NS 332: Exam 2 Flashcards
(150 cards)
1
Q
What is the digestive system?
A
A series of organs coordinated to facilitate nutrient intake and absorb into the bloodstream
2
Q
Where does digestion start?
A
Mouth
3
Q
Which enzyme is used to break down glycosidic bonds (carbohydrates)?
A
Amylase
4
Q
What chemical does the stomach secrete in order to denature proteins?
A
HCl - Hydrochloric acid (Aids in the process of digestion and absorption)
5
Q
What is the function of protease?
A
An enzyme to break down proteins into smaller polypeptides or amino acids (Secreted by the stomach)
6
Q
The mixture that leaves the stomach for the small intestine is called ____?
A
Chyme
7
Q
Which nutrient starts its breakdown in the mouth?
A
Carbohydrates
8
Q
What is the primary function of the epiglottis?
A
To block the larynx and protect the airway during swallowing
9
Q
How is chyme produced?
A
Food churns, mixes with acid and enzymes, and grinds in the stomach
10
Q
Where does chyme go after the stomach?
A
Through the pyloric sphincter to the small intestine, in small amounts
11
Q
What are three functions of muscles in the digestive system?
A
- Sphincter contractions
- Segmentation
- Peristalsis
12
Q
Where does most digestion and absorption occur?
A
Small intestine
13
Q
Glucose is taken up by the enterocytes through _____.
A
Active transport
14
Q
Fructose is taken up by the enterocytes through _____.
A
Facilitated transport. Moves with conc. gradient. Fructose is transported by GLUT5 transporter
15
Q
What do goblet cells do in the intestinal lining?
A
Secrete mucus
16
Q
What is the single layer of cells forming the mucosa of the intestine?
A
Intestinal epithelial cells
17
Q
The secretion and motility functions of the digestive system are coordinated by which two systems?
A
Nervous system and hormonal system
18
Q
When water-soluble nutrients, like glucose and amino acids, are absorbed across the enterocytes, they are released into the ____, and are delivered to the liver, through the portal vein.
A
blood
19
Q
When water-soluble nutrients, like glucose and amino acids, are absorbed across the enterocytes, they are released into the blood, and are delivered to the _____, through the portal vein.
A
liver
20
Q
When water-soluble nutrients, like glucose and amino acids, are absorbed across the enterocytes, they are released into the blood, and are delivered to the liver, through the _____.
A
Portal vein
21
Q
What is the enzyme used to break down starch?
A
Pancreatic amylase
22
Q
What enzyme is used to break down dextrin?
A
Isomaltase
23
Q
What enzyme is used to break down triglycerides?
A
Lipase
24
Q
What enzyme is used to break down protein?
A
Pepsin
25
How long is the small intestine?
20 ft long
26
Where are bile acids produced?
Liver
27
Where are bile acids stored?
Gallbladder
28
Where are digestive enzymes (small intestine) produced?
Pancreas
29
How long is the large intestine?
3.5 ft
30
What is the "central hub" of digestive physiology?
Liver
31
What happens during swallowing?
reflex initiated by the voluntary movement of food from the mouth to the pharynx
32
What is unique about pepsin?
Protease that functions at a very low pH to break peptide bonds
33
What is peristalsis?
mechanism of how the GI tract propels food through itself, beginning in the esophagus. It is a sweeping motion that helps propel food forward. It happens during swallowing, in the stomach, and small sections of the small intestine
34
What happens in the esophagus?
Food enters through the Upper esophageal sphincter (UES) and then peristalsis pushes the food down to the Lower esophageal sphincter (LES) which closes the distal end of the esophagus and blocks reflux of stomach contents back into the esophagus.
35
What is the stomach?
very muscular organ that creates chyme and allows for the breakdown of nutrients, using HCl, pepsin, gastric lipase, and the intrinsic factor.
36
What is gastroesophageal reflux disease?
A condition in which the lower esophageal sphincter is loose. Stomach contents reflux back up into the esophagus. The acid content irritates the lower esophagus.
37
What three drugs help to combat (not treat) GERD?
1. Neutralize acid (antacid), 2. Block acid secretion, 3. Proton pump inhibitor. These drugs block acid secretion
38
How long does it take for food to make it through the small intestine?
3-10 hours
39
What is the lumen? How are villi related?
