Cardiovascular system pt.1 Flashcards
What is heart rate, resting value for untrained/trained and calculation?
- Heart rate is the number of times a heart beats per minute
- Untrained resting value is 72bmp. Trained resting value is 50bmp
- HR= CO/SV.
What is stroke volume, resting value for untrained/trained and calculation?
- Stroke volume is the amount of blood ejected from the left ventricle per beat.
- Untrained resting value is 70ml. Trained resting value is 100ml
- SV= CO/HR.
What is cardiac output, resting value for untrained/trained and calculation?
- Cardiac output is the amount of blood ejected from the left ventricle per minute.
- Untrained and trained resting value is 5l/m.
- CO= HR x SV.
What is the cardiac cycle?
- The cardiac cycle refers to cardiac muscle contraction and the movement of blood through it’s chambers
- One complete cardiac cycle is a single heartbeat
- At rest, a complete cardiac cycle takes 0.8 seconds
- It has 2 phases, diastole and systole.
What is diastole? Describe the process.
Diastole is the relaxion phase of the cardiac muscle where muscles fill with blood:
- Relaxation of the atria and ventricles lowers pressure within the heart
- Blood then passively flows through the atria and into the ventricles
- AV valves are open, allowing blood to move freely from the atria to the ventricles
- Semilunar valves are closed at this time.
What is systole? Describe the process.
Systole is the contraction phase of the cardiac muscle where blood is forcibly ejected into the aorta and pulmonary artery:
Atrial systole-
1. Atria contract, forcing blood into ventricles
Ventricular systole-
- Ventricles contract
- AV valves close
- Semilunar valves open
- Blood is pushed out of the ventricles and into the large arteries leaving the heart.
What is the conduction system?
The conduction system is the set of 5 structures which pass the electrical impulse through the cardiac muscle:
- SA node, generates electrical impulses, causing atria walls to contract
- AV node, collects the impulse and delays it by 0.1 seconds to allow atria to finish contracting
- Bundle of His, located in the septum, this splits the impulse in two, ready to be distributed to the ventricles
- Bundle branches, these carry the impulse to the base of each ventricle
- Purkinje fibres, these distribute the impulse through the ventricle walls, causing them to contract.
How does heart rate respond to sub-maximal exercise?
- Anticipatory rise before event begins, adrenaline is released
- Rapid increase when exercise starts as demand for oxygen for muscles quickly increases
- HR max is then reached, heart rate plateaus
- Rapid decrease when exercise finishes as demand for oxygen for muscles quickly decreases
- Slower decrease until heart rate reaches resting level.
How does heart rate respond to maximal exercise?
- Anticipatory rise before event begins, adrenaline is released
- Rapid increase when exercise starts as demand for oxygen for muscles quickly increases
- Slower increase but plateau is never reached
- Rapid decrease when exercise finishes as demand for oxygen for muscles quickly decreases
- Slower decrease until heart rate reaches resting level.
How does stroke volume respond to sub maximal exercise?
- SV increases in proportion to exercise until a plateau is reached at approximately 40-60% working capacity
- SV is able to increase due to increased venous return which applies the Frank-Starling mechanism
- SV reaches a plateau as increased HR towards maximal intensities does not allow enough time for the ventricles to completely fill in the diastole phase, limiting the Frank-Starling mechanism.
What is venous return and the Frank starling mechanism?
- Venous return is the return of the blood to the right atria through the veins
- Frank-Starling mechanism is when an increased VR leads to an increased SV, due to an increased stretch of the ventricular walls and therefore force of contraction.
How does cardiac output respond to maximal intensity?
- Cardiac output increases in a line with exercise intensity
- Plateaus during maximal exercise.
What is the sub-maximal/maximal heart rate, stroke volume and cardiac output for untrained/trained performers
HR-
Untrained: 100-130 bpm at sub-maximal, 220-age at maximal
Trained: 95-120 bpm at sub-maximal, 220-age at maximal
SV-
Untrained: 100-120ml at sub-maximal and maximal intensity
Trained: 160-200ml at sub-maximal and maximal intensity
CO-
Untrained: 10-15 l/m at sub-maximal, 20-30 l/m at maximal
Trained: 15-20 l/m at sub-maximal, 30-40 l/m at maximal
What is bradycardia?
Bradycardia is a heart rate below 60bpm
