Midterm 2 Flashcards
During maximal exercise, as time increases, intensity _______ and demand for ATP______ (increases or decreases)
decreases, decreases
During the first minute of maximal exercise, which metabolism pathway is being used the most?
Anaerobic (no oxygen)
At 2 minutes of maximal exercise, what is the energy contribution?
50% aerobic, 50% anaerobic
During the first 10 seconds of maximal exercise, what is the % energy contribution? (anaerobic and aerobic)
85% anaerobic, 15% aerobic
When does the glycolytic pathway take over?
30 seconds of maximal exercise
Which anaerobic metabolic system trumps for the first 10 seconds of maximal exercise?
phosphagen system
Duration of maximal exercise & example event…
(Phos / Glyc / Oxid)
85/10/5
5 sec & 40 m dash
% energy contribution at 30 seconds at maximal exercise
Phos / Glyc / Oxid
30/50/20
% energy contribution during 1500m run
Phos / Glyc / Oxid
<1 /20/80
1 PCr yields how much ATP?
1 ATP
1 Lac yields how much ATP?
1.5 ATP
1 glycogen = 2 Lac + 3 ATP
What is the direct way to measure aerobic metabolism?
calorimetry (heat)
What is the indirect way to measure aerobic metabolism?
spirometry (air)
Open circuit or closed circuit?
Which one determines O2 consumption AND CO2 production?
Open circuit
“quantification of energy production by the body”?
calorimetry
Oxygen uptake of 1.0 L = ____ kcal ?
5 kcal
Respiratory exchange ratio (RER)
Ratio of CO2 produced to O2 consumed
VCO2/VO2
Is glucose or palmitate more O2 efficient?
Glucose
RER = 6/6 = 1
38 ATP/ 6 O2 = 6.3
% of CHO and fat when RER = 1.00
100% CHO, 0% Fat
% of CHO and fat when RER = 0.85
50% CHO, 50% Fat
What’s the RER when % CHO = 0 and % Fat = 100
0.70
Assumptions of RER
- no protein contribution
- steady-state conditions
Limitations of RER
- hyperventilation
- intense exercise
As CO2 increases, RER______
increases
VO2
volume of O2 consumed per minute
Absolute VO2
actual amount of O2 being used
L/min or ml/min
Relative VO2
relative to body mass
ml/kg/min
average absolute resting VO2
250 mL/min
average relative resting VO2
3.5 mL/kg/min
1 MET = ?
3.5 mL/kg/min
maximal rate of O2 consumption by the body…
VO2 max
reflects highest rate of oxidative metabolism…
VO2 max
VO2 max determinants
- O2 delivery to muscles
- O2 utilization by muscles
Which VO2 max determinant is limiting?
O2 delivery to mucles
Which system?
O2 delivery to muscles
cardiorespiratory system
Which system?
O2 utilization by muscles
mitochondrial conent
Criteria for determining VO2 max
- Plateau in VO2
- Reach age-predicted max HR
- High blood [lactate] - 8x rest
- RER > 1.1 (oxidative metabolism maxed out)
- Voluntary exhaustion
“the exercise intensity at which there is an abrupt increase in blood [lactate]”
the lactate threshold
The lactate threshold reflects ability to sustain_______ metabolism
oxidative
At what %VO2max does lactate threshold occur at?
60% of an individuals VO2max
Why does lactate threshold occur?
oxidative system is starting to not being able to maintain the demand on its own easily, metabolic by-products are building up
Is muscle [lactate] faster than blood?
yes
Factors affecting muscle lactate
- oxygen availability
- enzyme activity
- muscle fibre type
- muscle lactate transporters
- sympathetic nervous system activity
What metabolic pathway includes slow-twitch muscle fibres?
oxidative metabolism
What metabolic pathway includes fast-twitch muscle fibres?
non-oxidative metabolism
Does muscle [lactate] increase or decrease when there are not a lot of muscle lactate transporters?
increases
catecholamines, epinephrine, norepinephrine
sympathetic nervous system hormones
Which sympathetic nervous system hormone breaks down carbs
catecholamines
What measures are important for the performance of endurance athletes? (Performance VO2)
- VO2 max
- Lactate threshold
- Efficiency
True or false…
Is having a high lactate threshold less favourable for performance VO2?
