medterm chapter 5

Cardiovascular System

Also known as the circulatory system.

Function of the Cardiovascular System

Maintains distribution of blood throughout the body.

Distributes oxygen and other nutrients.

Components of the Cardiovascular System

Composed of the heart and blood vessels.

Heart

A muscular pump made of cardiac muscle fibers. Collects waste products from body's cells.

Each time a cardiac muscle contracts...

blood is ejected from the heart and pushed throughout the body within the blood vessels.

Heart Location

Located in the mediastinum in the center of the chest cavity.

Heart Size and Shape

About the size of a fist and shaped like an upside down pear.

Heart Chambers

Contains four chambers: two atria and two ventricles. Divided into right and left sides by walls: interatrial septum and interventricular septum.

Atria

Upper chambers. Receive blood returning via veins.

Heart Rate

Beats 60-100 BPM and 100,000 times a day.

Apex of the Heart

The tip of the heart at the lower edge.

Layers of the Heart Wall

Composed of three layers: endocardium, myocardium, epicardium.

Endocardium

Inner layer of the heart lining the heart chambers. Smooth, thin layer. Reduces friction as the blood passes through the heart chambers.

Myocardium

Thick, muscular middle layer that develops pressure to pump blood. Contraction develops the pressure required to pump blood through vessels.

Epicardium

Outer layer of the heart.

Visceral Pericardium

The epicardium, or the inner layer of the sac.

Parietal Pericardium

The outer layer of the sac.

Pericardium

A double-layered pleural sac enclosing the heart. Fluid between the two layers of the sac reduces friction as the heart beats.

Valves of the Heart

Control the direction of blood flow.

Tricuspid Valve

Atrioventricular valve. Controls the opening between the right atrium and right ventricle.

Pulmonary Valve

Semilunar valve. Located between the right ventricle and pulmonary artery. prevents blood from returning to right ventricle.

Mitral Valve

An atrioventricular valve with two cusps. Blood flows through this valve to the left ventricle and cannot go back up the left atrium.

Aortic Valve

Semilunar valve. Located between the left ventricle and aorta. Leaves left ventricle through this valve and cannot return.

Blood Flow Pathway

Blood flow progresses through the heart to the lungs, where it receives oxygen; then goes back to heart; then out to body tissues and parts.

Step 1 of Blood Flow

Deoxygenated blood from all the tissues in the body enters a relaxed right atrium via two large veins: the superior vena cava and inferior vena cava.

Step 2 of Blood Flow

The right atrium contracts and blood flows through the tricuspid valve into the relaxed right ventricle.

Step 3 of Blood Flow

The right ventricle then contracts and blood is pumped through the pulmonary valve into the pulmonary artery, which carries it to the lungs for oxygenation.

Step 4 of Blood Flow

The left atrium receives blood returning to the heart after being oxygenated by the lungs. This blood enters the relaxed left atrium from the four pulmonary veins.

Step 5 of Blood Flow

The left atrium contracts and blood flows through the mitral valve into the relaxed left ventricle.

Step 6 of Blood Flow

When the left ventricle contracts, the blood is pumped through the aortic valve and into the aorta, the largest artery in the body. The aorta carries blood to all parts of the body.

Diastole

The period of time a chamber is relaxed.

Systole

The contraction phase of the heart.

Electrical Impulse Path step 1

The sinoatrial (SA, S-A) node, or pacemaker, is where the electrical impulses begin. From the sinoatrial node, a wave of electricity travels through the atria, causing them to contract, or go into systole.

Electrical Impulse Path step 2

The atrioventricular node is stimulated.

Electrical Impulse Path step 3

The atrioventricular node transfers the stimulation wave to the atrioventricular bundle (formerly called bundle of His). The bundle of His is an eponym in recognition of the Swiss cardiologist who first discovered these fibers.

Electrical Impulse Path step 4

The electrical signal next travels down the bundle branches within the interventricular septum.

Electrical Impulse Path step 5

The Purkinje fibers in the ventricular myocardium are stimulated, resulting in a ventricular systole.

Bundle of His

Eponym in recognition of the Swiss cardiologist who first discovered these fibers.

Blood Vessels

Pipes that circulate blood throughout the body.

Lumen

The channel within blood vessels through which the blood flows.

Arteries

Large and thick walled. Carry blood away from the heart. Walls have a thick layer of smooth muscle that can contract or relax to change size of arterial lumen.

Artery Path

The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs. The aorta (the largest artery) begins from the left ventricle and carries oxygenated blood to all the systems in the body. Coronary arteries branch from the aorta and provide blood to the myocardium.

As arteries travel, they branch into progressively smaller-sized arteries called arterioles that delivers blood to capillaries.

Capillaries

Tiny, thin walled blood vessels allowing for diffusion of oxygen, carbon dioxide, waste products, and nutrients. Blood does not flow as quickly (blood has time for exchange). Blood exits capillary bed and returns to the heart through a vein.

Capillary Pathway

Arterial blood flows into a capillary bed. Blood exits capillary bed and returns to the heart through a vein.

Veins

Carry blood back to the heart. Have valves that help prevent blood from back flowing. Muscular action against the veins and skeletal muscle contractions help move blood. Thin walls, can collapse easily. Blood pressure in the veins is much lower than the arteries.

Inferior vena cava

Vein that enters heart. Carries blood from lower body.

Superior vena cava

Vein that enters heart. Carries blood from upper body.

Vein Pathway

Blood leaves capillaries and enters small venules, which merge into larger veins.

Blood Pressure

Measurement of the force exerted by blood against the wall of a blood vessel.

