All of it Flashcards
1
Q
What was seen in starving populations in eastern europe during WWI?
A
Amenorrhea (lack of menstruation)
2
Q
When was the first large cross-sectional study examining reproductive health in female athletes?
A
60s
3
Q
What were the 3 answers given as a result of the 1962 study on reproductive health in female athletes?
A
favourable change, no change, unfavourable change
4
Q
What was the conclusion of the 1962 study?
A
“We may find menstrual disorders that may be associated with too much sports activities”
5
Q
What is menarche?
A
The onset of menses
6
Q
What is menses?
A
Blood being discharged from the uterus at menstruation (period)
7
Q
What did the results of the 1993 study show regarding age at menarche in athletes vs non athletes?
A
The age at menarche of athletes was generally higher than non athletes
8
Q
What is secondary amenorrhoea?
A
An interruption to menses after they have already occured
9
Q
What was observed in the 1978 study regarding secondary amenorrhoea and training mileage?
A
The incidence of secondary amenorrhoea increased with the weekly training mileage done by the participants
10
Q
What are the three components of the female athlete triad?
A
Disordered eating, Amenorrhea, Osteoporosis
11
Q
What is osteoporosis?
A
premature bone loss/inadequate bone formation
12
Q
Conditions of 1985 study regarding female athletes menstruation?
A
28 untrained women
8 wks training
4mls up to 10 mls per day run
3.5 daily moderate intensity sorts
weight maintenance (-1kg) and weight loss (-4kg) groups
13
Q
What were the results of the 1985 study regarding exercise effect on menstrution?
A
Higher % of menstrual abnormalities compared to control
14
Q
What happened to the menstrual cycles of the 28 subjects in the 1985 study 6 months after the study?
A
All the participants cycles had returned to normal
15
Q
What is energy availability?
A
The amount of energy that is left over excluding physical activity
16
Q
Energy availability formula?
A
Energy availability = energy intake – exercise energy expenditure
17
Q
Why is energy availability normalised to fat free mass (the weight of fat is removed)?
A
Fat is metabolically inert–> doesn’t use up much energy
18
Q
What is the energy availability target for physically active women per day?
A
45 kcal·kgFFM-1·d-1
19
Q
When does luteinizing hormone spike in concentration during the menstrual cycle?
A
ovulation (day 14)
20
Q
What does luteinizing hormone affect?
A
Progesterone and oestrogen release
21
Q
Effect of reduced energy availability on LH pulse frequency?
A
Lower energy availability means a reduced LH pulse frequency by 23%
22
Q
Effect of exercise on LH pulse frequency?
A
Not much
23
Q
Effect of decreased energy availability on markers of bone breakdown?
A
Increase in markers of bone breakdown
24
Q
Effect of decreased energy availability on markers of bone formation?
A
Decrease in markers of bone breakdown
25
Inflammation definition?
a defensive process that a living body initiates against local tissue damage
26
What can cause inflammation?
Physical agents, chemical agents, biological agents
27
What are the stages of inflammation?
Onset of inflammation, onset of resolution and resolution
28
What happens in the onset of inflammation?
Identification of damage, production of proinflammatory mediators, vasodilation and recruitment of white blood cells
29
Cytokines present in early inflammation?
TNF-alpa, IL1
30
Cytokines present in resolution of inflammation?
IL-10
31
What occurs during the onset of resolution of inflammation?
down regulation of pro-inflammatory signals, up regulation of anti-inflammatory signals, destruction of infecte tissue, clotting factors
32
Role of clotting factors?
stop clotting
33
What occurs during the resolution of inflammation?
production of anti-inflammatory mediators, apoptosis of immune cells, vascular repair
34
Five cardinal signs of inflammation?
Redness, heat, swelling, pain, loss of function
35
Outcome of increased blood flow?
Redness and heat
36
Outcome of accumulation of fluid?
swelling
37
Outcome of release of nerve stimulating chemicals?
pain
38
What are the 5 stages of inflammaiton resolution?
Removal of dead cells, restoration of vascular integrity, regeneration of tissue, remission of fever and relief of pain
39
What are biomarkers used to assess inflammation?
Acute phase proteins, cytokines
40
Which proteins increase or decrease in blood acutely in response to inflammation?
Acute phase proteins
41
What is an example of an acute phase protein?
CRP (C-reactive protein)
42
What is the role of CRP?
Helps clear dead cells
43
Where is CRP synthesised?
Liver
44
What are cytokines?
Small (hormone like) acute phase proteins released by a variety of different cells
45
What does IL6 do in regards to CRP?
induces its release from the liver
46
Meaning of pleiotropic?
Affects many different cell types in different ways
47
Autocrine hormone?
Acts on the cell it was released from
48
Paracrine action?
Acts on a nearby cell
49
Endocrine action?
Acts on a distant cell
50
IL8 role?
Chemokine--> a chemical that promotes chemotaxis
51
TNF-alpha role?
A pro-inflammatory cytokine that "ramps up" local inflammatory responses
52
IL1 role?
Affects nearly every cell type in the body, in synergy with TNF-alpha
53
Which cytokines are generally considered inflammatory?
IL8, TNF-alpha, IL1
54
Role of IL1RA?
Inhibition of IL1, so anti-inflammatory
55
Which cells produce IL-10?
macrophages, dendritic cells, t and b cells
56
Which cytokines are released near the beginning of infection?
TNF-alpha, IL1, IL8
57
Which cytokine is released in the middle of an infection?
IL6
58
Which cytokines are released at the end of an infection?
IL-1RA, IL-10
59
What is a bimodal response?
An acute spike followed by sustained elevation above baseline
60
What was observed in regard to IL6 levels and exercise?
A spike after exercise, followed by a maintained heightened level after the initial spike
61
What was initially thought to be the source of IL6? (THIS IS WRONG)
immune cells
62
What is eccentric exercise?
Uses target muscles to control a weight as it moves in a downward motion
63
Why is eccentric exercise used to assess the effect of muscle damage?
Eccentric exercise causes a lot of muscle damage in unaccustomed muscle compared to accustomed muscle, so they can be compared
64
What was observed in the 1999 study regarding IL6 and muscle damage?
There was no difference in IL6 released by muscles even when there were differences in the amount of muscle damage, thus muscle damage doesnt affect IL6
65
What was observed in the 2000 study regarding the absence of muscle damage on IL6?
IL6 release increased during exercise in the absence of muscle damage (as the exercise was only concentric)
66
How did the 2000 study show IL6 is produced as a result of exercise?
Did a bike test where one leg was exercising and one wasnt--> exercising leg produced most of the IL6
67
What was observed regarding the amount of increase in IL6 production over the duration of extended exercise in the 2000 study?