The lumen is the inside of the small intestine. Villi are the small folds inside of it
40
Why are the villi of the lumen highly pleated?
Villi are highly pleated to increase surface area by over 600 times. Increased interaction with food and increased opportunity for absorption.
41
What four things allow the small intestine to be as successful as it is at absorption of nutrients?
1. Surrounded by longitudinal and circular muscle
2. Rich blood supply
3. Receives digestive enzymes and bicarbonate from the exocrine pancreas
4. Receives bile acids from the liver via the gallbladder
42
Where does the small intestine receive bile acids?
From the gallbladder (produced in the liver)
43
What are crypt cells?
Crypt cells are cells surrounding the "crypts" that form in the villi structure. The crypt cells do not project out into the lumen. Stem cells are located at the bottom of the crypt.
44
What happens in turnover of epithelial cells of the lining?
Happens every three-five days. Stem cells that replenish these epithelial cells are down at the bottom of the crypt. Cells migrate from the crypt up the lumen
45
What are the four cell types?
Enterocytes, goblet cells, enteroendocrine cells, and paneth cells
46
What is the purpose of an enterocyte?
This type is the majority of the small intestine. It is used for digestion and absorption.
47
What is the purpose of a goblet cell?
Goblet cells secrete mucin for protection of the epithelial surface and lubrication for the passage of food.
48
What is the purpose of an enteroendocrine cell?
Hormone secretion
49
What is the purpose of a paneth cell?
Immune monitoring
50
What does the large intestine receive from the small intestine? What does it do with this material?
Leftover food residue from the small intestine. It begins to form fecal material
51
What does the large population of bacteria in the large intestine do?
These digest dietary fiber and can produce short chain fatty acids that can be absorbed into the blood stream.
52
Where are water and minerals absorbed?
Large intestine
53
How long does the transit of food take through the large intestine?
up to 3 days
54
What does frequency of bowel movements depend on?
Microbiome, food intake, genetics, etc.
55
What is the function of the rectum?
stores and expels feces via the anus
56
What three things help control gastrointestinal function?
1. Autonomic nervous system
2. GI hormones
3. GI Motility
57
What is the autonomic nervous system?
Branch of nervous system that regulates function of visceral organs
58
How do GI hormones assist with the control of GI function?
Released in response to meals to help with GI motility, regulation of GI function, and epithelial cell growth. These hormones are regulated to maintain homeostasis
59
What is segmentation?
Closely spaced contractions in discrete areas of the intestine that act to mix the chyme with digestive secretions and increase contact with the mucosal surface
60
What is mass movement?
Mass movement happens in the large intestine. It involves contractions that occur over a large area of intestine that act to move the waste towards the rectum
61
What is the gland and secretion for the mouth? What is the purpose of this secretion?
Salivary glands that secrete saliva. Saliva helps ease swallowing and salivary enzymes break down carbs
62
What are the glands and secretion for the stomach? What is the purpose of this secretion
Gastric glands to secrete gastric juice. Fluid mixes and and HCl denatures proteins, mucus protects stomach cells.
63
What are the two secretions (and organs that secrete them) for the small intestine?
1. The pancreas secretes pancreatic juice. The bicarbonate neutralizes acidic gastric juices, pancreatic enzymes break down carbs, fats, and proteins
2. The gallbladder secretes bile (from the liver). Bile emulsifies fat so that enzymes can have access to break it down
64
What is the secretion for the gallbladder and what secretes it?
The liver secretes bile that targets the gallbladder. Here, the bile is stored until needed in the small intestine
65
Rank saliva, gastric juice, bile, and pancreatic juice from basic to acidic.
Bile, pancreatic juice, saliva, and gastric juice
66
How does salivary amylase break down carbohydrates?
In the mouth, salivary amylase begins to break alpha-1,4 glycosidic bonds from amylose and amylopectin (Does not break alpha 1,6 bonds)
67
How does amylase convert amylose/ amylopectin into dextrins?
Small pieces of starch polymers containing alpha 1,4 and alpha 1,6. Dextrins are further broken down by brush border enzymes
68
What is the brush border?
Organization of microvilli on enterocytes looks like a fuzzy layer. This membrane is studded with glycosidases that break down dextrin.
