GI Anatomy & Function Flashcards
1
Q
The GI tract is made up of what 7 organs?
A
- Mouth 2. Esophagus 3. Stomach 4. Small intestine 5. Large intestine 6. Liver 7. Pancreas
2
Q
What happens in the stomach to aid digestion?
A
- Food is further broken down and converted to CHYME 2. Where protein digestion begins
3
Q
Where are nutrients absorbed in digestion?
A
Small intestines
4
Q
Where are water and electrolytes reabsorbed during digestion?
A
Large intestine
5
Q
Which organ produces bile for digestion?
A
Liver
6
Q
Where is bile stored until it is needed?
A
The gallbladder.
7
Q
Which GI organ plays a major role in glucose storage and release?
A
Liver
8
Q
Which pancreatic secretions does the pancreas produce?
A
Insulin and glucagon.
9
Q
What is the purpose of VILLI and MICROVILLI in the wall of the small intestine?
A
To increase its surface area for absorbing nutrients.
10
Q
Blood flows into the liver via the _______ vein and out of the liver via the __________ vein.
A
Portal, hepatic Acronym help: IPOH
11
Q
What are the major functions of the liver?
A
- Metabolizes Fat, Carbohydrates, and Protein (F, C, P) 2. Stores carbohydrates 3. Produces bile 4. Converts drugs, hormones, and toxins to soluble forms for excretion
12
Q
What do the endocrine secretions of the pancreas do?
A
Help regulate blood glucose levels.
13
Q
What do the exocrine secretions of the pancreas do?
A
Help digest food in the small intestine.
14
Q
Insulin consists of _____ and ______ amino acid chains linked by ______.
A
Alpha, beta, disulfide bonds
15
Q
What are the 4 primary functions of the GI tract?
A
- Ingesting food 2. Breaking food down into component parts 3. Absorbing nutrients 4. Excreting wastes
16
Q
Name all of the organs of the GI tract.
A
- Mouth 2. Esophagus 3. Stomach 4. Liver 5. Small intestine 6. Large intestine 7. Rectum 8. Anus 9. Gall bladder 10. Pancreas
17
Q
In what 2 organs does almost all digestion occur?
A
- Stomach 2. Small intestine
18
Q
What is the liquid called that is converted from the food mass in the stomach?
A
Chyme
19
Q
What happens to chyme after it leaves the stomach?
A
Passes through the small intestines where nutrients are absorbed.
20
Q
After leaving the small intestine, what happens next in digestion?
A
Chyme enters the large intestine where water, electrolytes, and some other substances are reabsorbed.
21
Q
There are deep folds on the inside wall of the stomach. Why are they there?
A
They allow the stomach to stretch to a capacity of about 1.5 L.
22
Q
In the stomach, what substances are secreted by special glands?
A
- Mucus - protects the stomach wall from itself being digested by stomach acid 2. Pepsinogen - converts to active enzyme pepsin in the presence of HCl and begins process of digesting protein 3. HCl - helps break down food and activates pepsinogen 4. Histamine, Serotonin, and Gastrin, which stimulate HCl production
23
Q
Where does carbohydrate digestion begin?
A
In the mouth.
24
Q
Where does protein digestion begin?
A
The stomach.
25
Chyme from the stomach is gradually released into the duodenum through the \_\_\_\_\_\_\_\_\_?
Pyloric sphincter
26
What are the 3 anatomical sections of the small intestine and their lengths?
1. Duodenum - 10 inches long 2. Jejunum - 8 feet 3. Ileum - 12 feet
27
The duodenum contains ducts from the liver that secrete ______ and \_\_\_\_\_\_\_\_. Pancreatic ducts secrete \_\_\_\_\_\_\_\_\_\_\_\_, which contain \_\_\_\_\_\_\_, \_\_\_\_\_\_\_\_\_\_, \_\_\_\_\_\_\_\_\_\_\_.
Bile salts, phospholipids. Pancreatic secretions. Water, enzymes, and electrolytes.
28
The secretions of the duodenum serve what purpose?
They neutralize stomach acid to create an appropriate environment for the enzymes to function.
29
Of the three sections of the small intestine, where does most of the digestion and absorption occur?
Jejunum.
30
On average, how long does it take chyme to pass through the small intestine and get to the large intestine?
