2.Digestion and Absorption Flashcards
1
Q
If a persons estimated energy requirement is 8000kJ per day, how many grames of fat would you recommend they consume to be within the AMDR?
A
43-76g
2
Q
What is the difference between digestion and absorption?
A
Digestion is the process by which food is broken down into absorbable units, absorption is the uptake of nutrients by the walls of the small intestine for transport into either the blood or the lymph.
3
Q
What are the 2 main functions of the GI tract?
A
- To convert food into nutrients that the body needs 2. to rid the body of waste
4
Q
What is the GI tract?
A
A flexible muscular tube that runs from the mouth to the anus.
5
Q
What are the roles of the mouth in digestion?
A
Digestion begins in the mouth, with mastication, stimulation of taste buds and swallowing.
6
Q
What is food called after is is swallowed?
A
A bolus
7
Q
What does the epiglottis do?
A
Protects the airway during swallowing
8
Q
What is the role of the oesophagus in digestion?
A
It transfers the bolus from the mouth to the stomach.
9
Q
Which enzymes are present in the mouth?
A
Primary: salivary amylase, which starts the digestion of carbohydrate. Secondary: salivary lipase, initiates minimal digestion of fats.
10
Q
How is a bolus formed?
A
Through mastication, addition of saliva and action of the tongue, which transforms food into a coarse mash.
11
Q
How much saliva do you make per day?
A
~1L
12
Q
Can you swallow if you are upside down?
A
Yes
13
Q
How is a sphincter muscle formed?
A
Tube form with circular muscles around the hollow inside, and longitudunal muscles around the outside.
14
Q
What condition can result from weakened lower esophogeal sphincter?
A
Reflux
15
Q
Why is reflux potentially harmful?
A
Acid from the stomach can damage tissue of the oesophagus.
16
Q
What are 4 symptoms of reflux?
A
heartburn, chest pain, nausea and regurgitation
17
Q
What are the main functions of the stomach?
A
Collecting and churning, and some digestion. Adds juices and converts bolus to chyme.
18
Q
What determines the activation of the pyloric sphicter, and how ofter does it occur?
A
The pyloric sphincter stays closed until chyme is completely liquified, ~3 times per minute.
19
Q
What happens with respect to digestion of each of the macronutrients in the stomach?
A
Carbohydrate - digestion by salivary amylase continues until the enzyme is deactivated by HCl in the stomach, Protein- proteins are denatured by stomach acid and pepsin is activated by the acid. Lipids- triacylglycerols start to break down (~20% of lipid digestion).
20
Q
What main processes occur in the small intestine?
A
Digestion and absorption
21
Q
Which organ(s) provide digestive juices to the small intestine?
A
The gallbladder and the pancreas.
22
Q
What are the 3 segments of the small intestine called?
A
- duodenum, 2. jejunum, 3. ileum
23
Q
What is the approximate length of the duodenum?
A
30cm
24
Q
What is the approximate length of the jejunum?
A
2.5m
25
What is the approximate length of the ileum?
4m
26
What is the structure of the epithelial lining designed to do?
Maximize suface area of the small intestine, increasing the ability to absorb nutrients.
27
What compounds are broken down by enzymes from the small intestine and pancreas?
proteins (peptides) triglyceride, starch, oligossacharides and disaccarides
28
With all of the folds in the lining, the surface area of the small intestine is comparable to a) a parking spot, b) a tennis court, c) a football field.
b.
29
What structures carpet the wall of the small intestine?
villi
30
What structures cover the surface of the vili in the small intestine?
microvilli
31
What do microvilli do?
Provide the absorptive surfaces that allow nutrients to pass through to the body.
32
What is the name of the process that moves food through the small intestine?
peristalsis
33
How does peristalsis work?
The inner circular muscles contract, tightening the tube and pushing food forward. When the circular muscles relax, the outer longitudinal muscles contract and the intestinal tube is loose. As the circular and longitudinal muscles tighten and relax, the chyme moves ahead of the constriction.
34
How does segmentation occur?
Circular muscles contract, creating segments in the small intestine. As each set of circular muscles expand and contract, the chyme is broken up and mixes with digestive juices.
