Cardiology and the Cardiovascular System: Medical Terminology Study Guide

Cardiology and the Cardiovascular System

Introduction to Cardiology

Cardiology is the medical specialty focused on the anatomy, physiology, diseases, and treatments of the cardiovascular system. Understanding medical terminology in this field is essential for accurate communication and patient care.

• Cardi/o-: means heart

• -logy: means study of

• Cardiologist: a physician specializing in heart and blood vessel disorders

Structures of the Cardiovascular System

The cardiovascular system consists of the heart and blood vessels, forming a continuous circuit that delivers blood throughout the body.

• Heart: muscular organ located in the thoracic cavity, behind the sternum and between the lungs

• Blood Vessels: arteries, veins, and capillaries that transport blood

Anatomy of the Heart

External and Internal Features

The heart is roughly the size of a fist and contracts at least once per second. Its external surface is irregular, with mounds and grooves reflecting internal chambers and containing fat, blood vessels, and nerves.

Membranes and Layers

The heart is surrounded by a two-layered membrane called the pericardium. The outer layer is the parietal pericardium, and the inner layer is the epicardium. Pericardial fluid fills the space between these layers, reducing friction during heartbeats. The myocardium is the muscular layer responsible for contraction, and the endocardium lines the chambers and valves.

Heart Chambers

The heart has four chambers:

• Atria: two small upper chambers (right and left)

• Ventricles: two large lower chambers (right and left)

• Septum: central wall dividing the heart into right and left sides

Heart Valves

Four valves control blood flow:

• Tricuspid valve: between right atrium and right ventricle

• Pulmonary valve: between right ventricle and pulmonary arteries

• Mitral valve: between left atrium and left ventricle

• Aortic valve: between left ventricle and aorta

The chordae tendineae are ropelike strands that help keep the tricuspid and mitral valves closed during ventricular contraction. Heart sounds "lubb-dupp" are produced by the opening and closing of these valves.

Thoracic Cavity and Mediastinum

The heart is located in the mediastinum, a central area within the thoracic cavity. The mediastinum also contains the great vessels, esophagus, trachea, and thymus.

Blood Vessels

Types and Functions

Blood vessels are vascular channels lined with endothelium. There are three main types:

• Arteries: carry blood away from the heart

• Capillaries: connect arteries and veins, deliver blood to cells

• Veins: carry blood toward the heart

Arteries

Arteries branch into arterioles and carry oxygen-rich blood. They have smooth muscle for vasoconstriction and vasodilation, which regulate blood pressure.

Capillaries

Capillaries are the smallest blood vessels, allowing single-file passage of blood cells and exchange of gases, nutrients, and waste.

Veins

Veins and venules carry oxygen-poor blood to the heart. Many veins have valves to ensure one-way flow and prevent backflow due to gravity.

Circulation Pathways

Blood circulates through two main pathways:

• Systemic circulation: vessels throughout the body except the lungs

• Pulmonary circulation: vessels to, within, and from the lungs

Blood passes through both pathways in one complete trip:

1. Deoxygenated blood from the body enters the right atrium via the superior and inferior vena cava

2. Blood moves to the right ventricle, then through the pulmonary valve to the pulmonary arteries and lungs

3. In the lungs, blood releases CO2 and picks up O2

4. Oxygenated blood returns via pulmonary veins to the left atrium

5. Blood moves to the left ventricle, then through the aortic valve to the aorta and systemic circulation

Physiology of the Heart

Conduction System

The heart's conduction system initiates and transmits electrical impulses:

• Sinoatrial (SA) node: pacemaker, initiates heartbeat

• Atrioventricular (AV) node: receives impulse from SA node

• Bundle of His and bundle branches: transmit impulse through septum

• Purkinje fibers: cause ventricles to contract

Heart Rhythm and Rate

• Systole: contraction phase

• Diastole: relaxation phase

• Normal sinus rhythm (NSR): SA node controls heart rate

• Ectopic sites: abnormal rhythm if other areas produce impulses

Nervous System Control

• Parasympathetic division: releases acetylcholine, maintains resting heart rate

• Sympathetic division: releases norepinephrine and epinephrine, increases heart rate during activity and stress

Common Cardiovascular Diseases

Heart Diseases

• Angina pectoris: chest pain due to reduced blood flow to the heart

• Congestive heart failure: heart's inability to pump effectively, causing edema

• Myocardial infarction: heart attack, death of heart tissue due to lack of oxygen

Blood Vessel Diseases

• Aneurysm: abnormal bulging of an artery wall

• Atherosclerosis: buildup of plaque in arteries, narrowing the lumen

• Hypertension: high blood pressure

• Varicose veins: enlarged, twisted veins, often in the legs

Conduction System Diseases

• Arrhythmias: abnormal heart rhythms, including bradycardia, tachycardia, fibrillation, and asystole

Laboratory and Diagnostic Procedures

Exercise Stress Tests

• Bicycle and treadmill stress tests: monitor heart function during exercise

Electrocardiography (ECG/EKG)

• Precordial chest leads: electrodes placed on chest

• 12-lead ECG: comprehensive heart electrical activity recording

• ECG tracing: shows P wave, QRS complex, and T wave

Ultrasonography and Echocardiography

• Color flow duplex ultrasonography: visualizes blood flow and velocity

• Echocardiography: uses sound waves to create images of heart structures

Medical Procedures

Blood Pressure Measurement

• Sphygmomanometer: device for measuring blood pressure

• Systolic pressure: force of ventricular contraction

• Diastolic pressure: resting pressure in the artery

Automatic External Defibrillator (AED)

• AED: device used to restore normal heart rhythm in emergencies

Pulse Points

• Pulse points: locations where arterial pulse can be felt

• Used to assess heart rate and blood flow

Drugs and Surgical Procedures

Cardiovascular Drugs

• Digitalis drugs: derived from the foxglove plant (Digitalis purpurea), used to treat heart conditions

Surgical Procedures

• Open heart surgery: sternum is split to access the heart

• Pacemaker implantation: device placed under skin to regulate heart rhythm

• Balloon angioplasty: catheter with balloon compresses plaque in arteries

• Stent placement: expanded stent keeps artery open

• Valve replacement: artificial valve implanted to restore function

Summary Table: Heart Chambers and Valves

Chamber	Valve	Location
Right Atrium	Tricuspid Valve	Between right atrium and right ventricle
Right Ventricle	Pulmonary Valve	Between right ventricle and pulmonary arteries
Left Atrium	Mitral Valve	Between left atrium and left ventricle
Left Ventricle	Aortic Valve	Between left ventricle and aorta

Key Equations

• Blood Pressure Formula:

$\text{Blood Pressure} = \text{Cardiac Output} \times \text{Peripheral Resistance}$

• Cardiac Output Formula:

$\text{Cardiac Output} = \text{Heart Rate} \times \text{Stroke Volume}$

Additional info:

• Scientific names and terminology are expanded for clarity.

• Tables and equations are provided for academic completeness.