Brief essay on the Heartbeat (AS Biology)
THE HEARTBEAT
Heartbeats are needed to pump blood around our bodies. Heartbeats are initiated with electrical impulses which start out in Sino Atrial Node. The Sino Atrial Node sends its electrical impulse to the atrium when it detects that it is full as when the atrium is full it contracts and squeezes the blood in to the ventricles. In order for the ventricles to squeeze the blood out of the ventricles and in to the arteries so it can be pumped around the body, the electrical message from the Atrial Ventricular Node needs to be at the bottom of the heart, otherwise known as the apex. This is so that the blood is squeezed from the bottom to the top so as to not put pressure on the apex of the heart. However, the Atrial Ventricular Node is positioned towards the top of the heart so in order for the electrical pulse to get to the apex, it has to travel down the septum (the middle of the heart). 1 problem with this is that the electrical impulse could spread to the cardiac muscles, causing it to contract which we do not want. To prevent this from happening we have a protective case surrounding our septum known as the Bundle of His. This prevents the contraction of cardiac muscle. When the ventricles or atriums contract, this is called ventricular/atrial systole. When the heart is relaxed, it is also known as dystole.
An ECG (electrocardiogram) is used to measure the rate and regularity of heartbeats, as well as the size and position of the chambers, the presence of any damage to the heart, and the effects of drugs or devices used to regulate the heart, such as a pacemaker. The first two ‘bumps’ in the ECG below show first the contraction of the atrium (P) (atrial systole) and secondly the contraction of the ventricles (QRS) (ventricular systole).
Heartbeats are needed to pump blood around our bodies. Heartbeats are initiated with electrical impulses which start out in Sino Atrial Node. The Sino Atrial Node sends its electrical impulse to the atrium when it detects that it is full as when the atrium is full it contracts and squeezes the blood in to the ventricles. In order for the ventricles to squeeze the blood out of the ventricles and in to the arteries so it can be pumped around the body, the electrical message from the Atrial Ventricular Node needs to be at the bottom of the heart, otherwise known as the apex. This is so that the blood is squeezed from the bottom to the top so as to not put pressure on the apex of the heart. However, the Atrial Ventricular Node is positioned towards the top of the heart so in order for the electrical pulse to get to the apex, it has to travel down the septum (the middle of the heart). 1 problem with this is that the electrical impulse could spread to the cardiac muscles, causing it to contract which we do not want. To prevent this from happening we have a protective case surrounding our septum known as the Bundle of His. This prevents the contraction of cardiac muscle. When the ventricles or atriums contract, this is called ventricular/atrial systole. When the heart is relaxed, it is also known as dystole.
An ECG (electrocardiogram) is used to measure the rate and regularity of heartbeats, as well as the size and position of the chambers, the presence of any damage to the heart, and the effects of drugs or devices used to regulate the heart, such as a pacemaker. The first two ‘bumps’ in the ECG below show first the contraction of the atrium (P) (atrial systole) and secondly the contraction of the ventricles (QRS) (ventricular systole).