Initial increase was modest, later increase was dramatic
68
What was observed regarding muscle glycogen content and IL6 release at the start of exercise?
Lower muscle glycogen content caused a higher increase in IL6 during exercise
69
What was observed regarding muscle glycogen content and IL6 release at the start of exercise?
The muscle glycogen content did not massively affect the amount of IL6 released
70
What was confirmed regarding muscle glycogen content and IL6 secretion in the 2004 study?
Higher IL6 secretion is associated with depleted muscle glycogen content
71
Which processes does IL6 stimulate?
glycolysis and lipolysis
72
What cytokines does IL6 stimulate the release of?
IL-1RA and IL10
73
What is a myokine?
A signalling cell that is released in response to muscle contraction
74
What is resistance exercise?
Any exercise that causes the muscle to contract against an external resistance with the primary aim of improving muscle strength
75
Three types of resistance exercise?
Concentric, eccentric, isometric
76
How do concentric exercises work?
They shorten the muscle
77
How do eccentric exercises work?
They lengthen the muscle
78
How do isometric exercises work?
They generate force without changing the length of the muscle
79
Issue with definition of resistance exercise?
"external resistance" is a relative term
80
What is strength?
Capacity to exert force under a set of biomechanical conditions
81
What is the short term effect of resistance training?
negative
82
Actual short term effects of resistance training?
Fatiguing, damaging
83
What is supercompensation?
An increase in capacity after a recovery from a resistance exercise
84
What is involution?
The returning to original capacity after a supercomposition if nothing is done to maintain it
85
What makes a muscle stronger?
size
86
What attaches a muscle to a bone?
A tendon
87
Name for a bundle of muscle fibres?
Fasiculus
88
How many myofibrils in a single muscle fibre?
roughly 2000
89
What makes up muscle fasicles?
Muscle fibres
90
How many myonuclei per muscle fibre?
200-300
91
What connects myosin to Z lines?
titin
92
Step 1 of muscle contraction?
AP arrives at neuromuscular junction
93
What happens after AP arrives at neuromuscular junction?
ACh is released
94
What happens as a result of ACh release in muscle?
Depolarization as a result of binding to receptors in myocyte membrane
95
What happens as a result of depolarisation?
Ca2+ is released inside the cell from the sarcoplasmic reticulum
96
What does Ca2+ bind to after being released?
Troponin
97
What happens as a result of Ca2+ binding to tropinin?
Troponin changes shape
98
What happens as a result of troponin changing shape?
Tropomyosin is moved from the active site of the actin filament
99
What happens after tropomyosin has moved from the actin filament's active site?
Myosin attaches to actin, forming a cross bridge at a binding site?
100
What happens as a result of myosin forming a cross bridge?
ATP attached to the myosin head it broken down to release energy for a power stroke of the myosin filament
101
What happens as a result of a power stroke?
Z lines move together
102
What does it mean if Z lines have moved together?
Sarcomere length is reduced--> contracting
103
What happens after the Z lines have moved closer together?
A new ATP molecule binds to the myosin head
104
What happens as a result of a new ATP binding to the myosin head?
The head is released from the actin binding site
105
What happens if there is still calcium left in the cell once the myosin head has released?
It will attach to the next nearest actin filament binding site
106
What happens if there is no Ca2+ or ATP?
The process stops
107
What is hypertrophy?
Net muscle gain
108
What is atrophy?
Net muscle loss
109
What happens to muscle synthesis when amino acids are ingested?
The rate of muscle synthesis increases
110
What happens to the rate of muscle breakdown when AAs are ingested?
decreases
111
What happens to the rate of muscle synthesis a while after AA ingestion?
Decreases
112
What happens to the rate of muscle breakdown a while after AA ingestion?
Increases/ returns to original level
113
What happens to muscle breakdown if you do exercise a while after eating?
It increases higher than it would do if you hadn't done exercise
114
What happens to muscle synthesis if you do exercise after eating?
It increases a lot
115
How does muscle synthesis increase after doing exercise?
The anabolic response is primed as a result of doing resistance exercise
116
How long is the anabolic response primed post exercise?
24-48 hrs
117
What happens to hypertrophy after the onset of training?
It is delayed
118
Why is hypertrophy delayed after training?
A lot of the muscle protein synthesis is repairing the muscles that were damaged as a result of the training, so it isnt "new" muscle
119
What happens to muscle synthesis as you train more?
There is less muscle damage, so more of the muscle synthesis is going to hypertrophy instead of repair
120
Why do muscles look larger after training even though they have been damaged?
Oedema induced muscle swelling
121
What is Oedema induced muscle swelling?
A swelling in response to the muscles being damaged
122
What happens as a result of Oedema induced muscle swelling?
The muscle size/cross sectional area is artificially increased
123
Why does hypertrophy slowly plateau as you train more?
The "priming effect" loses its potency so less hypertrophy occurs
124
What did the Damas 2017 study show about trained muscle hypertrophy effect in response to damage compared to non-trained muscle?
The initial increase in hypertrophy immediately post training for the trained muscle was the same as the untrained muscle ("priming effect") however it dropped off over time a lot faster than the untrained muscle did
125
What is muscle fibre hypertrophy?
The muscle cells getting bigger
126
What is muscle fibre hyperplasia?
The amount of cells increasing
127
What increases post resistance training?
Fibre hypertrophy
128
How does myofiber hypertrophy happen?
myofibril splitting
129
What is a myofibril?
An organelle in a muscle cell
130
Role of myofibril?
produce contraction
131
Why is it a challenge to measure hyperplasia
Would have to chop leg in half, count number of cells, do exercise, chop leg in half and count cells again
132
When does hyperplasia definitely occur?
In utero (when foetus is growing)
133
At what point in utero does myofiber hyperplasia stop?
24 weeks (60-70% of mammalian gestation)
134
Is muscle fibre hyperplasia the cause of muscle hypertrophy?
NO
135
What factor other than muscle size can influence how much force a muscle will produce?
Neural factors--> how much of the action potentials are actually getting to the muscle to cause it to contract
136
What does each motor neuron axon join up with?
Muscle fibres
137
How many muscle fibres per axon?
multiple
138
How many axons per muscle fibre?
1
139
What makes up a motor unit?
The spinal cord, the motor neuron axon and the muscle fibres
140
How is motor unit size measured?
Fibres per unit
141
How many fibres per motor unit are there in the eye?
10 bc fine motor control is needed
142
How many fibres per motor unit are there in the hand?
300
143
How many fibres per motor unit are there in the gastrocnemius?
2000
144
What needs to happen for neuromuscular co-ordinaiton?
Agonist muscle must be maximally switched on at the right time, Support from appropriate synergistic ans stabiliser muscles, opposed by minimal antagonist activation
145
What can be increased regarding the motor unit to generate more force?
