CH 9: Cardiovascular Response to Exercise Flashcards
What is the purpose/driving factor of the cardiovascular system?
To create and maintain pressure appropriate to the circumstances (Exercise intensity)
Name and briefly characterize the layers of the heart wall
-Epicardium: Lubricative outer covering
-Myocardium: Provides muscular contractions that eject blood from the heart chambers
-Endocardium: Serves as the protective inner lining of the chambers and valves
What structure in myocardium cells allow them to share a depolarization signal?
Intercalated Disks
How many fiber types are in the heart and how can they be characterized?
The heart has a homogenous fiber type.
Similarly to type I muscle fibers, they are slow-oxidative and resistant to fatigue.
True or False: One of the biggest advantages of myocardium compared to muscle, is the presence satellite cells.
False - Satellite cells are absent from myocardium
How is the absence of satellite cells significant to the heart?
Satellite cells facilitate the repair of damage in muscle cells (mainly following exercise). Since the heart does not contain satellite cells, scar tissue appears when damage occurs in the heart (i.e. after a heart attack).
What is the meaning of “Cardioprotective benefit of aerobic exercise” (aka cardioprotection)?
If an individual suffers from a heart attack, adverse effects are minimal if a moderate aerobic session occurred shortly prior (6~10 days). Training should be frequent
EDV, aka __________ is primarily influenced by _______ ________.
Preload
Venous Return
Name at least 3 factors that influence Venous Return.
1.) Q/Cardiac Output
2.) Blood flow redistribution
- Vasoconstriction
3.) Muscle Pump/ One-way venal valves
4.) Respiratory Pump
5.) Gravity
What 2 factors outside of venous return influence EDV?
1.) Stiffness of the heart
- More likely in older/diseased population
2.) Heart Rate
What issues may be inferred if the venous return is not equivalent to cardiac output in an individual?
If venous return is less than cardiac output, this may point towards some form of blood loss (internally or externally) or a blockage in the system.
True or false? Myocardium cells have a resting membrane potential similarly to muscle cells.
False: Myocardium cells constantly creep towards depolarization as they have an affinity for both sodium and calcium ions to leak.
The SA Node acts as what mechanism in the heart?
Pacemaker
What is the intrinsic rate of the SA Node in a normal healthy person?
Approximately 100 BPM
What is the advantage of the use of Beta-Blockers in heart patients if it lowers heart rate?
Lowering heart rate allows for longer fill time which increases the stretch on the heart making the contraction force stronger (by way of the Frank-Starling mechanism) without excess oxygen demand.
What is the role of the intercalated disks inside the myocardium?
It facilitates the transmission of the depolarization signal from one cell to the next cell.
True or false? Intercalated disks are found in the myocardium of the atrial and ventricular chambers.
True. There are no intercalated disks between the atrial and ventricle chambers but there are intercalated disks inside the myocardium within their chambers.
Fill in the blanks.
A patient who has been battling some serious heart problems and was very susceptible to a myocardial infarction ended up having one today. As we are familiar with the heart’s muscular structure we know that after a heart attack _____ ______ cells will replace the _______ ________. With this adverse event, the lack of _________ _____ cells found in ___________ ___________ which ____________ _____ __________ _____ ___________ in muscle cells would lead to higher caution to prevent instances like this from occurring.
Scar Tissue Cells
Myocardial Cells
Satellite Cells
Skeletal Muscles
Facilitate the repair of damage
What are the two things that influence ESV?
Inotropic Factors and afterload
What are the Inotropic factors that influence ESV?
- EDV, Elasticity, and Length Tension (Frank-Starling) meaning the greater we stretch the heart the more forceful the contraction or shortening force will there be.
- Intrinsic Contractility, (The strength of contraction regardless of EDV)
What hormones are responsible for intrinsic contractility that influences ESV and what is their action?
Epinephrine and Norepinephrine
(Released during moderate and above exercise)
Increase extracellular calcium entry into the MYOCARDIUM, which will lead to more cross-bridging and more contractions.
True or false? An increase in intrinsic contractility leads to an increase in ESV at any given EDV.
False, An increase in intrinsic contractility will cause a decrease in ESV.
What determines Afterload?
Aortic Pressure and Aortic Distensibility
What is the role of chronotropic factors on the heart?
It affects the rate or timing of the heart’s contractions
What external factors control the heart?
- PNS (Parasympathetic Nervous System) and Vagus nerve will act on the SA Node decreasing the natural 100bpm to values under 100.
- CSN (Cardiac Sympathetic Nerve) will act on the SA Node increasing the natural 100bpm to values over 100.