69
What is lactose intolerance?
No production of the enzyme lactase. Most common in Asia, Africa, and the Mediterranean
70
True or false: Monosaccharides are the only carbohydrate absorbed in the intestine.
True. Glucose and galactose are actively transported by the Na+ dependent transport protein (goes uphill against concentration gradient
71
What does GLUT2 do?
Basal transporter that moves glucose, galactose, and fructose out of the cell and into the blood. It moves with the concentration gradient.
72
Where does protein digestion start and what happens during the process?
Starts in the stomach. HCl denatures proteins. Pepsin is released and breaks apart proteins into pieces. Small intestine is where the majority of protein digestion and amino acid absorption occur. The pancreas secretes digestive enzymes/ bicarbonate into the small intestine. These enzymes hydrolyze peptide bonds producing oligopeptides
73
How are amino acids absorbed?
Amino acids are transported across the intestinal cell membrane by brush border transporters (active and facilitate transport). Further breakdown can occur inside the cells. Transporters then move the amino acids and small peptides out of the basal region of the cell and into the blood.
74
How are lipids digested?
Starts in the stomach with gastric lipase. It hydrolyzes TG to FFA and monoglycerides. Small intestine is the major site of fat digestion and absorption. Gallbladder stores and releases bile acids and lecithins. Bile acids and lecithins emulsify lipids and facilitate breakdown and transport.
75
What will happen if energy in and energy out are about equal?
Weight will not change (maintenance)
76
What will happen if energy in is more than energy out?
Weight will be gained and primarily stored as fat
77
What happens if energy out is higher than energy in?
Weight will be lost
78
What is the first law of thermodynamics?
Energy can't be created or destroyed, only transformed
79
What is adipose tissue?
Fat stores in the human body used for "endless" storage.
80
Where is energy stored in the body?
VAST MAJORITY of energy is stored in adipose tissue triglyceride. Muscle triglyceride and then muscle glycogen store the next most. After that, liver triglyceride and then liver glycogen stores.
81
How many kcals per gram of fat?
9 kcal/g in fat
82
How many kcals per gram of carbohydrate?
4 kcal/gram
83
How many kcal per gram of protein?
4
84
What is the path of metabolizable energy and where is energy potentially lost through the path?
Gross energy -> Digestible energy -> Metabolizable energy. Energy can be lost between gross and digestible through feces. Energy can be lost between digestible and metabolizable through urine and gas.
85
What is the difference between Orlistat and Olestra? What do they have in common
Orlistat is a lipase inhibitor drug that doesn't allow for the digestion of fat (for people trying to lose weight). Olestra is a type of fat that is undigestible by the human body found in "fat-free" foods.
86
How does Olestra affect gross energy and metabolizable energy?
Olestra increases intake of gross energy, but not metabolizable because the body cannot metabolize this type of fat.
87
Do vitamins or minerals provide energy to the body?
No. Vitamins have energy, but they don't have metabolizable energy. Minerals do not provide any energy at all.
88
What are 4 non-biological factors impacting energy in?
1. Accessibility
2. Geographical
3. Socioeconomic
4. Culture
5. Family
6. Culture
89
What are 4 biological factors impacting energy in?
1. Hunger
2. Appetite
3. Satiation
4. Satiety
90
What is the difference between hunger and appetite?
Hunger is the physiological response to nerve signals and hormones after a lack of sufficient food intake. Appetite is the desire to eat, regardless of hunger.
91
What is the difference between satiation and satiety?
Satiation is the sensation that prompts the cessation of eating during a meal. Satiety is the feeling of fullness after a meal; satisfaction that persists between meals.
92
What is ghrelin?
A hunger hormone that is synthesized in the stomach and sent to the hypothalamus
93
What is the CCK hormone?
A protein hormone that is the Satiation response. Stimulates gallbladder for bile production
94
What is the GLP1 hormone?
It is a peptide hormone responsible for the satiation response. Released in the small intestine.
95
What is leptin?
Satiation signal synthesized in adipose tissue.
96
If you have more adipose tissue, will you produce more or less leptin?
More
97
What is the problem in an Ob/Ob mouse?
These mice have a mutation in the gene that encodes leptin -> so they can't produce leptin, but they can respond to leptin if it is in their system. These mice become obese because they do not receive the satiation signal.