False
- having a high lactate threshold is more favourable because they can exercise for a longer period of time
- more O2 efficient
- can perform ar a higher workload
Four main fuels for exercise
- muscle glycogen
- fast source of energy - blood glucose
- coming from the liver
- gluconeogenesis - muscle triglyceride
- blood fatty acid
Which TWO fuels stay fairly constant as exercise intensity (%VO2max) increases? (Blood glucose, muscle glycogen, Plasma FFA, Muscle TG)
blood glucose and muscle TG
As intensity increases, which fuel increases?
carbs
At 25% VO2 max, which fuel dominates?
fats (plasma FFA)
At 50% VO2max, what’s the percentage of carbs and fats fuel usage?
50% carbs, 50% fats
Why does plasma FFA decrease as intensity increases?
decrease blood flow to adipose tissue compared to active skeletal muscle
When expressed as rate of energy use (kcal/min), at what %VO2max does plasma FFA maximize?
50% VO2 max
When expressed as rate of energy use (kcal/min), which fuels increase as intensity increases? (blood glucose, muscle glycogen, plasma FFA, muscle TG)
blood glucose, muscle glycogen, muscle TG,
Determine the rate of energy use @25% VO2max when VO2 = 1.0 L/min
5 kcal/min
1.0 L x 5kcal / L O2
Over time, during aerobic activity, which energy source do we rely on?
fats (plasma FFA) ——> RER will go down
When aerobic exercise time increases (prolonged exercise), muscle TG _______ and plasma FFA_______ (increases or decreases)
decreases, increases
How do researchers determine specific fuel use?
- Measure overall rate of energy use (VO2)
- Determine % CHO and % Fat use (RER)
- Measure muscle glycogen utilization (biopsy)
- Measure muscle uptake of FFA (A-V catheters)
“the combined activity of tissues which regulate hormone release and control bodily function”
neuroendocrinology
chemical substance secreted into body fluids, with specific effects on local or distant target tissues
hormone
sources of hormones
- endocrine glands
- nerve fibres (SNS)
- other tissues (kidneys)
Does norepinephrine increase or decrease HR?
increase
- derived from protein
- soluble —–> faster acting
- never entered a cell, just binds to transporters
peptide
- derived from lipid (cholesterol)
- insoluble ——> slower acting
- includes sex hormones (testosterone + estrogen)
- enters cell
steroids
Major functions related to exercise
- alter enzyme activity
- alter membrane transport
- alter protein synthesis rate
alter enzyme activity (P or S)
peptide
- hormones turn on enzymes of metabolic pathways
alter membrane transport (P or S)
peptide
- insulin triggers glucose transporters to increase rate of glucose uptake from the blood
alter protein synthesis rate (P or S)
steroid
Insulin:
Site of release_____
Primary action_____
- pancreas (beta cells)
- increases glucose/FFA/AA uptake
- increase glycogen/TG/ pro syn
- decreases lipolysis
Does insulin have a catabolic or anabolic role
anabolic role (building things with exercise)
Hormone:______
Site of release: pancreas (alpha cells)
glucagon
Does glucagon have a anabolic or catabolic role?
catabolic (breaking things down)
Whats the primary action of glucagon?
- increase liver glycogenolysis (stimulates glycogen phosphorylase)
- increase gluconeogenesis
Epinephrine:
Site of release:_______
Primary actions:_______
- adrenal medulla
- increase muscle glycogenolysis (stimulates glycogen phosphorylase)
- increase lipolysis (muscle + adipose) (stimulate HSL)
Hormone:______
Site of release: SNS fibres, adrenal medulla
Primary Action:________
- norepinephrine
- increase in lipolysis (adipose) (stimulates HSL)
- increases cardiorespiratory function (increases HR, more oxygen to working muscles)
Effect of exercise intensity on key blood hormones (glycogen, norepinephrine, epinephrine, insulin)
- increase in glycogen, norepinephrine epinephrine (slight increase)
- decrease in insulin because of anabolic role
Explain the Cyclic AMP (cAMP) “Second Messenger” System
- a hormone in the blood binds to a receptor on the cell membrane
- the G protein activates adenylate cyclase
- adenylate cyclase breaks down ATP ——> cAMP
- cAMP activates ACTIVE protein kinase
- this stimulates a cellular response (turns on/off enzymes)
What are the three possible cellular responses due to the cAMP system?
