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132 Cards in this Set
- Front
- Back
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Explain how skeletal muscle regulates it's own blood flow. |
Regulates its own blood flow through "autoregulation". The increased metabolic rate of the skeletal muscle during exercise causes local changes such as decreases in O2 tension and pH, and increases in CO2 tension, nitric oxide, K+, and adenosine. All of these changes cause vasodilation. |
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Explain the electrical activity of the heart. |
Spontaneous electrical activity in the SA node due to a decay in resting membrane potential via the inward diffusion of Na+ during diastole. The SA node fires. The wave of depolarization spreads over the atria which cause the atria to contract. The wave of depolarization is conducted through the AV node to the right and left bundle branches. Action potential decends down the AV bundles to the apex of each ventricle. The AV bundles then branch into smaller fibers called purkinje fibers. Purkinje fibers then spread the wave of depolarization throughout the ventricles. |
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What are the two classifications of hypertension? |
Primary hypertension - multifactoral 95% of all reported cases Secondary hypertension - result of some known disease. |
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What health problems can hypertension lead to? |
Can lead to increased work load on the left ventricle which results in an adaptive left hypertrophy. This can change the orientation of the cardiac muscle fibers with time. This results in diminished pumping capacity which could lead to heart failure. HBP is also a major risk factor for atheriosclerosis, heart attacks, kidney damage, and stroke. |
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What is considered high blood pressure? |
140/90 |
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Why is MAP important? |
Because it determines the rate of blood flow through the systemic circuit. |
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What device is used to measure blood pressure? |
Sphygmomanometer |
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Is blood pressure higher in the venous or arterial portion of the cardiovascular system? |
Arterial |
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What is the normal blood pressure for an adult male? Adult female? |
Male = 120/80 Female = 110/70 |
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What does the first and secondary heart sounds represent? |
First = closing of the AV valves Second = closing of the aortic and pulmonary valves |
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When do the AV valves open to allow blood into the ventricles? |
When ventricular pressure is lower than atrial pressure |
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When do the pulmonary and aortic valves open? |
As soon as ventricular pressure exceeds the pressure of the pulmonary artery and the aorta. |
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Approx. ______% of blood entering the atria during diastole flow directly into the ventricles through the AV valves before the atria contract. Upon atrial contraction, atrial pressure _________. |
70% rises |
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During heavy exercise, which is longer, diastole or systole? |
Systole is longer |
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What is the function of the endocardium? |
Protective inner lining of the chambers and valves. |
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What function does the epicardium serve? |
Lubricative outer covering |
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At rest, contraction of the ventricles during systole ejects about _____ of the blood in the ventricles. |
2/3 |
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The right and left atria contract _____, which empties atrial blood into the ventricles. Approx. ______ seconds after the atrial contraction, the ventricles contract and deliver blood into both the ________ _______ and _________ ________. |
Together 0.1 Systemic circuit and pulmonary circuit |
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When does atrial systole occur? When does atrial diastole occur? (relative to ventricular systole/diastole) |
During ventricular diastole During ventricular systole |
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At rest, is diastole or systole longer? |
Diastole |
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The ______ _______ refers to the repeating pattern of contraction and relaxation of the heart. The contraction phase is called _________ and the relaxation period is called _________. |
Cardiac cycle Systole Diastole |
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How are cardiac and skeletal muscle similar? |
Both are striated and have the same contractile proteins: Actin and myosin Both require Ca++ to activate the microfilaments Both contract via the sliding filament model Both can alter the force of contraction |
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How are cardiac muscle fibers similar to type 1 muscle fibers? |
Cardiac muscle is highly aerobic and contains large numbers of mitochondria. |
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Are the muscle cells in the atria and the ventricles connected? |
No, that is why they contract separately. |
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How do intercalated discs allow the transmission of electrical impulses? |
Intercalated discs are leaky membranes that allow ions to cross from one fiber to another. Therefore, when one fiber is depolarized to contract all connecting heart fibers become excited and contract as a unit called a functional syncytium. |
