cardiovascular system Flashcards
(159 cards)
1
Q
which blood vessel carries most of the blood in the body?
A
veins (65% of blood)
2
Q
cardiac output
A
the amount of blood leaving the heart every minute
-CO = SV x HR
3
Q
maximal heart rate can change with training
true or false?
A
false, max HR does not change
4
Q
what is the CO in an average person at rest?
A
5 L/min
5
Q
what is the difference in CO in an athletic person during exercise and a non athletic person? why does this differ?
A
athletic: up to 40 L/min
non athletic: 25 L/min
-differs because of the increased stroke volume but same HR in trained individuals
6
Q
most control of blood pressure (TPR) comes from which blood vessels?
A
arterioles
7
Q
a tube’s resistance in _____ proportional to the fourth power of its radius
A
inversely
8
Q
what are the two mechanisms that control blood vessel diameter?
A
1) adrenergic receptors (b1), E and NE bind and always cause constriction
- during exercise, E increases
2) as blood flow increases, blood pressure increases, and vessels dilate
- mechanoreceptors
- NO is released and causes vasodilation (autoregulation)
9
Q
_____ pressure within the capillaries draws fluid back in, ______ forces fluid from the capillaries
A
osmotic pressure, blood pressure
10
Q
ring of smooth muscle that controls capillary diameter
A
precapillary sphincter
11
Q
angiogenesis
A
the formation of new capillaries during increased metabolic needs
12
Q
what is the purpose of having 65% of our blood in our veins?
A
serves as a reservoir to quickly redirect blood back to the heart when metabolic needs increase
13
Q
as cross sectional area increases, the velocity of blood _____
A
decreases
-ex: capillaries
14
Q
at rest, there is about _____ of blood per minute in muscle tissue
A
5 ml/100 g
15
Q
what is the pressure in the venous system compared to the arteriole system?
A
pressure in aorta starts high (120 mmHg) and goes all the way down to about 5 mmHg in the venous system
16
Q
where is the lowest blood pressure? the highest?
A
lowest is in the vena cava, highest is in the aorta
17
Q
the low pressure of the venous system is potentially problematic, so which three things ensure venous return to the heart?
A
1) skeletal muscle pump
- muscular contractions squeeze blood vessels and push blood towards heart
- valves in veins - allows one way flow of blood back to heart
2) respiratory pump
- changes in pressure gradients (thoracic and abdominal)
3) venoconstriction
- constriction or narrowing of small veins/venules draining muscles
18
Q
when does venous pooling occur?
A
- force of gravity plays a role
- an issue when standing at attention, in an upright posture when skeletal muscle contraction is limited
- can lead to pooling of blood, reduced return to heart, decreased EDV - decreased SV - decreased CO - fainting
19
Q
why is it important to perform a cool down after exercise?
A
to prevent pooling of blood
20
Q
EDV - def.
A
the amount of blood in the ventricle at the end of diastole
21
Q
ESV - def.
A
the amount of blood in the ventricle at the end of systole
22
Q
_____ of the cardiac cycle is spent in diastole (ventricular filling)
A
2/3
23
Q
hypertension - def.
A
elevated blood pressure is response to systematic changes
24
Q
when does hypertension become problematic?
A
not dangerous at first, but after being hypertensive for a long time, heart becomes very strong and works too hard
-can cause heart attack, stroke, onset dementia, etc.
25
what is the optimal blood pressure?
systolic under 120, diastolic under 80
26
at what range does systolic pressure start to be categorized as hypertensive?
anything over 140 mmHg
27
how do we calculate blood pressure
BP = CO x TPR
28
systolic bp
work of the heart and force that blood exerts against the arteriole walls during ventricular systole
29
diastolic bp is an indication of what?
an indication of peripheral resistance or ease that blood flows from the arterioles into the capillaries
30
what is the pressure of systemic circulation?
125 mmHg
31
what is the pressure of the pulmonary circulation?
25 mmHg
32
increased _____ in arterioles increases TPR
vascular tone
33
where is there a higher likelihood to find larger blood vessels? in the legs or in the arms?
- in the legs
| - larger blood vessels are found when more blood is needed to supply the tissue
34
MAP is slightly higher than the mean of 120/80 mmHg
true or false?
false, it is slightly lower because of the variation in bp at different areas of the body
-dominated by diastolic pressure
35
how do we calculate MAP?
MAP = diastolic bp + (0.333 x pulse pressure)
36
what is pulse pressure?
pulse pressure = systolic bp - diastolic bp
37
what is the relationship between cardiac output and TPR?
