NFS284 Chapter 3 Flashcards
1
Q
Path of nutrients in the body
A
- Digestion
- Absorption
- Metabolism in cells
- Eliminate waste
2
Q
4 major types of tissue
A
- Muscle
- Nerve
- Epithelial
- Connective
3
Q
Tissues play a role in the…
A
Digestion stage of food
4
Q
2 types of tissue found in the stomach
A
- nervous
- connective
5
Q
Purpose of tissue in the stomach
A
signals brain when stomach is empty or full
6
Q
Purpose of muscles in the stomach
A
Begin digestion process by churing ingested food
7
Q
Purpose of specialized epithelial cells in the stomach
A
Produce acids and enzymes that help break down the food (faster)
8
Q
Digestion
A
Break down food chemically and mechanically into parts that are small enough to be absorbed by the body
9
Q
Absorption
A
Taking substances obtained from food into the interior of the body
10
Q
The digestive system is broken down into 2 steps.
A
- Digestion
2. Absorption
11
Q
Food can be broken down in 2 ways
A
- Chemically
2. Mechanically
12
Q
What does the GI tract include?
A
- mouth
- pharynx
- esophagus
- stomach
- small intestines
- large intestines
- anus
13
Q
What are the accessory organs that aid the digestive process?
A
- salivary glands
- liver
- pancreas
- gallbladder
14
Q
Function of:
mouth
A
chew food, mix food with saliva
15
Q
Function of:
salivary glands
A
produce saliva (contains amylase which break down starch)
16
Q
Function of:
pharynx
A
swallows chewed food + saliva
17
Q
Function of:
esophagus
A
moves food into stomach
18
Q
Function of:
liver
A
makes bile
19
Q
Function of:
bile
A
helps digestion & absorption of fat
20
Q
Function of:
pancreas
A
- Secretes bicarbonate to neutralize intestinal contents
- Produce enzymes that break down carbs, proteins, fats
21
Q
Function of:
gallbladder
A
stores bile, and release it into small intestines when needed
22
Q
Function of:
small intestines
A
- Finishes digestion process
- Absorption of nutrients into blood / lymph
23
Q
Function of:
large intestines
A
- Absorbs water, vitamins, minerals
- Intestinal bacteria
- Passes waste
24
Q
The large intestines consist of…
A
- Colon
- Rectum
25
Function of:
| anus
opens to allow waste to leave body
26
Transit time
Time it takes for food to pass through the GI tract
27
How long is transit time typically?
24 - 72 h
28
What impacts transit time?
- Food that is being digested
| - Fibres
29
How is transit time measured?
A dye that can't be absorbed by the body is added to the meal
How long does it take for dye to appear in poop?
30
What type of food passes through GI tract without absorption taking place?
Indigestible food
31
Which nutrient influences transit time?
Dietary fibre
32
What is the gut wall made up of?
- small intestine = layer of tissue
- lumen
- mucosa / mucosal cells / epithelial cells
33
Anatomy of the gut wall
(out -> in)
- connective tissue
- smooth muscle
- connective tissue
- mucosa
- lumen
34
Mucosa
layer of tissue lining the lumen in the GI tract
35
Function of mucosal cells
- absorb nutrients
| - secrete mucus
36
2 things secreted by the digestive system
1. digestive enzymes
| 2. mucus
37
What is gastric motility?
More gastric juices secreted
| More muscle activity
37
Amylase
Breaks down starch -> sugars
38
Where is salivary amylase found?
mouth
38
What causes increased gastric motility?
Senses food -> brain -> tells stomach to increase gastric motility
39
Where is rennin found?
stomach
39
Distension
Stretching
40
Where is trypsin found?
pancreas
40
What does stretching of the stomach stimulate?
send signals to brain
brain: release gastrin
gastrin: increase gastric secretions and motility
41
Where is carboxypeptidase, aminopeptidase, and dipeptidase found?
small intestines
41
What does gastrin do?
Increase gastric secretions (HCl), which is needed to convert pepsinogen to pepsin.