Motor unit firing frequency
146
How does resistance exercise affect motor units positively?
It allows us to increase firing frequency
147
Two types of motor units?
Type 1 and type 2
148
Type 1 motor unit?
Smaller, easier to switch on, less force
149
Type 2 motor unit?
Larger, harder to switch on, more force
150
What do type 2 fibres need to happen before they are recruited?
Type 1 fibres to be recruited, and a higher threshold of excitation than type 1
151
Use of type 1 fibres?
Lifting something light, clicking a button etc
152
How does resistance training positively impact the recruitment of motor units?
Reduces the electrical excitatory threshold required to switch on the type II motor units
153
What kind of runners have a higher proportion of type 1 muscle fibres?
Distance runners
154
Does weight load have an effect on muscle growth?
Sort of (maybe higher load better) but not 100% sure
155
What effect does exercise have on anabolic hormomes?
It increases the concentration of them
156
Examples of anabolic hormones?
insulin, growth hormone, testosterone
157
What happens to strength as a result of blocking testosterone?
Loss in strength
158
Why does leg press increase concentration of anabolic hormomes?
The muscles surrounding the gonads will spike testosterone and anabolic hormones if exercised
159
How many lines of defence are there in the immune system?
3
160
What are the components of the first line of defence?
Skin and mucous membranes (protective barrier)
161
What are the components of the second line of defence?
Macrophages, neutrophils, dendritic cells, NK cells
162
What do phagocytic cells do?
Eat other cells
163
What do cytotoxic cells do?
Secrete toxins that kill other cells
164
Which line of defence is specific?
The third line
165
Components of the third line of defence?
T cells, B cells (adaptive immune cells)
166
Which cells are cytotoxic?
NK cells and T cells
167
Which cells secrete antibodies?
Plasma cells
168
Where do immune cells start?
Bone marrow
169
What cell can differentiate into B cells, T cells and NK cells?
Common lymphoid progenitor cell
170
What cell can differentiate into platelets, erythrocytes, granulocytes and dendritic cells?
Common myeloid progenitor
171
What is the precursor cell to common lymphoid and myeloid progenitor cells?
Haematopoietic stem cell
172
What can monocytes differentiate into?
Macrophages
173
Which immune response occurs first in response to a pathogen?
Innate immune response
174
What are the four phases of an infection?
Establishment, inductive, effector, memory
175
How can immune memory capabilities be assessed?
T cell or B cell function
176
How are T cells used to measure memory capabilities?
Interferon-gamma production by T cells
177
How are B cells used to measure memory capabilities?
Antibody responses (IgG, IgA response)
178
How does a hematology blood analyzer work?
Each cell passes through a detector that has a light source, light is shone across the cell, the amount of light that passes around the cell to the forward scatter detector indicates the cell size
179
What tells you the size of a cell in a hematology blood analyze?
The amount of light going around the cell into the forward scatter detector
180
What tells you the granularity of the cell in a hematology blood analyzer?
The amount of light reflected off to the side into the side scatter detector
181
What are the characteristics of lymphocytes in a hematology blood analyzer?
Small (low FSC) and few granules (low SSC)
182
What are the characteristics of monocytes in a hematology blood analyzer?
Large with few granules
183
What are the characteristics of neutrophils in a hematology blood analyzer?
Large with many granules
184
What is done to immune cells before they are put into a hematology blood analyzer?
They are fluorescently labelled by attaching an antibody with a fluorescent tag
185
What are CD antigens?
Cluster of differentiation antigens--> antigens that are expressed on different immune cells and are used to identify them
186
Which CD does T cells express?
CD3
187
Which CD cells do B cells express?
CD19
188
Which CD do NK cells express?
CD56
189
Which CD do Th cells express?
CD4
190
Which CD do cytotoxic T cells express?
CD8
191
What does CD27 tell you?
The cells age
192
What does CD62L tell you?
The cells migration ability
193
What is interferon gamma a marker of?
Cytotoxicity
194
3 components of open window hypothesis?
Opportunistic infections follow acute strenuous exercise, changes to salivary IgA in the hrs post exercise, changes to immune cell frequency and functional capacity after acute strenuous exercise
195
What happens to the concentration of blood lymphocytes during exercise?
Increases
196
What happens to the concentration of salivary IgA during exercise?
It increases
197
What happens to the concentration of blood lymphocytes in the hours after exercise?
Drops significantly, below level before exercise
198
What happens to the concentration of salivary IgA in the hours after exercise?
Drops significantly, below level before exercise
199
1990 LA marathon study condition?
Compared runners who didn't run LA marathon to those who did
200
Results of LA marathon study?
More runners (12.9%) became sick in the week after the race than those who didn't run (2.2%)
201
What was the odds ratio of becoming sick after running a marathon compared to not running a marathon?
5.9*
202
Issues with LA marathon study?
The runners were at a mass participation event while the controls were not and this would have increased the likelyhood of getting an infection regardless of if they did exercise
203
How was the south africa run study better than the LA one?
The controls in the SA one lived with the runners, so the mass participation event aspect was nulified
204
What were the results of the SA study?
33.3% of runners got URTI symptoms compared to 15.3% of controls
205
What was observed regarding the majority of URTI symptoms in athletes?
Most of them are not of infectious origin (11/37 reported had a positive diagnosis)
206
What was observed regarding URTI symptoms and race time in the SA study?
People who ran a faster race were more likely to get URTI symptoms
207
What did the Mecca study observe?
The longer someone stayed there, the higher risk of URTI they had (URTI was not associated with age, sex, education or smoking)
208
What does the J shaped curve describe?
Those who undertake an excessive volume of exercises are at a greater risk of infection to those who are sedentary or moderate exercise. Those who are sedentary have a higher risk of infection than those who do a moderate amount of exercise
209
What did the Swedish study observe regarding the J shaped curve?
People who do higher amounts of physical activity have lower risk of infection compared to people doing medium or none--> contradicts J shaped curve
210
What was the makeup of the study done on mice to see the effect of exercise on immune response?
Mice were infected with influenza and the split into 3 groups: sedentary, moderate (20-30 mins) and prolonged (2.5 hrs)
211
What else could have caused the high intensity mice to die more?
The stress of having to do so much exercise
212
What was observed regarding morbidity in the infected mice that did different amounts of exercise?
The mice that had a prolonged bout of exercise had higher morbidity scores
213
What were the three groups of monkeys that had polio?
Forced swimming, kept in a cage, kept in water in a straitjacket
214
What is poliomyeltis?
An acute infection caused by poliovirus.
215
What was observed in the mice regarding survival?
30 mins per day exercise had 90% survival, sedentary control had ab 50% and prolonged exercise had ab 30%
216
Issues with the animal studies looking at effect of exercise on immune response?
