Cardiovascular physiology Flashcards
1
Q
What does a dot over a letter indicate?
A
That there is a time element. So if you see a V with a dot over it in eg VO2, it means volume of oxygen (probs in ml) per minute
2
Q
What is VO2max?
A
the maximum or optimum rate at which the heart, lungs, and muscles can effectively use oxygen during exercise
3
Q
What are the two ways you can measure VO2 max?
A
- absolute VO2max is the maximum amount of oxygen you can breathe (in eg ml) per minute
- relative VO2max measures that volume of oxygen (eg in ml) per minute, per kilogram of body weight
4
Q
Give 2 differences between the aerobic and anaerobic energy systems?
A
(1) Your aerobic energy system needs oxygen to convert muscle glycogen into fuel; your anaerobic system does not
(2) Your aerobic energy system can deliver fuel for hours and hours; your anaerobic system can deliver fuel for a short window of time (ie minutes)
5
Q
Which energy system does your body use first, aerobic or anaerobic?
A
Aerobic energy system is what muscles first use for fuel
6
Q
When would the body switch between energy systems?
A
- amount of fuel aerobic system can provide is limited by how much oxygen it receives from CV system
- when body is working so hard that muscles need more fuel than aerobic energy system can produce, anaerobic energy system takes over (and body’s ability to hold that effort level is limited to relatively short duration)
7
Q
How does VO2max relate to your aerobic and anaerobic energy systems?
A
- VO2max is oxygen limit that caps fuel production capabilities of your aerobic energy system
- higher VO2max = more oxygen your cardiovascular system can deliver to muscles
- more oxygen available to muscles = more fuel aerobic energy system can provide
- more fuel muscles have, the harder they can work and the longer they can last
8
Q
What is relative VO2 max useful for?
A
It’s VO2 max relative to an athlete’s body weight, so allows us to compare fitness between individuals
9
Q
How might you improve relative VO2 max?
A
You could lose weight (so there’s more 02 per kg of you), or do endurance or interval training
10
Q
What percentage of your blood flow goes to your skeletal muscles during maximal exercise?
A
about 85%
11
Q
What are the approximate maximums for male and female athletes VO2max ever recorded?
A
Male = just under 100ml/kg/min, Female = just under 80ml/kg/min
12
Q
What are average untrained female and male VO2max rates?
A
Female = around 25-30 ml/kg/min
Male = around 35-40 ml/kg/min
13
Q
Is there much difference in VO2Max between the genders in sedentary people?
A
No
14
Q
What are mitochondria?
A
- Membrane bound organelles within cells that generate ATP (the cell’s main source of energy) to power the cell’s biochemical reactions
15
Q
What is the name of the portion of your circulatory systems that moves blood between the heart and the lungs?
A
Pulmonary circuit
16
Q
What is the name of the portion of your circulatory systems that moves blood between the heart and the rest of the body?
A
Systemic circuit
17
Q
What are the two portions of cardiac cycle events?
A
Diastole and systole. Diastole represents ventricular filling, and systole represents ventricular contraction/ejection.
18
Q
What is normal untrained adult blood pressure and what do those numbers mean?
A
120 over 80. 120 is the systolic pressure in the arteries when the heart beats; 80 is the diastolic pressure ie that in the arteries in between beats
19
Q
What are the two sides of the heart responsible for?
A
- Left side receives oxygenated blood from pulmonary circuit and pumps it around systemic circuit
- Right side receives deoxygenated blood from systemic circuit and pumps it to the lungs-
- it’s left/ right as if it’s your heart, not as you look at it
20
Q
What are the main parts of the blood flow circuit?
A
- right atrium (towards the top)
- right ventricle (towards the bottom - remember bottom of heart is kind of pointy like a V)
- left atrium (towards the top)
- left ventricle
- superior and inferior vena cava (carry deoxygenated blood from body to heart)
- aorta (carries oxygenated blood from heart to body)
pulmonary arteries (carry deoxygenated blood from the right side of the heart to the lungs) - pulmonary veins (carry oxygenated blood from lungs to left side of heart)
- pulmonary arteries (carry oxygen-poor blood from the right side of heart to lungs) 🫁
21
Q
why do we measure blood pressure in the upper arm?
