5/24 Lecture E3 Flashcards
(237 cards)
1
Q
What is weight determined by?
A
The body’s energy balance; combination of heredity (30-50%) and environmental influences
2
Q
What is involved in the control of weight?
A
several peptide hormones and regulatory pathways that control sort and long-term appetite
3
Q
What do short term regulators of appetite do?
A
make one feel hungry or satiated to begin or end eating.
4
Q
What do short term regulators of appetite include?
A
peptides ghrelin, peptide YY, cholecystokinin, and amylin
5
Q
What is Ghrelin?
A
A substance secreted from parietal cells in the fundus of an empty stomach that produces the sensation of hunger.
6
Q
What gland does Ghrelin stimulate?
A
stimulates the hypothalamus to secrete growth hormone releasing hormone
7
Q
What is Peptide YY? (PYY)
A
a substance secreted by enteroendocrine cells of the ileum and colon that can sense that food has arrived in the stomach, in order to signal satiety and terminate eating.
8
Q
How much PYY is secreted?
A
the amount is proportional to the number of calories consumed
9
Q
What is Cholecystokinin (CCK)
A
a substance secreted by enteroendocrine cells in the duodenum and jejunum that stimulates the secretion of bile and pancreatic enzymes.
10
Q
What does CCK do?
A
stimulates brain and sensory fibers of vagus nerve, suppressing appetite.
11
Q
What is Amylin?
A
A substance secreted from beta cells of the pancreas that produces satiety and inhibits stomach activity.
12
Q
What substances act as a signal to stop eating?
A
Peptide YY, Cholecystokinin and Amylin
13
Q
What substance produces the sensation of hunger?
A
Ghrelin
14
Q
What do long-term regulators of appetite do?
A
Govern caloric intake and energy expenditure over periods of weeks to years.
15
Q
What peptides inform the brain of how much adipose the body has?
A
Leptin and Insulin
16
Q
What secretes Leptin?
A
adipocytes throughout the body
17
Q
What does leptin do?
A
informs the brain on how much fat it has.
18
Q
What secretes insulin?
A
pancreatic beta cells
19
Q
What does insulin stimulate?
A
glucose and amino acid uptake
20
Q
What does insulin promote?
A
glycogen and fat synthesis
21
Q
Which has a greater effect on appetite: insulin or leptin
A
leptin
22
Q
What has receptors for all short and long term chemical signals?
A
The Arcuate nucleus of the hypothalamus
23
Q
What are the two substances secreted by the arcuate nucleus of the hypothalamus that affect appectite?
A
Neuropeptide Y and melanocortin
24
Q
What is neuropeptide Y?
A
a potent appetite stimulant
25
what is melanocortin?
an eating inhibitor
26
What stimulates neuropeptide Y?
Gherlin
27
What inhibits neuropeptide Y?
insulin, PPY, and leptin
28
What stimulates Melanocortin?
Leptin
29
What does melanocortin inhibit?
the secretion of appetite stimulants (endocannabinoids)
30
What partly stimulates hunger?
gastric peristalsis
31
Does gastric peristalsis affect the amount of food consumed?
NO. Its the PYY and CCK that shut off food intake.
32
What are the lasting effects of satiety due to?
nutrients absorbed into the blood.
33
What do neurotransmitters do?
stimulate the desire for different types of food.
34
What food type does the neurotransmitter norepinephrine stimulate the desire for?
carbohydrates
35
What food type does the neurotransmitter galanin stimulate the desire for?
fats
36
What food type does the neurotransmitter endorphins stimulate the desire for?
protein
37
What is one calorie?
the amount of heat required to raise temperature of 1 g of water 1 degree C.
38
What is one Calorie (in dietetics)
1,000 calories, or 1 kcal in physiology
39
What is a calorie measure?
the capacity to do biological work.