Also increases motility
42
Function of salivary amylase
break starch -> smaller carbohydrate molecules
42
What are 2 ways to increase gastric secretion & motility?
1. Brain
| 2. Gastrin
43
Function of rennin
Curdles milk protein casein
43
Hormones in the intestines do what?
Decrease gastric secretion & motility
44
Casein
A milk protein
44
Where is the pyloric valve?
Between stomach & small intestines
45
Function of pepsin
Proteins & polypeptides -> AA
45
How long does it take for food to go through the stomach?
2-6 h
46
Function of trypsin
proteins & polypeptides -> shorter polypeptides
46
The small intestines is the major site for...
Digestion & absorption
47
Function of chymotrypsin
proteins & polypeptides -> shorter polypeptides
47
What are 3 ways in which the small intestines increase SA?
1. Large folds
2. Villi
3. Microvilli
48
Function of lipase
monoglycerides -> FA & glycerol
48
Villi are well supported by...
- Bld vessels (oxygen, nutrients)
| - Lacteal
49
Function of carboxypeptidase
polypeptides -> AA
49
How are dietary fats removed from the digestive tract?
Through lacteal -> lymphatic system
50
Function of pancreatic lipase
triglyceride -> monoglycerides & FA & glycerol
50
___ cells are on the surface of the villi
mucosal
51
Function of pancreatic amylase
starch -> shorter glucose chains & maltose
51
Nutrients pass from lumen through ___ to enter ___ or ____. This is then transported to the rest of the body.
Mucosal cells
Blood stream
Lympth
52
Function of carboxypeptidase, aminopeptidase, dipeptidase
Polypeptides -> AA
52
Another name for microvilli
brush border
53
Which 3 enzymes found in the small intestine tend to be grouped together?
carboxypeptidase
aminopeptidase
dipeptidase
53
Where are microvilli located?
On the mucosal cells that face the lumen in the small intestines
54
Function of sucrase
sucrose -> glucose & fructose
54
Enterocytes
mucosal cells with microvilli
55
Mucosal cells with microvilli on them are called...
enterocytes
55
Function of lactase
lactose -> glucose & galactose
56
What is secreted from the pancreas?
1. bicarb
| 2. digestive enzymes (amylases, proteases, lipases)
56
Function of maltase
maltose -> glucose
57
Which proteases are secreted by the pancreas?
- trypsin
| - chymotrypsin
57
Function of dextrinase
short chains of glucose -> individual glucose
58
Why are bicarb ions secreted by the pancreas?
Neutralize the HCl entering the small intestines along with the chyme
58
Location of pepsin
stomach
59
location of chymotrypsin
pancreas
59
Lipases are used for the digestion of...
triglycerides
60
Location of carboxypeptidase
pancreas
60
Which accessory organ in the digestive system can we live without?
Gall bladder
61
Location of lipase
small intestines
61
What is the purpose of the gall bladder?
Store bile
62
Location of sucrase
small intestines
62
What is the purpose of bile?
- Emulsify fats
| - Break fat into smaller droplets & keep them stabilized to be absorbed (digestive tract is polar)
63
Location of lactase
small intestines
63
Small intestines secrete...
1. intestinal juices
| 2. brush border enzymes
64
Purpose of intestinal juice
substance containing water & mucus.
Mix chyme with digestive juices
64
Location of maltase
small intestines
65
Location of dextrinase
small intestines
65
Purpose of brush border enzymes
Break down polypeptides -> AA
Digest carbohydrates
66
The digestive tract is made up of ____. Without mucus, it would be digested by the enzymes.
Proteins
66
Which 2 hormones are released when food enters the small intestine?
1. secretin
| 2. CCK
67
Enzymes protect cells from...
Autodigestion
67
Secretin stimulates secretion of...
1. Bile: liver -> gall bladder
| 2. Bicarb from pancreas
68
Mucus is secreted by
Mucous membranes (which are made up of epithelial cells)
68
CCK stimulates the release of...
1. Bile: gall bladder -> intestines
| 2. Digestive enzymes from pancreas
69
Cells in the mucosa layer is [long / short] lived. Why?
