Heart

Closed Circulation Blood never leaves vessels Blood never leaves vessels

Double Circulatory System -In mammals, birds and reptiles, the blood is pumped twice before returning to its origin -Fish, and other lower organisms pump the blood only once

Four Chambered Heart oxygenated and deoxygenated blood do not mix in the heart oxygenated and deoxygenated blood do not mix in the heart septum separates the right and left sides septum separates the right and left sides

Heart Chambers The top chambers are called atria (sing. Atrium) The top chambers are called atria (sing. Atrium) These collect blood from major veins and pump it into the bottom chambers These collect blood from major veins and pump it into the bottom chambers

Ventricles Much larger and more muscular than atria Much larger and more muscular than atria Pump blood into arteries for distribution to body (and lungs) Pump blood into arteries for distribution to body (and lungs)

Vessels Arteries – carry blood away from heart Arteries – carry blood away from heart Veins – carry blood toward heart Veins – carry blood toward heart Systemic circulation – blood flow to and from body organs (not lungs) Systemic circulation – blood flow to and from body organs (not lungs) Pulmonary circulation – blood flow to and from lungs Pulmonary circulation – blood flow to and from lungs

Heart Heart Heart How the Heart Works How the Heart Works How the Heart Works How the Heart Works

Atrioventricular Valves Separate the atria and ventricles Separate the atria and ventricles

Atrioventricular valves have: Atrioventricular valves have: –Chordae tendinae prevent flaps from everting (opening backward) –Papillary muscles to attach chordae tendinae to ventricle wall

The Bicuspid Valve (AV) Also called the mitral valve Also called the mitral valve On the left side of the heart On the left side of the heart Has two flaps Has two flaps

Tricuspid Valve (AV) On the right side On the right side Has three flaps Has three flaps

Semilunar Valves At the entrance to the major arteries are smaller valves with no muscular attachments At the entrance to the major arteries are smaller valves with no muscular attachments These have three flaps each and prevent backflow into the ventricles These have three flaps each and prevent backflow into the ventricles

Valve movie HeartValves.MOV HeartValves.MOV HeartValves.MOV HeartValves.MOV Video Video Video How a Normal Heart Pumps Blood How a Normal Heart Pumps Blood How a Normal Heart Pumps Blood How a Normal Heart Pumps Blood

Pericardium Membrane around heart which prevents friction between heart and lungs Membrane around heart which prevents friction between heart and lungs Also helps isolate infection Also helps isolate infection

Coronary Arteries The aorta branches and one of the branches comes back to serve the heart muscle (myocardium) The aorta branches and one of the branches comes back to serve the heart muscle (myocardium)

Coronary Circulation These arteries can become blocked with plaque (cholesterol and calcium deposits) and clots can occur causing: These arteries can become blocked with plaque (cholesterol and calcium deposits) and clots can occur causing: –pain: angina pectoris –Heart muscle death: myocardial infarction (heart attack)

Coronary Circulation

Risks for Heart Disease Genetics Genetics Male Male Smoking Smoking Obesity Obesity Diet (saturated fat and cholesterol) Diet (saturated fat and cholesterol) Lack of exercise Lack of exercise

Heart Beats Cardiac Muscle: striated, branched Cardiac Muscle: striated, branched Is myogenic muscle: can contract without nerve impulse Is myogenic muscle: can contract without nerve impulse

Heart Beats Chemoreceptors in aorta and carotid (neck) arteries detect high carbon dioxide levels in blood (lesser extent – oxygen is also monitored) Chemoreceptors in aorta and carotid (neck) arteries detect high carbon dioxide levels in blood (lesser extent – oxygen is also monitored) nerves carry this information to the heart nerves carry this information to the heart

Heart Beats The heart beat is controlled by the sympathetic (stimulating) and parasympathetic (relaxing) branches of the nervous system. The heart beat is controlled by the sympathetic (stimulating) and parasympathetic (relaxing) branches of the nervous system.

Heart Beats Tempo is set by the sinoatrial node (SA node) : the pacemaker Tempo is set by the sinoatrial node (SA node) : the pacemaker

Heart Beats Electrochemical impulses from the S.A. node cause contraction of atria muscle Electrochemical impulses from the S.A. node cause contraction of atria muscle

Heart Beats the impulse travels to another cluster of nervous tissue – the Atrioventricular node (A.V. node) the impulse travels to another cluster of nervous tissue – the Atrioventricular node (A.V. node)

Heart Beats The A.V. node sends impulses through Purkinje fibers to all parts of the ventricles The A.V. node sends impulses through Purkinje fibers to all parts of the ventricles Ventricles contract simultaneously Ventricles contract simultaneously

Heart Beats Heart muscle then ‘rests’ before the cycle begins again Heart muscle then ‘rests’ before the cycle begins again ‘systole’ – phase of heart contraction ‘systole’ – phase of heart contraction ‘diastole’ – phase of heart relaxation ‘diastole’ – phase of heart relaxation ‘lub – dub’ – heart sounds caused by valves slamming shut ‘lub – dub’ – heart sounds caused by valves slamming shut

Heart Beats Normal Heart Rate – 80 beats/minute Normal Heart Rate – 80 beats/minute Bradycardia - < 50 beats/min Bradycardia - < 50 beats/min Tachycardia - > 100 beats/min Tachycardia - > 100 beats/min

Monitoring Heart Beat EKG (or ECG) – electrocardiogram EKG (or ECG) – electrocardiogram Uses electrical activity in heart muscle to diagnose problems Uses electrical activity in heart muscle to diagnose problems

EKG P wave – depolarization preceding atrial contraction P wave – depolarization preceding atrial contraction QRS complex – precedes ventricular QRS complex – precedes ventricular T wave – repolarization of myocardium T wave – repolarization of myocardium

Ventricular Fibrillation

fibrillation fibrillation fibrillation

Defibrillator Used to shock hearts into proper rhythm Used to shock hearts into proper rhythm

Other Abnormal Rhythms tachycardia tachycardia

Bradycardia

Heart Technology stethescope stethescope

Heart Technology Artificial pacemakers – use batteries to produce a coordinated signal when ‘real’ pacemaker malfunctions

Heart Technology Valve Replacement : routinely done to fix valves scarred by infections, etc.

Cardiac Catheterization a thin catheter is inserted into a blood vessel, usually an artery in the leg or arm, and passed through the blood vessel to the heart. a thin catheter is inserted into a blood vessel, usually an artery in the leg or arm, and passed through the blood vessel to the heart. Dye is injected to make the coronary arteries and other structures visible on X- rays. Dye is injected to make the coronary arteries and other structures visible on X- rays.

Heart Technology Angioplasty: using a catheter and ‘balloon’ to open up blocked arteries Angioplasty: using a catheter and ‘balloon’ to open up blocked arteries

Heart Technology Coronary bypass: heart operation to use a vein from leg to bypass blockage Coronary bypass: heart operation to use a vein from leg to bypass blockage

Heart Transplant Often miraculous results Often miraculous results Shortage of organs Shortage of organs Person must take immunosupressants for life Person must take immunosupressants for life

Xenotransplants Dismal failures when whole heart is transplanted Dismal failures when whole heart is transplanted Pig arteries and valves have been used for years Pig arteries and valves have been used for years New genetic research hopes to produce pigs with human proteins New genetic research hopes to produce pigs with human proteins

Artificial Heart Some success as a bridge to transplant Some success as a bridge to transplant