They cant control for the stress response and other factors that arise in the animals as a result of the studies
217
Why is salivary IgA used to observe the effect of exercise on immune function?
obtaining it is non invasive
218
Why is IgA specifically looked at in saliva
It is the most abundant immunoglobulin in the body
219
Issues with the animal studies looking at effect of exercise on immune response?
They cant control for the stress response and other factors that arise in the animals as a result of the studies
220
Why is salivary IgA used to observe the effect of exercise on immune function?
It is non invasive
221
What was discovered regarding the Tomasi skiers IgA study?
Salivary IgA was reduced by 20% in cross country skiers after 2-3hrs of exercise
222
What was the conclusion of the skiing study?
A temporary antibody deficiency in saliva might lead to an increase in susceptibility to viral and bacterial infections following strenuous exercise
223
What was seen immediately post race in salivary IgA in the SA marathon study?
A sharp decrease in salivary IgA
224
Was there a correlation between URTI symptoms and salivary IgA conc?
No
225
What do most studies say about the effect of exercise on salivary IgA?
Exercise doesnt cause a decrease in IgA secretion
226
What happens to the levels of salivary IgA levels in the absence of exercise?
It is very variable
227
What are some factors that affect salivary IgA?
Diet, psychological stress, oral disease, menstrual cycle, medications, oral hygiene
228
What is the blood immune response during exercise?
Increased levels of blood lymphocytes
229
What is the blood immune response after exercise?
Decreased levels of blood lymphocytes (to lower levels than b4 exercise)
230
Biphasic response of blood lymphocytes during and after exercise?
Increases during, sharply decreases after
231
Which immune cell increases the most during exercise?
NK cells
232
Which immune cell increases by the lowest amount during exercise?
CD4+ T cells
233
Which type of immune cells increase the most during exercise?
cells with the greatest cytotoxic potential
234
What happens to immune cells a few hours post exercise?
They gradually increase again back to normal levels
235
Which organs had an increase in immune cells migrating to it in exercised mice?
Lungs, peyers patches (gut) and bone marrow
236
What are some non-infectious reasons that someone may have URTI symptoms?
Asthma, airway epithelial trauma due to increased ventilation or exposure to cold air, allergy
237
What are some viral related causes that might not be to do with catching the virus while exercising?
It is possible that viruses can be reactivated in someone's body--> epstein barr virus, herpes
238
What did Pedersen et al show regarding the effect of exercise on tumors?
Exercise can lead to tumor suppression in rodents
239
What were the conditions of the running wheel experiment done by Pedersen et al?
Two groups of mice, one had access to a running wheel, one didn't. Both were administered tumor cells
240
Tumor size results of running wheel experiment done by Pedersen?
Group without access to a wheel had larger tumors (statistically significant) than the group that did have a wheel
241
Immune cell results of wheel experiment done by Pedersen et al?
More CD3, CD8, CD4 and NK cells in group that had wheel access
242
How was the effect of stress controlled for in the wheel study?
Propranolol was administered
243
Effect of propanolol?
Beta blocker so blocked the effect of stress hormones
244
What happened to the tumor size of the exercised mice once the effect of adrenaline was blocked?
It increased to the same size as non-exercised animals
245
How does physical activity reduce risk of cancer?
Every time someone exercises immune cells are mobilised into the blood where they can go to tissues where they are needed, such as tumors
246
How can in vivo immune responses be assessed in humans?
Via vaccination
247
Conditions of Eskola study in 1978?
4 athletes ran a marathon distance and were immediately given tetanus vaccine. Blood was taken 15 days later to assess immune response
248
Results of Eskolas marathon study?
Showed that running for 2.5 hrs doesnt suppress antibody responses, might actually enhance responses
249
Groups in Kate Edwards study?
Exercise group exercised their upper arm eccentrically (to increase heart rate and damage and inflame tissues where the muscle would be administered) and control group who did nothing. Half of each group receive the full dose while the other half received a half dose (creating 4 groups)
250
Why were half doses of the vaccine given to participants in Edwards study?
To mimic what happens in older age--> older people don't respond as well to vaccination
251
Effects of exercise on full dose vaccine?
No benefits of exercise were observed for the full dose vaccine
252
Effects of exercise on half dose vaccine?
Generally the exercise group responds better than the control group to the vaccine
253
Why may exercise improve half dose vaccine response?
Increase in heart rate and thus blood flow to tissues
254
Why would an increase in blood flow to tissues improve vaccine response?
better identification of antigens in vaccine, and increase in immune cell release into blood which would go to inflammation sites (i.e. where the vaccine is administered)
255
How can inflammation increase vaccine response?
Inflammation attracts immune cells via the secretion of cytokines
256
Which group could benefit from exercising before vaccination?
Older individuals
257
What was the effect of a single bout of exercise in antibody responses in older adults?
No significant effect
258
What is aging of the immune system known as?
Immunosenescence
259
Where do T cells mature?
The thymus
260
What are three components of the thymus?
Cortex, medulla, fat
261
In which parts of the thymus do early T cells mature?
Cortex and medulla
262
What happens to the size of the cortex and medulla of the thymus as you age from 18 ish?
They reduce
263
What happens to the amount of fat in your thymus as you age?
It increases relatively and absolutely
264
Where do stem cell progenitors arise from?
Bone marrow
265
In what form do t cells enter the thymus?
Thymocytes or T cell precursors
266
In what form do t cells leave the thymus?
Naive t cells
267
Involution definition?
Shrinkage
268
What happens to the amount of naive t cells as you age?
Decreases
269
What happens to the amount of different memory t cells as you age?
Decreases (limited antigenic targets as you age)
270
Which homing markers do naive t cells express?
CD62L, CCR7
271
Which homing markers do senescent t cells not express?
CD62L, CCR7
272
What are senescent t cells?
Older t cells
273
Which differentiation markers do senescent t cells express?
CD57, KLRG1
274
Which differentiation markers do naive t cells express?
CD27, CD28
275
What was observed about the level of maintenance of naive CD8 t cells when aging in different fitness levels?
If VO2 max was higher, the maintenance of naive CD8 t cells in aging was better
276
What generally happens to the amount of effector CD8 t cells as you age?
It increases
277
What was seen regarding exercise effect on CD4 t cell count in older age?
More active people had more CD4 t cells when they are older
278
Effect of exercise on amount of senescent t cells as you age?
More exercise generally leads to less of an accumulation of senescent t cells
279
What effect did lifelong exercise have on the levels of IL6?
More exercise was correlated with lower levels of IL6
280
What can IL7 do regarding muscle hypertrophy?