98
What is the problem in a Db/Db mouse?
These mice have a mutation in the gene that encodes the leptin receptor. These mice produce leptin, but can't respond to it. These mice gain weight because they do not receive the satiation signal
99
What happens when an Ob/Ob mouse and a +/+ (wild type mouse) share circulation?
The wild type mouse stays the same. The Ob/Ob mouse will reduce its food intake, insulin levels, and blood sugar.
100
What happens in the case of when a Db/Db mouse and a wild type mouse share circulation?
The Db/Db (diabetic mouse) gained weight and adipose tissue. The lean mouse decreased its food intake, which led to insulinemia and reduced blood sugar. The lean mouse eventually dies by starvation due to a lack of appetite by too much leptin.
101
What happens in the case of when a Db/Db mouse and an Ob/Ob mouse share circulation?
Diabetic mouse gains weight and adipose tissue. The Ob/Ob mouse lowers food intake, which reduces adipose tissue and blood sugar, resulting in death by starvation.
102
What are the three methods of measuring energy expenditure?
1. Gas exchange
2. EER Formula
3. Wearables
103
What method of engery expenditure does this describe?
The most accurate and complicated measure of energy expenditure; measures O2 consumed and CO2 expelled based on the amounts that different macronutrients need.
The gas exchange method of energy expenditure
104
What factors are needed for the EER formula?
Age, weight, height, and activity level
105
What do wearables measure to determine energy expenditure?
Accelerometer (measures velocity) and heart rate. Fairly inaccurate (20-90%)
106
What are the three components of energy expenditure?
1. Basal metabolism (50-65%), 2. Physical activities (30-50%), 3. Thermic Effect of food (10%)
107
What component of energy expenditure is the amount of energy expended for the digestion of food, usually through heat production?
The thermic effect
108
Which macronutrient produces the most heat production through the thermic effect?
Protein! (20-25%) then Carbs, then fat
109
What is adaptive thermogenesis?
This is the homeostatic regulation of body temperature.
110
What happens during non-shivering thermogenesis?
Brown and beige adipocytes are activated when cold
111
Does NST or ST happen first?
NST (non-shivering thermogenesis)
112
What are adipocytes?
fat cells
113
What are the three types of adipocytes? What tissue are they in?
1. White in White adipose tissue
2. Brown in brown adipose tissue (modified mitochondria)
3. Brite/Beige in white adipose tissue (modified mitochondria)
114
What is hydrodensitometry?
measures body density, measures the difference between weight out of water and weight in water
115
What is air displacement plethsymography?
Determines amount of air displaced by person's body
116
What is bioelectric impedance?
Low intensity electrical current (leaner -> less resistance to current)
117
What is DEXA? What is one pro and one con?
Dual X-Ray Absorptiometry: low dose x-ray,
Con: Can't tell difference between water and muscle
Pro: most accurate
118
What are the five methods to measure body density?
1. Hydrodensitometry
2. Air displacement plethymography
3. Bioelectric impedance
4. DEXA
5. Skinfold
119
When a person overeats: Protein is broken down in the body into ______ and then used for ____, ____, and _____.
Protein is broken down in the body into (amino acids) and then used for (body fat stores), (loss of nitrogen in urine: urea), and (body proteins)
120
When a person overeats: Fats are broken down in the body into _______ and then used for ____.
Fats are broken down in the body into (fatty acids) and then used for (body fat stores).
121
When a person overeats: Carbohydrates are broken down in the body into _______ and then used for ______ and _____.
Carbohydrates are broken down in the body into (glucose) and then used for (liver and muscle glycogen stores) and (body fat stores)
122
When a person draws on stores (fasting), liver/muscle glycogen stores are broken down into ______ and then used for ______ and ______
When a person draws on stores (fasting), liver/muscle glycogen stores are broken down into (glucose) and then used for (energy for the brain, nervous system, and red blood cells) and (energy for other cells).
123
When a person draws on stores (fasting), body fat stores are broken down into ______ and then used for ______.
When a person draws on stores (fasting), body fat stores are broken down into (fatty acids) and then used for (energy for other cells).
124
If a fast continues beyond glycogen depletion, body protein is broken down in the body into _____ and then used for _______ and _____.