A
because when you’re upright it’s about the same level as your heart
22
Q
what blood vessels is blood pressure measured in?
A
arteries. pressure in your veins is v low (so their walls are much thinner than arteries) and there isn’t the same diastolic/ systolic range in veins
23
Q
if someone’s heart is bigger than average, is that a sign of training or disease?
A
either! endurance athletes’ hearts can grow bigger as a normal and beneficial response to exercise. or an enlarged heart can be eg if someone has high blood pressure, every time the heart beats it’s trying to send blood through a relatively thin tube so remodels through hypertrophy due to this extra work
24
Q
what is the relative structure of veins and arteries?
A
Vein has a larger lumen and less elasticity; veins work at a much lower pressure than arteries. The lumen in arteries is smaller but can change more than that of a vein. Arteries are more elastic and made of more layers than veins
25
Which type of blood vessels facilitate gas exchange in and out of muscle, and what can you say about their diameter?
Capillaries - diameter is smaller than the diameter of red blood cell. Makes the cells get slowly squeezed through to give time for 02 to diffuse out into the interstitial space
26
What is coronary circulation?
With every heart beat about 20-25% of blood is redirected back into the heart because it’s a muscle with huge energy requirements. This is coronary circulation
27
In a graph, which variable would you tend to put on the x axis (horizontal)?
x-axis (horizontal) = independent y-axis (vertical line) = dependent
The independent variable is the cause. Its value is independent of other variables in your study. The dependent variable is the effect. Its value depends on changes in the independent variable
28
What is the cardiac cycle?
It is the time taken for the heart to go through one round of diastole and systole. Measured in seconds
29
If you know someone's heart rate how do you work out their cardiac cycle?
Divide 60 by their heart rate.
So for a heart rate of 74bpm, divide 60 by 74 to give you 0.81sec
30
What proportion of resting cardiac cycle is spent in systole and diastole?
At rest, about 1/3 systolic and 2/3 diastolic
31
what effect does training have on diastole?
for most untrained people the heart doesn't fill completely during diastole. training can mean the heart fills more completely
32
How do you calculate cardiac output?
Cardiac output (Q) is the amount of blood pumped from the heart around the systemic circuit every minute and can be calculated by multiplying heart rate (HR) by stroke volume (SV). So Q = HR × SV
33
What is heart rate, and what is the average adult resting heart rate?
The number of times the heart beats (or the ventricles pump blood out) in one minute. Average resting HR is approx 70 beats per minute (bpm)
34
What is stroke volume, and what is the average adult resting stroke volume?
Stroke volume is the amount of blood pumped out of the heart each time it beats. The average resting SV is 70-80ml, which translates to 5litres per min
35
What function of the nervous system controls the heart?
Autonomic nervous system
36
How do the parasympathetic and sympathetic nervous systems operate on the heart?
Sympathetic activity increase heart rate; parasympathetic decreases heart rate
37
Which parasympathetic nerve innervates the heart, and how does its operation affect the heart?
Vagus nerve - increased vagal tone means a lower heart rate
38
What effect might training have on a person's resting and max exercise heart rate?
Training will tend to lower resting heart rate; it won't have much effect on max exercise heart rate
39
What effect might training have on a person's resting and max exercise stroke volume?
Training will increase resting AND max exercise stroke volume
40
What effect does training have on resting cardiac output and why is this?
Minimal effect. Cardiac output = heart rate x stroke volume. Training decreases resting heart rate but increases resting stroke volume, so it kind of works out to have no effect on cardiac output
41
What effect does training have on max exercise cardiac output and why is this?
It increases it, because training increases max exercise stroke volume (there isn't any change in max exercise heart rate with training). Cardiac output = heart rate x stroke volume
42
If you have a lower resting heart rate, what does that mean for diastole?
lower heart rate = a longer pause between beats = a longer filling time for the heart
43
What is the single most important cardiac change due to training?
Increases in stroke volume (NOT changes in heart rate)
44
What does EDV stand for in relation to the heart?
End Diastolic Volume ie how much blood is within the heart at the end of diastole/ the filling portion of the cardiac cycle
45
How much does resting stroke volume increase through exercise (in average, trained and olympic people)?
