Draw the human heart and the main blood vessels in/out of the heart.

Label the following on your diagram: 4 chambers 4 valves All blood vessels going into/out of heart Using a blue pencil, indicate oxygen-

poor blood flow Using a red pencil, indicate oxygen-rich

blood flow

Cardiac muscle cells can contract spontaneously and independently

Regulation of heart activity:1. Autonomic nervous system

▪Epinephrine, thyroxine: heart rate▪Low Ca2+ levels: heart rate

2. Intrinsic conduction system▪Built into heart tissue & sets basic rhythm▪Pacemaker = Sinoatrial (SA) NodeSinoatrial (SA) Node

Sequence of action:1.Sinoatrial (SA) node – right atrium

▪ Generates impulses Starts each heartbeat

2.Atrioventricular (AV) node – between atria & ventricles▪ Atria contract

3.Bundle of His (or AV bundle) 4.Bundle branches – interventricular septum5.Purkinje fibers – spread within ventricle walls

▪ Ventricles contract

Records the electrical activity of the heart Electrocardiograph: graphic record of heart activity

P wave: atria contact

QRS complex: ventricles contract

T wave: ventricles relax

Cardiac cycle Cardiac cycle = events of one heartbeat SystoleSystole: contraction of ventricles DiastoleDiastole: relaxation of ventricles Cardiac Output Animation

““LubLub””: : closing of AV valves

““DubDub””: : semilunar valves close at end of systole

Angina pectoris: heart muscle deprived of O2,crushing chest pain

Myocardial infarction (Heart Attack): prolonged angina, heart cells may die

Ischemia: Lack of adequate blood supply to heart

Fibrillation: uncoordinated shuddering of heart muscle, useless pump

Major cause of death from heart attacks

Damage to SA node slower heart rate Install artificial pacemaker

Damage to AV node Heart block: ventricles beat at own rate (slower or not at all)

Tachycardia: rapid heart rate (>100 beats/min)

Bradycardia: very slow heart rate (<60 beats/min)

Heart murmur: abnormal or unusual heart sounds Often valve problems

Cardiac Output (CO) = Heart Rate (HR) x Stroke Volume (SV) Stroke volume: volume of blood pumped

out by one ventricle with each best

Average adult:CO = HR (75 beats/min) x SV (70 ml/beat)

CO = 5250 ml/min

Progressive weakening of heart Low heart efficiency circulation

inadequate to meet tissue needs Caused by:

Coronary atherosclerosis – clogged coronary vessels

Persistent high blood pressure Multiple heart attacks – scar tissue