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How do skeletal and cardiac muscle differ? |
Cardiac muscle fibers are shorter and are connected in a tight series. Cardiac is branched and skeletal is elongated and do not branch. Cardiac is involuntary. Cardiac muscle fibers are all interconnected through intercalated discs which allow the transmission of an electrical impulse from one fiber to another. Cardiac muscle cannot be divided into diff. fiber types. |
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Describe a myocardial infarction and explain how exercise can prevent it. |
Blockage in coronary blood flow which results in cell damage. The severity of a heart attack is determined by the amount of cells that die from it. Cell damage results in tetany which turns the heart into a pipe rather than a pump. Exercise strengthens the myocardium and increases the amount of coronary arteries. |
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What is the myocardium responsible for and where does it receive its blood supply from? |
Contracts and forces blood out of the heart. Receives its blood supply via the right and left coronary arteries, which branch off the aorta and encircle the heart. |
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The wall of the heart is composed of what three layers? |
Outer layer called the epicardium Muscular middle layer called the myocardium Inner layer called the endocardium |
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Describe the systemic circuit. |
Left side of the heart. Pumps oxygenated blood to the whole body via arteries. Returns deoxygenated blood to the right side of the heart. |
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Describe the pulmonary circuit. |
Right side of the heart. Pumps deoxygenated blood to the lungs via pulmonary arteries. Returns oxygenated blood to the left side of the heart via pulmonary veins. |
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The mixture of venous blood from both the upper and lower body that accumulates in the right side of the heart and represents an average of venous blood from the entire body. |
Mixed venous blood |
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Small venous vessels are called? |
Venules |
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________ are the smallest and most numerous of blood vessels. All exchanges of oxygen, CO2, and nutrients between tissues and circulatory system occur across _________. |
Capillaries Capillaries |
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As arteries become microscopic they form _______, which eventually develop into "beds" of much smaller vessels called _______? |
Arterioles Capillaries |
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Blood travels away from the heart in ________ and returns to the heart by way of ________. |
Arteries Veins |
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Amount of blood pumped per min by the heart. |
Cardiac output |
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To meet the increased oxygen demands of muscle during exercise, what two major adjustments to blood flow must be made? |
Increased cardiac output A redistribution of blood flow from inactive organs to active skeletal muscles. |
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How do the respiratory and circulatory systems work together? |
Respiratory system adds oxygen and removes CO2 from the blood while the circulatory system is responsible for the delivery of oxygenated blood and nutrients to tissues in accordance with their needs. |
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What are the three functions of the cardiorespiratory system? |
The transport of O2 to tissues and the removal wastes from body tissues. The transport of nutrients to tissues. |
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During heavy exercise the demand for oxygen may be ______ to ______ times greater than at rest. |
15 to 25 |
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Does prolonged exercise at high HRs pose a risk for cardiac injury? |
Almost always "no" for healthy individuals |
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What is cardiovascular drift? |
Increased HR and decreased SV due to the influence of rising body temps. on dehydration and a reduction in plasma volume. Decreased plasma volume results in decreased venous return. Decreased venous return results in a decrease in SV. Hot/humid environment amplifies the affect. |
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How does the circulatory system respond to prolonged exercise? |
Gradual increase in HR and decrease in SV due to cardiovascular drift. Cardiac output is maintained because the magnitude of the increased HR offsets the decrease in SV. |
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How does the circulatory system respond to intermittent exercise? |
Depends on subject's fitness level, environmental conditions, duration, and intensity of exercise. Increased level of fitness leads to a faster recovery between bouts of exercise. Hot/humid climates slow recovery between bouts of exercise. |
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Why is both HR and BP higher when performing arm work as opposed to leg work? |
Higher HR is due to greater sympathetic outflow to the heart as-well as the fact that isometric exercise increases HR above the expected value based on relative oxygen consumption. Increased BP is due to the vasoconstriction of inactive muscle groups. Less arterioles are dilated due to the arms being a smaller muscle group than the quads. |
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At the same oxygen uptake, both HR and BP are ______ during arm work when compared to leg work. |
higher |
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How does the circulatory system respond to incremental exercise? |
