Anatomy and Physiology The Cardiovascular System The cardiovascular

Anatomy and Physiology The Cardiovascular System

�The cardiovascular system contains the heart, blood vessels (BVs), and blood. �Its function is to transport oxygen and nutrients throughout the body. It does this by circulating blood. �An average body contains ~5 liters of blood but the heart pumps ~7, 000 liters of blood daily while the heart contracts ~2. 5 billion times in an average lifetime.

The Heart: �This is a powerful pump �It is found in the thoracic (chest) cavity behind the sternum and mediastinum �Average heart size is 14 X 9 cm �It is separated into chambers: 2 right and 2 left (or 2 upper and 2 lower)

�It is covered by the pericardium (a membrane) which has 2 layers: ◦ Visceral pericardium (covers the heart; inner layer); a. k. a. epicardium ◦ Parietal pericardium (covers the visceral pericardium; outer layer) ◦ The pericardial cavity is the space between these layers which contains serous fluid ◦ Pericarditis is inflammation of the pericardium usually caused by viral or bacterial infection.

�This is composed of 3 layers: ◦ Epicardium protects the heart (reduces friction); this contains connective tissue & adipose ◦ Myocardium is the middle layer; contains mostly cardiac tissue ◦ Endocardium is the innermost layer; contains epithelium & connective tissue and elastic & collagenous fibers The Heart Walls

Heart Chambers and Valves: �There are 4 chambers: ◦ The atria (sing. atrium) receive blood ◦ The ventricles send blood (from the atria) �The right & left chambers are separated by a wall called the septum. �There are several valves in the heart that provide the main function of regulating blood flow in ONE direction only (prevents backflow).

The Heart Walls and Chambers: http: //www. texasheartinstitute. org/HIC/Topic s/images/myocard. jpg

◦ Atrioventricular valves (a. k. a. A-V valves b/c they are between the atria and ventricles): there is 1 on the right & 1 on the left. �Tricuspid valve is between the right atrium and ventricle; blood flows from the right atrium to the right ventricle. �Bicuspid valve is between the left atrium and ventricle; blood flows from the left atrium to the left ventricle. Heart Valves: ◦ Pulmonary valve: at the base of the pulmonary trunk; this enables blood to leave the heart (and flow to the lungs thru the pulmonary arteries); blood flows out of the right ventricle ◦ Aorta valve: at the base of the aorta (a large artery); blood flows out of the left ventricle

Heart Valves: http: //www. google. com/imgres

Pulmonary Circulation: (heart to lungs) �Pulmonary arteries: carry blood to lungs �Pulmonary veins: return blood from lungs to heart (left side) Systemic Circulation: (heart to rest of body) �Aorta: main artery (largest) that pumps blood from heart to all body tissues (except lungs) �Superior & Inferior Vena Cava: bring blood back into heart from body tissues.

Blood Flow Path: begins with O 2 poor blood: Right Atrium Right Ventricle Pulmonary Trunk Pulmonary Arteries Alveoli of lungs for O 2 Pulmonary Veins Left Atrium Left Ventricle Aortic Valve Aorta Body

http: //www. google. com/imgres

� This coordinates the cardiac cycle � Contains the sinoatrial node (a. k. a. S-A node) located beneath the epicardium: ◦ This acts as the pacemaker of the heart b/c it is rhythmic (meaning it starts impulses, thereby generating the heart’s rhythm). � Contains the atrioventricular node (a. k. a. A-V node) located beneath the endocardium � This acts as the impulse conduction pathway between the atria and ventricles The Cardiac Conduction System:

Cardiac Cycle & Sounds: http: //www. google. com/imgres �The cardiac cycle is 1 heart contraction AND 1 heart relaxation, or a complete heartbeat. �Atrial systole is atrial contraction while atrial diastole is atrial relaxation. �When listening to the heartbeat with a stethoscope, it sounds like lubb-dupp. The lubb is ventricular contraction while the dupp is ventricular relaxation.