40
How many kcal/g do carbs and proteins yield?
about 4 kcal/g
41
why are sugar and alcohol considered "empty" calories?
they provide few nutrients and suppress appetite
42
how many kcal/g do fats yield?
about 9 kcal/g
43
what is a nutrient?
any ingested chemical used for growth repair, or maintenance of the body.
44
What are the 6 classes of nutrients
water, carbs, lipids, proteins, vitamins, minerals
45
What are considered macronutrients?
nutrients that must be consume in relatively large quantities: water, carbs, lipids, proteins
46
What are considered micronutrients?
nutrients that are only needed in small quantities: vitamins and minerals
47
What are DRIs?
dietary reference intakes: RDAs (recommended dietary allowances) and AIs (adequate intake)
48
What are essential nutrients
nutrients that cannot be synthesized in the body: minerals, most vitamins, eight amino acids, and 1-3 of the fatty acids
49
A well-nourished adult body has what amount of carbs?
440 g:
325 g of muscle glycogen
90-100 g of liver glycogen
15-20 g of blood glucose
50
what are the functions of sugars?
1) structural components of other molecules including nucleic acids, glycoproteins, glycolipids, ATP, and related nucleotides (GTP, cAMP)
2) most serve as fuel
51
Why does most sugar serve as fuel for the body?
because they are easily oxidized source of chemical energy
52
What body components depend solely on carbohydrates?
Neurons and erythrocytes
53
What is hypoglycemia?
deficiency of blood glucose
54
What does hypoglycemia cause?
nervous system disturbances such as weakness and dizziness
55
How is plasma glucose concentration carefully regulated?
interplay of insulin and glucagon; balance between glycogen and free glucose
56
how does carb intake influence metabolism of other nutrients?
fats used as fuel when glucose and glycogen levels are low, and excess carbs are converted to fat.
57
What nutrient is required in greater amounts than any other nutrient?
carbohydrates
58
What is the RDA for carbs?
130 g
59
how many carbs does the brain consumer daily?
120 g of glucose per day
60
What is the average consumption of sugar and corn syrup per year?
60 lb of sugar and 46 lb of corn syrup
61
Dietary carbs come in what three principal forms?
glucose, galactose, and fructose
62
where do dietary carbs mainly come from?
mainly from digestion of starch and disaccharides.
63
What organs convert galactose and fructose to glucose?
small intestine and liver
64
What is a normal blood sugar (glucose) concentration?
70-110 mg/dL
65
What are the disaccharides?
sucrose (table sugar), maltose, lactose
66
What are the polysaccharides (complex carbs)?
starch, glycogen, and cellulose
67
is cellulose a nutrient?
no, because it is not digested, but is important as a dietary fiber.
68
where do nearly all dietary carbs come from?
plants
69
Where does sucrose come from?
Sucrose is refined from sugarcane and sugar beets
70
where does fructose come from?
Fructose is present in fruits and corn syrup
71
Where does maltose come from?
Maltose is present in some cereal grains
72
Where does Lactose come from?
Lactose is found in cow's milk.
73
What is dietary fiber?
All fibrous material of plant and animal origin that resists digestion: cellulose, pectin, gums, and lignins
74
What is the RDA for fiber?
25 g/day for females, 38 g/day for males
75
Where is water soluble fiber found?
In oats, beans, peas, brown rice, and fruits
76
What role does water-soluble fiber play in the body?
decreases blood cholesterol and LDL levels
77
What are some types of water-insoluble fiber?
cellulose, hemicellulose, lignin
78
Do water-insoluble fibers have an effect no cholesterol and LDL levels?
no
79
What does water-insoluble fiber do?
absorbs water in intestines
softens stool and increases its bulk
stretches the colon
stimulates peristalsis (quickens passage of feces
80
What can excessive intake of water-insoluble fiber do?
interfere with absorption of some elements such as iron, calcium, magnesium, phosphorous, and others
81
What is the average body fat percentage for females and males?
females: 25%
males: 15%
82
A well-nourished adult meets 80-90% of resting energy needs from what?
fat
83
which is superior for energy storage and why?
fat is superior to carbs because:
1) carbs are hydrophilic, absorbs water, and expands, occupying more space in tissue, whereas fat is hydrophobic and is more compact energy storage
2) fat contains over twice as much energy: 9 kcal/g for fat; 4 kcal/g for carbs
84
What are the glucose sparing effects of fat?