35
What is the purpose of segmentation in the small intestine?
to mix chyme, increase surface area to enzyme action and bring nutrients in contact with the intestinal lining for absorption.
36
How often do the muscle contractions that control segmentation in the small intestine occur?
12-16 times per minute
37
What main processes occur in the large intestine?
Reabsorbing and eliminating - absorbs, water, vitamins and any remaining absorbable nutrients (not much) and collects waste material for storage in the rectum.
38
What is the name of the valve at the beginning of the large intestine?
ileocaecal valve
39
What happens to fibre in the large intestine?
fermentation
40
What happens to energy yielding nutrients during digestion?
They are disassembled for absorption
41
What happens to vitamins and minerals during digestion?
They are absorbed but do not require disassembling.
42
What happens to undigestable material, including some fibres, during digestion?
They continue through the digestive tract and form the stool.
43
What substance is secreted by the salivary glands, and what does it do?
saliva - eases swallowing and contains amylase to begin the break down of carbohydrate
44
What substances are secreted by the gastric glands in the stomach, and what do they do?
gastric juice - contains HCL to denature proteins, and peptides break down proteins. Mucus protects the lining of the stomach.
45
What organ receives secretion from the pancreas?
The stomach
46
What is secreted by the pancreas and what does it do?
They are absorbed but do not require disassembling.
47
What happens to undigestable material, including some fibres, during digestion?
They continue through the digestive tract and form the stool.
48
What substance is secreted by the salivary glands, and what does it do?
saliva - eases swallowing and contains amylase to begin the break down of carbohydrate
49
What substances are secreted by the gastric glands in the stomach, and what do they do?
gastric juice - contains HCL to denature proteins, and peptides break down proteins. Mucus protects the lining of the stomach.
50
What organ receives secretion from the pancreas?
The stomach
51
What is secreted by the pancreas and what does it do?
pancreatic juice - includes pancreatic enzymes for the breakdown of carbohydrates, fats and proteins, and bicarbonate to neutralize acidic gastric juices.
52
What substance does the liver produce?
bile
53
What does the gallbladder do?
stores bile from the liver
54
What does bile do?
emulsifies fat so it can be broked down by enzymes
55
Which organs contribute secretions to the small intestine?
Liver and gallbladder, as well as intestinal glands in the small intestine
56
Where does digestion of fat take place in the body?
Saliva and gastric uices contain lipases, but most of the breakdown of fats occurs in the small intestine.
57
Arrange in order of increasing pH: Bile, pancreatic juice, saliva, gastric juice
Gastric juice ~2, saliva ~7, Pancreatic juice ~8, bile ~9.
58
Which macronutrients are not digested?
minerals, vitamins and water
59
Why are minerals, vitamins and water not digested?
they are small enough to be absorbed by the body without being broken down.
60
Is fibre digested?
No.
61
By which 3 processes are nutrients absorbed into the body?
1. simple diffusion, 2. facilitated diffusion, 3. active transport
62
Do all cells in the lining of the small intestine absorb the same nutrients?
No, cells are specialized to absorb different nutrients.
63
What substances are released to the bloodstream during absorption?
water soluble nutrients and small products of fat digestion.
64
What substances are released to the lymphaic system during absorption?
Fat soluble vitamins and larger fats form chlyomicrons and are released intot the lymphatic system.
65
How does simple diffusion occur in the small intestine?
Nutrient cross intestinal walls freely. Incl water and small lipids.
66
Which nutrients are absorbed in the small intestine by simple diffusion?
water and small lipids
67
How does facilitated diffusion occur in the small intestine?
requires a carrier protein to transport nutrient across membrane or to form a channel. Incl. water soluble vitamins and fructose
68
Which nutrients are absorbed in the small intestine by facilitated diffusion?
water soluble vitamins and fructose
69
How does active transport work to absorb nutrients in the small intestine?
requires a carrier protein and energy to move the nutrient across the concentration gradient. Incl glucose and amino acids.
70
Which nutrients are absorbed in the small intestine via active transport?
glucose, amino acids
71
Where does blood leaving the digestive system go, and via which route?
goes to the liver via the hepatic portal vein
72
Which nutrients go to the liver via the bloodstream after absorption?
water soluble nutrients and small products of fat digestion.
