The Heart

General Information The heart is the Pump of the Cardiovascular system The heart is the Pump of the Cardiovascular system Located behind the sternum, between the lungs Located behind the sternum, between the lungs Slightly shifted to the left side of the chest Slightly shifted to the left side of the chest Apex: Points downward Base: (Top) Where all major vessels leave the heart. Size: About the size of your fist

APEX BASE

Pericardium Membrane surrounding the heart Membrane surrounding the heart Two Parts: Two Parts: Fibrous Pericardium: Connects directly to heart Fibrous Pericardium: Connects directly to heart Dense connective tissue for protection Dense connective tissue for protection Serous Pericardium: Lines the inner surface of the pericardial sac Serous Pericardium: Lines the inner surface of the pericardial sac Pericardial Cavity: Lies between the two pericardial layers Pericardial Cavity: Lies between the two pericardial layers Filled with pericardial fluid: Reduces friction between membranes during heart beats Filled with pericardial fluid: Reduces friction between membranes during heart beats

Heart Anatomy Two Atria: Two Atria: Right and left atrium are receiving chambers Right and left atrium are receiving chambers Two Ventricles: Two Ventricles: Right and left ventricles are pumping chambers Right and left ventricles are pumping chambers Coronary Sulcus: Coronary Sulcus: Deep groove that separates atria from ventricles Deep groove that separates atria from ventricles

Major Vessels Superior Vena Cava: Returns blood from above the heart to the rt. Atrium Superior Vena Cava: Returns blood from above the heart to the rt. Atrium Inferior Vena Cava: Returns blood from below the heart to the rt. Atrium. Inferior Vena Cava: Returns blood from below the heart to the rt. Atrium.

Major Vessels Pulmonary Artery: Delivers Oxygen deficient blood to the lungs, from the rt. Ventricle Pulmonary Artery: Delivers Oxygen deficient blood to the lungs, from the rt. Ventricle Pulmonary Veins: Delivers oxygen rich blood to the left atrium from the lungs Pulmonary Veins: Delivers oxygen rich blood to the left atrium from the lungs Ascending Aorta: All oxygen rich blood being pumped from the left ventricle to the systemic circulation Ascending Aorta: All oxygen rich blood being pumped from the left ventricle to the systemic circulation Branches into many other major arteries Branches into many other major arteries

Heart Valves Atrioventricular Valves (cuspid valves): Atrioventricular Valves (cuspid valves): Between atria and ventricles Between atria and ventricles Rt. AV valve: Tricuspid valve (3 flaps) Rt. AV valve: Tricuspid valve (3 flaps) Lt. AV valve: Bicuspid valve (2 flaps) Lt. AV valve: Bicuspid valve (2 flaps) Cordae Tendinae: tendon like cords attached to valves that control blood passage Cordae Tendinae: tendon like cords attached to valves that control blood passage Valves open an close based on pressure differences Valves open an close based on pressure differences When pressure within the ventricles increase, valves close When pressure within the ventricles increase, valves close

Heart Valves Semilunar Valves: Semilunar Valves: Prevent the backflow of ejected blood Prevent the backflow of ejected blood Pulmonary Semilunar Valve: Between rt. Ventricle and pulmonary artery Pulmonary Semilunar Valve: Between rt. Ventricle and pulmonary artery Aortic Semilunar Valve: Between left ventricle and ascending aorta Aortic Semilunar Valve: Between left ventricle and ascending aorta

Heart Wall 3 Layers 3 Layers Epicardium: Very thin outer surface of the heart Epicardium: Very thin outer surface of the heart Myocardium: Muscular wall of the heart Myocardium: Muscular wall of the heart Cardiac muscle: Involuntary Cardiac muscle: Involuntary Endocardium: Inner surface of the heart Endocardium: Inner surface of the heart In direct contact with blood In direct contact with blood

Cardiac Blood Supply Coronary Circulation (Huge blood demand) Coronary Circulation (Huge blood demand) Lt. And rt. Coronary arteries: arise from ascending aorta Lt. And rt. Coronary arteries: arise from ascending aorta All coronary venous return empties into the coronary sinus and empties directly into the rt. Atrium All coronary venous return empties into the coronary sinus and empties directly into the rt. Atrium Angina Pectoris: Chest pain due to ischemia (lack of oxygen supply) Angina Pectoris: Chest pain due to ischemia (lack of oxygen supply) Myocardial Infarction (MI)/Heart Attack: death of tissue Myocardial Infarction (MI)/Heart Attack: death of tissue