CO = MAP / TPR
TPR = MAP / CO
38
is TPR higher at rest or during exercise?
TPR is much lower (3.7 mmHg) during exercise because of the increased vessel diameter compared to someone at rest (18.7 mmHg)
39
decreasing vessel diameter by 0.5 creates a resistance difference of ____ fold
16
40
what are the 3 things that affect blood pressure?
1) vessel length (constant unless you gain a lot of weight)
2) blood viscosity (increases pressure)
3) vessel diameter (largest factor that we can control)
41
what is a normal bp range?
systolic under 120 and diastolic under 85
42
what is a normal to high bp?
systolic from 130 to 139 and diastolic from 85 to 89
43
what is a high blood pressure?
systolic over or equal to 140 and diastolic over or equal to 90
44
as individuals age, _____ tend to have higher blood pressures when the age of about 70 is reached
women
45
why does hypertension happen?
1) hardening of the arteries with fat deposits in their walls or increased vessel connective tissue
- less elasticity of vessels, increases work of the heart
2) excessive resistance to peripheral blood flow due to neural hyperactivity or kidney malfunction
- increased response from SNS
- renin-angiotensin-aldosterone system which increases blood volume = higher pressure
3) idiopathic - arising with another disease
46
stage 1 hypertension
systolic from 140-159 mmHg
diastolic from 90-99 mmHg
-antihypertensive/medication indicated
47
stage 2 hypertension
systolic from 160 +
diastolic from 100+
antihypertensive drugs indicated, usually two different drugs
48
what is the difference in blood pressure between resistance trained athletes and aerobically trained athletes?
resistance trained women tend to have lower diastolic and systolic bp, whereas men tend to only have lower systolic
aerobically trained individuals have lower systolic pressure
they both help to control hypertension
49
exercise induced hypotension
- hydrostatic pressure from the heart wants to push blood out of vessels
- osmotic pressure wants to keep blood in vessels
- during exercise, we filter more blood than we keep in
- more loss of plasma, lower bp
50
which 4 factors are believed to be implicated in the reduction in blood pressure following exercise training?
1) decrease in plasma NE levels
- better able to control SNS, has a lot to do with HR
2) increase in circulating vasodilator substances
- autoregulation - blood produces NO which causes vasodilation, decreases bp
3) amelioration in hyperinsulinemia
- improving blood glucose profile, response of cells to insulin
4) alteration in renal function
- renal-angiotensin-aldosterone system
51
what can result from untreated hypertension?
- arteriosclerosis
- heart disease
- congestive heart failure
- kidney disease
- myocardial infarction
- stroke
52
any exercise that is over ___% intensity will decrease blood flow to the brain and anything that is lower will increase flow to the brain
65
53
what can happen to the brain in the result of untreated hypertension?
-blood clots can impair blood flow and cause strokes (and hemorrhage) from aneurysms that burst from increasing pressure
54
what can happen to the heart as a result of untreated hypertension?
left side of the heart must pump more forcefully against a higher pressure from increase arterial resistance (increased preload), causing the left ventricle to enlarge and fail to effectively respond to increased pressure
55
what can happen to blood vessels as a result of untreated hypertension?
damage to the interior arterial wall thickens it, thus reducing the space to transport blood
-fatty plaque can develop clogging blood flow and allowing clots to form and dislodge, causing blood clotts
56
how can we prevent hypertension?
lifestyle changes
-exercise, weight loss, stress management, cessation of smoking, reduce alcohol intake, reduce sodium intake, endure adequate potassium, Ca++ and Mg intake
57
how can we treat hypertension?
medication
- beta blockers (reduce contractility and slow HR)
- alpha and Ca++ blockers (dilate blood vessels), diuretics (increase renal excretion - less blood volume), etc.
58
what is the relationship between blood pressure and level of exertion during exercise?
systolic AND diastolic bp increase with increased exertion
59
what is the only type of training that increase both systolic and diastolic bp?
resistance training
60
why does resistance training increase systolic AND diastolic pressure if diastolic pressure is not supposed to change during exercise?
- it is harder to get blood to vessels during resistance training
- strong muscle contraction compresses vessels leading to muscles which increases the resistance
61
what happens to blood pressure during steady state exercise?
rhythmic muscle activity leads to decrease in TPR and enhanced blood flow through peripheral vasculature
- also provides increased venous return to heart
- rapid increase in blood flow in first few minutes - bp levels off around 140-160 mmHg
- bp may decrease due to continual increase in dilation
- no major change in diastole
62
if intense exercise decreases TPR, why is bp still at 180 mmHg or higher?
vessel diameter is larger, but there is a lot more blood flowing through the system (CO goes from 5 L/min to 25 L/min)
63
what is the difference in bp in the arms and the legs during exercises with similar percentages of VO2?