If a fast continues beyond glycogen depletion, body protein is broken down in the body into (amino acids, into urea, glucose, and ketone bodies) and then used for (Energy for the brain, nervous system, and red blood cells) and (Energy for other cells).
125
If a fast continues beyond glycogen depletion, body fat is broken down in the body into ______ and then used for ______ and ______.
If a fast continues beyond glycogen depletion, body fat is broken down in the body into (fatty acids and ketone bodies) and then used for (fatty acids -> energy for other cells) and (ketones -> energy for the brain, nervous system, and red blood cells).
126
In response to low blood glucose levels, what do the alpha cells in the pancreas increase the release of?
The hormone glucagon
127
In response to elevated glucose levels, what do the beta cells in the pancreas increase the release of?
The hormone insulin
128
What does glucagon do once it is in the bloodstream?
It stimulates liver cells to break down glycogen and release glucose into the blood. Blood glucose then begins to rise
129
In response to high blood glucose, what does insulin do once released?
Insulin stimulates the uptake of glucose into cells and storage as glycogen in the liver and muscles, promote protein synthesis in the muscle, and lipogenesis for storage. Insulin suppresses lipolysis.
130
What are the 4 characteristics of the fed state?
1. Blood glucose is elevated
2. Insulin is secreted
3. Relative concentration of insulin is higher than glucagon, favoring glucose utilization and energy storage
4. Glycogen and fat storage increases
131
What are the 4 characteristics of the post-absorptive state?
1. Blood glucose decreases
2. Insulin levels decrease and glucagon increases
3. Increased liver glycogen broken down for source of glucose
4. Increased fat breakdown and use of fatty acids for energy
132
What are the 5 characteristics of the fasting state?
1. Liver glycogen stores are depleted
2. Relative concentration of glucagon is higher than insulin
3. Glucose is supplied mainly by gluconeogenesis
4. Stored triglycerides are broken down with an increase of use of fatty acids for energy
5. Ketone formation (ketogenesis) increases
133
What is the difference between catabolism and anabolism?
Catabolism breaks down proteins, carbohydrates, and fats. Waste products include CO2, H2O, and NH3.
Anabolism builds proteins, glycogen, and triglycerides (and other lipids) from amino acids, sugars, fatty acids, and glycerol
134
Where are coenzymes/ cofactors derived from?
Vitamins and minerals
135
What is ketosis? How does this differ from ketoacidocis?
Ketosis is when there are high levels of ketones in blood (exhale in breath, excrete in urine)
Ketoacidosis is severe ketosis which leads to lowered blood pH, nausea, coma, and death (often occurs in patients with uncontrolled type I diabetes)
136
What are the two anabolic pathways during catabolic conditions?
Gluconeogenesis and ketogenesis
137
What two anabolic pathways allow for the storage of "surplus" after food intake?
Glycogenesis and lipogenesis
138
What is beta-oxidation?
Breakdown of fatty acids to acetyl CoA
139
What is glyconeogenesis?
Glycogen breakdown, glucose production
140
What is glycolysis?
Glucose breakdown, forming two molecules of pyruvate ATP production without oxygen (anaerobic energy metabolism)
141
What is lipolysis?
Breakdown of triglycerol to fatty acids and glycerol
142
What is proteolysis?
breakdown of protein to amino acids
143
What is transamination/ deamination?
Transfer/removal of amino group (NH3) from the amino acids.
144
What is the citric acid cycle (TCA/Krebs)?
A central metabolic pathway, oxidizing acetyl CoA to CO2 and generating reducing equivalents (NADH + H, FADH2) and GTP (ATP)
145
What is oxidative phosphorylation?
A series of coupled processes in which reducing equivalents are oxidized and the resulting proton gradient enables ATP production
146
What is gluconeogenesis?
Glucose synthesis from noncarbohydrate sources
- can happen in liver (and muscles?)
147
What is ketogenesis?
Formation of ketones from acetyl-CoA
148
What is glycogenesis?
Formation of glycogen (for storage)
149
What is lipogenesis?
Synthesis of fatty acids and formation of triglycerol (for storage)
150
What is the difference between glycemic index and glycemic load?
Glycemic index is the property of food that promotes a rise in blood glucose and how long that spike lasts (per 100g). Glycemic load is glycemic index x carb content.