Short.
| Mucosa cells have high nutrient requirements (one of the first to be affected by nutrient deficiencies)
69
What is the valve that separates small and large intestine?
ileocecal valve
70
Intestinal cells need...
High levels of nutrients
70
What enters the large intestine?
Food not absorbed in the small intestine
71
What are some parts of the body that is first affected by nutrient deficiency?
- Intestinal cells
| - Cells of the immune system
71
What are reabsorbed in the small intestine?
- water
| - micronutrients (continued from small intestines)
72
What regulates the function of the digestive system?
Nerve signals between brain GI tract
72
How long does food spend in the small intestines?
3-4h
73
Where can nerve signals be found in the digestive system?
Between GI tract and brain.
| Between different parts of the GI tract.
73
How long does food spend in the large intestines?
24h
74
What are the 5 hormones of the digestive system?
1. gastrin
2. somatostatin
3. secretin
4. CCK
5. Gastric inhibitory peptide
74
What happens to materials not absorbed in the colon?
excreted as feces
75
CCK
cholecystokinin
75
What is feces usually composed of?
- unabsorbed food matter
- dead intestinal cells
- mucus
- bacteria
- water
76
Gastrin is secreted by...
Stomach mucosa
76
What can examining poop tell scientists?
- What's going on in the interior of the body (non-invasive method)
- How bac't in the gut interacts with the body to promote health
77
Somatostatin is secreted by...
Stomach & duodenal mucosa
77
What helps prevent constipation?
high fibre diet:
fibre retains water (less water reabsorbed in large intestines), which softens feces.
WATER MUST BE CONSUMED WITH FIBRE FOR FULL BENEFIT.
78
Secretin is secreted by...
Duodenal mucosa
78
Why is the large intestine such a good place for intestinal microflora?
Things move slowly in the large intestines
79
CCK is secreted by...
Duodenal mucosa
79
What is something that the microflora in our intestines can do but we can't?
Break down some indigestible food components (e.g. dietary fibre)
80
Gastric inhibitory peptide is secreted by...
Duodenal mucosa
80
Define: fermentation
Breakdown of things by bacteria
81
What is 1 product of fermentation?
Intestinal gas (doots!)
81
Function of gastrin
- Stimulate HCl secretion by gastric glands in stomach
- Stimulate pepsinogen secretion by gastric glands in stomach
- Increase gastric motility & emptying
82
Probiotics
Live bacterial culture which may be beneficial to health
82
Function of somatostatin
- Inhibits stomach secretion, motility, emptying
- Pancreatic secretions
- Absorption by small intestines
- Gallbladder contraction
- Bile release
83
What are 2 common probiotics?
1. bifidobacterium
| 2. lactobacillus
83
Function of secretin
- Inhibits gastric secretion & motility
- Increase water & bicarb output from pancreas
- Increase bile release from liver
84
Function of CCK
- Gallbladder contractions (expel bile)
| - Increase output of pancreatic juice
84
Why are probiotics often found in yogurt?
They like the lactic acid
85
Function of gastric inhibitory peptide
- Inhibits gastric secretion & motility
85
What is the lifespan of probiotics once it is consumed?
Very short; must be consumed regularly
86
Where are hormones produced?
Accessory organs
| Cells in the gut
86
Prebiotic
Indigestible carbs in fruits and veggies used to feed microflora in intestines
87
Function of hormones for the digestive system?
- Regulate food intake
87
How can prebiotics be found in food?
Added to food in purified form
88
What is 1 example of a prebiotic?
Inulin
88
Hormones are released into the...
bloodstream
89
Do prebiotics contain bacteria? What is the relationship?
No, but it promotes growth of microflora by giving it a good food source.
89
Function of mucus (immunity)
Physical barrier to infection from micro-organisms that we swallow along with food.
90
Synbiotics
Contains both probiotics and prebiotics
90
Cells of immune system important for fighting disease (2 types of WBC)
1. phagocytes
| 2. lymphocytes
91
Why is the immune system sensitive to nutrient deficiencies?
Rapidly dividing WBC that need a lot of nutrients.
