 What is the name and location of the hearts ‘pacemaker’?  What is the function of the hearts ‘pacemaker’?  What is the location and purpose of the atrioventricular node (AVN)?  What is an electrocardiogram?  How is the heart controlled by the nervous system? What do I remember?

Higher Human Biology Unit 2 Physiology and Health 4. Blood pressure and electrocardiograms

 What is an electrocardiogram?  What are electrocardiograms used for?  What does PQRST stand for in an electrocardiogram reading?  How do you calculate heart rate from an electrocardiogram?  What is blood pressure?  What affects blood pressure  How is blood pressure measured?  What is hypertension?  What does hypertension lead to? What do I need to know?

 When the heart beats the transmission of impulses through atria and ventricles creates tiny electric currents  The electric currents can be detected by electrodes on the skins surface  When connected to an oscilloscope and electrocardiogram is generated What is an electrocardiogram?

 ECG’s are used to detect heart abnormalities  E.g. atrial flutter  Rapid excitation of heart results in atria contracting faster than they should What are ECG’s used for?

What does PQRST stand for?  P – wave of excitation from SAN through atria  QRS complex – wave of excitation passing through ventricles  T – electrical recovery of ventricles  This is one complete heart beat  If you know how long this lasts you can work out heart rate in a specific period of time

Calculating heart rate from and ECG

 Blood pressure is the force exerted on the walls of the blood vessels  Generated by contraction of the ventricles  Highest in the aorta and pulmonary artery following ventricular systole  Pressure drops during diastole What is blood pressure?

 Blood pressure decreases as blood travels through arteries, arterioles, capillaries, venules and veins  Caused by increase in friction between blood cells and walls of blood vessels – resistance Blood pressure in vessels

 Measured using a sphygmomanometer  High reading is during systole  Low reading during diastole  Average normal reading 120/70 mm Hg How is blood pressure measured?

What does high blood pressure cause?  Hypertension is prolonged high blood pressure even when at rest  Can lead to:  Coronary heart disease  Strokes  Commonly found in people who:  Are over weight  Lead sedentary lifestyle  Diet with too much salt and fat  Consume excess alcohol  Under continuous stress

 What is an electrocardiogram?  What are electrocardiograms used for?  What does PQRST stand for in an electrocardiogram reading?  How do you calculate heart rate from an electrocardiogram?  What is blood pressure?  What affects blood pressure  How is blood pressure measured?  What is hypertension?  What does hypertension lead to? What do I need to know?

 Take your blood pressure  Testing you knowledge Q’s p172 No 1 – 4  Summary Chapter 11 and 12 Activities