Promote it
281
Effect of IL7 on immune cells?
naive t cells (CD4 and CD8) increase
282
Effect of resistance exercise on IL7?
Increases it
283
One possible mechanism behind exercise effect on senescent t cells?
Naive and senescent t cells in blood at rest, they are mobilized into the blood in response to exercise. Hours post exercise, the senescent cells are sent to the bone marrow where they receive pro apoptosis signals. This death creates space for new naive t cells to be produced
284
285
How can energy balance be altered?
Changing energy intake or expenditure
286
Positive energy balance?
More in than out
287
Negative energy balance?
More out than in
288
How to increase energy balance?
Increase intake/decrease expenditure
289
How to decrease energy balance?
Decrease intake/increase expenditure
290
What components of energy intake are there?
Carbs, fat, protein, alcohol
291
Components of energy expenditure?
Resting metabolic rate (RMR), dietary induced thermogenesis (DIT), Physical activity energy expenditure (PAEE)
292
What is RMR?
Resting metabolic rate--> the energy needed to keep us alive
293
What is DIT?
Energy used to digest, absorb and metabolise the food we have eaten
294
What is PAEE?
Energy used by muscles when they produce force
295
Two main energy stores?
Carbs and fat
296
Which energy store can store more energy (fat or carbs)?
Fat
297
Where can fat be stored?
Blood, muscle and adipose tissue
298
Where is the largest method of storing fat?
Adipose tissue
299
How much fat (in kcal) can be stored?
>100,000
300
Where can carbohydrates be stored?
Blood, muscle, liver
301
Where is the largest carbohydrate store?
Muscles
302
In what form is the largest carbohydrate store kept?
Glycogen
303
What is the relationship between endurance training status and amount of muscle glycogen that someone can store?
More endurance trained means ability to store more muscle glycogen
304
How much carbs can the body store?
3200 kcal
305
What is denovolipogenesis?
Conversion of non-fat sources to fat
306
What happens if you have more than 3200kcal of carbs?
Denovolipogenesis
307
What is leptin?
A hormone
308
Role of leptin?
Regulates appetite
309
What is the result of someone with leptin deficiency?
They gain a lot of non-lean body mass
310
What kind of tissue releases leptin?
Fat tissue
311
What happens to leptin secretion as a result of an increase in fat?
The fat tissue releases more leptin
312
Cause of leptin deficiency?
Mutation in gene sequence coding for the leptin protein
313
Main issue with measuring energy intake?
Observation effect--> when you know someone is observing you you modify your behaviour,
reporting bias-->sometimes people underreport what they consume,
participant recall--> people forget what theyve eaten
314
Which kind of sports have the highest energy intake?
Endurance (cross country skiing, triathlon) and large muscle mass (rugby, bodybuilding)
315
What is the energy density of protein?
4kcal/g
316
What is the energy density of fat?
9kcal/g
317
What is the energy density of carbohydrates?
4kcal/g
318
What is the energy density of ethanol?
7kcal/g
319
Difference in energy balance in high or low fat diet?
High fat diet leads to more fat balance (high +ve) than low fat diet (-ve) , difference is >400g
320
What is the difference in calories consumed between high and low fat diets (mass of food consumed is same)?
High fat diets have a higher energy intake than low fat diets as fats are more energy dense than carbs
321
What is most of the difference in energy balance between high and low fat diets caused by?
Energy density
322
Which macronutrient is the most satiating?
Protein
323
What is a preload drink?
A drink drunk before a large intake of energy (a meal)
324
What happens to energy intake of a meal as the protein content of the preload drunk before increases?
It decreases
325
What is measured in direct calorimetry?
The heat produced by someone
326
Issues with a direct calorimetry machine?
Need to be quite small (people cant move), very expensive
327
What does indirect calorimetry measure?
Oxygen consumption and carbon dioxide production
328
Ways to measure energy expenditure in free living conditionds?
Self report questionnaire, doubly labelled water, pedometers, accelerometers, accelerometry and heart rate combined (aciheart)
329
Benefits of self report energy expenditure?
Easy to administer to a large group, low cost
330
Issues of self report energy expenditure?
Reporting bias--> underreport intake and overreport exercise
331
Benefits of doubly labelled water?
Precise and accurate
332
Issues with doubly labelled water?
Expensive and technically challenging-> cannot be used on a large group
333
What does the AciHeart measure?
Accelerometry and heart rate
334
How does doubly labelled water work?
Ingest a dose of water with heavier H and O isotopes. O loss is steeper when measured as it is lost in CO2 and H20 whereas H is only lost in H2O. Difference between the two is the average CO2 produced over that time period
335
Strengths of DLW?
Doesnt need to rely on accurate patient reporting
336
Limitations of DLW?
Ratio of CO2 production to O2 consumption varied depending on diet of person, so O2 consumption isnt an exact measure it is inferred
337
Issue with using DLW at high exercise intensities?
High exercise intensity results in acidosis (H+ production) which is buffered by bicarbonate system--> produces CO2 from non-metabolic processes
338
Fuel source issue w/ DLW?
Can be oxidising things like lactate, ketone bodies, protein as well as Carbs and Fat
339
Tissue specific measurement of substrate metabolism method?
Tracer based--> infuse a labeled form of glucose into a vein, ingest another form of carb--> measure exogenous carb oxidation
340
What can be measured from tissue specific measurement of substrate metabolism?
Exogenous carb production
341
Link between exercise intensity and fuel consumption?
At higher intensity exercises, carbohydrate fuels are used more than fats
342
Effect of duration of exercise on fuel consumption?
Decrease in carb use and an increase in fat use
343
Which metabolic fuels are blood based?
Plasma glucose, circulating FFA
344
Contribution of muscle based fuels as exercise duration increases?
Decreases
345
Why does the contribution of muscle based fuels decrease as exercise duration increases?
Muscle fuels are depleted over the course of exercise so the longer it goes on the less readily available they are
346
What effect on fuel use does ingesting Cho have?
Decrease fat oxidation and increase carb oxidation
347
Which sex has the greater capacity for fat oxidation?
Women
348
Effect of VO2max on muscle glycogen storage?
Increases it
349
Effect of a high carb diet on glycogen storage capacity?
Increases it
350
What effect does a higher glycogen conc pre exercise have on glycogenolysis?
More glycogen at start of exercise = more glycogen is used
351
What must be done to the triacyl glycerides in fat before they can be used as a fuel by muscle?
Hydrolysed
352
Product of hydrolysis of triacylglycerides?
Glycerol and FAs
353
Which transport protein allows FAs to get into muscle mitochondria?
CPT1
354
Which enzyme hydrolyses VLDLs and chylomicrons?
Lipoprotein lipase (LPL)
355
What could limit NEFA availability?
Adipose tissue blood flow
356
Transarcolemal meaning?
