Responses to Exercise Flashcards
1
Q
What inputs impact sympathetic nerve activity
A
Baroreceptors Muscle mechanoreceptors Muscle metaboreceptors Central command Chemoreceptors (inc in H and CO2 in blood --> CR --> SNS --> Inc HR)
2
Q
SNS output
A
Inc HR
Inc contractility
Inc VC
Inc EPI
3
Q
The more intense the exercise we have, the ___ SNS activity we will have
A
Greater –> more EPI
4
Q
As work gets harder and harder, what happens to oxygen being used?
A
Gets higher and higher to a point VO2 max = aerobic capacity When mitochondria (ETC) can't consume oxygen to make ATP anymore
5
Q
What happens if you are at a higher workload than VO2 max?
A
You would rely on more anaerobic pathways –> producing more lactate
6
Q
What determines VO2 or VO2 Max?
A
Q * aVO2 difference
Q = cardiac output
7
Q
With exercise, in order for VO2 to increase, we need
A
- CO to inc (HR and SV too)
2. Muscle to extract more oxygen
8
Q
When you hit VO2 max what other max will you likely hit?
A
HR Max
HR inc linearly with exercise intensity (inc %VO2)
9
Q
Intrinsic HR
A
100 bpm
10
Q
What determines if HR goes up or down
A
Autonomic NS
11
Q
At rest
A
PS tone on heart
HR is around 60 bpm
When exercise you withdraw this vagal/ps tone - just standing from your chair
12
Q
Vagus withdraw occurs
A
within 1 sec of exercise and sympathetic activation happens on top of it
13
Q
Sympathetic activation
A
will get HR above 100 bpm
NE binding to beta adrenergic receptors on SA node
Baroreflex is resetting to establish new setpoint
14
Q
Higher set point requires
A
more SNA to maintain that set point
15
Q
HR _____ VO2
A
HR mirros relative VO2 (%VO2 max)
16
Q
Estimated max HR
A
220-age
208-(.7*age)
17
Q
Vagal stimulus leads to
A
immediate drop in HR as compared to symp rise in HR
18
Q
When you exercise and have vagal withdrawal, the inc in HR is
A
Very fast and very immediate
19
Q
SV with upright exercise compared to lying down
A
SV laying down will be increased - close to max
20
Q
SV upright exercise
A
Will increase and then level off
21
Q
In trained athletes SV upright
A
the more of an increase you will see, almost linear like HR
22
Q
In untrained athlete SV
A
Will increase and then level out
23
Q
Why does trained keep going and not level out?
A
They have bigger heart and are more able to inc SV
24
Q
Why does SV increase
A
Inc Preload
Dec Afterload
Inc Contractility
25
1. What will increase preload during exercise?
Things that increase venous return
- muscle pump (inc contractility)
- respiratory pump (dec pressure in thoracic cavity improves gradient for venous return - dec RAP)
- redistribution of flow (splanchnic and skin)
26
2. Increased contractility --> to CO
increases CO
| During exercise - we inc contractility by increasing SNA - Ca induced Ca release
27
3. Afterload - if you decrease afterload of the heart --> CO
you can increase CO
| Decrease TPR during exercise because we are VD muscle and getting more blood to the muscle
28
Compliant circulations do what to flow
mobilize flow
29
At rest vs exercise - where is flow going
Exercise - kidney and splanchnic will give up the most and send to heart to send to muscle
Rest - gut and kidney get the most
30
Pressure =
Q * TPR
31
SV
EDV - ESV
| 120-50 = 70 at rest
32
EF is an index for
how hard the heart is working or its contractility
| SV/EDV (55%)
33
When exercise what is cardiac output
5L/min --> 22Lmin
34
Maximal HR with exercise?
200 bpm
| Someone who is not necessarily trained
35
Maximally SV
110 mL/beat - filling more and queezing more out
140-30 = 110
you are increasing EDV relative to rest
you are lowering ESV - more contractility - squeezing more out of heart --> lower ESV
36
EF with exercise
80%
| 80% of what filled it with is being ejected
37
avO2 difference =
Arterial concentration of O2 minus Venous concentration of O2
38
avO2 difference with exercise?
Increases
39
What is decreasing during exercise?
