Cardiovascular System at a Glance Functions of Cardiovascular (CV) System Distribute blood to whole body Delivery of needed substances to cells Removal of wastes Organs of Cardiovascular System Heart- pumps blood through the vessels Arteries – carries blood away from the heart Capillaries – exchange site between the blood and tissues Veins – carries blood toward the heart

Anatomy and Physiology Also called circulatory system Maintains distribution of blood throughout body Delivers oxygen and nutrients like glucose and amino acids to cells Picks up carbon dioxide and other waste products from cells and delivers to lungs, liver, and kidneys for elimination

Anatomy and Physiology Is composed of: Heart Blood vessels Arteries Capillaries Veins Divided into pulmonary circulation and systemic circulation

Systemic Circulation Between heart and cells of body Carries oxygenated blood away from left side of heart to body Carries deoxygenated blood from body to right side of heart

Pulmonary Circulation Between heart and lungs Carries deoxygenated blood away from right side of heart to lungs Carries oxygenated blood from lungs to left side of heart

Heart Muscular pump Made up of cardiac muscle fibers Could be called a muscle instead of an organ Beats an average of 60 – 100 beats per minute (bpm), or about 100,000 times a day Each time the muscle contracts: Blood is ejected from heart Pushed throughout body within blood vessels

Heart Located in the mediastinum, pericardial cavity More to left side of chest Directly behind sternum About size of a fist Shaped like upside-down pear Tip of heart at lower edge Called the apex

Medical Terminology: A Living Language, Fourth Edition Bonnie F. Fremgen and Suzanne S. Frucht Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Heart Layers Endocardium Myocardium Epicardium Inner layer Lines heart chambers Smooth, thin layer that reduces friction as the blood passes through heart chambers Middle layer Thick muscle Contraction of this layer develops the pressure required to pump blood through blood vessels Outer layer Forms the visceral layer of pericardial sac Fluid between layers of pericardial sac reduces friction as heart beats

Heart Chambers Divided into four chambers Two atria Two ventricles Heart is divided into right and left sides by a wall called the septum

Atria Left and right upper chambers Receiving chambers Blood returns to atria in veins Superior and inferior vena cava Pulmonary veins

Ventricles Left and right lower chambers Pumping chambers Thick myocardium Blood exits ventricles into arteries Aorta Pulmonary artery

Heart Valves Tricuspid, pulmonary, mitral, aortic Four valves in heart Act as restraining gates to control direction of blood flow Found at entrance and exit to ventricles Allow blood to flow only in forward direction by blocking it from returning to previous chamber

Tricuspid Valve An atrioventricular valve Between right atrium and ventricle Prevents blood in ventricle from flowing back into atrium Has 3 leaflets or cusps

Pulmonary Valve A semilunar valve Between right ventricle and pulmonary artery Prevents blood in artery from flowing back into ventricle Semilunar – valve looks like half moon

Mitral Valve An atrioventricular valve Between left atrium and ventricle Prevents blood in ventricle from flowing back into atrium Also called bicuspid valve - has two cusps

Aortic Valve A semilunar valve Between left ventricle and aorta Prevents blood in aorta from flowing back into ventricle

Figure 5.5 – Superior view of heart valves illustrating Medical Terminology: A Living Language, Fourth Edition Bonnie F. Fremgen and Suzanne S. Frucht Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Figure 5.5 – Superior view of heart valves illustrating position, size, and shape of each valve.

Path of Blood Flow Through Heart 1. Deoxygenated blood from body enters relaxed right atrium via two large veins called: Superior vena cava Inferior vena cava

Path of Blood Flow Through Heart 2. Right atrium contracts Blood flows through tricuspid valve into relaxed right ventricle

Path of Blood Flow Through Heart 3. Right ventricle contracts Blood is pumped through pulmonary valve into pulmonary artery Carries blood to lungs

Path of Blood Flow Through Heart 4. Relaxed left atrium receives blood that has been oxygenated by lungs Blood enters left atrium from the four pulmonary veins

Path of Blood Flow Through Heart 5. Left atrium contracts Blood flows through mitral valve into relaxed left ventricle

Path of Blood Flow Through Heart 6. Left ventricle contracts Blood is pumped through the aortic valve and into aorta Largest artery in the body Carries blood to all parts of body

Systole and Diastole Heart chambers alternate between: Relaxing to fill Contracting to push blood forward Relaxation phase is diastole Contraction phase is systole

Conduction System of the Heart Autonomic nervous system controls heart rate Therefore, no voluntary control over heart Special heart tissue conducts electrical impulses Stimulate different chambers to contract in correct order

Path of the Conduction System 1. Sinoatrial (SA) node, or pacemaker, is where electrical impulse begins From SA node a wave of electricity travels through atria Causing them to contract, or go into systole

Path of the Conduction System 2. Next, atrioventricular node (AV) is stimulated 3. This node transfers stimulation wave to bundle of His

Path of the Conduction System 4. Electrical wave travels down bundle branches within interventricular septum 5. Finally, Purkinje fibers in ventricular myocardium are stimulated Results in ventricular systole

Figure 5.7 – The conduction system of the heart. Medical Terminology: A Living Language, Fourth Edition Bonnie F. Fremgen and Suzanne S. Frucht Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Figure 5.7 – The conduction system of the heart.

Blood Vessels Pipes that circulate blood through body Three types: Arteries Capillaries Veins Lumen is the channel within blood vessels

Medical Terminology: A Living Language, Fourth Edition Bonnie F. Fremgen and Suzanne S. Frucht Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Figure 5.9 – Comparative structure of arteries, capillaries, and veins.

Arteries Large thick-walled vessels Wall contains smooth muscle and can dilate or constrict As arteries travel through body they branch into progressively smaller vessels called arterioles

Arteries Carry blood away from heart Towards either lungs or cells and tissues of body Pulmonary artery carries deoxygenated blood to lungs Aorta carries oxygenated blood to body Coronary arteries supply myocardium

Capillaries Network of tiny, thin-walled blood vessels called a capillary bed Connecting unit between arteries and veins Arterial blood flows into capillary bed Venous blood flows out of capillary bed Location for: Oxygen and nutrients to diffuse out of blood Carbon dioxide and wastes to diffuse into blood

Veins Much thinner walls than arteries Much lower pressure system than in arteries Have valves to insure blood flows only towards heart Squeezing by skeletal muscles also assists blood return to heart Smallest veins are called venules

Veins Carry blood towards the heart From either the lungs or the cells and tissues of body Pulmonary veins carry oxygenated blood from lungs Superior and inferior vena cava carry deoxygenated blood from body

Blood Pressure Measurement of force exerted by blood against walls of a vessel May be affected by several characteristics of blood and blood vessels Elasticity of arteries Diameter of blood vessels Viscosity of blood Volume of blood Amount of resistance to blood flow

Blood Pressure During ventricular systole During ventricular diastole Blood is under great pressure Gives highest pressure—systolic Top number of blood pressure reading During ventricular diastole Blood isn’t being pushed from heart at all Blood pressure drops to lowest point—diastolic Bottom number of blood pressure reading