that extends upwards from the cecum to the transverse colon.
Ascending Colon
156
# What is
The section of the colon that runs horizontally across the abdomen from the ascending colon to the descending colon.
Transverse Colon
157
# What is
The segment of the colon that descends from the transverse colon to the sigmoid colon.
Descending Colon
158
# What is
The S-shaped segment of the colon that connects the descending colon to the rectum.
Sigmoid Colon
159
# What is
Three bands of longitudinal muscle along the colon that contract to form haustra and move waste through the large intestine.
Teniae Coli
160
# What is
Pouch-like sacs formed by the contraction of the teniae coli in the large intestine.
Haustra
161
# What is
An involuntary muscle located at the anus, controlled by parasympathetic motor neurons, that maintains closure of the anal canal.
Internal Sphincter
162
# What is
A voluntary muscle located at the anus, controlled by somatic motor neurons, that can be consciously relaxed to allow defecation.
External Sphincter
163
# What is
Powerful, long contractions in the colon that propel contents toward the rectum and are typically triggered by eating.
Mass Movements
164
# What is
A blood vessel that supplies oxygenated blood from the systemic circulation to the liver, constituting approximately 20% of the liver’s blood supply.
Hepatic Artery
165
# What is
A blood vessel that supplies nutrient-rich blood from the digestive tract to the liver, constituting approximately 80% of the liver’s blood supply.
Hepatic Portal Vein
166
# What is
The system of veins that carries blood from the digestive organs to the liver for processing.
Hepatic Portal System
167
# What is
The structural and functional units of the liver, each composed of hepatocytes arranged around a central vein, and connected by the portal triad.
Liver Lobules
168
# What is
A collection of three vessels at each corner of a liver lobule: an arterial branch of the hepatic artery, a venous branch of the hepatic portal vein, and a bile duct.
Portal Triad
169
# What is
A vessel in the portal triad that collects bile produced by hepatocytes and transports it to the gallbladder.
Bile Duct
170
What isSpecialized capillaries in the liver with large fenestrations that allow the exchange of large molecules and filtering of blood.
Liver Sinusoids
171
# What is
The vein at the center of each liver lobule that collects filtered blood and drains it into the hepatic vein.
Central Vein
172
# What is
The vein that carries blood from the liver to the inferior vena cava, returning it to the systemic circulation.
Hepatic Vein
173
# What is
Small channels between hepatocytes that collect bile produced by the liver cells and transport it to the bile duct.
Bile Canaliculi
174
# What is
A plasma protein synthesized by the liver that maintains osmotic pressure, essential for proper fluid distribution between the extracellular fluid (ECF) and intracellular fluid (ICF).
Albumin
175
# What is
The process by which the liver metabolizes drugs and hormones into more water-soluble forms for excretion, occurring after substances are absorbed from the digestive tract.
First-pass Metabolism
176
# What is
Vitamins A, D, E, K, and B12, which are stored in the liver.
Fat-Soluble Vitamins
177
# What is
A yellow-green alkaline solution produced by the liver that aids in digestion by emulsifying fats, making them easier for digestive enzymes to break down.
Bile
178
# What is
The part of the pancreas that secretes hormones, including insulin and glucagon, to regulate blood glucose levels.
Endocrine Tissue
179
# What is
The part of the pancreas that produces pancreatic juice, which contains bicarbonate ions and digestive enzymes.
Exocrine Tissue
180
# What is
A fluid produced by the pancreas that contains bicarbonate ions to neutralize acidic chyme and enzymes to digest food.
Pancreatic Juice
181
# What is
A type of metabolic reaction that builds larger molecules from smaller ones, such as protein synthesis.
Anabolism
182
# What is
A type of metabolic reaction that breaks down complex structures into simpler ones, such as breaking down glycogen into glucose.
Catabolism
183
# What is
A metabolic state occurring during and up to four hours after eating, when the digestive tract provides nutrients that are used for energy and stored for later use.
Anabolic (or Absorptive) State
184
# What is
A metabolic state occurring more than four hours after eating, when the digestive tract is empty and the body breaks down stored nutrients to provide energy.
Catabolic (or Post-absorptive) State
185
# What is
A process where other cells in the body use fuels other than glucose to make ATP, preserving glucose for neurons.
Glucose Sparing
186
# What is
A biochemical process that extracts energy from nutrients by breaking down chemical bonds in glucose to produce ATP.
Cellular Respiration
187
# What is
The first step in cellular respiration, where glucose is broken down into pyruvate, producing ATP and NADH.
Glycolysis
188
# What is
The process of converting excess glucose into glycogen for storage in the liver and skeletal muscles.
Glycogenesis
189
# What is
The process of converting excess glucose or amino acids into triglycerides for storage in adipose tissue.
Lipogenesis
190
# What is
The process of breaking down glycogen into glucose to maintain blood glucose levels during fasting.