91
Food claim: probiotics
Calcium & vit D (health claim)
| Contribute to healthy gut flora (nutrient function claim)
92
Which WBC is first to respond to an infection?
phagocytes
92
What do the Canadian regulations require of food that contain probiotics?
Specific name of probiotic need to be listed in ingredients
93
How do phagocytes respond to an infection?
- Eat antigen
- Break down harmful organisms
- Present antigen
93
Colostrum
Breast milk produced during the first week after delivery that contain immune factors (antibodies) to protect infant from infection (in the GI tract)
94
Define: antigen
protein in an micro-organism that induces an immune response
94
What do the carbs in breast milk behave like, and what does it do?
Prebiotics.
| Promote growth of Lactobacillus to reduce risk of GI infections
95
Antigen presentation causes...
production of antibodies
95
What is the carb in breast milk?
Lactose
96
What will antibodies do?
Bind to any micro-organism displaying that specific antigen.
| Causes phagocytes to notice & find pathogens easier.
96
___% of kcal of breast milk comes from fat.
52%
97
What results in food allergies?
immune response to some protein found in food (allergen)
97
What is the purpose of high fat content in breast milk?
Support rapid growth of newborn
98
Example of a phagocyte
macrophage
98
Unlike adults, infants can absorb some ____ intact (i.e. does not get broken down to monomers)
proteins
99
Example of lymphocytes
- Helper T cells
- Cytotoxic T cells
- B cells
99
What enzyme is present in infants but not adults?
Rennin
100
What is rennin used for?
Digest specific proteins found in breast milk
100
B cells can develop into...
- plasma cells
| - memory cells
101
One of the proteins that infants are able to absorb whole is...
antibodies
101
What type of lymphocyte can bind to body cells that are infected?
Cytotoxic T cells
102
Which enzyme plays a more important role for the digestion of fats in infants > adults?
gastric lipase
102
Define: bolus
Chewed up food
103
Fat digestion is done mostly by ___ in adults, but hardly present in infants.
Pancreatic digestive enzymes
103
Function of epiglottis
Prevents food from going to the lungs (prevent choking)
104
Why is there low amylase in the infant gut?
No starch in milk (only lactase)
104
Lysozyme
Enzyme that kills bacteria responsible for decay
105
Where is lactase present in the infant?
near the brush border (it is a brush border enzyme)
105
Purpose of saliva
- Contain salivary amylase
- Contain lysozyme
- Wash away food particles
106
Why does lactose intolerance happen?
Production of lactase declines with age (a lot as a baby -> fewer as adult)
106
What is the epiglottis?
piece of elastic connective tissue
107
Infants can't consume solid food...(when)
first 6 months of life
107
Esophagus connects...
pharynx to stomach
108
___ reflex is used to draw liquid from a nipple placed towards the back of the mouth.
suckling
108
What does the esophagus do to push bolus down to the stomach?
Persistalsis
109
Why is it not possible to spoon feed newborns?
sucking reflex causes spoon (which is placed in front of mouth) to be pushed out by tongue
109
Define: persistalsis
Circular & longitudinal contractions that push food down from the esophagus
110
When does the the suckling reflex start to go away?
4-6 months
110
What is the purpose of the sphincters in the esophagus?
Separate esophagus from stomach; prevent acid reflux
111
When does teeth begin to grow?
4-6 months
111
Purpose of sphincters in the digestive system
Separate organs in the GI
112
When can solid food be introduced to babies?
4-6 months, when teeth begin to grow & suckling reflex goes away
112
Sphincters
Muscular valves that separate organs in the GI
113
What opens the sphincters in the esophagus - stomach area?
The wave of peristalsis reaches the stomach, and causes the sphincter to relax
113
What does breast milk have the formula cannot replace?
Immune factors
114
The stomach is very ____. It is to mix food.
Muscular
114
Health Canada recommends exclusive breastfeeding for...
6 months
115
Stomach has specialized cells to...
produce acid
115
What must babies be supplemented with?
Vit D: from birth
| Iron: from 4 months
116
What happens in the stomach?