5 hours
31
What are the fingerlike projections called that cover the inner wall of the small intestine?
VILLI, which are in turn covered with even tinier MICROVILLI, which extend from the tops of enterocytes.
32
Deep \_\_\_\_\_\_\_, \_\_\_\_\_\_\_\_\_\_, and __________ increase the total surface area of the small intestine wall.
Folds, Villi, MICROVILLI
33
When chyme reaches the small intestine, what is secreted by the intestines?
Incretins gastric inhibitory peptide (GIP) and glucagon like peptide-1 (GLP-1).
34
What secretes GIP in the intestine?
Cells in the Duodenum.
35
What secretes GLP-1 in the intestine?
Cells in the ileum and colon.
36
What is the large intestine also known as?
The colon.
37
Does the colon contain folds or villi?
No, because all nutrients have been absorbed by this point.
38
What function does the large intestine serve?
It serves as the area for reabsorbing most of the water and electrolytes secreted earlier in digestion.
39
Bacteria in the ______________ digest ____________ that the body cannot break down.
Large intestine, carbohydrates.
40
What are the primary functions of the liver?
1. Produces bile that aids in digestion 2. Further metabolizes nutrients into useful substances.
41
Blood flows into the liver via the __________ vein and out of the liver via the ___________ vein.
Portal, hepatic Acronym help: IPOH
42
Blood from vessels surrounding the ____________ passes into the ___________ via the ____________ \_\_\_\_\_\_\_\_\_\_\_\_ vein.
Small intestines, liver, hepatic portal.
43
How many mL of bile does the liver produce each day?
500-1000mL
44
Bile produced by the liver consists of ________ and \_\_\_\_\_\_\_\_\_, among other substances.
bile salts, phospholipids.
45
Bile is secreted by _________ cells and stored in the ____________ until it is released into the _____________ through the bile duct.
liver, gallbladder, duodenum.
46
What 3 substances can be metabolized in the liver?
Carbohydrates Fat Protein
47
What substances are converted to soluble forms for later excretion in the liver?
drugs, hormones, and toxins
48
Where does the pancreas lie in the body?
horizontally across the upper part of the abdomen, behind the stomach.
49
The ___________ duct runs the length of the pancreas and merges with the common ________ duct to enter the duodenum.
pancreatic, bile.
50
The pancreas contains 2 classes of cells with 2 distinctly different functions. What are the 2 classes of cells?
1. Pancreatic Acini 2. Islets of Langerhans
51
The pancreatic acini secrete what 2 substances? Where are they secreted?
1. Electrolytes 2. Enzymes into the pancreatic duct.
52
Describe the exocrine function of the pancreas.
The first function of the pancreas is to help with the digestion of food in the SMALL INTESTINE.
53
The acini surround what other group of cells?
islets of Langerhans
54
Pancreatic cells in the islets of Langerhans secrete what 3 hormones?
1. Glucagon 2. Insulin 3. Somatostatin Acronym help: G I S
55
The alpha cells produce \_\_\_\_\_\_\_\_\_\_.
Glucagon. Acronym help: A ---\> G
56
The beta cells produce \_\_\_\_\_\_\_\_\_\_\_\_.
Insulin. Acronym help: B -----\> I
57
The delta cells produce \_\_\_\_\_\_\_\_\_\_\_\_.
Somatostatin. Acronym help: D -----\> S
58
Describe the endocrine function of the pancreas.
The endocrine function of the pancreas involves the regulation of blood glucose.
59
\_\_\_\_\_\_\_\_\_\_\_ and ____________ have opposite effects on blood glucose. _________ keeps blood glucose from rising too high and ___________ keeps it from falling too low.
Insulin, glucagon. insulin, glucagon.
60
Describe the function of somatostatin.
Somatostatin inhibits secretion of insulin and glucagon and inhibits gastric motility. It is believed that this effect helps to prolong the time during which nutrients are absorbed into the blood and taken up by tissues.
61
Somatostatin inhibits secretion of what?
Insulin and glucagon as well as inhibiting gastric motility.
62
How is insulin made in the body?
It starts as a long protein called PROINSULIN within the beta cell. Proinsulin is broken down in the pancreas into insulin and a c-peptide fragment.
63
Insulin is packaged into _______________ that merge with the ___________ and release their contents into the bloodstream.
secretory granules, cell membrane.