73
Where does blood go after it leaves the liver?
To the heart
74
What is the role of the vascular circulatory system in digestion?
To transport blood containing nutrients to the liver.
75
What is the role of the liver after absorption?
It prepares nutrients that have been absorbed for use in the body.
76
What is the role of the lymphatic circulartory system in digestion?
provides a one-way route for fluid from the tissue spaces to enter the blood.
77
What drives circulation within the lymphatic system?
It has no pump: lymph circulates between cells and collects into tiny vessels.
78
Where does lymph collect before it enters the blood stream?
in the thoracic duct behind the heart.
79
Do large fats and fat soluble vitamins go via the liver into thte bloodstream?
No, they go tot the heart and are pumped into al the body's cells from there, bypassing the liver.
80
What is the role of the hepatic vein?
gathers blood from the liver and takes it to the heart.
81
How do the cells of the liver access the nutrients and oxygen in the blood?
From capillaries, which branch all over the surface of the liver
82
What is the role of the hepatic artery?
brings a supply of freshly oxygenated blood from the lungs (not loaded with nutrients) to supply oxygen to the liver.
83
How do nutrients from the digestive system get to the liver via the vascular circulatory system?
Blood vessels within the villi gather up the nutrients, these vessels merge into the hepatic vein, which take all nutrients to the liver.
84
What factors can influence the health and regulation of the GI tract?
diet and good absorption of nutrients, sleep patterns, physical activity, relaxed mealtimes
85
Where do the bacteria of the GI tract reside?
Primarily in the small and large intestines.
86
What do gut macrobiota do?
digest fibres and some complex proteins. When thriving, prevent infectious bacteria from establishing themselves.
87
What is the pH of the large and small intestines?
neutral.
88
What are the potential GI health benefits of probiotics?
help alleviate diarrhoea or constipation, inflammatory bowel disease, ulcers, allergies and lactose intolerance. Enhance immune function. Bacteria in the gut produce small amounts of vitamin K
89
Which body systems are involved in the regulation of the Gi tract?
The hormonal or endocrine system and the nervous system coordinates all digestive and absorptive processes.
90
How are the secretions involved in digestion in the GI tract controlled?
by hormones and nerve pathway 'feedback' mechanisms.
91
What controls pancreatic secretions?
content of the diet
92
Why can changing your diet result in an upset stomach?
lag in pancreatic secretion change
93
How does having relaxed mealtimes contribute to a healthy GI tract?
It promotes good regulatory hormonal control.
94
How does sleep contribute to the health of the GI tract?
By promoting maintenance and repair
95
How does physical activity promote a healthy GI tract?
By promoting good GI tract muscle tone.
96
Tim's meals are often rushed, he eats a lot of fast food, forgets to drink water, has constipation, gets an upset stomach when he goes home and eats well, and has been taking antibiotics. Why might Tim have constipation and/or diarrhea?
not enough water or fibre, no prebiotics in his diet.
97
Tim's meals are often rushed, he eats a lot of fast food, forgets to drink water, has constipation, gets an upset stomach when he goes home and eats well, and has been taking antibiotics. What can Tim do to improve his bowel heath?
take pro &/or prebiotics, drink more water, eat more vegetables, take more time for meals, and eat them sitting down, and getting more exercise if he isn't already.
98
Top top portion of the small intestine
Duodenum
99
cells of the GI tract (and lungs) that secrete mucous
goblet cells
100
an emulsifier that prepares fats and oils for digestion
bile
101
an exocrine secretion made by the liver, stored in the pall bladder and released into the small intestine when needed
bile
102
a word ending denoting an enzyme
-ase
103
a gland that secretes digestive enzymes and juices intot eh duodenum, and also secretes hormones into the blood that help maintain glucose homeostasis
pancreas
104
a lesion of the skin or mucous membranes characterized by inflammation and damaged tissues.
