ADVANCED BIOLOGY Heart

SIZE, SHAPE, LOCATION Fist Hollow, cone shaped Mediastinum, Rests on diaphragm, posterior to sternum, Lungs on each side

SIZE, SHAPE, LOCATION 2/3 lie to left of midsternal line Points toward right shoulder and left hip (apex, PMI)

STRUCTURE/FUNCTION 4 CHAMBERS 2 Superior Atria 2 Inferior Ventricles Divided by interatrial/interventricular septum

STRUCTURE/FUNCTION 4 CHAMBERS Most Mass in Right and Left Ventricles; pumping chambers Right= Forms most of the anterior surface Left= Forms inferoposterior aspect. Much more muscular!

STRUCTURE/FUNCTION 4 CHAMBERS Posterior Atrial walls are smooth Anterior Atrial walls are rigid with bundles of muscle tissue Atria are the Receiving chambers; thin walled

PATHWAY OF BLOOD Blood Flow through chambers Right Atrium – Superior Vena Cava, Inferior Vena Cava, Coronary Sinus Left Atrium – 4 Pulmonary veins pump blood back

PATHWAY OF BLOOD Right Ventricle – pumps blood to pulmonary trunk (goes to lungs) Left Ventricle – pumps blood to Aorta, then out to body

PATHWAY OF BLOOD Valves – Atrioventricular (AV) Right – Tricuspid Left – Bicuspid Semilunar valves in pulmonary trunk/aorta

PATHWAY OF BLOOD Pulmonary Circuit – Pulmonary veins have blood with oxygen Pulmonary arteries have blood without oxygen

PATHWAY OF BLOOD Systemic Circuit – Arteries have blood with oxygen Veins have blood without oxygen See page 662

MAJOR BRANCHES Coronary Circulation – supply blood to the heart Left Coronary – runs to left side and divides into two parts

MAJOR BRANCHES Anterior Interventricular artery Supplies blood to interventricular septum and anterior walls of ventricles

MAJOR BRANCHES Circumflex artery Supplies blood to the left atrium and posterior wall of left ventricle

MAJOR BRANCHES Right Coronary – Runs to the right and also divides into two parts

MAJOR BRANCHES Marginal Artery – lateral part of right side of heart (atrium) Posterior interventricular artery – Runs to the apex, supplies posterior ventricle walls

MAJOR BRANCHES Cardiac Veins – 1 major, 3 minor that dump into Coronary Sinus – empties blood into the right atrium. Located on Posterior side

MAJOR BRANCHES Great Cardiac Vein – Found in the anterior interventricular sulcus (groove) Middle Cardiac Vein – In posterior interventricular sulcus

MAJOR BRANCHES Small Cardiac Vein – runs along heart’s right inferior margin Several other anterior cardiac veins empty directly into Right Atrium

PROBLEMS? Myocardial Infarction (MI) – Heart Attack. Blockage to coronary arteries reduces blood flow Damage to the Left Ventricle is the most serious

CONDUCTION SYSTEM Intrinsic Cardiac Conduction System – Non- contractile cells that initiate and distribute impulses

CONDUCTION SYSTEM Sinoatrial Node (SA) – In right atria Heart’s Natural Pacemaker Atrioventricular Node (AV) – In interatrial septum above tricuspid valve

CONDUCTION SYSTEM Sinoatrial Node (SA) – In right atria Heart’s Natural Pacemaker Atrioventricular Node (AV) – In interatrial septum above tricuspid valve

CONDUCTION SYSTEM Atrioventricular Bundle (bundle of His) – electrical connection between atria and ventricle Bundle Branches – Run down interventricular septum to apex

CONDUCTION SYSTEM Purkinje Fibers – penetrate apex, run superiorly up ventricle walls Like milking a cow

ECG Electrocardiograph Waves include P – SA node sends first impulse

ECG QRS – Ventricular depolarization Precedes ventricular contraction T – Ventricular Repolarization

ECG Intervals P-R (P-Q) – Beginning of atrial excitation and ventricular contraction Q-T – Action potential through Heart

CARDIAC CYCLE Systole – Contraction of ventricles or atria Diastole – Relaxation of ventricles or atria

CARDIAC CYCLE Systolic Pressure – Ventricular contraction 120mmHg Diastolic Pressure – Ventricular refilling 80mmHg Hypertension – High BP Hypotension – Low BP

HEART SOUNDS Lub-dub Lub – AV valves close (systole) Dub – SL valves close (diastole)

HEART SOUNDS Murmurs – obstructions in BV Thin walled vibrations

CARDIAC OUTPUT CO = amount of blood pumped by each ventricle in 1 minute CO = HR x SV (stroke volume) SV = Volume of blood pumped out by ventricle (Force of contraction)

CARDIAC OUTPUT CO = 75 bpm x 70mLpb CO = 5250 mL/min

DEVELOPMENTAL ASPECTS Heart pumps by 23rd day 1-2 days later, chambers start to form Chambers are:

DEVELOPMENTAL ASPECTS Sinus venosus – receives all venous blood, becomes Rt. Atrium & Coronary Sinus, SA node Atrium – becomes muscle ridged parts of atrium

DEVELOPMENTAL ASPECTS Ventricle – Becomes left ventricle Bulbus cordis – Gives rise to the pulmonary trunk, first part of the aorta, most of the right ventricle

AGE RELATED CHANGES Sclerosis – Thickening of valve flaps Decline in Cardiac Reserve – Heart is less able to adjust to changes

AGE RELATED CHANGES Fibrosis of cardiac muscle – Scarred nodes, increase in arrhythmias Atherosclerosis – acclerated by inactivity, smoking, stress. CV disease