64
Describe 1st phase and 2nd phase insulin releases.
1st phase: an immediate release of pre-packaged insulin from the secretory granules in response to food. 2nd phase: a release of newly manufactured insulin.
65
Insulin molecules that do not react with cell-surface receptors are broken down within ___________ minutes.
10-15 minutes.
66
Summarize digestion from mouth to stomach.
1. Food ingested, chewed, mixed with saliva 2. Food propelled down the esophagus to the stomach. 3. In the stomach, HCl and enzymes further break down food into the liquid CHYME.
67
Summarize digestion from small intestine to large intestine.
1. Chyme from the stomach passes to the small intestine. 2. When the chyme enters the small intestine, the intestines secrete incretin hormones GIP and GLP-1 into the bloodstream to help regulate blood glucose levels. 3. As the chyme passes through the small intestine, nutrients, water, and electrolytes are absorbed into the bloodstream. 4. The chyme passes from the small intestine to the large intestine. 5. Once inside the large intestine, chyme is converted into waste products that are stored in the rectum until defecation.
68
Describe the functions of the liver in digestion and metabolizing nutrients.
1. Liver releases BILE into the duodenum. 2. As blood from the intestines passes through the liver, the carbohydrates, lipids, and proteins it carries are further metabolized and stored.
69
Carbohydrates consist of what 3 things?
Sugars (monosaccharides and disaccharides), Starches, and Fibers. Acronym help: S S F
70
Most carbohydrates (except fibers) can be converted to \_\_\_\_\_\_\_\_\_\_.
glucose
71
Name the 3 monosaccharides that are essential to human nutrition.
1. Glucose 2. Galactose 4. Fructose Acronym help: G G F
72
Name the only monosaccharide that the cells can metabolize for energy.
Glucose.
73
The liver converts almost all the __________ and ___________ to glucose to enable them to be used.
galactose, fructose.
74
When one glucose molecule is combined with itself or with either galactose or fructose, they form \_\_\_\_\_\_\_\_\_\_\_\_\_.
disaccharides
75
Name the 3 disaccharides and their component parts.
1. Maltose (2 glucose molecules) 2. Sucrose (glucose + fructose) 3. Lactose (glucose + galactose)
76
True or False: enzymes in the small intestine can convert disaccharides into monosaccharides.
True
77
\_\_\_\_\_\_\_\_\_\_\_\_\_ consist of many monosaccharides linked together in straight or branded chains.
Polysaccharides
78
What are the 3 most important polysaccharides in human nutrition?
1. Glycogen 2. Starches 3. Fibers Acronym help: G S F
79
What is the storage form of glucose in the human body?
Glycogen
80
Describe what happens with excess glucose.
As blood passes through the liver, excess glucose molecules are linked together to form glycogen and then stored in liver cells.
81
The production of glycogen is called what?
glycogenesis
82
What is glycogenolysis?
when glycogen is broken down into glucose and then released into the bloodstream
83
What stimulates glycogenolysis?
glucagon
84
Where is the body's largest reservoir of glycogen stores?
Muscle cells
85
Can muscle cells release glucose back into the bloodstream?
No, muscle cells can only provide energy to the muscle cell itself.
86
Can the brain and spinal cord store glucose?
No, the brain and spinal cord rely on a continuous supply from the bloodstream.
87
Where does carbohydrate digestion begin? What enzyme here aids in digestion?
The mouth. Ptyalin. \* Saliva contains ptyalin, which breaks down starches to maltose.
88
Ptyalin breaks down __________ into \_\_\_\_\_\_\_\_\_.
starches, maltose.
89
Alpha amylase works in the ___________ section of the stomach to digest \_\_\_\_\_\_\_\_\_\_.
Duodenum, carbohydrate
90
After chyme leaves the duodenum, it enters the \_\_\_\_\_\_\_\_\_\_, where almost all of the starch has been converted to \_\_\_\_\_\_\_\_\_\_\_.
Jejunum, disaccharides.
91
\_\_\_\_\_\_\_\_\_\_\_\_ digestion is completed by cells (\_\_\_\_\_\_\_\_\_\_\_) that line the intestinal villi and make up the _____________ of the small intestine.
Carbohydrate, enterocytes, brush border.