Glycogenolysis
191
# What is
The creation of new glucose from non-carbohydrate sources, such as glycerol and amino acids, when glycogen stores are depleted.
Gluconeogenesis
192
# What is
The breakdown of triglycerides in adipose tissue into glycerol and fatty acids, which can be used to produce glucose through gluconeogenesis.
Lipolysis
193
What are the other names for the digestive tract?
Gastrointestinal tract and alimentary canal.
194
What is the digestive system composed of?
The digestive tract and its accessory organs.
195
How long is the digestive tract approximately?
About 9 meters.
196
What are the two ends of the digestive tract open to?
The mouth and the anus.
197
What are the main components of the digestive tract?
Mouth, pharynx, esophagus, stomach, small intestine, large intestine, and rectum.
198
Which organs are considered accessory organs in digestion?
Teeth, tongue, salivary glands, gallbladder, liver, and pancreas.
199
What is the role of accessory organs?
They assist in digestion but are not part of the digestive tract.
200
What is the first major process of the digestive system?
Ingestion
201
How can food or water be introduced into the digestive system aside from eating?
Via a nasogastric tube or a tube placed directly through the abdominal wall.
202
What is a bolus?
A soft ball of food mixed with saliva that is swallowed.
203
What is the second digestive process?
Propulsion
204
What is peristalsis?
The rhythmic contraction of smooth muscles around the food bolus to move it through the digestive tract.
205
What two types of muscle contractions are involved in propulsion?
Circular and longitudinal muscle contractions.
206
How does the nervous system affect peristalsis?
The parasympathetic nervous system increases motility, while the sympathetic nervous system decreases it.
207
Where does mechanical breakdown occur?
In the mouth, stomach, and small intestine.
208
What happens during mechanical breakdown in the mouth?
Food is chewed and mixed with saliva to form a bolus.
209
What is chyme?
A liquefied substance formed in the stomach after food is mixed with gastric juices.
210
What is segmentation?
The rhythmic local constriction of circular muscles in the small intestine to mix food and digestive juices.
211
What does chemical digestion involve?
Breaking down complex foods into their component building blocks using enzymes.
212
What is cellulose, and why is it important?
A type of polysaccharide that is indigestible but provides dietary fiber, important for healthy bowels.
213
Which enzymes are necessary for breaking down carbohydrates into monosaccharides?
Amylases and brush border enzymes.
214
What are the monomers into which proteins must be broken down for absorption?
Amino acids.
215
Which enzymes are involved in protein digestion?
Pepsin, proteases, and brush border enzymes.
216
What are triglycerides, and why do they require emulsification?
The most abundant fats in the diet, requiring emulsification because they are insoluble in water and form fat globules.
217
What is emulsification?
The process of breaking down fat globules into smaller droplets to increase surface area for digestion.
218
What enzymes break down triglycerides into their monomers?
Lipases
219
How are nucleic acids digested?
By nucleases and brush border enzymes in the small intestine, breaking them down into a base, phosphate ion, and sugar.
220
Where does absorption primarily occur?
In the small intestine.
221
What needs to happen to monomers in the lumen of the digestive tract for them to enter the body?
They need to move into the bloodstream or the lymphatic system.
222
How much food, drink, and secretions do we consume daily?
Between 9 and 10 liters.
223
Where does a small amount of absorption occur aside from the small intestine?
In the stomach and large intestine.
224
What substances can be absorbed in the stomach?
Lipid-soluble substances, particularly alcohol.
225
What is absorbed in the large intestine?
A small amount of water, electrolytes, and some vitamins.
226
What is the final digestive process?
Defecation
227
Which digestive processes are managed by single organs?
Ingestion by the mouth and defecation by the large intestine.
228
Do most digestive processes require cooperation of several organs?
Yes, most processes require cooperation of several organs and occur gradually as food moves along the digestive tract.
229
What is the innermost layer of the digestive tract called?
Mucosa
230
What is the main function of the mucosa?
To secrete mucus, digestive enzymes, and hormones, and to absorb nutrients.
231
What is the role of the submucosa?
It contains elastic tissues that allow for stretch and recoil.
232
Which layer of the digestive tract is responsible for peristalsis and segmentation?
Muscularis externa.
233
What does the serosa do?
Supports the digestive organ and anchors it to surrounding structures.
234
What additional structures are found in the digestive tract besides the four basic layers?
Blood vessels, parasympathetic and sympathetic nerves, lymphatic vessels, and lymphoid tissue.
235
How is the mucosal layer modified in the mouth?
It is lined with multiple layers of epithelial cells for durability and protection.
236
What are the major salivary glands in the mouth?
Parotid, sublingual, and submandibular glands.
237
What are the functions of saliva?
Moistens the food and mouth, lubricates the oral cavity, facilitates taste, and begins the chemical digestion of carbohydrates.
238
Which enzyme in saliva starts the digestion of carbohydrates?
Amylase.
239
What antimicrobial proteins are found in saliva?
