Unit 3 Flashcards
(125 cards)
1
Q
What is the purpose of eating?
A
To obtain nutrients from foods in order to nourish the body
2
Q
What is the purpose of digestion?
A
It allows nutrients to be broken down and absorbed into the body so the body can use them
3
Q
What is digestion?
A
The process of breaking down foods into absorbable units.
“to take apart”
4
Q
How is the process of digestion done?
A
Food is taken from its whole form and digested both chemically and mechanically down to individual units small enough to be absorbed in the blood or lymph
5
Q
What are the variable absorbable units?
A
Starches, Fiber, Triglycerides, Cholesterol, Phospholipids, Proteins, Vitamins, Minerals, and water
6
Q
How are starches digested?
A
Starches and disaccharides will be broken down to monosaccharides
7
Q
Why don’t we eat glycogen?
A
Because the glycogen in the muscles of animals is broken down very quickly after the animals are slaughtered.
8
Q
Does animal meat contain carbohydrates?
A
No
9
Q
Is fiber digested?
A
No because humans do not make any enzymes that can break down fiber. Fiber goes undigested as it passes through the digestive tract and will end up in the stool
10
Q
How are triglycerides digested?
A
They are broken down into glycerol and fatty acids or one monoglyceride and two fatty acids
11
Q
How is cholesterol digested?
A
It can be absorbed as is and does not require any digestion
12
Q
How are phospholipids digested?
A
They must have their fatty acids removed. The left over phosphate and glycerol can be absorbed while still bonded together
13
Q
How are proteins digested?
A
They will be broken down into amino acids
14
Q
How are vitamins digested?
A
They do not require any digestion. Vitamins are already individual units
15
Q
What are exceptions to vitamins being digested?
A
Vitamin B12 and Folate because they come bound to proteins and require removal of the proteins before they can be absorbed
16
Q
How are minerals and water digested?
A
They do not require any digestion
17
Q
What is another name for the digestive tract?
A
The Gastrointestinal tract (GI Tract)
18
Q
What is the description of the GI tract?
A
It is a hollow tube about 30 feet long and runs from mouth to anus
19
Q
Is the digestive tract inside or outside the body?
A
Outside because it has an opening at both ends
20
Q
When is food “inside” you?
A
When it is absorbed into the blood or the lymph
21
Q
What is the inside of the GI tract called?
A
The Lumen
22
Q
What is the Mucosa?
A
The layer of mucosal cells that lines the lumen
23
Q
How long do mucosal cells live?
A
2-5 days, new cells are formed continuously to replace those that die.
24
Q
What is one of the first parts of the body to be affected by nutrient deficiencies?
A
The mucosa because it has high nutrient needs.
25
How does the mucosa protect the body?
It contains immune tissue that protects the rest of the body from invading substances
26
What is transit time?
The time it takes food to travel the length of the GI tract from mouth to anus
27
How does the body digest nutrients?
The GI tract uses both mechanical and chemical digestion to break down foods into absorbable nutrients
28
How does the body do mechanical digestion?
Involves the strong muscular movements such as the churning and grinding of the stomach
29
How does the body do chemical digestion?
Involves the use of digestive enzymes
30
What are enzymes?
Proteins that act on food substances breaking them down into simpler compounds
31
Where does digestion begin?
In the mouth (oral cavity) containing the tongue and teeth.
32
What are incisors for?
Flat front teeth that have chiseled edges that cut
33
What are canines for?
Pointed teeth that have pointed crowns that tear (for meat)
34
What are premolars and molars for?
Have ridged surfaces that crush and grind
35
What is the purpose of the tongue?
Used to move food around in the mouth and to taste food.
36
What detects taste sensations?
The taste buds detect one or a combination of the four basic taste sensations when stimulated
37
What is the purpose of saliva and beverages?
Help to moisten the food so you can swallow it
38
How does saliva work?
The salivary glands release saliva to moisten each mouthful of food so that it can easily pass down the esophagus.
39
What does saliva contain?
Water, salts, mucus, (to protect the teeth and the lining of the mouth, esophagus, and stomach) and enzymes
40
What helps break down carbohydrates in the mouth?
Salivary amylase
41
What helps break down fats in the mouth?
Lingual lipase
42
What is not digested in the mouth?
Protein is not digested chemically in the mouth because there aren't any proteases secreted in the saliva
43
Why aren't proteins digested in the mouth?
They are more chemically complex than carbohydrates and fats and require denaturing before enzymes can begin to hydrolyze the peptide bonds (the bonds between amino acids)
44
What is denaturation?
The uncoiling of a protein when exposed to an acid (such as stomach acid), a base, a heavy metal, agitation, heat, and alcohol
45
What happens to the food after it is chewed in the mouth?
When you swallow a mouthful of food it passes through the pharynx, a short tube that is shared by both the digestive and respiratory systems. To bypass the entrance to your lungs, the epiglottis closes off your air passages so that you don't choke when you swallow.