92
Inside the small intestines, specific enzymes reduce all the carbohydrates to \_\_\_\_\_\_\_\_, \_\_\_\_\_\_\_\_\_, and _________ for absorption into the bloodstream.
glucose, fructose, and galactose
93
What are the building blocks for most cell and body components and structures?
Proteins
94
What functions do proteins play?
1. Basic building blocks for cell and body components and structures. 2. Act as enzymes to speed up chemical reactions 3. Transport oxygen in the blood 4. Communicate signals between cells/organs 5. Perform many other essential functions.
95
If energy supplies are low in the body, what will the body do with proteins?
The proteins will be broken down and converted to glucose.
96
Energy obtained from _______ and __________ saves proteins for other important functions in the body.
fats, carbohydrates
97
Where does protein digestion begin?
in the stomach
98
Provide overview of protein digestion in the stomach.
1. Gastric acid activates pepsinogen to form pepsin 2. Pepsin breaks down collagen, which holds meat fibers together 3. This creates greater surface area for other enzymes to further break down proteins 4. Chyme enters the duodenum of the small intestine where enzymes break down peptides into chains of 2 or 3 amino acids. 5. Enterocytes of the small intestine complete digestion by breaking down the proteins into individual amino acids. 6. Amino acids are absorbed by cells of the liver and then reassembled into proteins needed throughout the body.
99
What happens to excess amino acids?
They are stored in the liver for release when needed.
100
What happens to the amino acid when it is used for energy?
Part of the molecule (called the amino group) is converted to urea, which is excreted by the kidneys. The remaining portion is broken down for energy or converted to glucose (gluconeogenesis) or to fatty acids that are part of tryglyceride molecules (ketogenesis). [These reactions occur in the liver.]
101
What are lipids?
essential cell membrane components and are stored for energy.
102
What are 2 forms of lipids?
1. Triglycerides (the most common form in the diet) 2. Cholesterol
103
Triglycerides consist of one molecule of ____________ attached to three \_\_\_\_\_\_\_\_\_\_.
glycerol, fatty acids.
104
Lipid digestion begins in the ___________ with lingual lipase.
mouth
105
Lipids need to pass through the ___________ system to reach the bloodstream.
lymphatic
106
\_\_\_\_\_\_\_\_\_ help separate lipid molecules.
Bile salts
107
What are micelles?
complexes of bile salts and lipids in the intestinal tract
108
Triglyceride molecules constantly __________ down and _____________ to diffuse into the _____________ system, \_\_\_\_\_\_\_\_\_\_\_\_, and body \_\_\_\_\_\_\_\_\_\_.
breakdown, recombine, lymphatic, cells.
109
Name the component parts of maltose.
Glucose + glucose
110
Glycogenolysis occurs when __________ is converted to \_\_\_\_\_\_\_\_\_\_.
Glycogen, glucose
111
When liver glycogen is exhausted, ________ stimulates gluconeogenesis from ________________ in the \_\_\_\_\_\_\_\_\_\_.
Glucagon, amino acids, liver.
112
Is glucagon an anabolic or catabolic hormone?
It is a catabolic hormone because it involved the breaking down of glycogen and amino acids.
113
Explain the incretin effect.
The phenomenon where ingested glucose causes a higher spike in insulin levels than IV infused glucose.
114
GIP is secreted by ______ cells in the \_\_\_\_\_\_\_\_\_\_\_\_.
K cells, duodenum.
115
GLP-1 is secreted by _______ cells in the ____________ and \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.
L cells, ileum, colon.
116
What is the half-life of GIP and GLP-1?
3-5 minutes
117
Research indicates that only ____ to \_\_\_\_\_% of the GIP and GLP-1 secreted actually reach the pancreas in active form.
10-15%
118
1st phase insulin response occurs ________ minutes after a meal.
30 minutes
119
2nd phase insulin response occurs over _____ hours after a meal.
1-2 hours
120
Insulin causes the ________ to absorb excess _________ and convert it to \_\_\_\_\_\_\_\_\_\_\_.
liver, glucose, glycogen.