Transport across the muscle membrane
357
What limits fat oxidation at high exercise intensities?
Transport into mitochondria
358
What is fatigue?
The inability to maintain power output or force during repeated muscle contractions
359
Which test could be done to assess exercise performance?
VO2max or VO2peak
360
Which test could be done to assess exercise capacity?
Time to exhaustion
361
What are the three exercise intensity domains?
Moderate, heavy, severe
362
What level of exertion is moderate?
Anything below lactate threshold/gaseous exchange threshold
363
When is lactate threshold reached?
When the production of lactate is occuring at a faster rate to the removal rate
364
What intensity of exercise is heavy?
Between lactate threshold and critical power/critical speed
365
What intensity exercise is severe?
Anything above critical power/critical speed
366
How is critical power tested?
VO2max test, record highest power output (wattage) from that. Then have them do several time to exhaustion tests with the resistance of the bike being different %s (500, 100, 50 etc) of their VO2max test. Measure the time they can go until exhausiton against these different %s. Can plot a curve which will flatten (after going down). Flattened curve is intensity that the person can maintain for a long period of time
367
What are the likely fatigue mechanisms for moderate exercise?
Hyperthermia, mental fatigue and muscle damage
368
What are the likely fatigue mechanisms for heavy exercise?
Glycogen depletion and hyperthermia
369
What are the likely fatigue mechanisms for severe exercise?
Depletion of finite energy stores (W')
370
Which three elements dictate performance velocity or power?
Performance VO2, Performance O2 deficit, Gross mechanical efficiency
371
What can limit performance VO2?
Lactate threshold, capillary density
372
What can limit lactate threshold directly?
Maximal oxygen consumption, aerobic enzyme activity, distribution of power output
373
What can limit maximal oxygen consumption directly?
Muscle capillary density, stroke volume, max heart rate, hemoglobin content
374
What directly influences performance O2 deficit?
Total buffering capacity and distribution of power output
375
What is total buffering capacity?
How good our muscles are at buffering acidosis
376
What is acidosis?
Acid build up in the muscles as a result of exercise
377
What can affect performance O2 deficit and performance VO2?
Distribution of power output
378
How can total buffering capacity be changed?
Training status and nutrition
379
Which compound can improve total buffering capacity during exercise?
Sodium bicarbonate, NaHCO3
380
Why can taking sodium bicarbonate help with high intensity exercise?
It can help with buffering of acidosis
381
What can influence gross mechanical efficiency?
% slow twitch (type I) muscle fibres, anthropometry and elasticity
382
Which type of muscle fibre is more efficient?
Slow twitch (type I)
383
If two athletes were the same height but one had longer legs, which one would be more efficient?
One with longer legs
384
Is it better to have stiffer or more relaxed tendons?
Stiffer as energy can be transferred more efficiently
385
Which type of athlete has the highest VO2max?
Endurance
386
What sports do "endurance athletes do?
Cross country skiing, running
387
Why do cross country skiers have a higher VO2 max than marathon runners?
They use both their arms and their legs
388
Highest every VO2max?
93-95mL/kg/min
389
Which type of marathon does VO2max correlate best with?
It correlated with normal marathon better than ultra marathon
390
Why does VO2max correlate better with a normal marathon than an ultramarathon?
Ultramarathons have a slower pace and so are less reliant on VO2 for performance
391
How does VO2max correlate with health?
It declines as you get older
392
What age related issues can VO2max be used to predict?
Mortality and post surgery outcomes
393
What is the Fick equation?
VO2 = Q (a-v O2diff)
Q is cardiac output
a-v O2diff is the muscle O2 extraction
394
How is cardiac output measured?
Stroke volume * heart rate
395
What is a-v O2diff in the fick equation?
The amount of oxygen in the artery going to the muscle minus the amount of oxygen in the vein leaving the muscle--> bigger means muscle is extracting more O2 from the blood
396
In what ways can the a-v O2diff be limited?
Either a limitation in the limitation in the delivery of the oxygen to the muscle, or a limitation in the muscle itself and its ability to extract oxygen
397
How is muscle VO2 measured?
Catheters are inserted into different blood vessels in the body.
398
What are the main key steps in O2 transport?
Lungs, respiratory muscles, heart, muscle, mitochondria
399
400
Arguments against lungs being a limiting factor in VO2max?
Alveolar area is v large, ventilation increases more than oxygen uptake, pp of oxygen in alveoli and arteries is maintained at VO2max
401
Arguments in favour of lungs being a limiting factor in VO2max?
At normoxia, the oxygen saturation of haemoglobin declines as the intensity of exercise does, hypoventilation, mechanical constraints
402
What is hyperoxia?
Atmospheric oxygen partial pressure is higher than usual
403
What is normoxia?
Atmospheric oxygen partial pressure is the same as usual
404
What is hypoxia?
Atmospheric oxygen partial pressure is lower than usual
405
What is hypoventilation?
breathing that is too shallow
406
How can hypoventilation be a limitation of VO2max?
Someone may have the capacity for a certain oxygen uptake but arent sensitive enough to the stimuli (exercise) to increase the ventilation rate
407
What are the axis of a flow volume loop?
Flow rate in L/s on Y axis, volume in L on the x axis
408
How to create a flow volume loop?
Maximal inspiration then forcefully expire all air in lungs as quickly and as hard as possible
409
How can we test whether lung function is a limiting factor of VO2?
Changing density of inspired air
410
What was observed as a result of changing the density of inspired air to see whether?
Less dense air overcomes the limitation of lungs reaching expiring capacity
411
What is pulmonary oedema?
Swelling in the lungs
412
How does pulmonary oedema negatively affect gas exchange in the lungs?
The swelling causes the interstitial space between the alveoli and capillary to increase thus gas exchange takes longer
413
How can alveolar capillary diffusion limit VO2max?
Only one RBC can pass through a capillary at a time. In untrained this is 0.4-0.5s whereas in trained it is <0.4. Longer means more time to take oxygen to blood so lower VO2max
414
Are lungs a limiting VO2max factor in untrained individuals?
Not a huge amount of evidence to support it
415
Are lungs a limiting VO2max factor in trained individuals?
Some evidence that this may be true
416
What is hyperpnea?
Increased ventilation
417
What is the cost of exercise hyperpnea?
Respiratory muscles have a power output of around 50 watts
418
WHat is unique about respiratory muscles?
They can produce a lot of force relative to their size
419
What is proportional assisted ventlation?
Participant begins inhaling--> rest of air is forced into lungs via machine
420
What is RPE?
Rating of perceived exertion
421
What happens to leg RPE in unloaded (proportional assisted ventilation) condition?
It is a lot lower than load or control
422
How to load inhalation?