- Epi increases muscle glycogenolysis
- Epi/NE increases lipolysis (muscle, adipose)
- Glucagon increases liver glycogenolysis
Does GLUT-1 have a high uptake rate?
No
Explain the stimulation of muscle glucose uptake during exercise
- As contraction occurs, calcium is increased in the muscle
2. Increase in calcium moves GLUT-4 pool to the plasma membrane to transport glucose into the muscle
Does insulin have the same role as Ca2+ regarding muscle glucose uptake during exercise?
Yes, they both move GLUT-4 pool to the plasma membrane of the skeletal muscle
What determines insulin “seen” by muscles?
- blood concentration
- muscle blood flow
As exercise increases, does insulin concentration increase or decrease?
Insulin concentration decreases, however, there is a significant increase in blood because of increase in blood flow during exercise
How do we maintain blood [glucose] during exercise?
- Minimize glucose use by less active tissues
- decrease [insulin], decrease blood flow - Mobilize alternative fuels to glucose
- increase [norepi] (increase FFA from adipose) - Stimulate muscle glycogen use
- increase [epi] (increase phos activity, glycogen phosphorylase) - Release glucose from liver sources
- increase [glucagon] (glycogenolysis/ gluconeogenesis)
Do mitochondria increase in number and size due to aerobic training?
yes
True or false?
During aerobic training, oxidative enzymes (PDH, CPT, betaHAD) in the mitochondria decrease
False
- they increase
During aerobic training does CHO use increase or decrease?
DECREASE
Does lactate threshold increase or decrease during aerobic training?
increases
True or false:
A trained person can reach the same RER at a much higher workload
True
- RER values are lower for aerobically trained individuals
True or False:
at the same [La], a trained person is allowed to do more work
true, lactate threshold increases for trained individuals
Why does RER decrease at a given workload during aerobic training?
- decrease workload per mito
- increase lipid delivery to mito
- increase enzymes for lipid oxidation
- decrease stimulation of CHO use (epi)
Why does [La] decrease at a given workload
- increase in mitochondria
- increase in [La] clearance
- increase in pyruvate oxidation
- decrease pyruvate production
What are the 3 components of the CV system?
- Heart (pump)
- Vasculature (tubing)
- Blood (fluid medium)
What are the 3 major CV adjustments to acute exercise?
- Cardiac output (Q) increased
- Q redistributed throughout body
- Tissues adjust rate of O2 removal from blood
Which heart valve?
Regulate flow within heart (between atria and ventricles)
atrioventricular (AV) valve
Which heart valve?
Regulate flow out of heart (into pulmonary and systemic circulation)
semilunar (SL) vales
the pacemaker of the heart
Sinoatrial (SA) node
P wave
atrial depolarization
QRS complex
ventricular depolarization
ST segment
ventricular repolarization
T wave
ventricular repolarization
“the events that occur between successive heart beats”
the cardiac cycle
which two components of the heart changes the pressure and volume?
systole and diastole
contraction phase
systole
relaxation phase
diastole
How long is your cardiac cycle if HR = 75 bpm?
60 sec/75 bpm = 0.8 sec
How long is your cardiac cycle if HR = 75 bpm?
60 sec/75 bpm = 0.8 sec
During rest, what’s the percentage of contraction (systole) and relaxation (diastole) for one cycle of a heartbeat?
systole = 40% diastole = 60%
During exercise, what’s the percentage of contraction (systole) and relaxation (diastole) for one cycle of a heartbeat?
systole = 60% diastole = 40%
During exercise, relaxation time of the heart_________ and the amount of blood coming back to the heart__________ (increases or decreases)
decreases, increases
What happens in ventricular filling?
- blood returning to the right atrium
- ventricular pressure is low
- AV vale is open
- semilunar valve is closed
4 phases of the cardiac cycle
- ventricular filling
- isovolumetric contraction
- ventricular ejection
- isovolumetric relaxation
What phase of the cardiac cycle?
- increase in pressure in ventricles
- ALL VALVES ARE CLOSED
- no volume changes
isovolumetric contraction
What happens in ventricular ejection?
- semilunar valves opens
- AV VALVE CLOSED
- blood is pumped out
What phase of the cardiac cycle?
