Module 3: Digestion and Absorption Flashcards
1
Q
where does digestion occur
A
gastrointestinal (GI) tract
2
Q
what does the GI tract consist of
A
- series of organs
- outer layers of muscles
- inner mucosal layer of glands and absorptive cells
3
Q
are things in the GI tract (mouth, stomach, intestines) inside or outside the body
A
- in the GI tract is outside the body
- inside the body would be things in cells, vascular systems, etc
4
Q
what are the primary organs of the GI tract
A
- mouth
- esophagus
- stomach
- small intestine
- large intestine
- rectum
5
Q
what are the accessory organs of the GI tract
A
- salivary glands
- liver
- pancreas
- gallbladder
6
Q
why are accessory organs important
A
although they never come into contact with food, accessory organs are imperative for digestion and absorption
7
Q
what are the two main functions of the GI tract
A
- digestion
- absorption
8
Q
define digestion
A
- moving food through the GI tract
- breakdown of food into smaller components
- primary site in small intestine
9
Q
define absorption
A
crossing the lining of the intestines to enter the body
10
Q
define transit time
A
period of time it takes food to travel through the length of the digestive tract
11
Q
what nutrient can decrease food transit time
A
fiber
12
Q
what is the most abundant biopolymer in earth
A
fiber
13
Q
define mechanical digestion
A
- physical break down of food
- chewing, mixing, peristalsis
14
Q
define paristalsis
A
wavelike muscular movements that move food through the GI tract
15
Q
what nerve controls peristalsis
A
vagus nerve
16
Q
define chemical digestion
A
- chemical breakdown of large compounds into smaller units for absorption
- secretions and enzymes
17
Q
define sphincters
A
- circular muscles that separate organs of the GI tract
- one-way doors that prevent food from flowing backwards
18
Q
are sphincters usually contracted or relaxed
A
always contracting unless food is coming through
19
Q
how do sphincters relate to surgery
A
you can’t eat before surgery because the anesthesia may relax your sphincters
20
Q
what are the 3 main sphincters in the GI tract
A
- lower esophageal sphincter
- pyloric sphincter
- ileocecal valve
21
Q
what complications are associated with improper function of sphincters
A
- heartburn
- vomiting
22
Q
what nutrients must be digested/broken down before it can be absorbed
A
- carbohydrates
- proteins
- fats
23
Q
what form of carbohydrates, proteins, and fats can we absorb
A
- carbs: monosaccharides
- proteins: amino acids (some dipeptides and tripeptides)
- fats: monoglycerides or free fatty acids
24
Q
how much of flavor perception is smell
A
80%
25
what are the 5 primary tastes
- sweet
- salty
- sour
- bitter
- umami
26
what is the taste umami
- savory
- from fats and proteins
27
where do you have taste receptors
- mouth
- nose
- stomach
- small intestine
28
where does the digestive process begin
mouth
29
what are two enzymes in saliva and what do they do
- salivary amylase: breaks down carbs
- lingual lipase: breaks down triglycerides into a diglyceride and a free fatty acid
30
where is food liquified into chyme
stomach
31
what is chyme
- bolus
- HCL
32
what is the capacity of the stomach
1 to 4 liters
33
what is in the stomach's gastric juices
- HCL
- mucus
- pepsinogen enzyme
- gastrin hormone
34
which cells make HCL and intrinsic factor (IF)
parietal cells in the stomach
35
which cells make pepsinogen
chief cells in the stomach
36
which cells make mucus
goblet cells
37
explain how is mucus expelled from goblet cells
- as food enters the stomach, blood goes to the GI tract
- the arteries expand and cause pressure to form on the walls on the stomach
- this pressure pushed mucus out of goblet cells
38
why might you feel cold after eating
blood moves towards your GI tract and away from other areas of the body
39
what is another name for mucus
mucin
40
what is mucus composed of
- water
- glycated proteins
41
what is the purpose of mucus in the stomach
protects the lining of the stomach from HCL
42
what is the purpose of HCL in the stomach
- denatures proteins
- liquifies foods
- activates enzymes pepsin and lingual lipase
- prepares iron for absorption
43
what is the purpose of intrinsic factor (IF)
- essential for absorption of vitamin B12
44
explain how intrinsic factor (IF) works
- IF binds to B12 to protect it from HCL in the stomach
- carries to the ileum and enterocytes on the surface
- binds to receptors on enterocytes
- enterocytes envelop the B12 to absorb it
45