Venous oxygen content because oxygen is being taken up by the muscle - the more that muscle takes up oxygen, less will be left in venous circulation
40
Arterial oxygen concentration with exercise
stays the same because lungs are still fully saturating blood with oxygen
41
During exercise then...
avO2 difference will increase because Arterial concentration stays the same and venous concentration decreases
42
Arterial oxygen capacity does what with exercise
increases
more of a duration thing
more duration = sweating more = concentrating blood more so see subtle increase in arterial O2 capacity
43
Arterial oxygen concentration is highly dependent on
lung
| saturation
44
What causes R shift in Hemoglobin curve
Inc in CO2
Dec pH
Inc Temp
Facilitates more unloading of oxygen at the tissue
45
Peripheral distraction depends on
perfusion pressure and how much blood is perfusing (getting to) the tissue
46
What will impact venous side of things
How much oxygen the muscle is taking up
| Could increase it if we had more mitochondria - we could extract more - more capillaries too
47
What will alter muscle blood flow
1. Sympathetic Nervous System
2. Mechanical - Muscle Pump
3. Autoregulation (intrinsic or local)
48
Sympathetic nerve activity ___ with exercise
increases
We are resetting the baroreflex setpoint and so we will need to increase SNA to maintain the higher set point
central command will help reset and so will exercise pressor reflex (metabo and mechanoreflex)
49
what will inc in SNA do to blood flow
decrease flow
| because sympathetic response on muscle is constriction
50
What impact will muscle pump have on flow
muscle pump will increase flow due to change in transmural pressure within the muscle
51
What impact will autoregulation have on flow
depends
1. Metabolic = increase flow with metabolites
2. Myogenic = decrease flow because Pt inc as you start to exercise - you stretch that muscle, channels open, allow more Ca to come in and muscle contracts
3. Endothelium - NO = VD so inc flow
52
If SNA increases during exercise, how does blood flow increase to muscle
Functional sympatholysis
There are constrictor and dilator elements but in the end the result is increased flow to muscle
Metabolites and muscle pump override it
No lysis of sympathetic activity - it is increasing a ton
53
Blood Pressure during exercise - Systolic
Increases
| Dependent on CO and CO is increasing
54
Blood Pressure during exercise - Diastolic
Not much of a change
| Dependent on TPR - if anything it is decreasing
55
Mean BP during exercise
slight increase
56
Dynamic exercise overall what happens with BP
Systolic Inc in proportion to Q
DBP dec due to TPR
MAP inc modestly
57
Static exercise overall what happens with BP - static contractions
Muscle tension --> Resistance --> more resistance so DBP would go up
Max BP can exceed 450/350 mmHg
58
Dynamic vs. Static Exercie - Which facilitates and which impedes blood flow
Dynamic facilitates flow and static impedes it when intensities are at 15-20% of maximum
59
What happens to intramuscular pressure and blood flow during isometric exercise
Increase in intramuscular pressure
| Decrease in blood flow
60
How do you get more blood flow to muscle if it is contracting? TO prevent ischemia
Raise perfusion pressure
| Greater the force, the faster rise in BP
61
What happens to SV during resistance exercise training
Decreases
because there is less blood returning to the heart because of increased resistance at muscle - decreased filling and increased CO
62
Why does HR increase even if you keep same intensity of exercise?
We need to consume a certain amount of oxygen - VO2 - to maintain a certain VO2 we need a certain CO to sustain that work - if thats the case, SV is decreased (because of sweating) so to prevent it from decreasing CO we have to inc HR
63
How do you prevent cardiovascular drift?
Fluid intake
64
Respiratory response with exercise
Inc ventilation with exercise (non linear)
65
What happens with alveolar? PAO2
Bends upward because you are blowing off more CO2 and are hyperventilating, getting more O2 into the alveolus
66
What happens with arterial? PaO2
Bends down slightly
67
What happens to the venous side? Partial pressure of CO2
will steadily go up with exercise
68
What happens to venous oxygen?
goes down because there is more unloading at the tissue - there is less in the veins
69
Equation for ventilatory control during exercise
VE = Tidal volume * fB
| Volume of air you are breathing in and frequency of breaths
70
After the ventilatory threshold what is VE driven by
frequency of breaths
71
What increases after ventilatory threshold?
Ventilatory equivalent
Rate of glycolysis
Lactate buffering by bicarbonate
VE
72
Ventilatory Control - Onset
Central Command
| Mechanoreceptors
73
Ventilatory Control - Exercise
Central chemoreceptors
| Inc Body Temp
74
Main hormone response with exercise and the exception
will increase
| Insulin declines during exercise
75
Insulin is secreted from
pancreatic beta cells when glucose levels are elevated (hyperglycemia)
76
What does insulin do once secreted
Will increase glucose uptake into cells
Increase glycogen synthesis
Inhibits glucose formation
Inhibited by catecholamines
77
Glucagon is secreted by
pancreatic alpha cells when glucose is low (hypoglycemia)
78
Glucagon - what will it do?