Explain how HR changes during physical activity. (Acute)
At rest, the heart is lower than the normal 100bpm and at the start of exercising the suppression of the vagus nerve decreases causing the HR to go around 100 and then the CSN will act on the SA node to cause the HR to go past 100.
Explain how HR changes with chronic training.
The heart gets stronger through aerobic training the vagus nerve gets stronger too which lowers resting HR.
What does HRV stand for and mean?
Heart Rate Variability
The distance between consecutive R waves. It is the measure of variation in time between each heartbeat.
What determines HRV and is it good to have a low HRV?
The PNS and CNS affect the heart rate variability.
Having a low HRV is considered dangerous as this means that one nervous system is more dominant than the other which can lead to cardiovascular problems.
How do we measure HRV?
Through the use of an EKG
What are the Q values of a resting untrained/trained male and female in L/min?
Untrained Male = 5.0 L/min
Trained Male = 5.0 L/min
Untrained Female = 4.50 L/min
Trained Female = 4.40 L/min
RESTING CARDIO OUTPUT (Q)
Explain how an untrained male and a trained male reach 5.0 L/min at different rates regarding HR and SV.
Untrained Male = 5.0 L/min
Trained Male = 5.0 L/min
Explain why there is a difference between these values compared to the male resting values.
Untrained Female = 4.50 L/min
Trained Female = 4.40 L/min
Even though an untrained and a trained male reach the same 5.0 L/min for cardio output because their stroke volume is higher it also reduces the amount of heartbeats it needs to reach it.
There is a difference in resting values for females and males due to body mass.
True or false?
Max heart rate is determined by age alone.
False, max heart rate can change through training, especially with high elite athletes who can have lower max heart rates than the age-predicted equations.
What is stroke volume? How do we calculate it?
The volume of blood pumped in one heartbeat.
EDV - ESV = SV
What determines SV?
- EDV, you can only deliver how much you can receive meaning higher EDV causes a higher SV.
- Strength of Contraction, forceful contractions of ventricular walls to decrease the volume and eject the blood.
- Afterload, the force or resistance to emptying.
What is an Ejection Fraction? What are the EF percentages when resting and at max exercise?
The fraction of EDV pumped.
SV / EDV = EF
Resting - 60 percent of EDV pumped
Max exercise - 90 percent of EDV pumped
What is the average cardio output at rest and when doing heavy exercise?
Rest - 5 L/min
Heavy Exercise - 25 L/min
Explain why a trained female’s cardiac output might by lower than an untrained female when at rest.
After going through training adaptations (i.e. higher hematocrit). The trained individual has a more efficient system which means they wouldn’t need to pump as much blood to deliver the same amount of oxygen/nutrients.
What is the average RHR and standing SV of an individual?
70 BPM
70mL/Beat
Based on the average RHR and standing SV of an individual, what is the usual resting Q?
70BPM x 70 ml/Beat = 4,900mL/min
or 4.9L/min
Even when working at the same METs, an athlete working supine/prone (i.e. swimming) will have a ______ heart rate than someone standing (i.e. running) due to the effects of __________. The difference is usually about __________ BPM at a given intensity.
1.) Lower
2.) Gravity
3.) -10BPM
How does dehydration play a role in SV during an endurance bout of exercise?
When dehydrated, decreasing volumes of fluid result in less venous return which lowers EDV.
What happens to ESV as a bout of exercise continues and explain why that it a good thing?
As exercise continues, ESV goes down. This indicates that there is less fluid in the heart at the end of the contraction cycle meaning that more blood has entered circulation.
In most individuals, EDV can only increase up to about __ -__% of VO2 max. As exercise intensity increases, the body responds by releasing ______________ such as ____________ and _______________. This allows for contractile strength to increase by allowing a greater amount of extracellular __________ to enter the __________ in order to keep up.
1.) 50-60%
2.) Catecholamines
3.) Epinephrine
4.) Norepinephrine
5.) Calcium
6.) Myocardium
True or False? During an endurance exercise session, excess sweating causes a decrease in blood plasma therefore decreasing hematocrit.
False: Decreasing blood plasma causes an increase in hematocrit
Explain why trained individuals tend to have a lower hematocrit when compared to untrained individuals?
Although both Blood plasma and RBC count increase from endurance training, a proportionally greater increase in blood plasma causes an overall lower hematocrit.
What is the difference between altitude acclimation and altitude acclimatization?
1.) Acclimation is the acute adaptation to increased elevation expressed by expelled plasma causing a higher hematocrit without increasing RBC count to compensate for less total oxygen in the air.
2.) The long-term adaptation of an increase in RBC count and a reinstitution of plasma in order to keep hematocrit consistent as if at sea level.
True or False? Aside from a small increase in plasma retention, the body does not go through any significant long-term heat adaptations.
True