Glucose is spared for consumption by cells that cannot use fat, like neurons
85
What are the protein sparing effects of fat?
Protein is spared as fuel as long as there is enough fat.
86
What are the fat soluble vitamins that are absorbed with dietary fat?
A, D, E, K
87
How much fat is needed per day in order to absorb the necessary amount of fat soluble vitamins?
20 g/day
88
What other diverse functions does fat have besides an energy source?
1) structural: phospholipids and cholesterol (components of plasma membranes and myelin
2) chemical precursors:
3) important protective and insulating functions
89
What are the chemical precursors that fat assists with?
cholesterol (precursor of steroids, bile salts, vitamin D
thromboplastin (an essential blood-clotting factor; a lipoprotein)
fatty acids (arachidonic acid and linoleic acid: precursors for prostaglandins and other eicosanoids
90
What are the daily fat requirements?
less than 35% of daily calorie intake:
1) less than 10% of fat as saturated
2) limit saturated fat and cholesterol
91
how much fat does the typical American get?
40-50%
92
Where are most fatty acids found?
they are synthesized by the body
93
Where are saturated fats from?
```
Animal origins (meat, egg yolks, dairy products)
some in coconut and palm oils
```
94
Where are unsaturated fats from?
nuts, seeds, and most vegetable oils
95
Where is cholesterol from?
egg yolks, cream, shellfish, meats
| only in tiny, trace amounts of food of plant origin
96
How much protein makes up the total body mass?
12-15%
97
Where is most of the body's protein found?
in skeletal muscle (65%)
98
What are the functions of proteins? (5)
1) Muscle contraction
2) motility of cilia and flagella
3) structural components
4) Buffer pH of body fluids
5) resting membrane potential of all cells
99
What structural components do proteins contribute to?
1) all cellular membranes
2) fibrous proteins
3) globular proteins
4) plasma proteins
100
What is the protein RDA?
46-56 g/day
101
How is protein RDA calculated?
weight in pounds x 0.37
102
When is higher protein necessary?
stress, infection, injury, and pregnancy
103
What can excessive protein intake do?
overload the kidneys with nitrogenous waste and cause kidney damage
104
What are the 8 out of 20 essential amino acids that cannot be synthesized by the body?
isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine
105
In addition to the 8 out of 20, what other two essential amino acids cannot be synthesized by an infant's body?
histidine and arginine
106
Can cells store surplus amino acids for later use?
no
107
What happens if a particular amino acid is missing when a protein is being synthesized?
The protein cannot be synthesized
108
What are complete proteins?
high-quality dietary proteins that provide all essential amino acids in the necessary proportions for human tissue growth, maintenance and nitrogen balance
109
What are incomplete proteins?
lower quality proteins that lack on or more essential amino acids
110
What is net protein utilization?
the percentage of amino acids in a protein that the human body uses
111
What percentage of animal and plant proteins do we use?
80% of animal
| 50% of plant
112
What are the advantages of decreasing meat intake and increasing plant intake?
more vitamins, mineral and fiber,
less saturated fat
no cholesterol
less pesticide
113
What are complete animal proteins?
meat, eggs, and dairy products
114
What is nitrogen balance?
Rate of nitrogen ingested equals the rate of nitrogen excreted
115
What is the chief dietary source of nitrogen?
proteins
116
what causes a positive nitrogen balance?
nitrogen ingestion exceeds its excretion (more into the body than out in the urine?)
117
When does a positive nitrogen balance most often occur?
in children because they retain protein for tissue growth, and pregnant women and athletes in resistance training
118
What two things promote protein synthesis and positive nitrogen balance
growth hormone and sex steroids
119
What is a negative nitrogen balance?
