CIRCULATORY SYSTEM AND THE HEART

Heart Anatomy 4 chambers of the heart

Right and Left Atrium (enters heart) Right and Left Ventricles (leaves the heart)

2 atria contract simultaneously and shortly after 2 ventricles contract

REAL THING!!! Minus the Pericardium

Posterior Surface View

Frontal section (interior chambers)

Heart ValvesKnow this and not what is in your text!

Atrioventricular valves Tricuspid valve (Right A.V. valve) Bicuspid valve (Left A.V. valve)

ALSO Mitral valve

Semilumar valves Aortic semilunar valve (aorta) Pulmonary semilunar valve (pulmonary trunk)

Heart Valves

Superior/ Inferior Vena Cava

Right Atrium

Right Ventricle

Pulmonary Artery

Lungs

Pulmonary Veins

Left Atrium

Left Ventricle

Aorta

Body Tissue

Sinoatrial (S-A) Node (Pacemaker)

Specialized muscle tissue, located in the wall of the R. atrium, stimulates the muscle fibers to contract and relax rhythmically

Atrioventricular (AV) Node As atria contract, impulse reaches A-V

node Transmits electrical impulse over the

walls of the ventricles to start ventricular contraction

Cardiac Intrinsic Conduction System

(ECG) Electrocardiogram Records electrical activity P = atrial depolarization QRS = ventricular depolarization T = ventricular repolarization

When does the atrial repolarization occur?

ELECTROCARDIOGRAPH (ECG)

Chemical Regulators Noradrenaline – makes the S-A node fire

more rapidly (during exercise or “fight or flight”)

Acetylcholine – slows the firing of the S-A node

Cardiac output and Fitness Cardiac output – amount of blood

pumped by the heart Affected by:

1) Heart Rate 2) Stroke volume – amount of blood forced

out of heart with each heart beat.Cardiac output = stroke volume X heart rate

Homework Page 311 # 1, 3, 7

Quiz tomorrow

Anterior Aspect (front)

Heart Anatomy cont’d Which heart chamber has the thickest

walls? Left Ventricle What is the significance of this structural

difference? Pumps blood to entire body (systematic

circuit)