IgA, lysozymes, and defensins.
240
How does the parasympathetic nervous system affect saliva secretion?
It increases saliva secretion.
241
What happens to saliva production during strong sympathetic activation?
It can lead to thick mucus or a dry mouth.
242
What are the four digestive processes involved in the mouth?
Ingestion, mastication (chewing), digestion, and propulsion.
243
What is mastication?
The mechanical breakdown of food through chewing.
244
What is a bolus?
A soft ball of food mixed with saliva formed in the mouth.
245
How does saliva help with taste?
It dissolves foods to facilitate taste.
246
What is the role of the pharynx in digestion?
To receive food pushed from the mouth and serve as a passageway to the esophagus.
247
What is the role of the esophagus in digestion?
To serve as a muscular tube that propels food from the pharynx to the stomach.
248
What is the role of the pyloric sphincter in the stomach?
The pyloric sphincter controls the emptying of the stomach and regulates the release of chyme into the small intestine.
249
What is the typical volume range of the stomach when empty and when full?
When empty, the stomach's volume is about 50 milliliters, and when full, it can expand to hold up to four liters.
250
How does the muscularis externa of the stomach differ from other parts of the digestive tract?
The muscularis externa of the stomach has an additional oblique layer of smooth muscle, in addition to the circular and longitudinal layers, which helps to pummel and mix food.
251
What are rugae, and when are they present in the stomach?
Rugae are large folds in the stomach lining that are present when the stomach is empty and collapse inward.
252
What are the three main types of specialized cells found in the gastric pits and glands?
The three main types are parietal cells, chief cells, and goblet cells.
253
What is the function of parietal cells in the stomach?
Parietal cells produce hydrochloric acid (HCl), which creates an acidic environment necessary for pepsin activity and digestion, denatures proteins, and helps kill bacteria.
254
What is pepsinogen, and how is it activated in the stomach?
Pepsinogen is an inactive form of the enzyme pepsin produced by chief cells. It is converted into active pepsin in the presence of hydrochloric acid.
255
What role do goblet cells play in the stomach?
Goblet cells produce mucus that forms a protective barrier on the stomach lining, preventing damage from stomach acid and enzymes.
256
What happens if the mucus barrier in the stomach is breached?
Breaching the mucus barrier can result in gastric ulcers, as stomach acid and pepsin may begin to digest the stomach wall itself.
257
How does the stomach contribute to the mechanical breakdown of food?
The stomach mixes food with gastric juice through its muscular contractions, forming a liquefied substance called chyme.
258
Which enzyme is responsible for the initial chemical digestion of proteins in the stomach?
The enzyme pepsin is responsible for the initial chemical digestion of proteins in the stomach.
259
Can the stomach absorb any nutrients or substances?
The stomach absorbs some fat-soluble substances, such as alcohol, aspirin, and certain drugs, but absorption is a minor role compared to the small intestine.
260
What is chyme, and how is it formed in the stomach?
Chyme is a liquefied food mixture formed in the stomach by the mechanical breakdown of food and mixing with gastric juice.
261
How does the stomach aid in the propulsion of food?
The stomach propels food into the small intestine by churning and mixing the contents, which helps to push the food forward.
262
What is the primary function of the small intestine?
The small intestine is the body's major digestive organ and the site where almost all absorption occurs.
263
What are the three divisions of the small intestine?
The three divisions are the duodenum, jejunum, and ileum.
264
What is the function of the pyloric sphincter?
The pyloric sphincter controls the emptying of the stomach into the duodenum.
265
What is the role of the hepatopancreatic sphincter?
The hepatopancreatic sphincter controls the release of bile and pancreatic secretions into the duodenum.
266
What are circular folds in the small intestine?
Circular folds are deep, permanent folds of the submucosa and mucosa that force the chyme to spiral around, slowing its movement for better nutrient absorption.
267
How tall are the circular folds?
The circular folds are about 1 centimeter tall.
268
What are villi?
Villi are finger-like projections of the mucosa that absorb nutrients and electrolytes from the food and fluids consumed.
269
What is found in the core of the villi?
The core of the villi contains capillary beds and a lymphatic capillary called a lacteal.
270
What is the function of goblet cells in the villi?
Goblet cells produce mucus to ease the passage of food.
271
What are intestinal crypts?
Intestinal crypts are indentations in the mucosa between the villi that contain cells secreting alkaline intestinal juice and stem cells.
272
What do enterocytes in the intestinal crypts secrete?
Enterocytes secrete alkaline intestinal juice to neutralize acids and add water to the chyme.
273
What are microvilli?
Microvilli are very small, densely packed projections on the surface of absorptive cells, giving a "brush border" appearance.
274
What is the function of the brush border enzymes?
Brush border enzymes complete the chemical digestion of carbohydrates, proteins, and nucleic acids.
275
What digestive process moves chyme through the small intestine?
Peristalsis moves the chyme through the small intestine.
276
What is segmentation in the small intestine?