HR and cardiac output increase linearly with workload and plateaus at 100% VO2 max. MAP increases linearly (increase in SBP while DBP remains the same) |
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What are the practical applications of the double product? |
Used as a guideline to prescribe exercise intensity for patients with coronary artery blockage. This would reduce the risk of the patient developing pain during exercise due to high metabolic demand on the heart. |
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Changes in HR and BP during exercise depend on what factors? |
Type, intensity, duration Environment Emotional influence |
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How does hot/humid conditions impact recovery? |
Prolongs recovery because elevated body temp delays the fall in HR during recovery |
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Why do well-conditioned subjects recover faster than untrained subjects? |
Because they don't achieve as high of a HR as untrained subjects. |
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Recovery time depends on what two factors? |
Duration and intensity Training state of the subject |
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How does the circulatory system respond when transitioning from exercise to recovery? |
HR, SV, and cardiac output all decrease rapidly back toward resting levels. |
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How does the circulatory system respond when transitioning from rest to exercise? |
There is a rapid increase in HR, SV, and cardiac output. If the exercise is submaximal, the increase will plateau with 2-3 min. |
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How does an "emotionaly charged atmosphere" impact the cardiovascular system's response to exercise? |
Can raise pre-exercise heart rate and blood pressure, but does not alter peak HR and BP during exercise. |
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What is nitric oxide? Where is it produced? How does it cause vasodilation? |
Potent vasodilator Endothelium of the arterioles Promotes smooth muscle relaxation in the arteriole |
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At rest, there is relatively low blood flow to muscle (_____ to ______ mL per min. per ______ grams of muscle), but because muscles have a large mass, this accounts for ______% to ______% of total blood flow from the heart. |
4-5mL 100g 20-25% |
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At rest, arterioles in skeletal muscle have a _______ vascular resistance. This is due to _______ ________ _________, which causes arteriole smooth muscle to contract. |
High Adrenergic sympathetic stimulation |
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What makes the blood flow to the viscera decrease during exercise? |
The sympathetic nervous system increases output to these organs which is regulated by the cardiovascular control center. This results in vasoconstriction which decreases blood flow to 20-30% of resting values. |
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How do skeletal muscles regulate blood flow during exercise? |
Through the process of autoregulation combined with "recruitment" of the capillaries in skeletal muscle. |
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Skin blood flow ________ during both light and moderate exercise, but _______ during maximal exercise. |
increases decreases |
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During heavy exercise, the percentage of total cardiac output that goes to the brain is _______ compared to rest. However, the absolute blood flow that reaches the brain is slightly _______ above resting values. |
Reduced increased |
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The amount of blood redistributed during exercise is dependent upon the _______ ________. |
Metabolic rate; increased intensity = increased redistribution |
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During maximal exercise, blood flow ______ to the liver, kidney, and GI tract. |
decreases |
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At rest, _______% to _______% of total cardiac output is directed toward skeletal muscle. During maximal exercise, _____% to ____% of total cardiac output is directed to contracting skeletal muscle. |
15-20% 80-85% |
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Why does an endurance athlete's SV not plateau at 40-60% VO2 max? |
They have improved ventricular filling during heavy exercise due to increased venous return. This increase in EDV results in increased force of contraction and an increase in stroke volume. |
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What is the physiological explanation for the plateau of SV at 40-60% VO2 max in untrained subjects? |
At high HRs, the time available for ventricular filling is decreased. Therefore, diastole and EDV decreases. |
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Would an increase in either cardiac output or a-vO2 diff. result in a higher or lower VO2? |
Would cause an increase (higher) |
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An increase in the a-vO2 diff. during exercise is due to what? |
An increase in the amount of O2 taken up and used for oxidative production of ATP by skeletal muscle. |
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What does a-vO2 diff. represent? |
The amount of oxygen that is taken up from 100mL of blood by the tissues during one trip around the systemic circuit. |
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What is the Fick Equation? |
VO2 = Cardiac output * (a-vO2 diff.) |
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At work loads greater than 40% to 60% VO2 max, the rise in cardiac output is achieved by ________ _________ alone. |
heart rate |