Resting stroke volume is average 70ml. This increases to:
- 100ml heavy exercise
- 120ml for trained subjects
- 160ml for olympians
46
What is the Starling or Frank-Starling law of the heart?
Stroke volume of the heart increases in response to an increased volume of blood in the ventricles, before contraction (the end diastolic volume), when all other factors remain constant.
Raising the EDV (/end diastolic volume) stretches the myocytes (/muscle cells) of the heart more. This means systole (/the heartbeat) is more forceful, simply due to the elasticity of the myocytes
47
Through what 2 methods does stroke volume increase with exercise?
1. Blood volume increases
2. Starling law of the heart
48
What can you say about blood volume expansion?
Called hypervolemia. Change in plasma volume account for most of change during the first 1 to 2 weeks of different physical activity patterns; after that altered blood volume may be distributed equally between plasma and red cell volumes
49
What benefits does increased blood volume provide for an exercising body?
1. greater body fluid for heat dissipation (sweating)
2. greater cardiac filling and stroke volume
50
What types of hypertrophy can occur in the heart?
1. Eccentric hypertrophy - caused by volume overload. Heart muscle has stretched so can accommodate more blood
2. Concentric hypertrophy - caused by pressure overload. What happens in heart conditions: lower amount of blood can enter. Sometimes strength based athletes have a lower level of this kind of adaptation but it’s not damaging like a heart condition would be
51
How might cardiac output range in humans in litres per minute?
Cardiac output in humans is generally 5-6 L/min at rest to more than 35 L/min in elite athletes during exercise
52
What is ventilation rate?
Breaths taken per minute
53
How might ventilation rate change with exercise?
Increases from about 15 breaths a minute (12 litres of air) at rest, up to about 40–60 breaths per min (100 litres of air) during exercise
54
Aerobic exercise causes changes in what 3 areas increase VO2max?
Respiratory, cardiovascular and muscular
55
What respiratory changes occur with aerobic training to increase VO2max?
Respiration rate increases
56
What CV changes occur with aerobic training to increase VO2max?
Increased:
- blood volume
- cardiac output
- number of capillaries
57
What muscular changes occur with aerobic training to increase VO2max?
Trained muscles show:
- increase in mitochondrial oxidative enzymes
- increase in slow twitch muscle fibres
58
When is lactate produced?
Lactate is produced by the breakdown of glucose through anaerobic glycolysis to supply cells with ATP. The more glucose used by your muscles as fuel, the more lactate they produce
59
What is lactate threshold (Tlac)?
- first sudden and sustained increase in blood lactate above resting values during exercise of increasing intensity
- determined by blood measurement
- values inc pH and VO2 are able to reach a steady state
- marks the boundary between moderate and heavy domains of exercise
- LT is sustainable for several hours with sufficient endurance training
- the higher above LT, the shorter the time to exhaustion
60
What is gas exchange threshold?
- like lactate threshold, it can mark the dividing line between moderate and heavy exercise domains
- unlike LT, which is measured via blood, GET is measured using gas analysis
61
What is critical power?
- the highest work rate at which values including pH and VO2 can attain a steady state
- marks the boundary between heavy and severe domains of exercise
- determined using numerous measurable values inc VO2
62
Why might an athlete soon tire after passing their critical power threshold?
Past this threshold they are operating on mainly anaerobic respiration and using their limited supply of glycogen which will run out in minutes (defo less than an hour)
63
How is lactate threshold (Tlac) usually expressed?
As a percentage of VO2max
64
Why is lactate threshold important?
Lactate can be easily measured using a blood sample eg from earlobe and lactate threshold is a really good predictor of performance. Eg for an endurance runner, if you know their lactate threshold and how fast they are running when they reach that threshold, you can predict their performance ie how long will they take to run a marathon. Endurance athletes often trying to operate just around this threshold
65
How does lactate relate to pH?
Measuring lactate isn't a measure of pH but it allows us to infer blood pH (as lactate rises, acidity levels rise, so pH falls)
66
What happens physiologically after lactate threshold (Tlac)?