Segmentation, or intestinal churning, is the process where smooth muscle squeezes food back and forth to break it down and mix it with digestive juices.
277
What happens to nutrients, electrolytes, and water by the end of the small intestine?
Virtually all nutrients, electrolytes, and water have been absorbed by the end of the small intestine.
277
Where does the large intestine begin?
The large intestine begins at the ileocecal valve.
278
What is the function of the ileocecal valve?
The ileocecal valve prevents waste from moving back into the small intestine.
279
What is the cecum?
The cecum is a pouch that lies beneath the ileocecal valve.
280
What is the role of the vermiform appendix?
The vermiform appendix contains lymphoid tissue and plays a role in the immune system.
281
What are the divisions of the colon?
The colon is divided into the ascending colon, transverse colon, descending colon, and sigmoid colon.
282
What are teniae coli?
Teniae coli are three bands of muscle along the walls of the colon that contract and form pocket-like sacs called haustra.
283
What are haustra?
Haustra are small pocket-like sacs formed by the contraction of teniae coli.
284
What is the rectum?
The rectum is an expandable organ that allows for the temporary storage of feces.
285
What triggers the defecation reflex?
The presence of feces in the rectum triggers the defecation reflex.
286
What are the internal and external anal sphincters?
The internal anal sphincter is involuntary and innervated by parasympathetic motor neurons, while the external anal sphincter is voluntary and composed of skeletal muscle, innervated by somatic motor neurons.
287
What is the primary function of the large intestine?
The primary function of the large intestine is to propel waste toward the anus and eliminate it from the body.
288
What are haustral contractions?
Haustral contractions are slow, short-lived contractions that move food into the next haustral segment and mix the waste.
289
What are mass movements or mass peristalsis?
Mass movements are long, powerful contractile waves that push contents through the colon and into the rectum.
290
What is the composition of semi-solid feces?
Semi-solid feces consist of food residue, mucus, sloughed-off epithelial cells, bacteria, and enough water for smooth passage.
291
What effect does fiber have on colon contractions and stool?
Fiber increases the effectiveness of colon contractions and softens the stool by retaining water.
292
How is defecation controlled?
Defecation is controlled by the contraction of the rectal wall, relaxation of the internal anal sphincter, and voluntary relaxation of the external anal sphincter.
293
What role do enteric bacteria play in the large intestine?
Enteric bacteria produce vitamins like B and K, ferment indigestible carbohydrates into fatty acids, and produce gas.
294
Does the large intestine perform chemical digestion?
No, chemical digestion is not a function of the large intestine; it is performed primarily in the small intestine by enzymes produced by the body.
295
What is the largest gland in the body?
The liver is the largest gland in the body.
296
Where is the liver located?
The liver is located beneath the diaphragm and lies almost entirely within the rib cage.
297
What organ rests on the inferior surface of the right lobe of the liver?
The gallbladder rests on the inferior surface of the right lobe of the liver.
298
What is the dual blood supply of the liver?
The liver receives blood from the hepatic artery (20%) and the hepatic portal vein (80%).
299
What is the function of the hepatic artery?
The hepatic artery delivers oxygenated blood from the systemic circulation to the liver.
300
What is the function of the hepatic portal vein?
The hepatic portal vein supplies nutrient-rich blood from the digestive tract to the liver.
301
How is blood processed in the liver?
Blood delivered to the liver is filtered and processed by hepatocytes before returning to the systemic circulation.
302
What are liver lobules?
Liver lobules are structural and functional units of the liver, each about the size of a sesame seed.
303
What cells surround the central vein in a liver lobule?
Hepatocytes surround the central vein in a liver lobule.
304
What is the portal triad in a liver lobule?
The portal triad consists of an arterial branch from the hepatic artery, a venous branch from the hepatic portal vein, and a bile duct.
305
What are liver sinusoids?
Liver sinusoids are capillaries with large fenestrations that allow large molecules to enter or exit the vessel.
306
What is the function of the bile duct in the portal triad?
The bile duct collects bile produced by hepatocytes and carries it to the gallbladder.
307
How does blood flow through the liver lobule?
Blood flows from the hepatic artery and hepatic portal vein into the sinusoids, then to the central vein, and finally to the hepatic vein and systemic circulation.
308
What is the role of hepatocytes in the liver?
Hepatocytes filter blood, remove or add substances, and produce bile.
309
What are bile canaliculi?
Bile canaliculi are small canals that collect bile produced by hepatocytes.
310
How does bile flow in the liver lobule?
Bile flows from the hepatocytes through the bile canaliculi to the bile duct in the portal triad.
311
What is the function of macrophages in the liver sinusoids?
Macrophages in the liver sinusoids remove debris such as old red blood cells, cellular debris, and bacteria.
312
Where does filtered blood from the liver lobules eventually return to?
Filtered blood from the liver lobules returns to the systemic circulation via the hepatic vein and inferior vena cava.
