Week 8 - Cardiovascular System (Heart) Flashcards
List the main function of the heart
1) To transport O2, hormones and nutrients around the body
2) To remove CO2 and other waste products
Describe the flow of blood through the heart
1) Deoxygenated blood enters the right atrium via the superior and inferior vena cava
2) Right atrium contracts, propelling blood into the right ventricle
3) Right ventricles contracts, pumping blood to the lungs via the pulmonary arteries
4) Oxygenated blood enters the left atrium via the pulmonary veins
5) left atrium contracts forcing blood into the left ventricle
6) Oxygenated blood is pumped around the body
Why does the left ventricle have more muscle than the other 4 chambers?
It has to pump blood all around the body.
What is the purpose of heart valves?
To prevent the back flow of blood in the heart
What controls whether a heart valve is open or closed?
It is controlled by the blood pressure difference within the different chambers.
What are the 2 different classifications of heart valves and where are they located?
- Atrioventricular valves - Triscuspsid and mitral valves
* Semilunar valves - Pulmonary and aortic valves
What are the two heart sounds and what causes them?
- LUB - Closing of the atrioventricular valves
* DUB - Closing of the semilunar valves
What is the cardiac conduction system and what are its two functions?
Are a series of cardiac muscle cells and conducting fibres that are responsible for:
1) Initiating the normal cardiac cycle
2) coordinating the contraction of the 4 heart chambers
Describe the pathway of the electrical conduction system
• 1) Sinoatrial node (SA) - Is the natural pacemaker of the heart which initiates all heart beats and stimulates atrial contraction.
• 2) Atrioventricular node (AV) - electrical impulses travel to the AV node which delay the signal before atrial contraction
3) Atrioventricular bundle - Receives electrical signals from AV and transmits them to left and right bundle branches
4) Bundle branches - conduct impulses to the Purkinje fibres
5) Purkinje fibres - spread signals to the ventricular myocardium causing them to contract.
What does an electrocardiogram (ECG) represent?
Measures the electrical activity of the heart
Complete the following: • P-wave: • P-Q segment: • QRS complex: • T-wave:
Complete the following:
• P-wave: Represents atrial contraction (depolarisation), atrial repolarisation also occurs but is not visible.
• P-Q segment: Time taken for signal to be sent from SA to AV node.
• QRS complex: Represents ventricular contraction (depolarisation)
• T-wave: Represents ventricular repolarisation (relaxation).
What is the ‘cardiac cycle’ describing?
All the events that happen within a single heartbeat - involving the contraction and relaxation of the different areas of the heart.
Define systole
Involves the contraction of the myocardium of the heart
Define diastole
Involves the relaxation of the myocardium that allows the heart chambers to fill with blood.
List and describe the three phases of the cardiac cycle
1) Atrial systole - atria contracts forcing blood into the ventricles
2) Ventricular systole - ventricles contract forcing blood into the pulmonary artery and aorta
3) Atrial and ventricular diastole - atria and ventricles relax causing them to fill with blood.
Describe the events that occur in atrial systole: • Which part of the ECG - • Chamber contraction/relaxation - • What chamber changes pressure - • How does ventricular volume change - • What valves open and close -
- Which part of the ECG - P wave
- Chamber contraction/relaxation - Atrial contracts
- What chamber changes pressure - Increase in atrial pressure
- How does ventricular volume change - Increases
- What valves open and close - Atrioventricular valves open
Describe the events that occur in ventricular systole (isovolumetric contraction): • Which part of the ECG - • Chamber contraction/relaxation - • What chamber changes pressure - • How does ventricular volume change - • What valves open and close -
- Which part of the ECG - QRS
- Chamber contraction/relaxation - Ventricles contract
- What chamber changes pressure - Ventricular pressure increases
- How does ventricular volume change - No change in volume
- What valves open and close - All valves closed
Describe the events that occur in ventricular systole (ventricular ejection): • Which part of the ECG - • Chamber contraction/relaxation - • What chamber changes pressure - • How does ventricular volume change - • What valves open and close -
- Which part of the ECG - QRS
- Chamber contraction/relaxation - Ventricles contract
- What chamber changes pressure - Ventricular pressure increases
- How does ventricular volume change - Decreases
- What valves open and close - Semi lunar valves open
Describe the events that occur in ventricular diastole (isovolumetric relaxation): • Which part of the ECG - • Chamber contraction/relaxation - • What chamber changes pressure - • How does ventricular volume change - • What valves open and close -
- Which part of the ECG - T wave
- Chamber contraction/relaxation - ventricles relax
- What chamber changes pressure - decrease in ventricular pressure
- How does ventricular volume change - remains the same
- What valves open and close - All 4 valves closed
Describe the events that occur in ventricular diastole (volumetric relaxation): • Which part of the ECG - • Chamber contraction/relaxation - • What chamber changes pressure - • How does ventricular volume change - • What valves open and close -
- Which part of the ECG - after T wave
- Chamber contraction/relaxation - ventricles fill pasively
- What chamber changes pressure - ventricle pressure decreases
- How does ventricular volume change -incerases
- What valves open and close - atrioventricular valves open
Define cardiac output
Is the amount of blood that can be pumped from the left ventricle in one minute.
Define heart rate
Is the number of times a heart beats per minute
Stroke volume
Is the volume of blood pumped by the left ventricle with each heart beat
What is the equation for cardiac output?
Cardiac output (ml/min) = Heart Rate (beats/min) x Stroke volume (ml/beat).
What are the three factor that effect stroke volume?
- Contractility: The more forceful the contraction of the ventricles the more blood that can be pumped in each heart beat.
- Pre-load (end diastolic volume) - Is the amount of blood that is present in the ventricles before it contracts
- Afterload: The pressure that must be overcome for the semilunar valves to open to allow blood to be pumped around the body.
What is end diastolic volume?
Is the volume present in the ventricles after filling
What is end systolic volume?
Is the volume present in the ventricles after ejection
