The Cardiovascular System Flashcards
Describe the path of blood flow through the heart
- Superior/ inferior vena cava
- Right atria
- Tricuspid valve
- Right ventricle
- Pulmonary artery - lungs
- Pulmonary vein
- Left atria
- Bicuspid valve
- Left ventricle
- Aorta - muscles and organs
What does myogenic mean?
The capacity of the heart to generate its own electrical impulse, which causes the cardiac muscle to contract
What happens during diastole?
Relaxation phase. Passive filling of blood in the atria and ventricles
What happens during atrial systole?
Contraction of the atria
What happens during ventricular systole?
Contraction of the ventricles
Explain how the conduction system controls the cardiac cycle
An impulse is sent from the medulla oblongata. It arrives at the SA node. Atrial systole begins. The impulse travels to the AV node but is delayed to allow atrial systole to be completed. The impulse then travels along the Bundle of His to the Purkinje fibres where ventricular systole occurs.
Define heart rate
The number of times the heart beats per minute
Define stroke volume
The volume of blood ejected from the left ventricle per beat
Define cardiac output
The volume of blood ejected from the left ventricle per minute
What is the formula linking CO, SV and HR?
HR x SV = CO
Define venous return
Volume of blood returning to the heart
Give an average value for resting heart rate for both untrained and trained individuals
Untrained: 70-72bpm
Trained:5obpm
Give an average value for resting stroke volume for both untrained and trained individuals
Untrained: 70ml
Trained: 100ml
Give an average value for resting cardiac output for both untrained and trained individuals
Untrained: 5l/min
Trained: 5l/min
What is the difference between sub-maximal exercise and maximal exercise?
Sub-maximal: low-to-moderate intensity. Associated with aerobic work
Maximal: high intensity. Associated with anaerobic work and fatigue
What happens to heart rate BEFORE sub-maximal exercise commences? (graph)
Increases due to an anticipatory rise caused by adrenaline
What happens to heart rate DURING sub-maximal exercise? (graph)
There is a rapid increase to increase blood flow and oxygen delivery. The graph then plateaus and the heart rate is at a steady state as oxygen supply=oxygen demand
What happens to heart rate AFTER sub-maximal exercise? (graph)
Rapid decrease as recovery begins and then a more gradual decrease to bring HR to resting levels
How does the graph of heart rate over time during maximal exercise differ from the graph of sub-maximal exercise?
Does not plateau as exercise intensity continues to increase. There is a growing demand for oxygen and waste removal so HR must meet this demand -rapid increase then slower increase
Why does stroke volume increase due to increased venous return?
There is a greater volume of blood returning to the heart so greater volume of blood can be ejected
What is Starling’s law?
Shows how stroke volume is dependent on venous return. Greater venous return causes greater pressure in ventricles which causes greater stretch on the ventricular walls. This increase the force of contraction so a greater volume of blood is ejected from the heart