313
What is the only digestive function of the liver?
The liver produces bile.
314
What is the role of albumin produced by the liver?
Albumin maintains osmotic pressure, which is necessary for the proper distribution of body fluids between the extracellular fluid (ECF) and intracellular fluid (ICF).
315
What is the liver's role in detoxification?
The liver detoxifies harmful chemicals, including alcohol and drugs, by converting them into less harmful materials that can be excreted.
316
What is first-pass metabolism?
First-pass metabolism is the process where the liver metabolizes drugs and hormones, transforming them into more water-soluble forms for excretion.
317
How does the liver handle excess glucose?
The liver stores excess glucose in the form of glycogen.
318
What metabolic processes occur in the liver involving amino acids?
The liver uses amino acids to synthesize proteins or produce ATP for energy.
319
How does the liver store vitamins and minerals?
The liver stores fat-soluble vitamins (A, D, E, K, and B12) and minerals like iron.
320
What is the role of bile in digestion?
Bile emulsifies fats, breaking them into smaller droplets to increase the surface area for digestive enzymes to act on.
321
Where is bile stored before being released into the duodenum?
Bile is stored in the gallbladder.
322
How often can bile recirculate during the digestion of a single meal?
Bile can recirculate up to five times during the digestion of a single meal.
323
What is the primary function of the gallbladder?
The gallbladder stores and concentrates bile until it is needed for digestion.
324
What are the two main parts of the pancreas?
The two main parts of the pancreas are the endocrine tissue and the exocrine tissue.
325
What hormones are secreted by the endocrine tissue of the pancreas?
The endocrine tissue secretes hormones such as insulin and glucagon to regulate blood glucose levels.
326
What does the exocrine tissue of the pancreas produce?
The exocrine tissue produces pancreatic juice, which contains bicarbonate ions and digestive enzymes.
327
What is the function of bicarbonate ions in pancreatic juice?
Bicarbonate ions help neutralize the acidic chyme entering the duodenum from the stomach.
328
What are the four classes of enzymes produced by the pancreas and their functions?
Pancreatic amylase: Breaks down carbohydrates.
Pancreatic proteases: Digest proteins.
Pancreatic lipases: Break down triglycerides into fatty acids and glycerol.
Pancreatic nucleases: Break down nucleic acids.
329
What can result from a failure of the pancreas to secrete or deliver digestive enzymes?
It can impair digestion and lead to malnutrition.
330
What is metabolism?
Metabolism is the sum total of all the chemical reactions that occur within the body.
331
What does anabolism involve?
Anabolism involves reactions that build larger molecules from smaller ones, such as protein synthesis.
332
What is catabolism?
Catabolism involves processes that break down complex structures into simpler ones, such as breaking down glycogen into glucose.
333
Can products from anabolic reactions be used in catabolic reactions?
Yes, products made during anabolic reactions can be broken down in catabolic reactions and then rebuilt as needed.
334
What is metabolic rate?
Metabolic rate is the energy the body uses to drive metabolism.
335
What is basal metabolic rate (BMR)?
Basal metabolic rate (BMR) is the energy required for essential activities like breathing and maintaining resting levels of organ functions.
336
What is the anabolic (or absorptive) state?
The anabolic state occurs during and up to four hours after eating when the digestive tract provides a large amount of nutrients, which are used to supply stable fuel for all body cells and convert excess nutrients into storage forms.
337
What is the catabolic (or post-absorptive) state?
The catabolic state occurs when the digestive tract is empty, more than four hours after eating, and the body uses stored nutrients from the anabolic state to provide energy and nutrients.
338
What is the main function of the body during the anabolic state?
The main function is to supply energy to all body cells for activities such as active transport, muscle contraction, and chemical reactions.
339
What is ATP, and why is it important?
ATP (adenosine triphosphate) is a universal energy source that stores energy from food and releases it when needed by body cells.
340
Which cells rely entirely on glucose to supply ATP?
Neurons and red blood cells rely entirely on glucose to supply ATP.
341
What is glucose sparing?
Glucose sparing is the process that allows other cells to use fuels other than glucose to make ATP, preserving glucose for neurons.
342
What biochemical process produces ATP from glucose?
Cellular respiration produces ATP by breaking down chemical bonds in glucose.
343
Where does cellular respiration occur?
Cellular respiration occurs in the mitochondria.
344
What are the three main processes involved in cellular respiration?
The three main processes are glycolysis, the tricarboxylic acid cycle (Krebs cycle or citric acid cycle), and the electron transport chain.
345
Can foods other than carbohydrates be used to produce ATP?
Yes, other foods such as fats, alcohol, and amino acids can also be used to produce ATP either directly or by being converted into other molecules used in cellular respiration.
346
What happens to amino acids during metabolism?
Amino acids can be used to produce ATP, and their metabolism results in the production of urea, which is excreted in urine.
347
What occurs during the anabolic or absorptive state?