-pressure in the arms is higher because legs have larger vessels
64
which artery has a greater blood flow in coronary circulation? left or right coronary artery?
left
65
when is blood pushed into the coronary arteries? how many ml/min?
fills during diastole
| -2 ml/min
66
the coronary sinus empties in the _____ coronary artery and the anterior cardiac veins empty into the ____ coronary artery
left, right
67
impaired blood supply to the heart can lead to what?
Myocardial infarction - a.k.a. heart attack
- caused by inadequate blood supply
- narrowing of arteries (plaque broken off can get clogged)
- thrombus (blood clot) can form causing blockage
- necrosis (cell death)
68
when does vascular degeneration begin?
early in life
69
which factors positively relate to the extend of vascular lesions in young people?
- BMI
- systolic/diastolic bp
- total serum cholesterol
- TAGs
- excess LDL
- smoking
70
what are some revascularization options once the vasculature in the heart has degenerated?
1) coronary bypass graft surgery
- using either the mammary artery or the saphenous vein in the leg
2) percutaneous transluminal coronary angioplasty
- insertion of a double lumen dilation catheter
- goes through the femoral artery and into coronary circulation - pushes plaque out and insert a stent
71
what are the modifiable risk factors of coronary heart disease?
-diet, elevated blood lipids, hypertension, personality and behaviour patterns, cigarette smoking, high serum uric acid, sedentary lifestyle, pulmonary function abnormalities, excess body fat, ECG abnormalities, tension and stress, poor education, etc.
72
what are the non-modifiable risk factors of coronary heart disease?
-age (women at 50, men at 40), gender, ethnic background, male pattern baldness, family Hx
73
what is the relationship between the number of risk factors present and the odds of someone having a coronary heart disease?
the more risk fasctors present, the higher the exponential increase in risk of having coronary heart disease
74
rate pressure product (RPP) equation
RPP = systolic blood pressure x HR
75
what is rate pressure product (RPP)?
- measures myocardial O2 consumption and coronary BF in healthy individuals
- upper body and resistance training leads to increased RPP compared to lower body and rhythmic exercise
76
how could RPP help in assessing exercise related improvement in cardiac patient?
-there is a strong relationship between RPP and onset of angina
77
angina - def.
chest pain caused by reduced blood flow to the heart
78
what is the main contributor to the intrinsic regulation of the heart?
- in the right atrium, there is the SA node which fires at 60-100 bpm
- pacemaker of the heart
- impulse spreads to AV node
79
through which nerve is the heart parasympathetically innervated?
vagus nerve
| -depresses the rate of heart beat
80
how does the SNS affect the heart?
release of E and NE increases HR and stronger contraction
| -fibers innervated sympathetically are found from T1 through T5
81
sequence of events of electrical activity in the heart
1) SA node
2) atria
3) AV node
4) AV bundle (His)
5) purkinje fibers
6) ventricles
82
purkinje fibers transmit electrical signals ____ times faster than normal ventricular fibers
6 (0.06s)
83
P wave
- first ECG deflection
| - depolarization of atria
84
QRS complex
-ventricular depolarization
85
T wave
repolarization of ventricles
86
what happens to an ECG trace during exercise?
-positive dromotropic effect (increased speed)
87
what are stress tests useful for?
- determines how much heart can undergo before arrhythmia
- most common cause of ST segment abnormality (elevation or depression) is myocardial ischaemia ( inadequate blood supply to an organ or part of the body) or infarction (obstruction of the blood supply to an organ or region of tissue)
88
which two types of ECG abnormalities are indications of ischemia?
- depressed S-T degment
| - preventricular contraction (PVC)
89
when the left ventricle contracts, the valves of the heart are _____
closed
90
when does the aortic valve open?
when the pressure in the ventricle is higher than that of the aorta
91
what are two extrinsic controls of the heart?
