WK6- Circulatory System Flashcards
Define: Cardiovascular Drift.
Cardiovascular drift can be described as the increased heart rate and decrease in stroke volume during prolonged exercise. Rising body temperature and dehydration contribute to less plasma volume therefore less stroke volume.Heart rate then increases as a compensation.
Define cardiac output and describe how it changes during exercise.
Cardiac output= HR X SV, in other words it is a measure of blood output per heart beat
Cardiac output increases during exercise in direct proportion to the metabolic rate required to perform the task at hand.
Cardiac output does plateau in moderately trained and untrained individuals but not in highly trained elite athletes.
How does body position impact stroke volume during exercise ?
in a standing position and at rest, blood pooling in the legs is favored, however when undergoing exercise like cycling and and running there is an improved stroke volume even when compared to supine exercise because supine positions naturally favor venous return of blood
Define: Mean Arterial Pressure.
Mean arterial pressure gives an average of pressure during a cardiac cycle.
It is given by the formula:
MAP= DBP +.33 ( SBP-DBP)
Define: Double product as it relates to the circulatory system.
Double product provides a visualization of cardiac workload given by the expression: DP= HR x SBP
How does exercise training impact the heart ?
regular exercise training is cardioprotective in that it protects the heart from the risk of MI’s. Additionally, if an MI does occur then a trained heart will have less cardiac damage when compared to an untrained heart. The heart becomes more able to rid itself of free radicals; mitochondrial function is more resilient
What are the differences between arm and leg exercises as they pertain to oxygen consumption, heart rate and blood pressure ?
Arm exercise, for the same amount of oxygen consumption leads to higher heart rate, and blood pressure due to greater sympathetic outflow during arm work when compared to leg work. pressure increases are due to greater vasoconstriction in the arm muscles that supply inactive muscle groups, since larger muscle groups require that more arterioles be dilated which leads to less resistance and therefore less pressure.
How is arterial blood pressure measured manually ?
with a sphygmanometer which approximates blood pressure by using korotoff sounds as markers of arterial pressure.
What is the relationship between MAP, cardiac output, and total vascular resistance ?
MAP increases as both cardiac output increase and vascular resistance increases.
How are EKG’s used for diagnosis during exercise ?
EKG’s leads may be attached to persons during stress tests meant to measure cardiac changes under stress. An EKG may show heart repolarization abnormalities if there is an obstruction causing ischemia. Because ATP levels are in short supply during a supply–demand mismatch, electrical repolarization of the heart is often the first indication
that something is wrong. This is often seen is S-T segment as a depression, since the S-T segment is where ventricular depolarization normally occurs.
Describe regulation of heart rate by the SA node, ANS (both symp and parasymp), and vagus nerve.
The SA node is known as the pacemaker of the heart because it sets heart rate therefore changes to heart rate are typically done by modulation of the SA node. The parasympathetic chain of the autonomic nervous system arises from the medulla oblongata’s cardiovascular control center and make up a portion of the vagus nerve which innervates the SA and AV node. When these fibers are stimulated Ach is released which leads to hyperpolarization of the SA and AV nodes which leads to a reduction of heart rate. A decrease in parasympathetic tone can also increase heart rate. The sympathetic segment produces increases in heart rate.
What is the impact of beta blockers on exercising heart rate ?
beta blocking medications compete with epinephrine and norepinephrine for the beta receptors located on cardiac cells, this effect lowers heart rate and should be considered when implementing exercise programs in those who suffer from advanced coronary diseases.
What is heart rate variability ?
heart rate variability refers to the amount of time between two heart beats, generally longer time intervals between beats are a good indication of someone’s autonomic nervous system’s health.
How is blood redistributed during exercise ? locally and and generally
Generally, blood will flow from less active muscles to muscles that need it most. At rest blood flow to muscles is in the 15-20% range compared to 80-85% during exercise.
Locally, regulation of blow is controlled by sympathetically controlled vasoconstriction of arterioles, capillaries become far more active during exercise. Additionally, nitric oxide has dilating effects on vessels.
How does the circulatory response change during emotionally charged exercise environments ?
exercise in an emotionally charged atmosphere results in higher heart rates and blood pressures because of sympathetic activity, high emotion situations do no alter peak heart rate or blood pressures.