Bolus is mixed with acidic gastric juices to form chyme
116
What is the pattern between exclusive breast feeding and age of baby?
Decreases as baby ages
117
Chyme
semi-liquid mixture of bolus and gastric juices
117
Breast feeding is more common...
- mothers with partners
- non-smokers
- at-home birth
- non-working mothers
118
What does the word gastric refer to?
anything to do with the stomach
118
Gastric bypass surgey
Reduce body weight by
- decrease stomach size
- shorten length of intestine
(less food can be consumed)
119
Obesity can lead to health issues such as...
- high risk for chronic diseases (type II diabetes, CVD)
119
What are the muscle layers of the stomach?
- longitudinal muscle layer
- circular
- diagonal
120
Problem caused by gastric bypass surgery
Gastric dumpling syndrome
120
What are the cells that line the stomach?
- parietal cells
| - chief cells
121
Gastric dumping syndrome
- Pyloric sphincter bypassed: food goes straight from stomach -> intestines
121
What do gastric pits do?
Have specialized cells that secrete various products
122
What do parietal cells do?
- Produce HCl in the stomach
| - Produce intrinsic factor
122
What does gastric dumping syndrome cause?
If a lot of food consumed & quickly enters small intestines:
- water goes into small intestines (osmosis)
Micronutrients not absorbed fully (supplements & vit injections needed to prevent deficiency)
123
Symptoms of gastric dumping syndrome
Dizziness
Nausea
Diarrhea
123
Intrinsic factor
Glycoprotein produced by the parietal cells that is necessary for the absorption of vit B12
124
What do chief cells do?
- Produce pepsinogen
125
How is pepsin made?
Pepsinogen + HCl
126
What is the purpose of pepsin?
Active enzyme that breaks protein -> short AA (polypeptides)
127
What is the precursor for pepsin?
Pepsinogen
128
Where are the stomach cells located?
Gastric pit
129
What is the order/location of the cells found in the stomach (gastric pits -> muscles)
1. mucus-secreting cells
2. parietal cells
3. Gastric glands
4. Chief cells
130
In which layer are all the stomach cells PLUS the epithelium located?
Mucosa
131
Digesting of which macronutrient does not happen in the stomach and why?
Carbohydrates;
| salivary amylase is inactivated in the acidic environment
132
Digestion of which macronutrient begins in the stomach?
Proteins
133
What are peptic ulcers caused by?
pepsin & acid penetrating the mucous layer
134
Heliobacter pylori
acid-resistant bacteria that eats through mucus
135
What is the leading cause for stomach ulcers?
H. pylori
136
H. pylori is associated with what stomach problems?
- Inflammation
| - Ulcers
224
How was the association between H. pylori and ulcers determined?
Epidemilogical studies
225
During digestion, carbohydrates are divided into two categories. What are they?
Starches
| Sugars
226
What enzymes act on carbohydrates?
1. salivary amylase (mouth)
2. pancreatic amylase (small intestines)
3. brush border enzymes (small intestines)
227
What enzymes act on sugars?
1. brush border enzymes (small intestines)
228
What enzymes act on proteins?
1. acid / pepsin (stomach)
| 2. trypsin & other enzymes (small intestines)
229
What enzymes act on dietary fibres?
bacterial enzymes in the large intestines
230
Final breakdown product of fats?
long-chain FA
| short-chain FA
231
Breakdown process of carbohydrates?
Starches -> smaller starches -> double sugars -> single sugars
232
Salivary amylase break starches to...
smaller starches
233
pancreatic amylase break smaller starches to...
double sugars
234
Brush border enzymes (amylase) break down double sugars to...
single sugars
235
What goes into the portal vein?
1. single sugars
2. amino acids
3. short-chain FA
236
What goes into the lymph vessel?
Long-chain FA
237
Where does the portal vein lead?
Liver
238
Where do short chain FA end up after digestion?
Hepatic portal vein
239
Where does the lymph vessel lead?
Blood stream
240
Where does long-chain FA go after digestion?
Lymph vessel
241
How does H. pylori survive in the acidic environment of the stomach?