ulcer
105
the vein that collects blood from the GI tract and conducts it to the capillaries in the liver
hepatic portal vein
106
the circular muscle that separates the stomach from the small intestine and regulates the flow of partially digested food intot eh small intestine
pyloric sphincter
107
the main lymphatic vessel that collects lymph and drains into the left subclavian vein
thoracic duct
108
a substance with both water soluble and fat soluble portions that promotes the mixing oils and fats in a watery solution
emulsifier
109
solutions inserted into the rectum and colon to stimulate a bowel movement and empty the lower large intestine
enemas
110
a periodic squeezing or partitioning of the intestine along its length by its circular muscles
segmentation
111
sacs or pouches that develop in the weakened areas of the intestinal wall
diverticula
112
the condition of having infrequent or difficult bowel movement
constipation
113
a burning sensation in the chest area caused by backflow of stomach acid into the oesophagus
heartburn
114
all the organs and glands associated with the ingestion and digestion of food
digestive system
115
the popular but potentially harmful practice of "washing" the large intestine with a powerful enema machine
colonic irrigation
116
proteins found in digestive juices that act on food substances, causing them to break down into simpler compounds
digestive enzymes
117
medications used to prevent of relieve indigestion by suppressing production of acid in the stomach, also called H2 blockers
acid controllers
118
What protective mechanism prevents erosion in the stomach?
mucus secretion
119
Which of the following is not true of digestion? A) When the pyloric sphincter opens, chyme enters the duodenum B) a small amount of vitamin K is made by colonic bacteria C) water and minerals are mainly absorbed in the stomach D) carbohydrate digestion begins in the mouth.
c
120
A personal who has a history of gastrointestinal problems related to indigestion and heartburn might have problems with the…?
lower eosophageal sphincter
121
Name the three transport processes involved in the absorption of nutrients
simple diffusion, faciliftated diffusion, active transport
122
What transport process accounts for the absorption of water?
simple diffusion
123
Which gastrointestinal hormone is released in response to fat in the diet?
Cholecystokinin
124
A person is experiencing frequent heartburn after each meal. What measure could help relieve this type of discomfort?
increase the time spent while eating any meal or snack item.
125
Which organ releases bicarbonate to neutralize gastric acidity
pancreas
126
What two actions help to propel a bolus of food through the digestive tract?
peristalsis and segmentation
127
Because an enzyme does not change its chemical structure, but promotes other chemical reactions, ,it is called a
catalyst
128
absorption
the uptake of nutrients by the cells of the small intestine for transport into either the blood or the lymph
129
acid controllers
medications used to prevent or relieve indigestion by suppressing production of acid in the stomach; also called H2 blockers. H2 blockers include ranitidine and famotidine
130
antacids
medications used to relieve indigestion by neutralising acid in the stomach. Calcium-containing preparations usually contain available calcium in the form of calcium carbonate. Antacids with aluminium or magnesium hydroxides can accelerate calcium losses
131
anus
the terminal outlet of the gastrointestinal tract
132
aorta
the large, primary artery that conducts blood from the heart to the body's smaller arteries
133
appendix
a narrow blind sac extending from the beginning of the colon that stores lymph cells
134
arteries
vessels that carry blood from the heart to the tissues
135
belching
the expulsion of gas from the stomach through the mouth
136
bicarbonate
an alkaline compound with the formula HCO3 that is secreted from the pancreas as part of the pancreatic juice. (Bicarbonate is also produced in all cell fluids from the dissociation of carbonic acid to help maintain the body's acid?base balance.)