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At what percent VO2 max does stroke volume plateau in untrained subjects? |
40-60% |
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What is the formula for calculating max HR in children? |
208-.7(age) |
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What is the formula for calculating max HR in adults? |
220-age +/-15 |
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Maximal cardiac output tends to decrease in a linear fashion in both men and women after age _____? |
30 |
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Cardiac output increases during exercise in direct proportion to the _________ _________ required to perform the exercise task. |
Metabolic rate |
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Increased oxygen delivery to exercising skeletal muscle is accomplished via what two mechanisms? |
Increased cardiac output Redistribution of blood flow from inactive organs to the working skeletal muscle |
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During exercise, oxygen demand by muscles is ______ to ______ times greater than at rest. |
15-25 |
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Arterioles are often called? |
Resistance vessels |
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The greater vascular resistance in blood flow occurs in? It is responsible for ______% to _____% of the decline in mean arterial pressure. |
Arterioles 70-80% |
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When calculating the change in pressure, P1 and P2 represent what? |
P1 = pressure of the blood in the aorta P2 = pressure in the right atrium |
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The primary factor regulating blood flow through the organs is? |
The radius of the blood vessel |
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Reducing the radius of a blood vessel would increase or decrease the resistance? |
Increase |
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An increase in either length or viscosity woul result in an increase or decrease in resistance? What about a decrease? |
An increase in resistance A decrease in resistance |
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Increases in blood flow are achieved primarily by? |
A decrease in resistance with a small rise in blood pressure. |
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An increase in blood flow would mean there is an increase or decrease in delta pressure? |
Increase |
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An increase in blood flow would mean there is an increase or decrease in resistance? |
Decrease |
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What are the equations for blood flow and resistance? |
BF = delta pressure/resistance Resistance = length * viscosity/Radius^4 |
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The average hematocrit of a college age male is ______% and _______% for females. |
42% 38% |
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Which type of cell constitutes the largest fraction of cells within the blood? |
Red blood cells |
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The percentage of the blood that is composed of cells is called? |
Hematocrit |
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What are the functions of red blood cells, white blood cells, and platelets? |
RBCs contain hemoglobin used to transport oxygen. WBCs prevent infection. |
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What are the three types of cells found in the blood? |
RBC WBC Platelets |
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The liquid portion of the blood that contains numerous ions, proteins, and hormones. |
plasma |
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The study of pressure, flow, resistance, and physical properties of the blood. |
Hemodynamics |
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How is the strength of ventricular contraction enhanced? |
Circulating catecholamines increase entry of extracellular Ca++ into cardiac muscle fibers. Direct sympathetic stimulation of the heart by cardiac accelerator nerves. |
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How does the average aortic blood pressure influence stroke volume? |
In order for the ventricles to eject blood, the pressure generated by the left ventricle must exceed the pressure of the aorta. Therefore, a decrease in aortic pressure results in increased stroke volume. Aortic pressure is minimized during exercise due to arteriole dilation in working muscles. |
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How does the respiratory pump increase venous return? |
During inspiration, pressure in the thorax decreases and abdominal pressure increases which creates a flow of venous blood into the thorax. This effect is enhanced during exercise due to greater respiratory rate and depth. *Primary factor in venous return* |
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How does the muscle pump increase venous return? |
Rhythmic skeletal muscle contractions compress veins and push blood back towards the heart. Veins refill between contractions. Blood is prevented from flowing away from the heart by one way valves located in the larger veins. Muscle pump cannot operate during isometric exercise. |
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How does venoconstriction increase venous return? |
By reducing the volume capacity of the veins to store blood. This results in more blood moving back to the heart. Occurs via a reflex sympathetic constriction of smooth muscle in veins which drains skeletal muscle. This is controlled by the cardiovascular control center. |
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What principle variable influences EDV? |
venous return |
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What factors regulate venous return during exercise? |
