EXSS1010 Lecture Notes - Lecture 6: Vasoconstriction, Aorta, Cardiac Output
30 May 2018
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EXSS1010 - CARDIOVASCULAR RESPONSES TO EXERCISE
LECTURE OBJECTIVES
1. Discuss the anatomy of the heart including chambers, values and blood supply
2. Understand the relationship between blood pressure and blood flow
3. Discuss how the vascular system assist blood flow both via the arterial and venous systems
4. Understand the concepts of heart rate, stroke volume and cardaic output
5. Discuss how they change under exercise related stress
THE CV SYSTEM
• Three major circulatory elements
1. A pump (heart)
2. Channels or tubes (blood vessels)
3. A fluid medium
• Heart is a four-chambered organ generates pressure to drive blood through vessels
• Muscular organ - myocardium
• Blood flow must meet metabolic demands
• Pumps ~70 mL for each beat
o At rest ~7220 L/day or ~198 million L over a 75 year timeline
THE HEART
• Four chambers
o Right and left atria: Receiving chambers
o Right and left ventricles: Pumping chambers
• Right side: Receives blood returning from the body & sends blood to lungs (pulmonary
circulation)
• Left side: Receives blood returning from the lungs & sends blood to the body (systemic
circulation)
• Separated by the interventricular septum
• Enveloped by the pericardium (Reduce any friction from the heart beating)
HEART CONTRACTION
• Atrial chambers to receive and store blood during ventricular contraction
• ~70% of the blood returning to the atria flows directly into the ventricles before the atria
contract (only 30% will be stored in the atria)
• The simultaneous contraction of both atria forces the remaining blood into the ventricles (to
be more efficient)
• Almost immediately after atrial contraction, the ventricles contract and propel blood into the
arterial system
THE HEARTS VALVES
• Prevent backflow
• Atrioventricular valves: (sits between atrium and ventricles)
o Tricuspid: flow from the right atrium to the right ventricle
o Bicuspid/Mitral: flow from the left atrium to the left ventricle
• Semilunar valves:
o Located in the arterial wall just outside the heart, prevent blood from flowing back into
the heart between contractions
find more resources at oneclass.com
find more resources at oneclass.com
ANATOMY OF THE HEART
Pulmonary artery carries deoxygenated blood (even though its an artery).
CORONARY CIRCULATION
• Right coronary artery
o Supplies right side of heart
o Divides into marginal, posterior interventricular
o Anterior cardiac viens
• Left (main) coronary artery
o Supplies left side of heart
o Divides into circumflex, anterior descending
o Coronary Sinus
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Four chambers: right and left atria: receiving chambers, right and left ventricles: pumping chambers, right side: receives blood returning from the body & sends blood to lungs (pulmonary circulation) Left side: receives blood returning from the lungs & sends blood to the body (systemic circulation) Separated by the interventricular septum: enveloped by the pericardium (reduce any friction from the heart beating) The hearts valves: prevent backflow, atrioventricular valves: (sits between atrium and ventricles, tricuspid: flow from the right atrium to the right ventricle, bicuspid/mitral: flow from the left atrium to the left ventricle. Semilunar valves: located in the arterial wall just outside the heart, prevent blood from flowing back into the heart between contractions. Pulmonary artery carries deoxygenated blood (even though its an artery). Coronary circulation: right coronary artery, supplies right side of heart, divides into marginal, posterior interventricular, anterior cardiac viens.