During the anabolic state, which occurs during and up to 4 hours after eating, there is an abundant supply of nutrients in the blood. Body cells use glucose to create ATP and, if glucose is utilized, other food sources and amino acids can be used for protein synthesis.
348
What happens to excess nutrients during the anabolic state?
Excess nutrients consumed during the anabolic state must be stored for use during the catabolic state, as there is a limit to how much ATP can be stored.
349
What is glycogenesis?
Glycogenesis is the process of converting excess glucose into glycogen, which is then stored in the skeletal muscles and liver.
350
What happens to excess glucose after glycogenesis?
Any excess glucose remaining after glycogenesis is converted into triglycerides through a process called lipogenesis and stored in adipose tissue.
351
What is lipogenesis?
Lipogenesis is the process of creating lipids (triglycerides) from excess glucose and amino acids, which are then stored in adipose tissue.
352
How are amino acids managed during the anabolic state?
Amino acids are used for protein synthesis in body cells. Any excess amino acids are converted to triglycerides through lipogenesis and stored in adipose tissue.
353
What happens to triglycerides in the anabolic state?
Triglycerides are broken down into glycerol and fatty acids, which are used to produce ATP. Any excess glycerol and fatty acids are recombined to form triglycerides and stored in adipose tissue through lipogenesis.
354
What is the role of insulin during the absorptive state?
Insulin regulates blood glucose levels by prompting body cells to take up glucose and amino acids after a meal. It is released by the beta cells of the pancreas in response to increased blood glucose levels.
355
Do brain and liver cells require insulin to take up glucose?
No, brain and liver cells take up glucose regardless of the presence of insulin.
356
What is the fate of glucose when ATP storage is full?
When ATP storage is full, excess glucose is converted into glycogen through glycogenesis and then stored in the liver and skeletal muscles. Any remaining glucose is converted into triglycerides through lipogenesis.
357
What is the primary storage form of glucose in the body?
The primary storage form of glucose in the body is glycogen, stored in the liver and skeletal muscles.
358
How are triglycerides used for energy during the anabolic state?
Triglycerides are broken down into glycerol and fatty acids, which are used to produce ATP. Any excess components are recombined into triglycerides and stored in adipose tissue.
359
What happens to amino acids if glucose is insufficient during the anabolic state?
If glucose is insufficient, amino acids may be used to produce ATP. Any remaining excess amino acids are converted into triglycerides through lipogenesis and stored in adipose tissue.
360
What is the catabolic or post-absorptive state?
It is the metabolic state that begins more than 4 hours after eating, where larger molecules stored during the anabolic state are broken down into smaller ones.
361
What are the primary metabolic processes during the catabolic state?
Catabolic reactions, where stored molecules are broken down into smaller molecules to maintain blood glucose levels.
362
Why is it important to maintain blood glucose levels between 4.0 and 6.0 millimoles per liter?
To ensure adequate glucose for neurons and to maintain homeostasis.
363
What happens if blood glucose levels drop below 4.0 millimoles per liter?
It results in hypoglycemia, which can make the extracellular fluid hypotonic and affect neurons.
364
What happens if blood glucose levels rise above 6.0 millimoles per liter?
It results in hyperglycemia, which makes the extracellular fluid hypertonic and can also affect neurons.
365
What is glycogenolysis?
The process of breaking down glycogen stored in the liver and skeletal muscles to release glucose into the bloodstream.
366
What is gluconeogenesis?
The production of new glucose from non-carbohydrate sources when glycogen stores are exhausted.
367
What role does lipolysis play in the catabolic state?
Lipolysis breaks down triglycerides into glycerol and fatty acids, with glycerol used for gluconeogenesis to produce glucose.
368
What is glucose sparing?
The process where fatty acids produced during lipolysis are used by all body cells except neurons to produce ATP, conserving glucose for neurons.
369
Which hormone dominates during the catabolic state?
Glucagon.
370
What stimulates the release of glucagon?
Decreased plasma glucose levels and the sympathetic nervous system through adrenaline.
371
How does glucagon help maintain blood glucose levels?
By stimulating glycogenolysis and gluconeogenesis, increasing plasma glucose levels.
372
What happens to proteins during periods of starvation?
Proteins are broken down into amino acids, which are converted into glucose through gluconeogenesis.
373
What is the main source of glucose production once glycogen stores are depleted?
Gluconeogenesis from glycerol and amino acids.
374
What is the main difference between the anabolic and catabolic states?
The anabolic state involves building and storing nutrients, while the catabolic state involves breaking down stored nutrients to maintain glucose levels.
375
How is glucose utilization different for neurons compared to other cells during the catabolic state?
Neurons rely entirely on glucose for ATP, while other cells can use fatty acids for energy, preserving glucose for neurons.
376
Which of the following is not one of the six major processes of the digestive system?
A) Ingestion
B) Propulsion
C) Filtration
D) Digestion
C) Filtration
377
What is the primary function of the digestive process known as absorption?