Ventricular Systole

Phase when blood is under a lot of pressure from the ventricular contraction, giving the highest blood pressure reading—the systolic pressure.

Systolic Pressure

The highest blood pressure reading during ventricular systole.

Pulse (P)

The surge of blood felt at the wrist or throat caused by heart contraction.

Ventricular Diastole

Phase when blood is not being pushed by the heart, causing blood pressure to drop to its lowest point—the diastolic pressure.

Diastolic Pressure

The lowest blood pressure reading during ventricular diastole.

Factors of blood pressure

Elasticity of the arteries, the diameter of the blood vessels, the viscosity of the blood, the volume of blood flowing through the vessels, and the amount of resistance to blood flow.

Pulmonary Circulation

Transports deoxygenated blood to lungs to get oxygen, and then back to the heart.

Systematic Circulation

Carries oxygenated blood away from heart to tissues and cells, and then back to the heart.

Cardiology

Branch of medicine involving diagnosis and treatment of conditions and diseases of cardiovascular system; physician is a cardiologist

Cardiovascular technologist/technician

Healthcare professional trained to perform variety of diagnostic and therapeutic procedures including electrocardiography, echocardiography, and exercise stress tests

Angiitis

Inflammation of a vessel

Angiospasm

Involuntary muscle contraction of smooth muscle in wall of a vessel; narrows vessel

Angiostenosis

Narrowing of a vessel

Embolus

Obstruction of blood vessel by blood clot that has broken off from thrombus somewhere else in body and traveled to point of obstruction; if it occurs in coronary artery, may result in myocardial infarction

Infarct

Area of tissue within organ or part that undergoes necrosis (death) following loss of its blood supply

Ischemia

Localized and temporary deficiency of blood supply due to obstruction to circulation

Murmur

A sound, in addition to normal heart sounds, arising from blood flowing through heart; extra sound may or may not indicate a heart abnormality

Orthostatic hypotension

Sudden drop in blood pressure a person experiences when standing straight up suddenly

Palpitations

Pounding, racing heartbeats

Plaque

Yellow, fatty deposit of lipids in artery that is hallmark of atherosclerosis; also called an atheroma

Regurgitation

To flow backward; in cardiovascular system this refers to backflow of blood through a valve

Thrombus

Blood clot forming within blood vessel; may partially or completely occlude blood vessel

Angina pectoris

Condition in which there is severe pain with sensation of constriction around heart; caused by deficiency of oxygen to heart muscle; commonly called chest pain (CP)

Cardiac arrest

Complete stopping of heart activity

Cardiac tamponade

Pressure on heart as a result of fluid buildup around heart inside pericardial sac; heart becomes unable to pump blood effectively

Cardiomegaly

Enlarged heart

Cardiomyopathy

General term for disease of myocardium; can be caused by alcohol abuse, parasites, viral infection, and congestive heart failure; one of most common reasons a patient may require heart transplant

Congenital septal defect

Hole, present at birth, in septum between two heart chambers; results in mixture of oxygenated and deoxygenated blood; can be an atrial septal defect (ASD) and a ventricular septal defect (VSD)

Congestive heart failure

Pathological condition of heart in which there is reduced outflow of blood from left side of heart because left ventricle myocardium has become too weak to efficiently pump blood; results in weakness, breathlessness, and edema

Coronary artery disease

Insufficient blood supply to heart muscle due to obstruction of one or more coronary arteries; may be caused by atherosclerosis and may cause angina pectoris and myocardial infarction

Endocarditis

Inflammation of lining membranes of heart; may be due to bacteria or to abnormal immunological response; in bacterial endocarditis, mass of bacteria that forms is referred to as vegetation

Heart valve prolapse

Condition in which cusps or flaps of heart valve are too loose and fail to shut tightly, allowing blood to flow backward through valve when heart chamber contracts

Heart valve stenosis

Condition in which cusps or flaps of heart valve are too stiff and are unable to open fully or shut tightly

Myocardial infarction

Condition caused by partial or complete occlusion or closing of one or more of coronary arteries; symptoms include squeezing pain or heavy pressure in middle of chest

Myocarditis

Inflammation of muscle layer of heart wall

Pericarditis

Inflammation of pericardial sac around heart

Tetralogy of Fallot

Combination of four congenital anomalies: pulmonary stenosis, interventricular septal defect, improper placement of aorta, and hypertrophy of right ventricle; needs immediate surgery to correct

Valvulitis

Inflammation of a heart valve

Arrhythmia

Irregularity in heartbeat or action; comes in many different forms; may be too fast, too slow, or irregular pattern

Bradycardia

Condition of having a slow heart rate, typically less than 60 beats/minute

Bundle branch block

Occurs when electrical impulse is blocked from traveling down bundle of His or bundle branches

Fibrillation

Extremely serious arrhythmia characterized by abnormal quivering or contraction of heart fibers

Flutter

Arrhythmia in which atria beat too rapidly, but in regular pattern

Premature atrial contraction

Arrhythmia in which atria contract earlier than they should

Premature ventricular contraction

Arrhythmia in which ventricles contract earlier than they should

Tachycardia

Condition of having a fast heart rate, typically more than 100 beats/minute while at rest

Aneurysm

Weakness in wall of artery resulting in localized widening of artery

Arteriosclerosis

Thickening, hardening, and loss of elasticity of walls of arteries; most often due to atherosclerosis

Atherosclerosis

Most common form of arteriosclerosis; caused by formation of yellowish plaques of cholesterol on inner walls of arteries

Deep vein thrombosis

Formation of blood clot in a vein deep in the body, most commonly the legs

Hypertension

Blood pressure (BP) above normal range