1) nerves and chemical messengers
- accelerate HR during anticipation of exercise or stress (feedforward)
- can decrease HR to very low rates
- E and NE increase HR - positive chronotropy
- PNS decreases HR - negative chronotropy
2) ventrolateral medulla located in the brainstem - cardiovascular control center
92
_______ nerve endings concentrate in the atria, including the SA and AV nodes
parasympathetic
93
______ nerve fibers supply the SA and AV nodes and the muscle of the atria and ventricles
sympathetic
94
positive ionotropy
increase in contraction strength of the heart
95
beta blockers inhibit the activity of which nervous system?
SNS
96
how does the PNS control HR extrinsically?
- through the vagus nerve
- muscarinic ACh receptors
- decreases HR
97
how does the SNS control HR extrinsically?
- catecholamine NE and E
- alpha adrenergic and beta adrenergic receptors
- increase HR and strength of contraction
98
the stimulation of sympathetic nerves leads to the release of _____ or ____ hormones - acceleration of SA node depolarization; this is said to be a _____ effect
catecholamines, neural, positive chronotropic
99
what is another word for increased HR?
tachycardia
100
what is another word for decreased HR?
bradycardia
101
NE and E increase heart contractility
true or false?
true, this is an ionotrophic effect
102
NE and E cause vasoconstriction every except for where?
coronary arteries
103
where are sympathetic preganglionic neurons found?
in the grey matter of the spinal cord
| -between T1 and T5
104
where do sympathetic axons emerge from?
ventral roots of the thoracic and lumbar segments of the spinal cord
105
PNS - preganglionic fibers
- emerge from the brainstem and sacral spinal cord (S1 and S3)
- axons longer than sympathetic axon bc the ganglion is near or within target tissue
106
vagal nerve stimulation has both negative chronotrophy and negative ionotrophy
true or false?
false, there are no ionotropic effects
107
what are the three main sources of feedback to the cardiovascular control center?
1) arterial baroreceptors - aortic and carotid arterial mechanoreceptors
2) cardiopulmonary reflexes - cardiac mechanoreceptors
3) exercise pressor reflex - skeletal muscle ergoreceptors (mechanoreceptors, metaboreceptors)
108
what are the 4 main modes of outflow of information from the cardiovascular control center?
1) heart chronotropic and inotropic function
2) modulation of vasomotor tone (Active muscles)
3) muscle vasoconstriction (inactive muscle)
4) kidney and splenic bed vasoconstriction
109
pre exercise, what kind of central commands are happening?
- activation of central command to increase SNS and inhibit PNS
- results in a increase in HR, myocardial contractility, vasoconstriction to arteries of gut, spleen, kidneys, local vasodilation (non essential muscles)
110
increased HR is often due to an increase in SNS activity
true or false?
false, the PNS is constantly putting on the breaks on HR so the initial increase in HR is due to a decrease in PNS activity
111
during exercise, what kind of central commands are happening?
- further PNS withdrawal; reflex feedback from (mechanical and chemical receptors) autoregulatory vasodilation in increased musculature (increased K+, PCO2, Ca++, Mg++); E, and NE release
- results in constriction of vasculature in inactive tissue, action of muscle pump and visceral vasoconstriction
112
active muscle reflex feedback to medulla is mediated by what?
group III and IV afferents
| -mechanical, thermal, and chemical
113
chemoreflex feedback to medulla is mediated by what and initiates what?
1) mediated via III and IV afferents in interstitial space
- lactic acid, CO2, H+, arachadonic acid, potassium, phosphate, bradykinin
- serves to increase SNS output
2) function increases SNS output
- positive inotropic effect
114
where are baroreceptors located?
-aortic arch and carotid sinus
115
how are baroreceptors activated?
- pressure sensitive (respond to increase in bp)
| - function as negative feedback controllers
116
how do baroreceptors modulate HR and vasculature?
-HR via increase in vagal nerve tone; vasculature by decreasing SNS activation
117
what is the purpose of cardiopolmunary baroreflexes?
-monitor changes in heart chamber and pulmonary vasculature filling pressure; cardiac contractility, and afterload
- the reflex acts to suppress SNS
- has a role in modulation of ANS during exercise (remains controversial)
118
slide 41
flow chart summary
119
what are the three methods with which we can measure CO?
1) direct Fick
2) indicator dilution
3) CO2 rebreathing
120
CO output measure - direct Fick method
Calculating CO requires knowing
1) average difference between O2 content or arterial and mixed venous blood (a-VO2 difference)
2) O2 consumption during 1 minute (VO2)
According to Fick,
CO (mL/min) = [VO2 (mL/min/ avo2 difference (mL/mL blood)] x 100
121
how do we measure CO with the indicator dilution method?