A) Breaking down food into smaller molecules
B) Transporting nutrients into the bloodstream
C) Ingesting food into the mouth
D) Eliminating waste products
B) Transporting nutrients into the bloodstream
378
Which organ is responsible for the majority of nutrient absorption in the digestive system?
A) Stomach
B) Liver
C) Small intestine
D) Large intestine
C) Small intestine
379
Which organ produces bile that aids in the digestion of fats?
A) Pancreas
B) Gallbladder
C) Liver
D) Small intestine
C) Liver
380
What is the primary role of the gallbladder in digestion?
A) Produces digestive enzymes
B) Stores and concentrates bile
C) Absorbs nutrients
D) Filters blood
B) Stores and concentrates bile
381
Which enzyme is produced by the pancreas to break down carbohydrates?
A) Pancreatic protease
B) Pancreatic amylase
C) Pancreatic lipase
D) Pancreatic nuclease
B) Pancreatic amylase
382
What is the function of pancreatic lipase?
A) Breaks down carbohydrates
B) Breaks down proteins
C) Breaks down fats
D) Breaks down nucleic acids
C) Breaks down fats
383
During the absorptive (anabolic) state, excess glucose is converted into which substance for storage?
A) Protein
B) Triglycerides
C) Amino acids
D) Urea
B) Triglycerides
384
In the post-absorptive (catabolic) state, what process releases glucose into the bloodstream from glycogen stores?
A) Glycogenesis
B) Glycogenolysis
C) Gluconeogenesis
D) Lipolysis
B) Glycogenolysis
384
Which metabolic process is responsible for the production of new glucose from non-carbohydrate sources during the post-absorptive state?
A) Glycogenesis
B) Gluconeogenesis
C) Glycogenolysis
D) Lipolysis
B) Gluconeogenesis
385
Which hormone primarily regulates blood glucose levels during the post-absorptive state?
A) Insulin
B) Glucagon
C) Adrenaline
D) Cortisol
B) Glucagon
386
What is the role of insulin in the absorptive state?
A) Stimulates glycogenolysis
B) Promotes the uptake of glucose and amino acids into cells
C) Stimulates gluconeogenesis
D) Inhibits the release of glucose from the liver
B) Promotes the uptake of glucose and amino acids into cells
387
Which of the following is NOT a function of the liver?
A) Producing bile
B) Synthesizing plasma proteins
C) Storing glycogen
D) Digesting proteins
D) Digesting proteins
388
What is the primary function of the large intestine in the digestive system?
A) Nutrient absorption
B) Digestion of fats
C) Water absorption and formation of feces
D) Protein synthesis
C) Water absorption and formation of feces
389
How does the pancreas contribute to neutralizing stomach acid?
A) By producing bile
B) By secreting pancreatic juice with bicarbonate ions
C) By releasing insulin
D) By breaking down proteins
B) By secreting pancreatic juice with bicarbonate ions
390
Which digestive organ stores and concentrates bile before it is released into the duodenum?
A) Liver
B) Small intestine
C) Gallbladder
D) Pancreas
C) Gallbladder
391
What is the role of glucose sparing during the post-absorptive state?
A) Allows neurons to use glucose while other cells use fatty acids
B) Converts fatty acids into glucose
C) Stores excess glucose as triglycerides
D) Increases the production of ATP in neurons
A) Allows neurons to use glucose while other cells use fatty acids
392
What is the primary source of energy for body cells other than neurons during the post-absorptive state?
A) Amino acids
B) Triglycerides
C) Glucose
D) Urea
B) Triglycerides
393
During the absorptive state, what happens to amino acids that are not used for protein synthesis or ATP production?
A) They are excreted in urine
B) They are converted into glucose
C) They are converted into triglycerides and stored
D) They are used to produce bile
C) They are converted into triglycerides and stored
394
What digestive processes are carried out in the mouth?
ingestion
propulsion (involves swallowing)
mechanical breakdown (chewing and mixing food with saliva to form bolus)
chemical digestion (carbohydrates)
395
What digestive processes are carried out in the pharynx & oesophagus?
propulsion (by peristalsis)
396
What digestive processes are carried out in the stomach?
propulsion (by peristalsis)
mechanical breakdown (mixes food with gastric juice to produce chyme)
chemical digestion (pepsin initiates breakdown of proteins)
absorption (fat soluble chemicals and alcohol)
397
What digestive processes are carried out in the small intestine?
propulsion (by peristalsis)
mechanical breakdown (segmentation to increase surface area)
chemical digestion (of all food classes)
absorption (majority of all building blocks move from lumen of digestive tract into the blood supply or the lymph)
398
What digestive processes are carried out in the large intestine?
propulsion (by haustral contractions)
absorption (water, electrolytes and vitamins produced by enteric bacteria)
defaecation
399
In what way is the layers of the digestive tract modified in the mouth?
lined by multiple layers of epithelial cell: to allow for continual abrasion and protect underlying tissue
400
In what way is the layers of the digestive tract modified in the pharynx & oesophagus?
no structural modifications
401
In what way is the layers of the digestive tract modified in the stomach?