When nitrogen excretion exceeds ingestion (more in urine than going into the body)
120
What causes a negative nitrogen balance?
1) Body proteins being broken down for fuel; muscle atrophy
| 2) Glucocorticoids (like cortisol) promote protein catabolism in states of stress
121
Why does muscle atrophy sometimes occur?
1) Muscles and liver proteins are more easily broken down than others
2) carb and fat intake is insufficient to meet body's energy needs
122
What are minerals?
inorganic elements that plants extract from soil or water and introduce into the food web
123
What are vitamins?
small dietary organic compounds that are necessary for metabolism
124
Why are vitamins and minerals important?
They are essential to our ability to use other nutrients
125
Can minerals and vitamins be used as fuel?
no
126
What percent of minerals is our body mass?
about 4%
127
What part of the body contains the most minerals?
calcium and phosphorous in bones and teeth (3/4)
128
What 4 minerals acts as cofactors for enzymes?
calcium, iron, magnesium, and manganese
129
What is important about phosphorous?
1) key structural component of phospholipids, ATP, cAMP, GTP, and creatine phosphate
2) basis for the phosphate buffer system
130
What is iron essential for?
the oxygen carrying capacity of hemoglobin and myoglobin
131
Where is chlorine found in the body?
It is a component of stomach acid
132
What is the function of mineral salts?
electrolytes and govern functions of nerve and muscle cells, osmotically regulate the content and distribution of water in the body, and maintain blood volume
133
What are the best sources of minerals?
vegetables, legumes, milk, eggs, fish, shellfish, and some other meats
134
What is the recommended daily sodium intake?
1.5 g/day
135
How much sodium does the typical American diet contain?
3.4 g/day
136
what can cause or contribute to hypertension?
elevated salt intake
137
Where must most vitamins be obtained from?
the diet
138
What are provitamins?
precursors that allow the body to synthesize some vitaims
139
What vitamins can the body synthesize using precursors?
```
Niacin
Vitamin A
Vitamin D
Vitamin K
Some B vitamins
```
140
How is niacin synthesized?
from amino acid tryptophan
141
How is vitamin A synthesized?
from carotene
142
How is vitamin D synthesized?
from cholesterol
143
How is vitamin K synthesized?
by bacteria of the large intestine
144
What are water-soluble vitamins?
vitamins that are absorbed with water in the small intestine and quickly excreted by the kidneys (not stored)
145
What are the water-soluble vitamins?
Vitamin C (ascorbic acid) and vitamin B
146
Why is vitamin C important to the body?
1) promotes hemoglobin synthesis, collagen synthesis, and sound connective tissue structure
2) an antioxidant that scavenges free radicals and possibly reduces the risk of cancer
147
Why are B vitamins important?
1) Function as coenzymes or parts of coenzyme molecules
2) Assist enzymes by transferring electrons from one metabolic reaction of cancer
3) Make it possible for enzymes to catalyze these reactions
148
What are the fat soluble enzymes?
Vitamin A, D, E and K
149
How are fat-soluble vitamins absorbed?
They are incorporated into lipid micelles in the small intestine and absorbed with dietary lipids
150
Why is Vitamin A important?
1) component of visual pigments
| 2) promotes proteoglycan synthesis and epithelial maintenance
151
Why is Vitamin D important?
Promotes calcium absorption and bone mineralization
152
Why is Vitamin K important?
Essential for prothrombin synthesis and blood clotting
153
Why are Vitamins A and E important?
They are antioxidants like ascorbic acid
154
What is the effect of vitamin A excess?
anorexia, nausea and vomiting, headache, pain and fragility in the bones, hair loss, an enlarged liver and spleen, and birth defects
155
What are the effects of vitamin A deficiency?
night blindness; dry skin, hair, and conjunctiva; cloudy cornea; increased incidence of infections
156
What is the world's most common vitamin deficiency?
vitamin A
157
What three processes are considered cellular respiration?