Have the participant lift a small weight when they breathe in--> lungs and respiratory muscles have to work harder
423
What is an MIP?
Maximum inspiratory mouth pressure test
424
What does a MIP do?
Measures the pressure someone can generate at their mouth when they breathe in
425
What happens to MIP following exercise?
It decreases
426
Issue with doing an MIP after endurance exercise?
Athletes may be tired and so might not inspire as hard as they can
427
What is a volitional measure?
Relating to someones will
428
How is the diaphragm isolated when measuring its exertion?
Using a nasoesophageal catheter
429
How does a nasoesophageal catheter work work?
It goes up the nose, down the throat and into the stomach where there is two pressure transducers, one in the stomach and one in the oesophagus. WHen diaphragm contracts it moves down which increases stomach pressure and decreases esophageal pressure
430
What is the respiratory metaboreflex?
When respiratory muscles become fatigued, it sends a signal that changes blood flow to other muscles
431
What is observed regarding leg blood flow when work of breathing is increased?
It decreases
432
When using a nasoesophageal catheter, where are the pressure transducers?
Stomach and oesophagus
433
What is observed regarding leg VO2 when work of breathing is increased?
It decreases
434
How efficient is muscle O2 extraction?
Very
435
Why is muscle oxygen extraction unlikely to limit VO2max?
At high intensity exercise the difference in oxygen conc between the artery entering the muscle and the vein leaving the muscle is high meaning it is very efficient
436
What explains most of the variance in VO2max between people?
Cardiac output
437
What explains the early increase in VO2max with exercise training?
Plasma volume
438
What is observed in the blood in the first week after beginning training?
Rapid increase in plasma volume
439
How to artificially increase plasma volume?
Dextran infusion
440
What is observed in the VO2max of people who have had their blood plasma volume artificially increased as a result of a dextran infusion?
An increase of ~4%
441
How does dehydration affect performance?
It leads to a lower plasma volume which leads to lower blood flow and stroke volume
442
In most people, what is the correlation between VO2max and performance time in a a marathon?
High
443
In elite athletes, what is the correlation between VO2max and performance?
Not as strong as in the general population
444
Why may the VO2max of elite athletes not perfectly correlate to performance?
other factors such as mechanical efficiency, running economy etc
445
Which test could be better than VO2max for elite athetes?
Lactate threshold
446
What was observed regarding time to fatigue differences at 70%VO2max in low, mixed and high CHO diets?
The low CHO diet performed the worst with around 1 hr, the high performed the best between 2 and 5 hrs
447
Correlation between CHO content in diet and muscle glycogen levels?
Higher CHO content in diet means a higher muscle glycogen content
448
What was observed when looking at the time when muscle glycogen depletion occurs in placebo and CHO-fed groups during exercise?
They reach muscle glycogen depletion at the same time (3hrs)
449
Why could CHO-fed people exercise for longer than placebo despite reaching muscle glycogen depletion at the same time?
Taking on more CHO means it no longer becomes a reason for fatigue
450
What role can muscle glycogen have other than a fuel?
A signalling molecule
451
Subsarcolemmal region meaning?
Below the sarcolema
452
Which type of muscle glycogen storage is most closely associated with fatigue?
Intramyofibrillar
453
How does a lack of muscle glycogen affect calcium?
It affects its release rate
454
Which out of glycogen, glucose, FAs can generate ATP the fastest?
Glycogen
455
What is McArdles disease?
Lack of enzymes required to break down muscle glycogen
456
Which fuel is more efficient, carbs or fats?
Carbs
457
458
What is known about the causal effect of diet on hard outcomes?
Little
459
Issues with non-randomised data?
It can be biased
460
What is revesed causality?
Smthn ab a disease might cause someone to change their diet
461
Example of reverse causality?
Obese people drink diet soft drinks--> diet soft drinks dont cause obesity its just that obese people drink them bc they want to lose weight
462
What are confounding factors?
One factor directly causing the disease, and another cause
463
Example of confounding factors?
Smoking--> causes cardiovascular disease, and changes in diet which in turn also cause cardiovascular disease
464
How does randomisation minimise systemic bias?
It can minimise the effect of known and unknown confounding factors
465
Example of long term study on diet effect on outcomes?
Mediterranean diet (oil, fish, vegetables and no red and processed meats) vs low fat diet (low fat dairy products, bread, potatoes, pasta) for 5 yrs
466
Observations of Mediterranean diet vs low fat diet?
Mediterranean diet has a lower risk of getting a cardiovascular event compared to low fat diet
467
What is metabolic health?
The ability to maintain metabolic control
468
Maximal eating study?
Ate dominoes pizza until comfortably full vs eating until they physically couldnt eat anymore
469
Results of maximal eating study?
1500kcal for normal, 3000 for maximal. 57g fat vs 113g. 187g Cho vs 367g
470
What happens when double the amount of fat is eaten?
Fat levels in the blood don't increase by 2* (triglyceride conc in blood increase was buffered)
471
Why do fat levels in blood not increase by 2* when 2* the amount of fat is consumed?
Metabolite conc in the blood is buffered
472
What is observed regarding insulin secretion in maximal eating group?
It is secreted more
473
What is the oral glucose tolerance test?
drink w/ 75g of glucose
474
What is an oral fat tolerance test?
Give people x amount of fat and observe the metabolism
475
What is measured in oral glucose tolerance test?
Blood glucose response
476
Association between metabolic control and cardiovascular mortality?
Better metabolic control = lower CVD mortality
477
Healthy blood glucose cond 2 hrs post OGTT?
<7.8 mmol/L
478
Prediabetic blood glucose cond 2 hrs post OGTT?
7.8-11 mmol/L
479
Diabetic blood glucose cond 2 hrs post OGTT?
>11 mmol/L
480
Average triglyceride conc difference between sexes?
Women have a lower average triglyceride conc than men
481
Issue with measuring conc of glucose?
Metabolism is dynamic so conc might be 5mmol/L, but there could be 130mg per min going in and out
482
Where does glucose come from if we haven't eaten a meal?
Liver--> breakdown of glycogen, and gluconeogenesis
483
What is the main glucose consumer from the bood when resting?
Brain
484
Causes of an abnormally high BGC?
Defective liver glycogen metabolism (too much) or defective glucose uptake in muscles (too little)
485
Glycemia?
Blood glucose cond
486
Effect of eating in blood?
Rise in BCG and lactate conc that reduces over time, and a suppression of circulating FAs
487
Why does blood lactate conc increase after eating?
Glycolysis stimulated by insulin
488
Why are circulated FAs suppressed after eating?
If FA conc remained high there would be competition for the muscle fuel uptake--> want muscle to take up glucose instead to buffer BGC
489
Effect of insulin on FFAs?
