📚 Seth MB


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Heart Revision Pack

Last updated May 26, 2023 Edit

# Order of cardiac cycle

Event -> Immediately followed by

Atrial walls start to relax -> ventricle walls start to contract

Sinoatrial node generates electrical signals -> electrical signals transmitted down septum

Atrioventricular node receives electrical signals from SA node -> Ventricle walls start to contract

Ventricle walls start to contract -> Walls of atria contract

Ventricle walls relax -> atrioventricular valves open


# Tachycardic ECG trace

# Effect of tachycardia on blood flow from heart

# Foramen Ovale open in fetus before birth – why?

The blood is oxygenated by the mother rather than the fetus, meaning that the heart does not need to pump blood around the lungs with the same vigour as normal. The foramen ovale allows blood to travel around the body in a more natural way despite the lungs being non-functional.

# Difference and reason for difference between adult and fetal haemoglobin

# Why does tissue fluid not contain erythrocytes but neutrophils?

# Erythrocytes are full of haemoglobin. Describe the role of haemoglobin in transporting oxygen around the body.

Haemoglobin is responsible for binding to oxygen and disassociating from it at appropriate points around the body. Adult haemoglobin will pick oxygen up in an area where the ppO2 (partial pressure of oxygen)is HIGH. And will disassociate from it in areas where the partial pressure is LOW.

# Describe how hydrogen carbonate ions are produced in erythrocytes

# High concentrations of carbon dioxide in the blood reduce the amount of oxygen transported by haemoglobin. Name and explain this effect.