121
Besides serving as essential components in various body structures, such as cell membranes, __________ are an efficient storage form of enery.
lipids
122
Lipids are stored in __________ tissue (fat cells) located throughout the body.
adipose
123
When dietary carbohydrates and stored glycogen are no longer sufficient to supply energy to the cells, what can be broken down and released into the bloodstream?
stored lipids
124
What is the most common form of lipid in the diet?
tryglycerides
125
What does triglyceride consist of?
one molecule of glycerol attached to 3 fatty acids
126
What is cholesterol the basis for?
bile salts and steroid hormones, and is also an essential part of the cell wall
127
What do bile salts do?
separate lipid molecules into tiny droplets with greater surface area for contact with enzymes
128
True or False: the brain requires insulin to absorb glucose.
False, the brain is the one exception in the body where insulin is not needed to absorb glucose because it absorbs glucose directly from the blood.
129
Insulin acts on muscle and adipose cells by linking to its specific receptor, \_\_\_\_\_\_\_\_, on the cell surface.
GLUT-4
130
Describe the process by which insulin induces cellular uptake of glucose.
1. Links to its specific receptor, GLUT-4, on the cell surface
2. Within seconds of binding to GLUT-4, activated cells increase their production of GLUT-4, which is brought to the cell surface in packages called vesicles
3. Higher levels of GLUT-4 on the cell surface faciltate glucose uptake
4. When insulin levels fall, the vesicles remove GLUT-4 so that glucose absorption falls.
131
Higher levels of GLUT-4 on the cell surface faciltate what?
glucose uptake
132
Insulin binding to the cell receptor increases the absorption of what?
glucose, many amino acids, as well as important ions
133
In muscle and liver cells, insulin promotes the conversion of __________ to \_\_\_\_\_\_\_\_\_\_.
glucose, glycogen
134
\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is absorbed and stored as glycogen in muscle and liver cells.
Glucose
135
How does insulin affect fat synthesis and storage?
Since insulin promotes glucose uptake, this shifts cell metabolism away from burning fat for energy.
136
Where in the body is excess glucose converted to fatty acids?
in the liver
137
Where in the body is glucose converted to glycerol?
in the fat cells
138
Glycerol and fatty acids combine into __________ and are stored.
triglycerides
139
Glucagon is secreted by the _________ cells of the pancreas in response to \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.
alpha, falling glucose levels
140
What is the major function of glucagon?
stimulate the conversion of glycogen into glucose (glycogenolysis)
141
Once liver glycogen is exhausted - and therefore unable to produce glucose - what does glucagon then do?
It stimulates gluconeogenesis from amino acids in the liver.
142
As food enters the small intestine from the stomach, the chyme contains what substances?
* monosaccharides, disaccharides, and some longer-chain carbohydrates
* amino acids and peptides
* small emulsified fat globules
143
In the postprandial period, monosaccharides are absorbed from _________ \_\_\_\_\_\_\_\_\_\_ into the blood and travel in the portal circulation to the \_\_\_\_\_\_\_\_\_.
intestinal villi, liver.
144
In the postprandial period, what does the liver do with excess glucose?
It takes up excess glucose and stores it in the form of glycogen.
145
True or False: Insulin facilitates amino acid uptake in body cells.
True.
146
How do most fats enter the bloodstream?
via the thoracic duct packaged as triglycerides inside chylomicrons.
147
What do VLDLs do?
shuttle cholesterol and triglycerides to body cells
148
What produces VLDLs?
the liver
149
In the postabsorptive state (or fasting state), the effect of incretins decline, and insulin secretion falls to basal levels and secretion of _____________ increases.
glucagon
150
Describe what happens in the fasting state in the liver.
* the liver stops producing glycogen
* glucagon promotes the breakdown of glycogen into glucose, and is released into the bloodstream
* when glycogen in the liver is gone, it begins gluconeogenesis from noncarbohydrate sources (glycerol and amino acids)
* this glucose is then released into the bloodstream
151
Describe what happens in adipose tissue in the fasting state.
* triglycerides are broken down into glycerol and fatty acids
* fatty acids are released into the blood to be used as energy for other cells
152
During the fasting period, what is the principal source of energy for almost all cells except for the brain.
fatty acids
153
What does the metabolism of fatty acids and amino acids in the liver produce?
ketones
154
Why are ketones dangerous?
Because they are highly acidic and when produced in high enough volumes they can cause blood pH to fall to dangerous levels.
155
During the fasting state, what happens in the muscle cells?
* glucagon stimulates breakdown of stored glycogen to glucose for energy
* glucose is used within the muscle cell because muscle cells lack the necessary enzyme to release glucose back into the blood
156