- involves arterial and venous punctures but not cardiac catheterization
- inject known [] of dye or radioactive substance into a large vein
- the substrate binds to plasma proteins or RBCs
- mixes into blood and travels to the lungs and back to the heart and then out into the arteries
- arterial blood samples are continuously taken
- dye becomes diluted and the area under the dilution [curve] can be measured to compute CO
CO = quantity of dye injected/ (avg [dye] in blood for duration of the curve x duration of the curve)
122
how can we measure CO using the rebreathing method?
- substitute CO2 values for O2 values in the Fick equation
- use of a rapid CO2 gas analyzer to measure mixed venous and arterial CO2 levels
- non-invasive (bloodless)
- breath by breath analysis
- only good for steady state exercise (because of respiratory buffering system, this is non metabolic CO2)
CO (mL/min) = [(VCO2 (mL/min) / v-a CO2 difference (mL/mL blood)] x 100
123
what is the SV and CO for untrained individuals at rest? (women and men)
men: 70 bpm with a CO of 5L at rest; SV = 70 mL
women: on average SV and CO 25% lower than men
- SV between 50 - 60 mL
124
what is CO at rest in endurance trained athletes?
- training brings SA node under greater PNS influence
- increased vagal nerve tone (ACh) (vagus nerve causing SA node to beat at a slower rate)
- HR is around 50 bpm to as low as 30 bpm (large contributing factor to increased SV)
125
SV can go up to ____ mL in men and ___ mL in women as a result of endurance training
100, 75
126
what are the two factors that affect resting HR in endurance athletes?
1) increased vagal tone and decreased sympathetic outflow
2) increased blood volume (increase up to 15%), contractility, and compliance of left ventricle (more compliance = easier to expand and fill)
- increased compliance = increased elasticity
127
systemic blood flow increases directly with exercise intensity
true or false?
true
128
world class endurance athletes can increase their CO to up to ____. why is this?
35-40 L/min
| -due to increased SV, achieve a slightly lower HRmax
129
what are the three mechanisms that can increase SV?
1) enhanced cardiac filling
2) greater systolic emptying
3) training adaptations
130
how can diastolic filling be enhanced to yield a larger SV?
- increases in venous return or slowing of heart leads to increased ventricular filling during diastole
- increased EDV = greater stretch myocardial fibers = powerful ejection phase
- relationship between contractile force and myocardial fiber length is also known as the frank-starling mechanism (everything has to do with the amount of venous return)
-method most effective for transition periods
131
how can systolic emptying become greater to increase SV?
- increased systolic emptying regardless of increase in MAP in the arterial circuit from exercise induced elevation of systolic bp (afterload)
- enhanced systolic emptying occurs due to the ventricles always containing a functional residual volume of blood
- increased circulating catacholamines leads to an increase in contractility and more emptying (ionotrophic)
132
how can training adaptations increase SV?
Training adaptation that expand blood volume and reduce resistance to blood flow in peripheral tissues
- redistribution of blood to working tissues
- neural and hormonal (SNS, PNS) (local metabolites, K+, Ca++, CO2, etc.)
- long term adaptation in blood volume (endurance trained athletes have larger plasma volume and more RBCs)
133
cardiovascular drift - def.
decrease in volume return during prolonged exercise at submaximal effort
- progressive decrease in SV
- progressive increase in HR
- CO maintained only due to increased HR
134
Poiseuille's Law
states that the flow (Q) of fluid is related to a number of factors: the viscosity (n) of the fluid, the pressure gradient across the tubing (P), and the length (L) and diameter(r) of the tubing
flow = [(pressure gradient x vessel radius (4)) / vessel length x viscosity)]
135
in Poiseuille's Law, which factor is most important?
- vessel radius
| - constriction or dilation of a blood vessel provides a crucial mechanism for blood flow regulation
136
what is the proposed method of NO transport to tissues?
- NO binds to Hb (a different NO, called s-nitrosohemoglobin) but not to the iron component of the Hb molecule
- in this way, NO can be delivered to working tissues to cause vasodilation
- the more O2 that is released, the more NO that is released (in cases of high O2 needs) because when O2 is released, the Hb molecule changes shape which is what allows the release of NO
has not been proven
137
how could RBCs release ATP to cause vasodilation?
-RBCs release ATP when exposed to reduced oxygen (quantity released is linked to decrease in Hb O2 saturation)
Used as a mechanism for vessel dilation
- diffusion to endothelium where binding to receptor occurs (P2y)
- activates synthesis of NO (because ATP has a group of receptors that it can act on to synthesize NO)
-has not been proven
138
how much blood flow goes where in the body, at rest?
