Heart rate.

• What does ECG stand for?

  Electrocardiogram.
• • What is the ECG measuring?​

  Record the electrical activity of the heart from different angles to both identify and located pathology.
• What is the name given to the normal rhythm of the heart?

  Sinus rhythm
• Depolarisation is increase in electrical signal.
• Repolarisation is decrease in electrical signal.
• What does the p wave represent?

  Represent atrial depolarisation.
• What does the ST segment represent?

  the time between depolarisation and repolarisation of the ventricles.
• What is atrial fibrillation?

  is condition that disrupts your heartbeat.
• What is ventricular fibrillation (v-fib)?

  Is a dangerous type of arrhythmia, or irregular heartbeat.
• What is the most common cause of ventricular fibrillation?

  Occur during acute heart attack.

  When heart muscle does not get enough blood flow.
• What are the most common risk factors for V-Fib?

  A weakened heart muscle. An acute or prior heart attack. Certain medicines that affect heart function. Electrolyte abnormalities.
• Sympathetic nerve/ accerlerator nerve-speed up.
• Parasympathetic nerve/vagus nerve- speed down.
• P wave = atrial systole - both atria contract and force the blood from the atria into the ventricles
• QRS wave = ventricular systole - both ventricles contract, blood is forced to the lungs via the pulmonary trunk, and the rest of the body via the aorta.
• T wave = Ventricular diastole -  the period of the cardiac cycle that encompasses ventricular relaxation, passive and active filling of blood into the heart, and the period just prior to ejection.​
• sympathetic nerve releases noradrenaline at the signoatrial node and speeds up the heart.
• Parasympathetic nerve releases acetylcholine at the signoatrial - slows down the heart.
• Control of heart rate ​The brain controls the heart rate by stimulating the sino-atrial node (SA Node).​

  •Nerves will either speed up the heart rate or slow it down.​
• Heart rate is controlled by the Cardiovascular centre Found in medulla oblongata – Part of the brain ​
• Signals are sent to the brain from: ​

  Muscles - as they stretch and move and the heat created by active muscles​

  Blood - changes in partial pressure of carbon dioxide, oxygen and pH​

  Arteries - blood pressure (stretch of vessels)​
• P waves represent atrial depolarisation.
• PR interval begins at the start of the P wave and ends at the beginning of the Q wave. It represents the time taken for the electrical activity to move between the atria and the ventricles
• ORS complex represents depolarisation of the ventricles it appears as three closely related waves on the ECG (the Q, R and S wave.)
• ST segment starts at the end of the S wave and ends at the beginning of the T wave. The ST segment is an isoelectric that represents the time between depolarisation and repolarisation of the ventricles (i.e ventricular contraction)
• T wave represents ventricular repolarisation it appears as a small wave after the QRS complex.
• RR interval begins at the peak of one R wave and ends at the peak of the next R wave it represents the time between two QRS complexes.
• QT interval begins at the start of QRS complex and finishes at the end of the T wave. It represents the time taken for the ventricles depolarise and then repolarise.
• Atrial fibrillation is a condition that disrupts your heartbeat. A glitch in the hearth's electrical system makes it's upper chambers (the atria) beat so fast they quiver, or fibrillate. This causes the lower chambers ( the ventricles) to beat out of sync.
• Atrial fibrillation can be dangerous because it raises your risk of stroke and heart failure. Usually the atria and ventricles work together so the heart pumbs blood steady rhythm. But in atrial fibrillation they don't. The irregular beats can cause a fast, fluttering heart rate 100-175 beats per minute instead of the normal 60-100 beats per minute.
• Ventricular fibrillation (V-fib) is a dangerous type of arrhythmia that occurs when the heart's electrical impulses are not being transmitted properly.
• Ventricular fibrillation (V-fib) is a dangerous type of arrhythmia, or irregular heartbeat. It affects your's hearts ventricles. Your heart is a muscle system that contains 4 chambers; the 2 bottom chambers are called ventricles. In a healthy heart, your blood pumps evenly in and out of these chambers. This keeps blood flowing throughout your body.
• An arrhythmia that starts in your ventricle is called ventricular fibrillation. This occurs when the electrical signals that tell your heart muscle to pump cause your ventricles to quiver (fibrillate) instead. The quivering means that your heart is not pumping blood out to your body. In some people, V-fib may happen several times a day. This called an "electrical storm"
• The cause of ventricular fibrillation is not always known but it can occur during certain medical conditions. V-fib most commonly occurs during an accute heart attack or shortlt thereafter. When heart muscle does not get enough blood flow, it can become electrically unstable and cause dangerous heart rhythms. A heart that has been damaged by a heart attack or other heart muscle damage is vulnerable to V-fib. Other causes include electrolyte abnormalities such as low potassium, certain medicines, and certain genetic diseases that affect the hearts ion channels or electrical conduction.