The Heartbeat Conducting System: Conducting System: Heart is self activating Heart is self activating The heart has specialized cells that initiate and transmit impulses throughout the heart’s muscular tissue (myocardium) The heart has specialized cells that initiate and transmit impulses throughout the heart’s muscular tissue (myocardium) Sinoatrial Valve (SA): in the wall of the right atrium Sinoatrial Valve (SA): in the wall of the right atrium Sets the rhythm/pace of the heart Sets the rhythm/pace of the heart Atrioventricular Node (AV): between atria and ventricles Atrioventricular Node (AV): between atria and ventricles AV bundles, Bundle Branches, and purkinje fibers transmit these impulses throughout the heart AV bundles, Bundle Branches, and purkinje fibers transmit these impulses throughout the heart

The Heartbeat Conducting Pathway: 1. SV Node 2. AV Node 3. AV bundles 4. Bundle Branches 5. Purkinje Fibers

Heartbeat Cycle Systole: Contraction Systole: Contraction Diastole: Relaxation Diastole: Relaxation Pathway of Blood Propulsion Pathway of Blood Propulsion 1. Atrial systole (blood pumped to ventricles) and ventricular diastole (receive atrial blood) occur at the same time 2. Ventricular systole (pumps blood out of heart) and atrial diastole (receives blood from body and lungs) occur at the same time

Heart Murmur Valves do not close properly and blood gets pushed back through valves Valves do not close properly and blood gets pushed back through valves Can occur at any valve Can occur at any valve Usually occurs due to faulty cordae tendinae or papillary muscles Usually occurs due to faulty cordae tendinae or papillary muscles

Heartbeat Dynamics Heart rate (beats/minute) ~ 75 times/min. Heart rate (beats/minute) ~ 75 times/min. Blood Pressure: Pressure exerted on vessel walls Blood Pressure: Pressure exerted on vessel walls Read by a sphygnomometer as sounds Read by a sphygnomometer as sounds Measures left ventricle diastole and systole Measures left ventricle diastole and systole Read systole/diastole Read systole/diastole Avg. adult male ~ 120/80 Avg. adult male ~ 120/80 Avg. adult female ~ 110/70 Avg. adult female ~ 110/70 What happens if part of the vessels are blocked??? (i.e. atherosclerosis) What happens if part of the vessels are blocked??? (i.e. atherosclerosis)

Electrocardiogram (ECG)/(EKG): Measures electrical events within the heart (ECG)/(EKG): Measures electrical events within the heart P wave: Atrial depolarization P wave: Atrial depolarization QRS wave: Ventricle depolarization (masks atrial repolarization) QRS wave: Ventricle depolarization (masks atrial repolarization) T wave: Ventricle repolarization T wave: Ventricle repolarization

Heart Sounds Recorded using a stethoscope Recorded using a stethoscope 1 st sound: Lubb 1 st sound: Lubb Caused by the closing of the Atrioventricular valves as the ventricles contract Caused by the closing of the Atrioventricular valves as the ventricles contract 2 nd sound: Dubb 2 nd sound: Dubb Caused by the closing of the Semilunar Valve as the ventricles relax Caused by the closing of the Semilunar Valve as the ventricles relax Murmur: Caused by the swirling and gurgling of blood as it is forced back through valves Murmur: Caused by the swirling and gurgling of blood as it is forced back through valves

Cardiac Output Cardiac Output = (Stroke volume) X (Heart rate) Cardiac Output = (Stroke volume) X (Heart rate) CO = 75 bpm X 80 ml/beat CO = 75 bpm X 80 ml/beat CO = 6000 ml/min or 6.0 Liters/minute CO = 6000 ml/min or 6.0 Liters/minute Cardiac output is altered by either heart rate or stroke volume Cardiac output is altered by either heart rate or stroke volume Elite athletes actually have slower heart rates but increased stroke volumes Elite athletes actually have slower heart rates but increased stroke volumes Both are altered by autonomic nervous system and chemicals within the body Both are altered by autonomic nervous system and chemicals within the body