F EBRUARY 17, 2016 Objective: Trace the movement of blood through the heart Compare and contract systole and diastole phases of the heartbeat Journal: Why are valves important to the heart?

C ARDIOVASCULAR S YSTEM

M AJOR C OMPONENTS Heart: pumps blood throughout the system Blood: connective tissue made of plasma, cells, and other substances Blood Vessels: vessels that carry blood around the body Arteries Arterioles Capillaries Venules Veins

H EART O VERVIEW Size of your fist Surrounded by protective layers Slightly left of the center of your chest and above your diaphragm

H EART P ROTECTIVE L AYERS = P ERICARDIUM Fibrous Pericardium –outer layer Parietal Pericardium – middle layer Visceral Pericardium – inner protective layer that attaches directly to the heart surface *In between the parietal and visceral layers there is a small space called the pericardial cavity

T HREE L AYERS OF THE H EART W ALL : Epicardium – outer layer of the heart wall Made up of visceral pericardium Myocardium – middle layer of the heart wall Made up of cardiac muscle Endocardium – inner layer of the heart wall Epithelium lining of the heart

H EART S TRUCTURE Base Top of the heart Tilted towards the head Apex Bottom of the heart Points away from the head

C HAMBERS OF THE H EART Right Atrium: Collects blood returning to the heart from circulating around the body Left Atrium: Collects blood returning from the pulmonary circuit Right Ventricle: Pumps blood through the pulmonary circuit Left Ventricle: Pumps blood throughout the rest of the body *Remember the locations of the chambers are based on the patients perspective

S EPARATION OF THE C HAMBERS Septum: walls of the heart that separate the chambers Interatrial Septum: separates the two atria Interventricular Septum: separates the two ventricles

V ESSELS FROM THE H EART Superior vena cava: vein that brings blood back to the heart from the head, neck, and chest, and upper extremities Inferior vena cava: vein that brings blood back to the heart from the abdomen, pelvic region, and lower extremities Aorta: artery that blood travels from the left ventricle to the rest of the body

V ALVES Tricuspid Valve - aka AV valve Keeps blood traveling in one direction from the right atrium to the right ventricle Bicuspid Valve – aka mitral valve Keeps blood traveling in one direction from the left atrium to the left ventricle

C ARDIAC C YCLE

P HASES The cardiac cycle can be broken down into two phases: Systole: contracting phase Diastole: resting phase

S TEPS OF THE S YSTOLE P HASE

S TEP 1 Blood enters the right atrium of the heart through the superior and inferior vena cava The tricuspid valve is closed and blood collects in the right atrium

S TEP 2 The tricuspid valve opens and the blood flows from the right atrium to the right ventricle Once the blood from the right atrium has moved to the right ventricle, the tricuspid valve closes to prevent blood from flowing backwards into the right atrium

S TEP 3 The right ventricle contracts causing the blood to flow through the pulmonary semilunar valve into the pulmonary trunk

S TEP 4 The blood divides into the left and right pulmonary arteries which bring the blood to the capillaries in the respective lung While at the lungs, the blood gives up carbon dioxide and picks up a fresh supply of oxygen ** Note: The pulmonary artery carries deoxygenated blood.

S TEP 5 The blood flows from the capillaries through increasingly larger blood vessels until it reaches the left and right pulmonary veins. **Note: The pulmonary veins carry oxygenated blood.

S TEP 6 The pulmonary veins meet and pour the oxygenated blood into the left atrium.

S TEP 7 Once the left atrium is full, blood flows through the AV valve into the left ventricle. Once the left ventricle is full the AV valve closes so blood cannot flow back into the left atrium.

S TEP 8 The left ventricle then contracts and blood is pumped through the aortic semilunar valve into the aorta, from which the blood will be sent around the body.

D IASTOLE P HASE While the atria fill with blood the heart rests before contracting again.

T IMING Both atria fill at the same time Both ventricles fill at the same time Both ventricles eject blood at the same time when the heart contracts Contraction begins at the apex and travels upward to ensure all the blood is expelled from the heart