- no volume changes
- pressure drops dramatically in ventricle
isovolumetric relaxation
Formula for stroke volume
EDV-ESV
Volume of blood in ventricles at end of diastole
end diastolic volume (EDV)
stretch on ventricles due to filling
preload
Trained rest EDV
120 mL
volume of blood ejected from ventricles per beat
stroke volume (SV)
Untrained rest EDV
70 mL
ejection fraction
proportion of the blood that’s pumped out of the heart per beat
SV/EDV = (rest) 70/120 = %60
As exercise intensity increases, EDV________ (increases or decreases)
increases
- more blood is being filled in the heart
As exercise intensity increases, ESV__________ (increases or decreases)
decreases
- more blood being pumped out of the heart
- less leftover blood
As exercise intensity increases, SV_________ (increases or decreases)
increases
- EDV increases, ESV decreases
- more blood pumped out per beat
Does EDV increase or decrease with training?
increases
- can hold more blood
Muscle pump
contraction of skeletal muscles squeezes veins and promotes venous return to the heart
“within physiological limits, the force generated by contracting ventricle is greater when the muscle is previously stretched”
Frank-Starling Law of the Heart
increase EDV—->________stretch on the walls—-> increase force of contraction—-> ________SV
increase, increase
Formula for cardiac output (Q)
Q= HR x SV
True or false:
cardiac output increases with training
FALSE
- stays the same
- resting HR decreases, SV increases (because of increase in EDV and ejection fraction)
Is HRmax fixed or adjustable?
fixed
~220-age
How is SVmax “semi-adjustable”?
genetics & training
At what %VO2max does SV in untrained people plateau?
~50% VO2max
Relationship between workload and VO2max
linear relationship
The relationship between HR and workload is NOT linear under _____bpm
110 bpm
Assumptions when using HR to predict VO2max
- Linear relation between HR and workload
2. HRmax= 220-age
Karvonen formula
HRR = HRmax - Resting HR THR = Resting HR + (% HRR)
Heart rate reserve
- range of HR that you can change
- how much you can go up in HR during exercise
%HRmax_________ workload (underestimates or overestimates)
underestimates
- HRmax is accurate at 90% or greater %VO2 max
2 regulatory influences of cardiac output
- chronotropic
2. inotropic
Chronotropic
- changing rate of contraction (HR)
- neural and hormonal
Inotropic
- changing strength of contraction (SV)
- neural, hormonal and mechanical
What nervous system?
lowers HR via vagus nerve
parasympathetic NS
What nervous system?
increases HR via chain ganglions
sympathetic NS
What hormones does the PNS release to decrease HR via the vagus nerve?
acetylcholine
What hormone does the SNS release to increase HR AND increase force of contraction via the cardiac accelerator nerve?
norepinephrine
Which part of the vasculature establishes ‘bulk flow’ and driving pressure?
arteries
Which part of the vasculature regulates flow to specific regions?
arterioles
Which part of the vasculature regulates surface area for exchange?
capillaries
Which part of the vasculature regulates flow return (muscle pump)?
veins/venules
What which vasculature is blood flow velocity at the lowest?
capillaries
As SA increases, blood flow velocity________
decreases
“dynamics of blood circulation”
hemodynamics
- flow, pressure, resistance
True or false:
Flow is proportional to pressure between end of a tube
true
True or false:
Flow is proportional to the resistance of tube
FALSE
- flow is inversely proportional
- as resistance increases, flow decreases
Formula to calculate flow
Flow = pressure/resistance
How to calculate resistance
Resistance = viscosity x length/radius^4
If vessel radius doubles, them flow increases by_______
a 16 fold
How much does cardiac output increase from rest to exercise?
5x
How much does cardiac output increase in skeletal muscle from rest to exercise?
20x
What % of Q is going to skeletal muscle during rest & exercise?
Rest= 20% Exercise= 80%
What % of Q is going to the splanchnic + renal area during rest & exercise?
Rest= 40% Exercise= 5%
What % of Q is going to the heart during rest & exercise?
Rest= 4% Exercise= 4%
Metarterioles
main pathway into the capillary beds from the arterioles
Precapillary sphincter
constrict or relax
Average speed of RBC through capillaries during exercise_____
doubles
During exercise, transit time reduces by______
half (0.8 sec—–> 0.4 sec)