137
bile
an emulsifier that prepares fats and oils for digestion; an exocrine secretion made by the liver, stored in the gall bladder and released into the small intestine when needed
138
bolus
a portion; with respect to food, the amount swallowed at one time
139
capillaries
small vessels that branch from an artery. Capillaries connect arteries to veins. Exchange of oxygen, nutrients and waste materials takes place across capillary walls
140
catalyst
a compound that facilitates chemical reactions without itself being changed in the process
141
cell membrane
the thin layer of tissue that surrounds the cell and encloses its contents; made primarily of lipid and protein
142
cholecystokinin (CCK)
a hormone produced by cells of the intestinal wall to aid in fat and protein digestion by stimulating the release of bile from the gall bladder and pancreatic secretions from the pancreas
143
chyme
the semiliquid mass of partly digested food expelled by the stomach into the duodenum
144
colitis
inflammation of the colon
145
colonic irrigation
the popular but potentially harmful practice of ?washing' the large intestine with a powerful enema machine
146
constipation
the condition of having infrequent or difficult bowel movements
147
crypts
tubular glands that lie between the intestinal villi and secrete intestinal juices into the small intestine
148
defecate
to move the bowels and eliminate waste
149
diarrhoea
the frequent passage of watery bowel movements
150
Digestion
the process by which food is broken down into absorbable units
151
digestive enzymes
proteins found in digestive juices that act on food substances, causing them to break down into simpler compounds
152
digestive system
all the organs and glands associated with the ingestion and digestion of food
153
diverticula
sacs or pouches that develop in the weakened areas of the intestinal wall (like bulges in an inner tube where the tyre wall is weak)
154
diverticulitis
infected or inflamed diverticula. About one in every six people in Western countries develops diverticulitis in middle or later life
155
duodenum
the top portion of the small intestine (about ?12 fingers' breadth' long in ancient terminology)
156
emulsifier
a substance with both watersoluble and fat-soluble portions that promotes the mixing of oils and fats in a watery solution
157
enemas
solutions inserted into the rectum and colon to stimulate a bowel movement and empty the lower large intestine
158
epiglottis
cartilage in the throat that guards the entrance to the trachea and prevents fluid or food from entering it when a person swallows
159
gall bladder
the organ that stores and concentrates bile. When it receives the signal that fat is present in the duodenum, the gall bladder contracts and squirts bile through the bile duct into the duodenum
160
gastric glands
exocrine glands in the stomach wall that secrete gastric juice into the stomach
161
gastric juice
the digestive secretion of the gastric glands of the stomach
162
gastrin
a hormone secreted by cells in the stomach wall. The target organ is the glands of the stomach. The response is secretion of gastric acid
163
gastro-oesophageal reflux
the backflow of stomach acid into the oesophagus, causing damage to the cells of the oesophagus and the sensation of heartburn. Gastro-oesophageal reflux disease (GORD) is characterised by symptoms of reflux occurring two or more times a week
164
gastrointestinal (GI) tract
`the digestive tract. The principal organs are the stomach and intestines
165
glands
cells or groups of cells that secrete materials for special uses in the body. Glands may be exocrine glands, secreting their materials ?out' (into the digestive tract or onto the surface of the skin), or endocrine glands, secreting their materials ?in' (into the blood)
166
goblet cells
cells of the GI tract (and lungs) that secrete mucus
167
haemorrhoids
painful swelling of the veins surrounding the rectum
168
heartburn
a burning sensation in the chest area caused by backflow of stomach acid into the oesophagus
169
hepatic portal vein
the vein that collects blood from the GI tract and conducts it to capillaries in the liver
170
hepatic vein
the vein that collects blood from the liver capillaries and returns it to the heart
171
hiccups
repeated cough-like sounds and jerks that are produced when an involuntary spasm of the diaphragm muscle sucks air down the windpipe;
172
homeostasis
the maintenance of constant internal conditions (such as blood chemistry, temperature and blood pressure) by the body's control systems. A homeostatic system is constantly reacting to external forces to maintain limits set by the body's needs
173
hormones
chemical messengers. Hormones are secreted by a variety of glands in response to altered conditions in the body. Each hormone travels to one or more specific target tissues or organs, where it elicits a specific response to maintain homeostasis
174
hydrochloric acid
an acid composed of hydrogen and chloride atoms (HCl) that is normally produced by the gastric glands
175
hydrolysis
a chemical reaction in which a major reactant is split into two products, with the addition of a hydrogen atom (H) to one and a hydroxyl group (OH) to the other (from water, H2O). (The noun is hydrolysis; the verb is hydrolyse.)
176
ileocaecal valve
the sphincter separating the small and large intestines
177
ileum
the last segment of the small intestine
178
indigestion
incomplete or uncomfortable digestion, usually accompanied by pain, nausea, vomiting, heartburn, intestinal gas or belching
179
irritable bowel syndrome
an intestinal disorder of unknown cause. Symptoms include abdominal discomfort and cramping, diarrhoea, constipation, or alternating diarrhoea and constipation
180
jejunum
the first two-fifths of the small intestine beyond the duodenum
181
large intestine or colon
the lower portion of intestine that completes the digestive process. Its segments are the ascending colon, the transverse colon, the descending colon and the sigmoid colon
182
larynx
the upper part of the air passageway that contains the vocal cords; also called the voice box
183
laxatives
substances that loosen the bowels and thereby prevent or treat constipation
184
liver
the organ that manufactures bile.