- Uses tail to swim through mucus layer
- Attaches to mucosal cells
- Produce acid-neutralizing compounds
242
What is a peptic ulcer?
Open sore in the GI tract
243
What is the significance of H. pylori?
Leading cause for ulcers
244
Why were epidemiological studied important in the study of H. pylori?
Dr. Marshall did not develop an ulcer when he tested H. pylori on himself. Further evidence was needed to link the bacterial to the formation of ulcers.
245
How has treatment for ulcers changed since the discovery of H. pylori?
- Antibiotic + acid suppression therapy
| - Before: bland diets & antacids
246
How are fat soluble nutrients absorbed?
Through lymphatic system -> bld stream
247
How are water soluble nutrients absorbed?
Through portal vein -> liver -> bld stream
248
Cardiovascular system
Network of vessels through which bld is pumped
249
Why does water soluble nutrients have to go through the liver before going to the rest of the body?
Liver = gatekeeper
Makes sure the level of nutrients entering the body is the amount needed (store extra)
ESPECIALLY GLUCOSE
250
What is glucose stored as and where?
Glycogen in the liver
251
Role of the lymphatic system?
- Project body from infection
| - Absorb fat-soluble nutrients
252
What happen to fat as they are absorbed?
Incorporated into chylomicrons
253
Thoracic duct
Largest lymphatic vessel in the lymphatic system
254
Where do chylomicrons go after the lacteal?
Drain into larger ducts (thoracic duct) -> bld stream
255
Why can't fats go through the hepatic portal vein?
Chylomicrons are too big to enter capillaries
256
Path of chylomicron in the body
Goes to different tissues/organs from the bld stream to give fat where needed
257
What happens when all the fat is used up from the chylomicron?
= chylomicron remnant
| Goes to liver where they are metabolized
258
Metabolic pathway
Series of reactions that convert compounds from 1 form to another
259
Metabolic pathways are divided into...
- Catabolic pathways
| - Anabolic pathways
260
Catabolic pathways
Breakdown of bigger molecules (glucose, AA, FA) -> smaller ones
261
What is a product of the catabolic pathway?
ATP
262
ATP is used for...
- Anabolic pathways
| - Muscle contractions, kidney functions, other body processes
263
Anabolic pathway
Use energy to synthesize more complex molecules from smaller molecules (glucose, AA, FA)
264
What's the process in which ATP is produced?
Cellular respiration
265
Cellular respiration
Glucose, AA, FA -> ATP
266
What is used to produce ATP when there is no oxygen?
Glycolysis (glucose -> 2 ATP)
267
When oxygen is available, glucose and FA are converted into...
acetyl CoA
268
What happens to acetyl CoA?
Citric acid cycle
| Produce CO2 and high energy electrons
269
What happens to the high energy electrons?
Electron transport chain
| Oxidation-reduction reactions that release energy -> ATP
270
Oxidation reaction
When a compound loses an electron
271
Reduction reaction
When a compound gains an electron
272
Why is oxygen essential to the electron transport chain?
Last reaction in the chain converts oxygen -> water
273
Summarize the process of cellular respiration
1. Glycolysis (-> acetyl CoA)
2. Citric acid cycle (acetyl CoA -> high energy electrons)
3. Electron transport chain (electrons -> ATP)
274
The process in which FA is used for energy
B-oxidation
275
The process in which AA is used for energy
Deamination
276
Anabolic pathway for glucose
Glucose -> glycogen
277
Anabolic pathway for FA
FA -> triglycerides
278
Anabolic pathway for AA
AA -> proteins
279
Routes of elimination
1. Feces (food not absorbed)
2. CO2 (respiration by lungs)
3. Water (perspiration & sweat)
4. Urine (kidneys for N-containing compounds)
280
How is waste eliminated from the digestive system?
Feces through anus
281
How is waste eliminated from the respiratory system?
CO2 exhaled from lungs
282
How is waste eliminated from the integumentary system?
Water & other waste are lost through perspiration & sweat
283
How is waste eliminated from the urinary system?
N-containing compounds lost through urine after process by the kidneys
284
Urine is a...
byproduct of metabolism