As acidity rises we get closer to fatigue because:
1. glycolysis (process of breaking down glycogen) doesn’t work when acidity levels are high
2. at level of sarcomere - high acid levels prevent actin and myosin from interacting
67
Name 3 main exercise domains (plus a fourth)
1. Moderate = below lactate threshold
2. Heavy = above lactate threshold, below critical power
3. Severe = above critical power but below VO2max
(4. Supramaximal = above VO2max)
68
Features of exercising in moderate domain?
- lactate levels low and steady, not much above resting
- increase in 02 demand is minimal and not using up glycogen stores
- Upper limit of 70% VO2 max
- Time to exhaustion ~ 3 hours +
- lactate/ gas exchange threshold marks upper boundary of moderate domain
69
Features of exercising in heavy domain?
- lactate levels can achieve steady state but takes about 10mins to adapt
- everything is harder than in moderate but can be held for ~ 1 hour (half-marathon/10 mile)/ poss elite levels 2 hours
- Above lactate threshold, below critical power
- Upper limit ~ 85 % VO2 max
70
Features of exercising in severe domain?
- lactate levels well over resting and always increasing - never reach a steady state
- above critical power threshold
- held for 5 to 40 min (VO2 max pace can be held for 4 to 8 min pace (3000 m)) - 40mins would only be elite level
71
What is more important than a high VO2max for endurance events?
The ability to sustain a high % of VO2 max without accumulating fatigue (eg Paula Radcliffe could run at 91% of her VO2max for half marathon)
72
Which ventricle of the heart is the pressure higher in?
Left: it has to send blood all around the body. Right only has to send to lungs
73
What are the five types of blood vessels?
Arteries, arterioles, capillaries, venules, veins
74
What percentage of air is oxygen?
Approx 21%
75
What is the partial pressure of oxygen and how does that relate to diffusion into mitochondria?
The partial pressure of oxygen in air is 21% of the total pressure in a given sample of air.
Diffusion is particles moving from high concentration to low concentration. If the partial pressure of o2 is low (eg at high altitude) it won't diffuse easily into mitochondria (that's why you have to gasp for air at high altitude; not because there's less oxygen in the same amount of air, but because there's less overall air pressure so the partial pressure of oxygen is lower)
76
how might you estimate someone's max heart rate?
220 minus their age
77
what cycle is used to recycle lactate in the body?
Cori cycle
78
what is the term used for body trying to reduce acidity levels?
'buffering' - We’re buffering acidity all the time. Main mechanism is renal via kidneys. Also, we buffer with ventilation - we store CO2 in blood, which is a weak acid. When we need to manage acidity levels in blood we exhale more
79
when considering blood test data, what are you looking for to spot lactate threshold?
First sudden and sustained increase. Often occurs around 1mmol/L
above resting levels
80
How would the timing for levels in a lactate threshold test differ from those in a VO2max test?
- LT test intention isn’t to get them to max; it’s to test their blood at different speeds and get data about where threshold is
- So LT stages are normally quite long eg at least 3 mins so the body has time to reach a steady state
- Cf VO2 tests about 8-10 mins in total; if shorter you might not have reached max; if too long muscles might fatigue before you reach max
80
which scale measures perceived exertion?
Borg scale (asks athlete how they feel)
81
How do you use speed and gradient in lactate threshold and VO2max tests?
In LT test you're increasing speed
For VO2max use gradient (most people can’t run fast enough to reach vo2max)
82
what 4 zones might athletes use for training?
Recovery - low intensity distance training, talking pace
Endurance - Volume endurance below LT may equal or exceed race distances according to time of year (might be same as recovery just longer)
Time-trialling - Continuous efforts at or slightly higher than LT, building time for sustaining intensity
Intervals/Sprinting - Brief intervals 12s-4min at intensity equal or exceeding V̇O2max
83
How often do elite athletes undergo tests?
Probs once pre season, one mid season, and one after
Don’t test too often because you’ll get lower engagement from athlete
if you test too close together you might not find much change = demotivating (unlikely to change LT in a month even with hard training)
84
How long are test results valid for?
Probs for weeks or months if they keep training. But if they take a break results will probs change after a couple of weeks
