Exercise Physiology - Cardiovascular system: The Heart
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What is the cardivascular system composed of?
- Blood vessels that carry blood through body
Describe the heart and the path of blood after it leaves the heart
Powerful, fatigue-resistant organ that acts as a pump to drive blood returning from all parts of the body;
When does blood travel through lungs after leaving the heart and why?
Travels through lungs first to be oxygenated
What is the myocardium?
Main muscle of heart that contracts to pump blood
What are blood veseels responsible for?
- Delivering the oxygen and nutrient rich blood ejected from the heart to all needy tissues of the body;
- Returning oxygen-depleted blood carrying metabolic by-products from those tissues back to heart
What are the 4 chambers of the heart
- Right Atrium -- upper chamber;
- Left Atrium -- upper chamber;
- Right Ventricle -- lower chamber;
- Left ventricle -- lower chamber;
What's the function of the Left and Right atriums? what is the general function of the atria?
- Left atrium receives blood from lungs;
- Right atrium receives blood from all other parts of the body;
What is the general function of the atria?
General function is to pumpt blood into the right and left ventricles, which drives blood to lungs and rest of the body
What is the Septum?
Seperates the left and right sides of the heart
T/F - L and R ventricles contract in unison and L and R atria contract in unison.
Why are the contractions of the atria and ventricles staggered?
- While blood is being delivered to the ventricles, those chambers are in their resting phase;
- During contraction of the ventricles, the atria are at rest;
What is the coronary circulation?
Specialized circulation to provide oxygen to the heart and feed highly oxidative myocardium with oxygen-rich blood
What is the cadiac cycle?
Sequence of events during the heart's pumping action
Describe the phases of the cardiac cycle and define each phase
- Systole - Contractile phase of the myocardium;
- Diastole - Relaxtion phase between contractions
What is Stroke Volume (SV) and what is a typical resting SV?
- Volume of blood ejected from each ventricular contraction;
- Resting SV = 70 mL/beat
What is heart rate (HR), and what is a typical resting HR?
- Number of times the heart contracts with each ventricular contraction;
- At rest, HR is 72 beats/min
What is cardiac output (Q) and what is the formula for Q?
What is the typcial resting Q?
- Amount of blood pumped from the heart by each ventricle per minute;
- Q = HR * SV;
- Resting Q: 72 beats/min * 70 mL/beat = 5 L/min
What is End-diastolic Volume (EDV) and what is typical resting EDV?
- Amount of blood in each ventricle at the end of the resting phase (diastole) of the cardiac cycle;
- EDV at rest is125 mL
Describe the Frank-Starling Law
- EDV will significantly affect SVbecause the greater the volume of blood in the ventricle, the greater the stretch imparted on the myocardium;
- As stretch increases, so does contractile force, both by elastic recoil of the muscle and by optimizing the length of the fibers in the myocardium
What is End-systolic Volume (ESV) and what is a typcial resting ESV?
- Volume of blood remaining in each ventricle following it's contraction;
- At rest, ESV is 55 mL
What is Ejection Fraction (EF) and what is a typcical resting EF?
- Percentage (%) of blood in the ventricle during diastole that is actually pumped out during systole; A ratio of SV to EDV.
- EF = SV / EDV;
- Resting EF is 60%, although in healthy adults can range between 50% and 75%
What happens as exercise begins?
- 1) Greater demand for blood
- 2) Increased cardiac output directly linked to exercise intensity
- 3) Increased SV and HR
- 4) Increased EDV
At max effort, how high can cardiac output (Q) get and how is this brought about?
- 5 - 6 times resting output (25 - 30 L/min vs. 5 L/min);
- Brought about by increase in both HR and SV
How long will SV increase? What is peak SV in young, untrained men?
- Until is reaches about 50% of VO2max at which it levels off;
- Further increases in cardiac output (Q) will result in increased HR only;
- SV increases to 100 mL/beat
How does HR increase as it relates to exercise intensity?
- Linear relationship exists between HR and exercise intensity;
- Monitoring HR is a common method of assessing exercise intensity during submaximal efforts
What leads to elevation of End-diastolic Volume (EDV) and how high can EDV get?
- As greater amounts of blood are pumped to the working muscle, the amount of blood returing to heart is similarly enhanced;
- EDV can reach 160 mL when SV is at peak value;
- As EDV increases so does SV
What is another method the heart uses to amplify its pumping ability?
Increase its contractility which results in ejection fraction (EF) change from 60% at rest to peak of 70%
How does chronic aerobic training affect your HR?
- Has no effect on Maximal HR;
- Significantly lowers Resting HR after prolonged training;
How does chronic aerobic training affect SV?
- Because resting cardiac output (Q) remains the unchanged, SV increases to counteract HR decrease;
- At rest SV could be almost 85mL following prolonged training, depending on resting HR;
- SV coul be as high as 170 mL in trained athletes
How does submaximal training affect HR and SV as it relates to cardiac output (Q) in trained athletes?
Cardiac output remais unaltered and can be sustained with lower HR and higher SV values than in untrained people.
How does normal upright posture affect blood flow?
Greatly affects bood return to the heart
How does supine or prone position affect blood flow? How does this affect SV and HR?
- Allow more efficient return of blood from the legs;
- SV is greater during exercise in supine position (swimming) at any given intensity than during upright exercise (running, cycling);
- HR is lower during exercise in supine position than during upright exercise
What is the connective tissue that enclose the heart?
Pericardium in the mediastinum
What is the coronary sulcus?
Marks the border between the atria and the ventricles
What are auricles?
This muscular wall of the atria -- only called this when the walls are not filled with blood
What is the interventricular sulcus?
Marks the boundry between the right and left ventricles
Where do the great veins and arteries of the circulatory system connect to the heart?
At the base of the heart
What do the superior and inferior venae cavae do?
Send blood to the right atrium
What do coronary veins do?
Return venous blood from the myocardium to the coronary sinus which opens into the right atrium
What are atrioventricular valves (AV)?
- Allow each atrium to communicate with the ventricle;
- Right AV is called tricuspid valve;
- Left AV is bicuspid valve
Describe the sequence of how blood from the periphery flows through the heart.
- 1) Superior and inferior cavae;
- 2) right atrium;
- 3) tricupid valve;
- 4) right ventricle;
- 5) pulmonic semilunar valve;
- 6) pulmonary arteries;
- 7) lungs
Describe the sequence of how blood from the lungs flows to the heart
- 1) Left pulomonary vein;
- 2) Left atrium;
- 3) bicuspid valve;
- 4) left ventricle;
- 5) aortic semilunar valve;
- 6) ascending aorta;
- 7) systemic circulation
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