Suppresses their availability-> inhibits adipose tissue lipolysis
490
Effect of insulin on liver?
Suppresses liver glucose output
491
Postprandial meaning?
After a meal
492
What is glycaemic index?
A way to classify carbs
493
How is glycaemic index calculated?
Give people 50g of available carbs, measure blood glucose conc over 2 hrs and calculate area under curve and compare this to a refernce
494
What is the reference for a glycaemic index?
Pure glucose, white bread
495
What if the area under the curve of a food is the same as glucose?
GI=100
496
What if the area under the curve of a food is half that of glucose?
GI=50
497
What are high GI foods?
>55
498
What are low GI foods?
<55
499
What GI is spaghetti regardless of wholemeal or white?
Low GI
500
What GI is bread regardless of wholemeal or white?
High GI
501
Monosaccharides example?
Glucose, fructose, galactose
502
Difference between sucrose and isomaltulose?
Bond between glucose and fructose is stronger isomaltulose
503
Oligosaccharide example?
Maltodextrin
504
Polysaccharides?
Amylopectin (starch) and amylose (starch)
505
Benefits of isomaltulose over sucrose?
Lower GI (more slowly digested) and better for teeth as it isnt fermented in the mouth
506
What is maltodextrin used ?
Sports nutrition products
507
What is maltodextrin made up of?
8-12 glucose molecules
508
Differences between amylopectin and amylose?
Amylopectin is branched, amylose is straight & Amylose has a lower GI as it takes longer to digest--> enzymes can only work on ends and in branch there is more ends
509
How is area under curve counted for BGC?
Look at resting BGC, only count area that goes above it (incremental area under curve)
510
511
Why do differences in GI arise?
Gross matrix structure (different sized oats--> smaller oats are ground up so increased SA so more digestion), cell wall present/absent
512
Second meal effect?
Thing eaten can affect digestion of foods eaten after it
513
What does a slower glucose appearance do to insulin response?
Reduces it
514
How can foods with different exogenous glucose appearance rate result in similar blood glucose concentrations?
Foods that are digested faster (and so would cause a higher glucose appearance rate) cause a larger increase in insulin conc so the higher glucose conc is then buffered
515
Why do rapidly and slightly slowly digestible starches result in a similar (moderate to high) glycaemic response?
Rapidly causes a high insulin response which cancels out the higher glucose and leads to a similar glycaemic response
516
What kind of starch foods leads to a low glycaemic response?
Very slowly digestable starch
517
Exercise interaction with GI?
Low GI combined with exercise can improve glucose control (via insulin)
518
How to study positive energy balance effect on metabolic control?
Have one group who overate (150% of normal) and were sedentary while the other group overate but did enough exercise to offset the extra 50% calories
519
Effect of flux on insulinemia independent of energy balance?
Exaggerated insulin response (bad as less sensitive to insulin) is only seen in non-exercise group even though both groups were eating 150% of what they normally would
520
Effect of quantity of fat ingested on triglyceride response?
If a meal has more fat (and all else is equal) there is a higher plasma triglyceride concentration
521
In the fasted state, where do triglycerides come from?
Liver
522
How are triglycerides generally transported when fasted?
VLDLs
523
What are VLDLs cleared by?
Adipose tissue and muscle
524
What does adipose tissue and muscle have that allows them to digest lipids?
Lipoprotein lipase
525
What does lipoprotein lipase break triglycerides into?
Non esterified fatty acids and glycerol
526
Fate of fatty acids in adipose tissue?
Storage
527
Fate of fatty acids in muscle?
Oxidation
528
What kind of triglyceride enters circulation in the fed state?
Chylomicron triglycerides
529
What competes for clearance with VLDL in the fed state?
Chylomicrons
530
Which type of fat storage does LPL have the higher affinity for?
Chylomicrons so it will preferentially clear those
531
What happens as a result of eating fats?
Increase in VLDL conc in blood
532
Why does eating fat increase VLDL blood conc?
Chylomicrons are preferentially cleared
533
Effect of insulin on VLDLs?
It directly suppresses the output of VLDL from the liver (reduced triglyceride appearance in circulation), also indirectly suppress VLDL appearance as it suppresses adipose tissue lipolysis (fewer FAs to incorporate in VLDLs)
534
Effect of insulin on LPL in adipose tissue?
Stimulated it--> more storage
535
Effect of insulin on LPL in muscle?
Inhibits it, so less oxidation
536
Effect of high sugar diet on triglyceride clearance?
Can reduce triglyceride clearance so when eating fats the fats are cleared at a lower rate
537
Clearance rate of fats on a lower carb diet compared to a higher carb diet?
Lower carb diet results in faster triglyceride clearance
538
Effect of high carb diet on fatty acid fate?
High carb diet leads to a lower dietary fat oxidation
539
Why should free sugars not exceed 5% of total dietary intake?
Free sugars can cause dental issues, and a higher energy intake
540
Example of free sugar?
Sugar in apple juice is a free sugar, sugar in an apple is not (as matrix has been altered)
541
Main difference in glucose and fructose metabolism in liver?
Fructose is two step metabolism, glucose is one step metabolism
542
Glucose metabolism in liver?
Glucose--> glucose-6-phosphate-->G1P-->UDP glucose--> glycogen
543
Why does fructose have a two step metabolism whereas glucose has a 1 step metabolism?
Fructose is not oxidised as fructose, it needs to be converted to other things before it can be used by peripheral tissues
544
What can the liver convert fructose into?
Glucose, lactate or triglycerides
545
What do high fructose diets increase the production of?
Fats
546
What is denovolipogenesis?
The production of fats from non-fat sources
547
Triglyceride response to glucose compared to fructose?
Fructose leads to a larger triglyceride response than the same amount of glucose
548
VLDL and chylomicron response to glucose compared to fructose?
higher in response to fructose than glucose
549
Why is the circulatory TAG response higher to fructose than glucose?
Fructose stimulates denovo lipogenesis
550
How does fructose increase denovolipogenesis?
It can be the substrate and the signal, and it can saturate liver glycogen stores
551
How is fructose the substrate for denovo lipogenesis?
It provides the fuel--> it can be converted into palmitate (fats)
552
How is fructose the signal for denovo lipogenesis?
It stimulates glucose, AAs to be converted into fat
553
How much fructose is converted to fat?
Not much
554
More important role for fructose in denovo lipogenesis?
It is more important as a signal than as a substrate
555
How does fructose saturating liver glycogen stores mean it can stimulate denovo lipogenesis?
Higher glycogen conc in the liver causes carbohydrates to be converted into fats instead of more glycogen
556
Exercise effect on fructose denovolipogenesis?
Exercise reduces fructose induced de novo lipogenesis
