intro to cardiovascular system Flashcards
Name the 3 layers of cardiac muscle
(innermost layer to the outermost)endocardium, myocardium and epicardium.
Name the two parts of the major vein that drain venous blood back into the heart.
Inferior vena cava and the superior vena cava, empty out into the right atrium.
Name the two chambers and the valve of the right side of the heart.
The right atrium, the tricuspid valve (remember: you have to try it to be right) and the right ventricle.
Explain how blood flows through the right side of the heart.
Venous blood drains into the right atrium via the IVC and SVC. Then the right atrium contracts to force blood through the triscuspid valve before it is pumped into the right ventricle. The right ventricle contracts to pump blood through the pulmonary valves into the pulmonary artery. This blood is going to the lungs to be oxygenated.
Which ventricle is bigger, the left or right? Why?
The left ventricle is bigger because; -it must pump blood to the whole body, not just the lungs. -it must pump this blood at a higher pressure to reach the periphery.
Name the two chambers of the left side of the heart and the valve between them.
The left atrium, the bicuspid or mitral valve and the left ventricle.
Explain how blood flows through the left side of the heart.
Oxygenated blood returns to the left atrium from the lungs via the 2 pulmonary veins. The left atrium contracts to push blood through the mitral valve into the left ventricle. The left ventricle contracts to push blood through the aortic valves into the aorta, and onto the periphery.
In which vessel type does gas exchange take place in the periphery?
Capillaries-they are only one cell thick and enable easy diffusion and exchange of gases and fluid.
Does the myocardium have the potential to store energy?
No- the myocardium requires a constant supply of oxygen because it is always producing its own energy to use on a minute to minute basis.
How is venous blood from the cardiac tissue itself returned to the right atrium?
It is returned via the coronary sinus. The coronary sinus collects all the cardiac venous blood and drains directly into an opening in the right atrium, bypassing the systemic venous circulation.
Where does the heart get its own blood supply from?
The aorta has small openings in it called the coronary orifices. These orifices are closed off by the aortic valves during systole, but are opened during diastole. oxygenated blood drains into the coronary orifices during diastole, supplying the myocardium with blood.
What is the location and function of the sinoatrial node?
The sinoatrial node is located on the right atrium, near the opening of the SVC. It is a cluster of specialised pacemaker cells that maintain heart rate by generating action potentials.
Depolarisation of the sinoatrial node results in the contraction of which heart chambers?
The right and left atria will contract simultaneously.
The Sinoatrial node is located on the right atrium. Given that both atria contract from the depolarisation of the SA node, how then does the left atrium get the message to contract?
Bachmann’s bundles: This is a connecting bridge or bundle of nerves from the right atrium to the left atrium. When the SA node depolarises, then the AP spreads to the left atrium via Bachmann’s bundles.
What is the location and function of the atrioventricular node?
The AV node is located on the surface between the atria and ventricles (middle of the heart). The AV node recieves the AP from the SA node and delays the signal long enough to allow all the blood to drain from the atria into the ventricles. Finally, the AV node will pass the signal onto the ventricles, where they contract.
What does this wave on the ECG represent?
This is a P-wave
The P-wave indicates atrial depolarisation by the SA node, and thus atrial contraction.
Note that the single P-wave is indicative of the contraction of both atria contracting.
What does this segment on the ECG represent?
This is the PR segment
It represents the AV node recieving and delaying the AP from the SA node.
During this time, the ventricles are filling up in preparation for systole.
what does this wave on the ECG represent?
This is the QRS complex.
It represents ventricular depolarisation and contraction.
what does this segment on the ECG represent?
This is the ST segment.
It represents the period of time where no ions are moving after ventricular contraction, but before ventricular repolarisation.
In depolarisation of the myocardium, we see a Na+ ion influx into the cell.
During repolarisation, we see a K+ ion efflux out of the cell.
The ST segment represents the time between these two stages, where no ions move at all.
what does this wave on the ECG represent?
This is the t-wave.
It represents ventricular repolarisation and the K+ efflux that causes this. Ventricular repolarisation is a time when the ventricle is relaxing after its big contraction