Krebs Cycle, Electron Transport Chain, Oxidative Phosphorylation
158
Where does glycolysis occur?
in cytoplasm
159
Where does the krebs cycle occur?
in mitochondrial matrix
160
Where does the electron transport chain occur?
inner mitochondrial membrane
161
where does oxidative phosphorylation occur?
inner mitochondrial membrane
162
Where is most cellular energy stored?
in the chemical bonds of storage molecules such as adenosine triphosphate (ATP)
163
When is chemical energy captured by cells?
during glucose breakdown when oxygen is available
164
What are two general "rules" about ATP?
1) ATP is NOT transported from one cell to another
| 2) ATP is NOT stored by cells to any substantial extent
165
What does a cell's work rate depend on?
the rate at which that cell is able to produce ATP
166
What are heterotrophs?
Consumers of organic materials to acquire energy (eating meats and veggies)
167
What are autotrophs?
Producers of their own energy (photosynthesis by plants and algae etc)
168
What is the ultimate source of cellular energy?
photosynthesis
169
what do autotrophs store their energy in the form of?
glucose
170
what processes do heterotrophs and autotrophs use to break down glucose?
glycolysis and cellular respiration
171
What is the equation for photosynthesis?
6 CO2 + 6 H2O + light energy --> C6H12O6 + 6 O2
172
What is the equation for complete glucose breakdown?
C6H12O6 + 6 O2 --> 6 CO2 _ 6 H2O + ATP energy + heat energy
173
How do plants use glucose as a source of energy?
convert glucose to sucrose or starch for storage
174
How is energy stored in humans?
as long chains of glucose, called glycogen, or as fat.
175
What are the two general phases of the breakdown of glucose?
1) glycolysis
| 2) cellular respiration (kreb's cycle, ETC, Ox Phos)
176
What is the process of glycolysis?
the splitting of glucose (a 6 carbon sugar) into two molecules of pyruvate (3-carbon sugars)
177
Does glycolysis make ATP or use ATP?
both: glycolysis has energy investment and energy harvesting stages
178
How does glycolysis begin breaking down glucose?
an initial investment of 2 ATP molecules
179
How does the addition of phosphates effect the fructose biphosphate?
makes it highly reactive
180
What is the net gain of ATPs per glucose molecule?
2 ATP
181
What is the "empty" electron carrier?
NAD+
182
What is added to the NAD+?
2 high-energy electrons and a hydrogen ion
183
What is made when 2 high-energy electrons and a hydrogen ion are combined with NAD+?
NADH
184
How many NADH carriers are produced per glucose molecule?
2
185
During glycolysis, what is fructose biphosphate broken down into?
2 G3P molecules
186
What are the two G3P molecules are converted into?
2 pyruvate molecules
187
What results from the 2 pyruvate molecules?
4 ATP and 2 NADH
188
What is the net result?
2 ATP and 2 NADH
189
How does cellular respiration extract energy from glucose?
It breaks down the 2 pyruvate molecules into 6 carbon dioxide molecules and 6 water molecules
190
How many ATP molecules are formed during cellular respiration?
36 (2 from glycolysis and 34 from cellular respiration)
191
what organelles are specialized for the aerobic breakdown of pyruvate?
mitochondria
192
what is contained in the inner mitochondrian membrane?
a central compartment containing the fluid matrix
193
what does the outer mitochondrian membrane form?
the outer surface of the organelle
194
What lies between the outer and inner mitochondrian membranes?
an intermembrane space
195
What two stages does cellular respiration occur in?
1) the conversion of pyruvate to acetyl CoA, as it moves through the Krebs cycle
2) Electrons move through the ETC and ATP is created by chmiosmosis (oxidative phosphorylation)
196
Where is pyruvate synthesized?
in the cytosol
197
Where does cellular respiration begin?
In the mitochondrial matrix?