�A murmur is a sound that is heard when there is slight damage to a valve of the heart. ◦ The damage is the leaking of blood through a valve b/c the valve does not completely close. http: //www. google. com/imgres

�An electrocardiogram (a. k. a. ECG) is a recording of electrical charges in the myocardium during a cardiac cycle. http: //www. google. com/imgres �Heart problems can be detected with the use of an ECG. http: //www. google. com/imgres

Heart Regulation: The heart rate can change(temporarily) by certain factors: � Neural (ANS) controls: stress � Hormones & ions: changes or imbalances in electrolytes (Ca++, Na+, K+), thyroxine, or epinephrine � Physical factors: temperature, age, gender http: //www. google. com/imgres

Blood Vessels (BVs): �These include the arteries, arterioles, capillaries, venules and veins. �The arteries take blood away from the heart; vasoconstriction & vasodilation (opening & closing of an artery) controls blood flow and blood pressure. Oxygenated Blood (red) http: //cache. eb. com/eb/image? id=92806&rend. Type. Id=34

◦ Tunica intima is the innermost layer containing endothelium (internal epithelium) which helps prevent blood clotting Arteries (& Veins) have 3 layers: ◦ Tunica media is the middle layer ◦ Tunica externa is the outermost layer �The arterioles come from the arteries (they are smaller arteries) http: //www. medicalook. com/systems_images/Veins. jpg

�Capillaries are the smallest BVs ◦ Found between arteries and venules ◦ Gases & nutrients are exchanged thru their membranes (semipermeable) � This occurs by diffusion, filtration & osmosis �The amount of capillaries found within a tissue varies according to the tissue’s O 2 requirement (more O 2 required=more capillaries)

http: //biology. bangor. ac. uk/images/bsx 1009/fig 15 -3

�Venules are small veins �Veins carry blood to the heart from the body; these run parallel to arteries. ◦ Veins have 3 layers (like arteries) but not as distinct ◦ Thinner walls than arteries ◦ Less elastic but greater diameter than arteries ◦ Many contain valves which act as flaps preventing backflow of blood

http: //www. brvsa. com/venous. htm

Varicose Veins: http: //www. brvsa. com/images/varicose 2. jpg http: //www. brvsa. com/venous. htm http: //www. wakeradiology. com/Portals/0/Varicose 1. jpg

�Vital Signs: Arterial pulse, blood pressure, rate of respiration, and body temperature. �Pulse: each beat of the left ventricle as it travels through the arterial system. Physiology of Circulation:

� A pulse is felt at certain points on the body. This is due to an artery close to the surface of the skin. � This is the contraction and relaxation of an arterial wall. http: //www. google. com/imgres

Blood Pressure: �Blood pressure can be defined as the force of blood against BVs. �When the ventricles contract with the maximum pressure is the systolic pressure. �When http: //www. google. com/imgres the ventricles relax with the lowest pressure is the diastolic pressure.

�Heart action: this determines the total volume of blood entering the arterial system. �Blood volume: this is ~5 liters or 8% of body weight. This equals the sum of the elements and plasma. �Blood volume is proportional to bp (normally). When blood volume decreases, bp drops; dehydration will also influence bp b/c it affects blood volume. http: //www. google. com/imgres Factors that Influence Blood Pressure:

Factors that Influence Blood Pressure: �Peripheral Resistance: this is the force of the friction between blood and blood vessels. This can hinder blood flow. �Blood viscosity: this is the ease with which blood particles move past each other. Greater viscosity=greater resistance. �Thicker blood (meaning it has more parts) creates higher bp. http: //www. google. com/imgres

Additional Factors that may influence blood pressure: �ANS �Renal Factors (kidneys) �Temperature �Hormones �Diet Factors that Influence Blood Pressure:

�Look up in text or online! �Know the following: endocarditis, angina, infarct, ischemia, fibrillation, tachycardia, bradycardia, congestive heart failure, pulmonary edema, varicose veins, thrombophlebitis, hypotension, hypertension, atherosclerosis, and coronary artery disease

THE END!

This slide show was developed by Dana Halloran, � Cardinal Mooney High School, Sarasota, FL. � Used with her personal permission, � adapted and amended by Rosa Whiting, � Manatee School for the Arts, Palmetto, FL. �