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Exercise Physiology
Blood Pressure
Term | Definition |
---|---|
components of blood | plasma and hematocrit (RBC's, WBC's, platelets) |
blood viscosity | thickness of blood |
EPO | hormone that controls RBC production |
blood doping | taking out blood, letting the body replenish that blood defect and then adding it back in so you have additional red blood cells than you did before |
short-term control of blood pressure | sympathetic nervous system, stimulatory |
baroreceptor response | pressure receptors in the arteries detect a drop in blood pressure and signals the cardioregulatory center to increase heart rate so that more blood is being delivered to the body (negative feedback loop) |
long term control of blood pressure | kidneys control the hormones that affect blood volume in the cardiovascular system |
why does cardiac output increase during exercise? | heart rate will increase with an increased respiratory rate, therefore strove volume will increase due to this increase. As more blood is being pumped out per beat to deliver more O2 to the working muscles, more blood will also be pumped out per minute |
redistribution of blood flow during exercise | vasodilation in working areas, vasoconstriction in non-working areas. most RBC's where oxygen is needed |
predicting maximum heart rate | 220-age OR 200-.67(age-20) |
autoregulation | vasodilation in arterioles feeding working muscles caused by metabolic changes in the local muscles, influenced by decreased oxygen tension, increased CO2 tension, nitric oxide, potassium and adenosine concentrations, decrease in pH |
capillary recruitment | assists auto regulation, at rest only about 5-10% of capillaries are open. during exercise, pre-capillary sphincters open access to almost all of the capillaries in contracting muscle |
factors that cause a rise in cardiac output | vascular resistance (vasoconstriction) and an increase in mean arterial pressure |
why does diastolic blood pressure drop during exercise? | the arteries must dilate to accommodate the increase in cardiac output but stay dilated during diastole when there is less blood in the arteries. bigger arteries with less blood volume leads to a drop in arterial pressure |
fick equation | VO2 = Q x a-vo2 difference |
intrinsic control of heart rate | electrical activity of the heart |
SA node | sino-atrial node pacemaker, depolarizes and fires and impulse to the surrounding cardiac muscle fibers in order to contract |
AV node | avio-ventricular node conducts the electrical impulse to the next chamber conductive tissue (gate) |
bradycardia | extremely slow heart rate , under 60 bpm |
tachycardia | extremely high heart rate , above 100 bpm |
extrinsic control of heart rate | nervous system |
parasympathetic nervous system | cardiovascular control center in the medulla slows activity in the heart |
sympathetic nervous system | cardiovascular control center in the medulla stimulates activity in the heart |
vagus nerve | PNS, crianial nerve that when stimulated will slow or completely stop heart rate. works by dampening the signals of the SA node |
vagus escape | heart rate continuing even after the vagus nerve is stimulated and another cardiac muscle fiber takes over as pacemaker |
how does HR increase during exercise? | by withdrawal of the PNS stimulation |
stroke volume | amount of blood pumped out per beat |
factors influencing stroke volume | EDV, contractility, peripheral resistance, |
end-diastolic volume | amount of blood in ventricle after contraction of ventricle |
venous return | blood coming back to heart after oxygen delivery, venoconstriction, muscle pump, respiratory pump |
starling law | as EDV increases, the length of the cardiac fibers will stretch causing their contractions to be stronger |
ejection fraction | amount of blood pumped out of the ventricles each contraction, in a healthy heart should be 70% |