what is pepsinogen
inactive/deactivated form of pepsin
46
how is pepsinogen activated to make pepsin
HCL
47
what is the purpose of pepsin in the stomach
digestion of proteins
48
what is the purpose of the gastrin hormone in the stomach
controls the movement of the stomach and the secretion of HCL
49
define rugae in the stomach and their purpose
- folds of tissue in the stomach
- can fold to conserve space or flatten to increase space
50
how often does the pyloric sphincter open
every 1-3 minutes
51
how much chyme is deposited from the stomach through the pyloric sphincter and into the small intestine at one time
3 mL of chyme
52
why does the pyloric sphincter deposit small amounts of chyme into the small intestine at one time
- the chyme is very acidic and the small intestine is more basic
- the small amount allows the chyme to neutralize in the duodenum
53
what is the primary site of digestion and absroption
small intestine
54
what are the 3 sections of the small intestine
- duodenum
- jejunum
- ileum
55
which section of the small intestine is the site of most digestion and absorption
jejunum
56
what structures assist nutrient absorption in the small intestines
- villi
- microvilli
57
what is the folded interior of the small intestine called
plicae circulares
58
how much do plicae circulares increase the surface area of the small intestine
increase 3x
59
how much do villi increase the surface area of the small intestine
increase 10x
60
are villi tissue or cell projections
tissue
61
describe the inside of villi (what might be in a cross section image)
- vascular structures where blood is sent to absorb nutrients (carbs and amino acids)
- lymphatic vessels (lacteals) which also absorb nutrients (fats)
62
which nutrients are absorbed through the blood
- carbs
- proteins
63
which nutrients are absorbed through the lymphatic vessels called lacteals
fats
64
what type of cells are on the surface of villi
enterocytes
65
what are the cellular projections on enterocytes on villi
microvilli
66
explain how lactase and the absorption spot of lactose monosaccharides is efficient
- lactase sits on the tip of a microvilli projection and breaks down lactose
- the absorption spot for the monosaccharides is at the adjacent microvilli so the monosaccharides don't have to be transported anywhere else
67
how much do microvilli increase the surface area of the small intestine
increase 60x
68
how big is the surface area of the small intestine
size of a tennis court
69
what is the function of the pancreas
- secretes alkaline bicarbonate (basic) which raises pH of chyme to neutralize it
- provides many digestive enzymes
70
what is the function of the liver
produces bile to digest fats
71
what is bile composed of
- 97% water
- 3% salts made of cholesterol
72
what is the biliary tree
connects the liver, gallbladder, and pancreas to the duodenum
73
what is the function of the gallbladder
stores and releases bile
74
where are water-soluble nutrients absorbed
through intestinal wall and into capillaries
75
where do water-soluble nutrients in capillaries travel to
liver
76
where are fat-soluble nutrients absorbed
through intestinal wall and into lacteals of the lymphatic system
77
what nutrients are absorbed in the duodenum and upper part of jejunum
most minerals except electrolytes
78
what are the 3 primary electrolytes
- sodium
- potassium
- chloride
79
what nutrients are absorbed in the jejunum and upper ileum
- carbs
- amino acids
- water-soluble vitamins
80
what nutrients are absorbed in the terminal segment of the ileum
- lipids
- fat-soluble vitamins (ADEK)
- vitamin B12
81
where do undigested food components move
to the large intestine
82
how long is the long intestine
5 to 6 feet
83
what is the transit time of the long intestine
12 to 24 hours
84
what are the functions of the large intestine
- propulsion
- absorption of water and sodium
- preparation of waste for defecation
85
how much bacteria is in the large intestine
100 trillion bacteria
86
which vitamins do bacteria in the large intestine produce
- vitamin K
- some B vitamins
87
how much of the vitamin K you have is produced by E. coli in the large intestine
80%
88
what are the functions of bacteria in the large intestine
- produce vitamin K and some B vitamins
- ferment plant fibers to short chain fatty acids
- metabolize any remaining nutrients
89
describe the digestion and absorption of carbohydrates
- broken down in the mouth by salivary amylase
- broken down in the duodenum by pancreatic amylase