* additional oblique layer of muscle for pummelling food and forcing chyme into small intestine
* mucosa indented into gastric pits containing goblet cells, parietal cells and chief cells.
402
In what way is the layers of the digestive tract modified in the small intestine?
* circular folds
* villi
* microvilli
403
In what way is the layers of the digestive tract modified in the large intestine?
* single layer of epithelial cells rich in goblet cells to ease passage of faeces and protect from acids and gases
404
What do Goblet cells of the stomach secrete and what is the function of the secretion?
produce (Insoluble) mucus: to create a barrier and protect stomach from HCL
405
What do Parietal cells of the stomach secrete and what is the function of the secretion?
produce HCL: activates pepsin, denatures proteins, and destroys bacteria
406
What do Chief cells of the stomach secrete and what is the function of the secretion?
produce pepsinogen, the precursor to pepsin: chemically digest protein
407
What is the primary function of the circular folds, villi and microvilli in the small intestine?
increase surface area
408
Other than increasing surface area, what is the additional function of the circular folds?
slow down the speed chyme moves through small intestine to enhance absorption
409
Other than increasing surface area, what is the additional function of the villi?
composed of absorptive epithelial cells with blood vessels and lacteals in the core for nutrient absorption
410
Other than increasing surface area, what is the additional function of the microvilli?
has brush border enzymes embedded in membrane required to complete chemical digestion of carbohydrates, proteins and nucleic acids
411
What is the secretion produced by the salivary gland. If applicable list the enzyme(s) included in the secretion.
What is the function of the secretion?
Saliva with salivary amylase
Starts chemical digestion of carbohydrates in the mouth
412
What is the secretion produced by the liver. If applicable list the enzyme(s) included in the secretion.
What is the function of the secretion?
bile
emulsifies fats
413
What is the secretion produced by the pancreas. If applicable list the enzyme(s) included in the secretion.
What is the function of the secretion?
produce pancreatic juice with pancreatic enzymes:
amylases
proteases
lipases
nucleases
chemical digestion of:
carbohydrates
proteins
fats
nucleic acids
414
1. Where does pancreatic juice and pancreatic enzymes enter the digestive tract?
Duodenum of the small intestine
415
2. Identify the blood vessel that supplies nutrient rich blood to the liver.
Hepatic Portal Vein
416
3. Identify the blood vessel that supplies the oxygenated blood to the liver.
Hepatic Artery
417
4. Identify the 3 vessels found in the portal triad and what travels in the vessels.
Bile duct: Bile
Portal venule: nutrient rich blood
Portal arteriole: oxygenated blood
418
What is the one digestive function of the liver?
Production of bile
419
What are the enzymes or secretion required for chemical digestion of carbohydrates and what is the end product/monomer?
Amylases and Brush Border enzymes
Glucose/ monosaccharide
420
What are the enzymes or secretion required for chemical digestion of Proteins and what is the end product/monomer?
Pepsin, proteases and Brush Border enzymes
Amino Acids
421
What are the enzymes or secretion required for chemical digestion of Fats/Triglycerides
and what is the end product/monomer?
Bile and Lipases
Glycerol and Fatty acids
422
What are the enzymes or secretion required for chemical digestion of Nucleic Acids
and what is the end product/monomer?
Nucleases and Brush Border enzymes
Base, sugar and phosphate ions
423
During the absorptive state, what is the immediate use of glucose and what happens to any excess?
Immediate: used to produce ATP (cellular respiration)
Excess: converted to glycogen (glycogenesis)
converted to triglycerides and stored in adipose tissue (lipogenesis)
424
During the absorptive state, what is the immediate use of amino acids and what happens to any excess?
Immediate: used in protein synthesis or used to produce ATP (cellular respiration)
Excess: converted to triglycerides and stored in adipose tissue (lipogenesis)
425
During the absorptive state, what is the immediate use of glycerol and fatty acids and what happens to any excess?
Immediate: used to produce ATP (cellular respiration)
Excess: converted to triglycerides and stored in adipose tissue (lipogenesis)
426
2. Identify the process that converts glucose into ATP?
Cellular respiration
427
3. Which hormone is released during the absorptive state to stimulate the processes listed above to occur and maintain the blood glucose levels?
Insulin
428
What is the function of Glycogenolysis?
breakdown of glycogen to glucose
429
What is the function of Gluconeogenesis?
production of glucose from non carbohydrate sources:
glycerol produced by the breakdown of fats
amino acids produced by the breakdown of protein
430
2. Which hormone is released during the post-absorptive state to maintain the fasting blood glucose levels?
Glucagon
431
3. Why do we need to maintain fasting blood glucose levels between 4- 6 mmol/L?
Homeostasis of neurons