Venoconstriction Muscle pump Respiratory pump |
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What is the Frank-Starling mechanism? |
States that the strength of ventricular contraction increased with an enlargement of the EDV (stretch of the ventricles). Increased EDV results in a stretching of the ventricles which improves force of contraction. Allows more myosin cross bridges to form with actin. |
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The volume of blood in the ventricles at the end of diastole. "pre-load" |
End-diastolic volume |
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Stroke volume is regulated by what three variables? |
EDV average aortic pressure strength of ventricular contraction |
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The balance between the effects of the sympathetic and parasympathetic nervous systems is called? |
Sympathovagal balance |
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What is the physiological cause of low HRV? |
imbalance in sympathetic/parasympathetic regulation |
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Low HRV is a risk factor for what diseases? |
CVD Heart failure Myocardial infarction Hypertension |
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Variation in the time between heart beats. |
heart rate variability |
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What are beta blockers? |
Blocks the effects of epinephrine and norepinephrine by binding to the beta receptors in the heart, blocking both hormones. Results in a decrease in HR and a decrease in the force of myocardial contraction. |
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How does the sympathetic nervous system increase HR? |
Sympathetic fibers reach the heart by means of the cardiac accelerator nerves. These nerves innervate the SA and AV nodes by releasing norepinephrine upon stimulation. Norepinephrine acts on the beta receptors of the heart and causes an increase in HR and force of myocardial contraction. |
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During exercise, the initial increase in HR (up to 100 BPM) is due to? At higher work rates, what is responsible for increasing HR? |
Withdrawal of the parasympathetic tone Stimulation of the SA and AV nodes by the sympathetic nervous system. |
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During heavy exercise, both untrained males and females have a _______ HR and a _______ SV when compared to trained males and females. |
Higher Lower |
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At rest, both untrained males and females have a ________ HR and a _______ SV when compared to trained males and females. |
Higher Lower |
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Impulses carried to the SA and AV nodes by the vagus nerve. |
Parasympathetic tone |
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How does the parasympathetic nervous system decrease HR? |
Parasympathetic fibers that supply the heart arise from neurons in the cardiovascular control center in the medulla oblongata. Upon reaching the heart, the fibers make contact with the AV and SA nodes. The nerve endings release acetylcholine which decreases SA and AV node activity due to hyperpolarization which results in decreased heart rate. |
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The amount of blood ejected in contraction of the heart is called? |
Stroke volume |
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What causes the gender diff. in SV and cardiac output? |
Men typically are larger than women. |
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What is the formula for cardiac output? |
Q = HR * SV |
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Why is atrial repolarization not seen on an ECG? |
It is hidden within the QRS complex |
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What does the T-wave of an ECG represent? |
Ventricular repolarization |
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What does the QRS complex of an ECG represent? |
Depolarization of the ventricles |
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What does the P-wave of ECG represent? |
Atrial depolarization |
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Collection of fatty plaque inside coronary vessels. |
Atherosclerosis |
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What can ECGs be used to diagnose? |
Electrical problems within the heart Coronary artery disease |
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A recording of the electrical changes that occur in the myocardium during the cardiac cycle. |
Electrocardiogram (ECG) |
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Why is there a .10s delay in the depolarization of the AV node? |
Allows atrial contraction to empty atrial blood into the ventricles prior to ventricular depolarization and contraction. |
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Serves as the pacemaker for the heart. |
Sinoatrial node (SA node) |
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How is blood pressure regulated? |
Acute regulation is achieved by the sympathetic nervous system. Long term regulation is a function of the kidneys. Baroreceptors in the carotid artery and aorta send impulses to the cardiovascular control center which responds by decreasing sympathetic activity. This results in a lower cardiac output and/or reduced vascular resistance. If BP decreased, there is a decrease in baroreceptor activity which results in the cardiovascular control center increasing sympathetic nervous system outflow. |
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What factors influence mean arterial blood pressure? If any of these factors increase, blood pressure will also increase, and vice versa. |
Blood volume Heart rate Stroke Volume Blood viscosity Peripheral resistance |