185
lumen
the space within a vessel, such as the intestine
186
lymph
a clear yellowish fluid that is similar to blood except that it contains no red blood cells or platelets. Lymph from the GI tract transports fat and fat-soluble vitamins to the bloodstream via lymphatic vessels
187
lymphatic system
a loosely organised system of vessels and ducts that convey fluids towards the heart. The GI part of the lymphatic system carries the products of fat digestion into the bloodstream
188
microvilli
tiny, hairlike projections on each cell of every villus that can trap nutrient particles and transport them into the cells (singular microvillus)
189
mineral oil
a purified liquid derived from petroleum; can be used to treat constipation
190
mouth
the oral cavity containing the tongue and teeth
191
mucus
a slippery substance secreted by cells of the GI lining (and other body linings) that protects the cells from exposure to digestive juices (and other destructive agents). The lining of the GI tract with its coat of mucus is a mucous membrane. (The noun is mucus; the adjective is mucous.)
192
oesophageal sphincter
a sphincter muscle at the upper or lower end of the oesophagus. The lower oesophageal sphincter is also called the cardiac sphincter
193
oesophagus
the food pipe; the conduit from the mouth to the stomach
194
pancreas
a gland that secretes digestive enzymes and juices into the duodenum. It also secretes hormones into the blood that help to maintain glucose homeostasis
195
pancreatic juice
the exocrine secretion of the pancreas, containing enzymes for the digestion of carbohydrate, fat and protein as well as bicarbonate, a neutralising agent. The juice flows from the pancreas into the small intestine through the pancreatic duct. (The pancreas also has an endocrine function, the secretion of insulin and other hormones.)
196
peptic ulcer
a lesion in the mucous membrane of either the stomach (a gastric ulcer) or the duodenum (a duodenal ulcer)
197
peristalsis
wave-like muscular contractions of the GI tract that push its contents along
198
pharynx
the passageway leading from the nose and mouth to the larynx and oesophagus
199
probiotics
living microorganisms found in foods that, when consumed in sufficient quantities, are beneficial to health
200
pyloric sphincter
the circular muscle that separates the stomach from the small intestine and regulates the flow of partially digested food into the small intestine; also called pylorus or pyloric valve
201
rectum
the muscular terminal part of the intestine, extending from the sigmoid colon to the anus
202
reflux
a backward flow
203
saliva
the secretion of the salivary glands. Its principal enzyme begins carbohydrate digestion
204
salivary glands
exocrine glands that secrete saliva into the mouth
205
secretin
a hormone produced by cells in the duodenum wall. The target organ is the pancreas. The response is secretion of bicarbonate-rich pancreatic juice
206
segmentation
a periodic squeezing or partitioning of the intestine at intervals along its length by its circular muscles
207
small intestine
a 3-metre length of small-diameter intestine that is the major site of digestion of food and absorption of nutrients. Its segments are the duodenum, jejunum and ileum
208
sphincter
a circular muscle surrounding, and able to close, a body opening. Sphincters are found at specific points along the GI tract and regulate the flow of food particles
209
stomach
a muscular, elastic, sac-like portion of the digestive tract that grinds and churns swallowed food, mixing it with acid and enzymes to form chime
210
stools
waste matter discharged from the colon; also called faeces
211
subclavian vein
the vein that provides passageway from the lymphatic system to the vascular system
212
thoracic duct
the main lymphatic vessel that collects lymph and drains into the left subclavian vein
213
trachea
the air passageway from the larynx to the lungs; also called the windpipe
214
ulcer
a lesion of the skin or mucous membranes characterised by inflammation and damaged tissues. See also peptic ulcer
215
veins
vessels that carry blood to the heart
216
villi
finger-like projections from the folds of the small intestine (singular villus)
217
vomiting
expulsion of the contents of the stomach up through the oesophagus to the mouth
218
yoghurt
milk product that results from the fermentation of lactic acid in milk by Lactobacillus bulgaricus and Streptococcus thermophilus
