the heart Flashcards
What are the functions of the right and left sides of the heart? (3)
Right side = Pumps deoxygenated blood to the lungs
Left side = Pumps oxygenated blood around the body
The left ventricle has thicker muscle to generate enough pressure for systemic circulation
How do AV and SL valves prevent backflow of blood? (3)
Valves open one way, and the relative pressure in the heart chambers determines whether they open or close
Open: When the pressure is higher behind the valve
Closed: When the pressure is higher in front of the valve
What are the key steps in examining the external and internal structure of the mammalian heart? (2)
External: Identify the four main blood vessels
Internal: Measure the thickness of the ventricle and atria walls, and locate and examine the AV and SL valves
What happens during atrial systole? (2)
- Atria contract, increasing pressure and pushing blood into the ventricles through open AV valves
- Ventricles are relaxed, and the SL valves are closed
What happens during ventricular systole? (3)
- Ventricles contract
- Increasing pressure + decreasing volume and causing the AV valves to close (‘lub’ sound)
- The pressure forces the SL valves open, and blood is pumped into the pulmonary artery and aorta
What happens during cardiac diastole? (3)
- Atria and ventricles relax
- SL valves close (‘dub’ sound) as the pressure in the pulmonary artery and aorta is higher
- Blood flows passively into the ventricles from the atria.
How is heart action initiated and coordinated? (6)
- The heart is myogenic, meaning it can contract without nervous signals
- The sino-atrial node (SAN) in the right atrium initiates electrical signals
- Causing both atria to contract
- Electrical activity is passed to the atrioventricular node (AVN)
- Then through the bundle of His to the Purkyne fibres
- Causing the ventricles to contract
What do the P wave, QRS complex, and T wave represent on an ECG trace? (3)
P wave: Atrial contraction (depolarisation)
QRS complex: Ventricular contraction (depolarisation)
T wave: Ventricular relaxation (repolarisation)
What does the height of the waves on an ECG represent? (2)
The height corresponds to the amount of electrical activity in the heart
The bigger the wave, the stronger the contraction
What are some common heart rate abnormalities seen on an ECG? (4)
Tachycardia: Heartbeat is too fast (at rest)
Bradycardia: Heartbeat is too slow
Ectopic heartbeat: An extra heartbeat
Fibrillation: Irregular heartbeat, with the atria and ventricles losing their rhythm
