Circulatory Responses to Exercise Flashcards
List the 3 main purposes of the cardiovascular system. (homeostasis)
Transport of O2 to tissues and removal of wastes. Transport of nutrients. Regulation of body temperature.
What is preload?
initial stretching of the cardiac muscle cells prior to contraction
What is afterload?
force or load against which the heart has to contract to eject the blood.
Explain pulmonary circulation.
right side of the heart pumps blood through the pulmonary circulation which is low pressure.
Explain systematic circulation.
left side of the heart delivers blood to the systemic circulation which is high pressure.
Does each side of the heart have equal cardiac output?
Yes, but different pressures.
What are the arteries?
large vessels that carry arterialized blood away from the heart. Systemic arteries are fully oxygenated blood.
What are the veins?
the blood vessels that accept blood from the venues and bring it back to the heart. For pulmonary system, veins bring back oxygenated blood to the heart.
What are arterioles?
a small branch of an artery that communicates with a capillary network
What are capillaries?
microscopic blood vessels that connect arterioles and venules. portion of vascular system where blood/tissue gas exchange occurs.
What are the venules?
small blood vessels carrying capillary blood to veins.
Describe the basic anatomy of the heart (chambers).
Heart is comprised of four chambers and is often described as two pumps in one – right atrium and right ventricle form the right pump/left atrium and left ventricle make the left pump.
What is the difference between right and left side of the heart?
There is never blood without oxygen, just much lower. Right side is “deoxygenated” blood and left side is “oxygenated” blood.
What do Atria do and where are they located?
Atria are located on top and collect blood.
What do ventricles do and where are they located?
Ventricles are on the bottom and eject blood.
List the 4 valves of the heart.
Tricuspid valve, semilunar valve, bicuspid valve and aortic valve.
Describe the cardiac cycle.
the cardiac cycle is all events between consecutive heartbeats.
List the 3 layers of cardiac muscle.
Epicardium, myocardium, endocardium.
What is the inner layer of cardiac muscle?
endocardium
What is the middle layer of cardiac muscle?
myocardium
What is the outer layer of cardiac muscle?
epicardium
What is the ventricular contraction phase called?
Systole. Ventricles contract, atria relax.
What is ventricular relaxation phase called?
Diastole. Atria contract, ventricles relax.
How long does systole and diastole last during rest and heavy exercise?
During rest, systole lasts 0.3 s and diastole lasts 0.5 s. During exercise, systole lasts 0.2 s and diastole lasts 0.13 s. This can be explained because during exercise the cardiac cycle is much shorter due to the large increase in heart rate so diastole is shortened.
What is the average blood pressure during a cardiac cycle called? What is the formula?
Mean Arterial Pressure (MAP). MAP = DBP + 0.33 x (pulse pressure)
How do you calculate pulse pressure?
Systolic blood pressure - diastolic blood pressure
List the factors that increase blood pressure.
Increase in blood volume, heart rate, blood viscosity, stroke volume and peripheral resistance.
What is the Sinoatrial node?
The “pacemaker of the heart”. specialized tissue located in the right atrium of the heart that generates electrical impulse to initiate heartbeat.
Describe EKG and list the parts on a graph.
EKG is a recording of the electrical activity of the heart during the cardiac cycle. P Wave (atrial depolarization), QRS Complex (ventricular depolarization and atrial depolarization) and T Wave (ventricular repolarization)
What are intercalated discs?
portion of cardiac muscle cell where one cell connects to the next. Facilitates spread of electrical activity as well as hormones and other chemical signals.
What is functional syncytium?
cardiac muscle works like a single giant cell
What is the atrioventricular node?
a specialized mass of muscle tissue located in the interventricular septum of the heart; functions in the transmission of cardiac impulses from the atria to the ventricles.
What is cardiac output?
the amount of blood ejected from left ventricle
How is stroke volume calculated?
EDV - ESV
How is cardiac output (Q) calculated?
Q = HR x SV
How is sinoatrial node activity modified?
Parasympathetic nervous system slows HR while sympathetic nervous system increases HR
Why does heart rate increase at the beginning of exercise?
Heart rate increases at the beginning of exercise due to withdrawal of parasympathetic tone. At higher intensity work rates, the increase in heart rate is achieved via and increased sympathetic outflow to the SA nodes.
What are the 3 things that regulate stroke volume?
End diastolic volume, after load, strength of ventricular contraction
Why does venous return increase during exercise?
venoconstriction, muscle pump and respiratory pump
What is stroke volume?
the amount of blood pumped the ventricles in a single beat
What is the vagus nerve?
a major parasympathetic nerve
What are the cardiac accelerator nerves?
part of the sympathetic nervous system that stimulates the SA node to increase heart rate.
What is heart rate variability?
refers to the variation in the time between beats measured as R-R time interval using an EKG tracing
What is the ejection fraction?
the fraction of the EDV represented by the SV as a percent and is an index of efficiency. Represents the fraction of the EDV ejected during systole.
What is venous return influenced by?
sympathetic outflow, body position, temperature and muscle contraction
What factors increase venous return?
venoconstriction, muscle pump, respiratory pump, temperature, body position/gravity
What is the Frank Starling Mechanism?
a need to increase cardiac contractility and compensate for decreased filling time
What does Hemodynamics mean?
“blood movement” Study of blood flow or circulation through vasculature
What does blood flow through vasculature depend on?
Pressure difference between the 2 ends, blood properties (viscosity), driving pressure generated by the heart and overall resistance to blood flow
What are the two components on blood?
Plasma and hematocrit
What is plasma and hematocrit?
Plasma is the portion of blood composed of clear liquid (60%). Hematocrit is the portion of blood composed of cells (40%) and is higher in males.
What changes happen to plasma and hematocrit with training?
Plasma increases rapidly, hematocrit increase slowly. Blood viscosity decreases
What is the most important factor determining resistance to blood flow?
Radius of the blood vessel
What is the Resistance formula?
Resistance = Length x Viscosity / Radius^4
Where is the greatest vascular resistance?
Arterioles
What is formula for maximum heart rate for the general population?
Max HR = 220 - age in years
What is formula for maximum heart rate in older adults and children?
Max HR = 208 - 7 x age in years
What does the Fick equation determine?
the relationship between cardiac output, A - V O2 difference and oxygen uptake
What is the Arterial venous oxygen difference?
the A - V O2 difference is the difference in oxygen content between the arterial blood leaving the left ventricle and the mixed venous blood returning to the right atrium.
What is the Fick equation?
VO2 = [HR x SV] x (A – V O2 difference)
What is auto regulation?
mechanism by which an organ regulates blood flow to match the metabolic rate
What is cardiovascular drift?
the increase in heart rate that occurs during prolonged exercise
What does the central command theory of the cardiovascular system propose?
initial signal to “drive” the cardiovascular system at the beginning of exercise comes from higher brain centers/motor signals.
How is the cardiovascular response fine tuned?
muscle chemoreceptors, muscle mechanoreceptors, and arterial baroreceptors to the cardiovascular control center.
What are feed forward signals?
signals from the cardiovascular control centre
What are feed back signals?
signals from various receptors in the periphery providing fine tuning