46
What do you call a mouthful of swallowed food?
Bolus
47
What are sphincters?
Muscles that control the passage of food through the digestive tract
48
What happens to the upper esophageal sphincter during a swallow?
It relaxes, the muscle at the upper end of the esophagus opens and the bolus then slides down the esophagus, which passes through a hole in the diaphragm to the stomach
49
What happens when the bolus reaches the end of the esophagus?
The lower esophageal sphincter (cardiac sphincter) at the entrance of the stomach opens, lets the bolus into the stomach, and closes.
50
When does digestion become involuntary?
Once the bolus is in the esophagus
51
How does the bolus move through the esophagus?
By muscle contractions, peristalsis
52
What type of muscle helps move the bolus toward the stomach?
Longitudinal muscles and circular muscles
53
What organ has the thickest walls and strongest muscles of the GI?
The stomach. In addition to the circular and longitudinal muscles, it has a layer of diagonal muscles
54
What does the stomach secrete?
Hydrochloric acid, which prevents bacterial growth and kills most bacteria that enter the body with food.
55
How do the cells of the stomach wall protect themselves from gastric juice?
By secreting mucus, a thick, slippery substance.
56
What is the sphincter at the end of the stomach called and what does it connect?
The pyloric sphincter and it connects the stomach to the small intestines
57
What is the mechanical action of the stomach?
the peristalsis action churns and grinds to turn the bolus into Chyme
58
What is chyme?
A semiliquid mass of partly digested food expelled by the stomach into the duodenum
59
What is the chemical action of the stomach?
Gastric glands in the stomach secrete gastric juices (water, enzymes, and HCl).
60
What triggers the release of HCl in the stomach?
Triggered by the hormone gastrin, which is secreted by the cells of the stomach wall
61
What digestion stops temporarily in the stomach and why?
Chemical digestion of carbohydrates because the enzymes from the saliva are being digested and can no longer do their job.
62
What is being digested in the stomach?
Fat digestion through the use of gastric lipase's which continue to cleave the bonds between the glycerol and fatty acid molecules
63
What digestion begins in the stomach?
Protein digestion chemically HCl also denatures proteins
64
How are proteins digested?
Proteins are very tightly coiled and in order for the enzymes to cleave the peptide bonds, the polypeptide chains must be uncoiled (denatured)
65
What enzyme does HCl activate in the stomach?
HCl is used to activate pepsinogen to pepsin (a protein digesting enzyme) once activated pepsin can hydrolyze the peptide bonds cutting the long polypeptide chains into smaller ones.
66
How does pepsin work?
It hydrolyzes the peptide bonds of polypeptides
67
How are vitamins digested in the stomach?
Stomach acids are needed to remove proteins from vitamin B12
68
Where does the bolus become chyme?
The stomach forms the bolus into chyme and the chyme moves into the small intestine
69
How long is the small intestine?
20 ft.
70
What are the parts of the small intestine?
Duodenum, Jejunum, and Ileum
71
What is the problem when the chyme enters the small intestine?
It is still very acidic because it combined with the HCl in the stomach. The SI doesn't produce mucus.
72
How is the small intestine protected from the acidic chyme?
The pancreas secretes sodium bicarbonate to neutralize the acids and protect the lining of the small intestine. Sodium bicarbonate is basic and will raise the pH of the chyme bringing it to neutral
73
What is digested in the small intestine?
Carbohydrates
74
What is the purpose of the pancreas for the small intestine?
It secretes pancreatic juices into the duodenum via the pancreatic duct. The pancreatic juices are rich in enzymes and water.
75
What pancreatic juice digests carbohydrates?
Pancreatic amylase, which will continue the work that the salivary amylase started. The polysaccharide chains will get smaller and smaller.
76
What other enzymes (besides pancreatic amylase) is secreted by the cells of the small intestine?
Sucrase, lactase, and maltase. Which will act on any disaccharides that are still intact and complete the job of carbohydrate digestion
77
What does sucrase break down?
Sucrose to glucose and fructose
78
What does maltase break down?
Maltose to 2 glucose molecules. Maltose is mostly the leftover product of polysaccharides
79
What does lactase break down?
Lactose to glucose and galactose
80
When are polysaccharides ready to be absorbed?
When they are broken down to monosaccharides (single sugars) in the small intestine
81
What makes fat digestion difficult?
the fact that it is insoluble in the watery juices of the digestive tract.
82
Where does the majority of fat digestion occur?
In the small intestine because fat needs to be emulsified
83
What is the purpose of bile?
The liver makes bile to emulsify fat.
84
Where is bile stored?
In the gallbladder
85
What causes the gallbladder to release bile?
When any fat is present in the duodenum, the hormone cholecystokinin (CCK) targets the gallbladder to release bile.
86
What is bile?
An emulsifier that breaks large fat globules into smaller ones so that the lipase's can get to work.
87
Where are lipase's coming from?