Increase liver glycogenolysis
Inc liver gluconeogenesis
Hepatic glucose production
Stimulated by catecholamines
79
Catecholamines during exercise
Increase
They bind to beta adrenergic receptors on alpha cells in the pancreas to stimulate glucagon and get more glucose in bloodstream
and at the same time catecholamines bind to alpha receptors on the beta cell to decrease insulin
80
Net effect of catecholamines
to mobilize energy so it can be used
| Stimulate glucagon and inhibit insulin
81
Is glucose uptake inhibited during exercise
No
Skeletal muscle uptake increase as exercise intensity goes up
Mechanism = contracting muscle
82
How does contraction increase glucose uptake during exercise?
Contraction of muscle causes translocation of GLUT4 channels to sarcolemma
Insulin independent - ONLY contracting muscle
83
Why is it important to maintain blood glucose during exercise?
Brain needs it for fuel
84
With short, high intensity exercise - what happens to glucose
A slight increase because of the effects of glucagon - liver is kicking out glucose
85
So is it necessary to decrease insulin during exercise?
to prevent the drain from getting so large
| SNA will inhibit insulin to stop the drain from widening so much
86
With long, low intensity exercise, what happens to glucose?
It is maintained by an increase in heptic glucose production
87
When do we see decline in blood glucose>
After 90 minutes of exercise
88
When would be best time to take one of those energy things if you need the energy instantly
Immediately before you race - would be good because your SNA is already going since youre nervous about the race so your drain is already being prevented from widening too much
89
Goals of CHO metabolism during exercise
1. Provide fuel for exercise while maintaining blood glucose
2. To retain or spare muscle glycogen for as long as possible
90
How does CHO metabolism provide fuel while maintaining blood glucose
Balance btw muscle uptake and liver release
liver = increase hepatic glucose production (gluconeogenesis and glycogenolysis)
muscle = increase glycogenolysis and glycolysis
91
How does liver to gluconeogenesis
Can use lactate to make glucose
Cori Cycle
Can also use alanine
92
The three Cs of CHO metabolism and sometimes 4
1. Catecholamines
2. Contraction
3. Calcium
4. Cortisol (minor player)
93
Catecholamines and CHO metabolis,
Increase glucagon (hepatic glucose prodution)
Decrese insulin
Increase glycogenolysis
Inc lipolysis
94
Contraction and CHO metabolism
GLUT 4 translocation increases glucose uptake
95
Calcium and CHO metabolism
Can stimulate glycogen phosphorylase to support the breakdown of glycogen
96
Cortisol and CHO metabolism
increases protein catabolism to support gluconeogenesis
| Increase lipolysis during prolonged exercise (GH does the same)
97
What stimulate glycogen synthesis
High blood glucose
Does so by glucose 6 phosphate
(liver can create it from lactate)
98
Glycogen in muscle
Glycogen synthesis occurs primarily from blood glucose
99
Ability to use fat storage
depends on CHO
| you are prevented from using fat storage due to lack of oxygen and OAA which is supported by CHO metabolism
100
As exercise intensity is low...you are using
fat
101
As exercise intensity becomes more intense
fat oxidation goes to nearly nothing and CHO becomes exclusive source
RER = 1
102
Where does fuel source come from?
25% of VO2 max
As you increase intensity?
mainly from fat = 25%
| Less on fat and more on glycogen muscle stores
103
Low intesity exercise at 50% VO2 max
| High intensity exercise at 75% VO2 max
50% of kcal from fat oxidation
33% of kcal from fat oxidation
BUT still getting 110 kcal for 30 min fat (amount of calories burned coming from fat)
104
Fat oxidation rate is highest at what percent of VO2 max
50-60% moderate intensity
| Advantage of this too is that they can go for longer period of time
105
Exercise duration
As duration goes on (at same pace) you are relying more on fat metabolism than on carbs
106
Exercise duration and fuel source
you rely more on what you have in blood as duration goes on
107
Fat CANNOT be exclusively burned during exercise nor during rest
We need OAA to continue to turn kreb cycle
108
When can ketones be used as fuel
if we have a lot of acetyl co A that cant bind to OAA
109
WHy can ketones be good?
Can be used by brain
Can be used as fuel source
DOnt need ATP tp synthesize it
110
Why ketones can be bad
Ketoacidosis
Secreted by kidney and kidney doesnt like to do that - can lead to renal failure
Changes in BMR (decrease it) and can inhibit lipolysis