198
Once pyruvate is transported into the mitochondrion matrix, further breakdown occurs in what two stages?
1) the formation of acetyl CoA
| 2) the Krebs cycle
199
What results when pyruvate is split?
acetyl group is formed and CO2 released
200
Who discovered the Krebs cycle?
Hans Krebs: he won the nobel prize in 1953
201
What else is the Krebs cycle called?
1) citric acid cycle (CAC)
| 2) tricarboxylic acid cycle (TCA)
202
How does the Krebs cycle begin?
Combining acetyl CoA with a 4-carbon molecule to form 6-carbon citrate, and releasing CoA.
203
How much CO2 is released during the Krebs cycle?
2
204
In the Krebs cycle, how much ATP is produced by each acetyl CoA?
1
205
In the Krebs cycle, how much NADH is produced by each acetyl CoA?
3
206
In the Krebs cycle, how much FADH2 is produced by each acetyl CoA?
1
207
What is FAD?
a high-energy electron carrier (similar to NAD)
208
What is generated as a waste product during the mitochondrial reactions?
CO2
209
In the Krebs cycle, how is chemical energy released?
by breaking down each acetyl group
210
In the Krebs cycle, how is the released chemical energy captured?
in energy-carrier molecules
211
For every glucose molecule that was broken down, how many high-energy electrons are captured in carrier molecules?
10 NADH and 2 FADH2
212
How many electrons are released by the carriers and where do thy go?
2 electrons into the ETC
213
What is the flow of electrons through the whole ETC called?
oxidative phosphorylation
214
In the ETC, what is the buildup of H+ in the intermembrane space used for?
to generate ATP
215
At the end of the ETC, what happens to the energy-depleted electrons?
they are transferred to oxygen (which acts as an electron acceptor)
216
What do energy-depleted electrons, oxygen, and hydrogen ions combine to form?
water
217
How many water molecules are produced in the ETC?
1 water molecule is produced for every 2 electrons
218
What is most needed to allow the ETC to function and for ATP synthesis to continue?
Oxygen
219
What is the final electron acceptor in the ETC?
oxygen
220
How much metabolic water is produced per day in the process of voiding electrons from cells?
0.8 L
221
What is chemiosmosis?
the process by which energy is first used to generate a gradient of H+ and then captured in the bonds of ATP as H+ flows down its gradient
222
During ETC, where is the concentration of H+ the highest?
in the intermembrane space.
223
During ETC, where is the concentration of H+ the lowest?
in the matrix
224
When H+ flows across the membrane through the ATP synthase channels, what is generated by this movement?
ATP from ADP and Phosphate
225
For each molecule of glucose, how many molecules of ATP are synthesized due to the flow of H+ through the synthase channel?
32
226
After leaving the mitochondrion, where does the ATP go?
into the cytoplasm to be used by the cell
227
How much ATP do people produce, use, and regenerate daily?
The equivalent of their body weight.
228
What does cyanide poisoning do to the process?
inhibits Cyt C oxidase enzyme (phase IV) which "uncouples" the ETC (suffocation from the inside at every cell)
229
What are the three components of a cyanide antidote package?
amyl nitrite, sodium nitrite, and sodium thiosulfate
230
What does a cyanide antidote do?
helps convert cyanide to thiocyanate, which is excreted renally.
231
What does fermentation produce?
lactate or alcohol and carbon dioxide
232
What is the second stage of glucose breakdown if oxygen is not available?
fermentation
233
Does fermentation produce any ATP?
no
234
In fermentation, what happens to the pyruvate?
remains in the cytoplasm and is converted into lactate or ethanol and CO2
235
How does fermentation allow an organism to continue to function?
it regenerates NAD+, which must be available for glycolysis to continue
236
What does lactate fermentation produce?
lactic acid from pyruvate
237
What happens during alcoholic fermentation?
pyruvate is converted into ethanol and CO2. It also converts NADH to NAD+, which is then available for glycolysis