The pancreatic juice that was secreted by the pancreas. They are called pancreatic lipases
88
What further breaks down polypeptides in the small intestine for absorption?
Pancreatic enzymes and enzymes in the microvilli of the intestine.
89
Where does the majority of protein digestion occur?
In the small intestine
90
What is the sphincter separating small and large intestines?
Ileocecal valve
91
What happens to materials not absorbed in the small intestine?
They travel down into the large intestine (colon) through the ileocecal valve. The contents bypass the opening that leads to the appendix and travel through the colon to the rectum.
92
What happens to the intestinal contents as they pass through the colon?
The colon withdraws water leaving semisolid waste
93
Is anything besides water absorbed in the colon?
Most nutrient absorption occurs in the small intestine, but water and some vitamins and minerals are also absorbed in the colon
94
Approximately how long do water, nutrients, and fecal matter spend in the large intestine?
May spend 24 hours because the peristalsis occurs more slowly in the colon. This slow movement favors growth of bacteria called intestinal microflora
95
How many sphincters of the anus are there?
2, the internal and external sphincters
96
Which anal sphincter is involuntary?
Internal anal sphincter
97
Which anal sphincter is voluntary?
The external anal sphincter
98
What can be absorbed in the mouth?
Glucose to some extent, simple sugars that have been consumed that do not require digestion (juices and candy, glucose tablets and gels) can be absorbed in the mouth.
99
Where does the majority of absorption occur?
The mall intestine though absorption can happen throughout the tract (mouth, stomach, and colon)
100
Describe the lining of the small intestine.
The lining of the small intestine contains large, circular folds which increase the surface area that comes in contact with nutrients. The folds contain fingerlike projections called villi
101
What does each cell of the villus have?
Microvilli, and in the crevices between the villi are the crypts (tubular glands that secrete the intestinal juices into the small intestine)
102
Where are nutrient molecules small enough to be absorbed trapped?
Among the microvilli and drawn into the cells. Some partially digested nutrients are caught in the microvilli, digested further by enzymes and then absorbed into the body.
103
How are nutrients absorbed into the the body?
Simple diffusion, Osmosis, Facilitated diffusion, and active transport
104
What happens to water-soluble nutrients (monosaccharides, amino acids, water-soluble vitamins and minerals) and the smaller products of fat digestion (glycerol and short and medium chain fatty acids)?
They are released directly into the bloodstream and guided directly to the liver
105
What is the purpose of the liver?
To act as a gate keeper, detoxifying any harmful substances that might have been ingested
106
How are glycerol and short and medium chain fatty acids absorbed?
Through simple diffusion
107
What happens to single amino acids, dipeptides, and tripeptides in absorption?
They can be absorbed into the mucosal cells of the small intestine using different transport systems and amino acids compete for absorption.
108
What happens in absorption to Dipeptides?
They are further broken down into single amino acids
109
What happens in absorption to single amino acids
They pass into the blood and are brought to the liver.
110
What happens in absorption to monoglycerides (a glycerol with one fatty acid still attached) and long chain fatty acids?
They merge into micelles
111
What are micelles?
Emulsified fat droplets formed by molecules of bile surrounding monoglycerides and fatty acids. The micelles allow for the monoglycerides and long chain fatty acids to be absorbed into the intestinal wall. The only purpose of the micelle.
112
What happens once a micelle is across the intestinal membrane?
The micelle releases its contents (the long chain fatty acids and monoglycerides) and they are reassembled into new triglycerides. within the cells the new triglycerides and other fats (cholesterol, phospholipids, and fat-soluble vitamins) are packed with protein into transport vehicles called chylomicrons
113
What happens to fructose and galactose that was absorbed?
It will travel in the blood to the liver where the liver converts them to glucose
114
What happens after fructose and galactose are made into glucose?
The glucose is then delivered via the blood to various cells where the glucose will be used for energy (ATP)
115
What happens to lipid an fat-soluble transport after absorption?
The intestinal wall releases the chylomicron into the lymphatic system via a lacteal
116
What is a lacteal?
A lymph vessel located in the small intestine
117
Why does the chylomicron not enter the blood stream in the small intestine?
Because capillaries have an outer layer of polysaccharides that prevent the chylomicron from entering.
118
Where does the lymphatic system enter the blood stream?
At the left subclavian vein near the heart.
119
What carries the lipids to the rest of the body for immediate use or storage?
The blood
120
What is the lymphatic system?
A loosely organized system of vessels and ducts that convey fluids toward the heart.
121
What is the purpose of the GI part of the lymphatic system?
To carry produce of fat digestion into the bloodstream.
122
In what direction is the lymphatic system?
The lymphatic system provides a one way route for fluid from the tissue spaces to enter the blood.
123
Does the lymphatic system have a pump?
NO
124
What does lymph circulate between?
The cells of the body and collects into tiny vessels
125
What transports amino acids, water soluble vitamins, and minerals?
The bloodstream