- enzymes on microvilli break down into monosaccharides
- monosaccharides absorbed from small intestine into the blood
90
which enzymes break down maltose, sucrose, and lactose
- maltase breaks down maltose
- sucrase breaks down sucrose
- lactase breaks down lactose
91
what are the monosaccharides in maltose
- glucose
- glucose
92
what are the monosaccharides in sucrose
- glucose
- fructose
93
what are the monosaccharides in lactose
- glucose
- galactose
94
describe the digestion and absorption of proteins
- proteins denatured by HCL in stomach
- proteins broken down by pepsin in the stomach
- enzymes from pancreas break down into amino acids
- amino acids absorbed into the blood
95
where does protein digestion begin
stomach
96
describe the digestion and absorption of fats
- broken down in the mouth by lingual lipase
- bile salts enter duodenum from gallbladder and begin to emulsify fats into smaller particles
- lipase from the pancreas breaks down fats into monoglycerides and fatty acids
- monoglycerides and fatty acids are absorbed through the villi and then reform into triglycerides which become chylomicron
- fats enter the lymphatic system
97
how much bile is made by the liver per day
12 to 14 oz
98
what does bile being an emulsifier mean
helps mix fats in water
99
what is chylomicron
- reformed triglycerides after absorption into the small intestines
- acts as an emulsifier
100
how are fat soluble vitamins absorbed
- facilitated by dietary fat
- transported in chylomicron
101
how are water soluble vitamins absorbed
into the blood
102
what is required for absorption of vitamin B12 and where is it absorbed
- requires intrinsic factor
- absorbed in distal ileum
103
where is alcohol absorbed
- some absorbed in stomach
- most absorbed in small intestine
- travels to liver for detoxification
104
where are minerals absorbed
along the small intestine
105
what should be absorbed along with sodium
- glucose
- amino acids
106
what are two examples of nutrients that are only absorbed based on the body's need
- iron
- calcium
107
where is water absorbed
- most in small intestine
- some in large intestine
108
define ulcer and peptic ulcer
- any removal of epithelial cells
- peptic ulcer is erosion in the lining of the stomach or upper part of small intestine
109
what is the primary cause of peptic ulcers
Helicobacter pylori
110
what is the route of transmission for H. pylori
- oral-oral
- fecal-oral
111
what are causes of ulcers that aren't H. pylori
- regular use of aspirin
- excessive use of alcohol
- smoking
112
define constipation
- makes having a bowel movement difficult
- fewer than 3 times per week
113
what causes constipation
- low fiber
- not enough exercise
- medication
- dehydration
- ignoring the urge to defecate
114
how to treat constipation
- eat 30g of fiber per day
- drink fluids
- exercise
115
define diarrhea
- loose and watery stools
- more than 3 times per day
116
what causes diarrhea
- infections
- food intolerance
- medication
117
what should you do if you have diarrhea
hydrate
118
define heartburn/GERD
pain in chest when stomach acid refluxes into esophagus
119
what causes heartburn/GERD
- overweight
- pregnancy
- hiatal hernia
120
how to treat heartburn/GERD
- lose weight
- limit foods that increase symptoms
121
define lactose intolerance
inability to break down lactose because of a lack of the enzyme lactase
122
define irritable bowel syndrome
- affects large intestine
- leads to cramping, diarrhea, and constipation
123
what causes irritable bowel syndrome
- overly sensitive muscles and nerves of large intestine
- may react more to stress or certain foods
124
how to treat irritable bowel syndrome
- increase fiber intake
- eat small and frequent meals
- avoid foods that aggravate condition
125
define ulcerative colitis
- chronically inflamed large intestine
- surface of small intestine flattens and absorption surface area decreases
126
what causes ulcerative colitis
autoimmune condition
127
how to treat ulcerative colitis
- eat omega 3 fatty acids
- decrease consumption of foods that aggravate flare-ups
128
define probiotics
foods containing live bacteria that have undergone fermentation
129
examples of sources of probiotics
- yogurt
- kefir
- sauerkraut
- miso soup
- kombucha
130
define prebiotics
- fiber sources used to support microbes in large intestine
- snacks for the bacteria
131
examples of sources of prebiotics
- asparagus
- artichokes
- oatmeal
132
define symbiotics
combinations of probiotics and prebiotics