5000 mL in total (CO)
- muscle - 1000 mL (20%)
- heart - 200 mL (4%)
- skin - 300 mL (6%)
- brain - 700 mL (14%)
- kidneys - 1100 mL (22%)
- liver - 1350 mL (27%)
- other - 350 mL (7%)
139
how much blood flow goes where in the body, during exercise?
25, 000 mL in total
- muscle - 21, 000 mL (84%)
- heart - 1000 mL (4%)
- skin - 600 mL (2%)
- brain - 900 mL (4%)
- kidneys - 250 mL (1%)
- liver - 500 mL (2%)
- other - 780 mL (3%)
140
local metabolites act on _____, ______, and ______ to cause vasodilation
smooth muscle, small arterioles, pre-capillary sphincters
141
what are the three major stimuli that cause vasodilation in tissue?
1) decreased tissue O2 levels - potent vasodilator
2) increased blood flow, temperature, CO2, K+, NO, Mg, acidity, and adenosine cause local dilation (autoregulation of blood flow)
3) endothelial derived relaxing factor (NO)
142
mitral stenosis
narrowing of the mitral/bicuspid valve
143
what is the difference between an athlete, a sedentary person, and someone with mitral stenosis when it comes to HRmax and SV?
- HRmax is approximately the same between all individuals
- stroke volume is much larger in athletes and very low in individuals with mitral stenosis
- resting HR in athletes contributes to larger SV
144
why is there a difference in SV between individuals that are supine and upright?
laying supine eliminates most of the opposite force of blood flow that comes from gravity
145
how does blood volume change in response to endurance training?
- increase in plasma and blood volume right away - peaks in the first 10 days then levels off
- erythrocyte generation due to mild state of hypoxia that occurs during exercise (levels off after about 25 days)
146
in cardiovascular drift, why is SV decreasing over time?
- blood volume decreases over time as a result of prolonged PA
- when exercise stops, lymphatic system can bring back fluid into circulation
147
increased contractility of the heart negatively affects ESV
true or false?
true, the stronger the contraction, the less blood is left in the ventricle afterwards
148
HR positively affects filling time of the ventricles
true or false?
false, the higher the heart rate, the less filling time there is, the smaller the EDV
149
is the release of NO paracrine or autocrine?
autocrine - it is a local response for vasodilation released from the endothelium
150
what is the relationship between Q and VO2 in sedentary people vs endurance athletes?
both of them have a linear relationship, as one increases, so does the other, but endurance athletes are capable of consuming more O2 in general
151
at rest, how many mL of O2 are there per dL of blood?
20 (1000 mL/L)
152
during maximal exercise, how does an increased SV help VO2max?
- at rest, only about 3200 mL/min of oxygen circulates - so VO2 can not surpass 3.2 L
- an increased SV to 200 mL gives a Q of 40 L which makes it possible to extract 8L of O2 instead of 3.2 L
so increased Q = increased capacity and max VO2 (more circulating blood/O2)
153
what are the two mechanisms whereby we can increase O2 consumption?
1) increased Q
2) greater usage of O2 being carried by the blood (i.e. greater a-VO2 difference)
VO2 = Q x a-VO2 difference
a.k.a. O2 transport and O2 use
154
what is the a-VO2 difference at rest and during exercise?
Rest: 5 mL of O2 is extracted per dL of blood
Exercise: 16 to 18 mL of O2 is extracted per dL of blood (a-VO2 difference in larger during exercise)
155
the increased arterial O2 capacity during exercise is due to what?
- increase in capillary hydrostatic pressure
| - osmotic pressure that draws fluid from plasma into tissue spaces
156
at rest, the heart uses mostly _____ and ______ for energy, and during intense exercise, it can adapt to use mostly _____ in periods of hypoxia
fatty acids, glucose, lactate
157
at any given intensity, the legs consume more oxygen than the arms
true or false?
false, the arms consume more than the legs because of the vessel size, the heart has to work harder to send blood through the vessels of the arms
158
the SNS and the PNS both exert chronotropiv and inotropic effects on the heart
true or false?
false, the SNS exerts both but the PNS only exerts a chronotropic effect through stimulation of the SA node through the vagus nerve
159
what are the consequences of stopping regular exercise?
- only 12 days after the cessation of exercise, all adaptations start to wear off
- decreased VO2max, decreased SV, decreased Q, decrease a-VO2 difference, higher HRmax
