THE HEART AND HEART DISEASE

Chapter 14

Objectives Describe 3 layers of heart wall Describe structure of pericardium and it’s functions Compare right and left heart Name 4 chambers of heart and compare functions Name the valves at the entrance and exit of ventricles and cite

functions Describe blood circulation through the myocardium Describe the cardiac cycle Name and locate components of heart’s conduction system Explain effects of the autonomic nervous system on heart rate List and define several terms that describe variations in heart

rates Explain what produces the two main heart sounds Describe several common types of heart disease List 5 actions that can be taken to minimize the risk of heart

disease Describe 4 methods for studying the heart List several approaches to the treatment of heart disease WORD ANATOMY!!!

Circulation and the Heart

Structure of the Heart

3 LAYERS :- Endocardium (thin

smooth lining of interior)

- Myocardium (thick, muscular middle layer)

- Epicardium (serous membrane on outside)

Myocardium Cells are striated (actin and myosin) Has single nucleus Involuntarily controlled Intercalated disks (allow for rapid

electrical impulse transfer) Branching fibers (enables coordinated

contraction) Thick muscle that pumps blood through

the blood vessels and through body

Pericardium

Consists of fibrous outermost layer that anchors the heart to supporting structures.

Divided into parietal and visceral layers.

There is a potential space between the two layers.

Divisions of Heart Right HeartFunctions to pump

blood low in oxygen to the lungs.

This is called the Pulmonary Circuit.

Consists of right atrium, right ventricle and valves

Left HeartFunctions to pump

blood high in oxygen to the entire body.

This is called the Systemic Circuit.

Consists of left atrium, left ventricle and valves.

Chambers of the Heart

Atria and Ventricles

Right AtriumReceives blood that is returning from the body tissues.

Pumps blood low in oxygen to right ventricle.

Superior and Inferior Vena Cava are the large vessels entering.

Coronary Sinus also enters right atrium with blood drained from heart itself.

Right VentricleReceives blood from the right atrium.

Pumps venous blood to the lungs via the pulmonary trunk.

Pulmonary trunk divides into right and left pulmonary arteries.

Left AtriumReceives oxygen rich blood from the lungs.

Blood enters through the pulmonary veins.

Pumps blood into the left ventricle.

Left VentricleReceives blood from the left atrium.

Has the thickest walls.

Pumps oxygen rich blood to the all parts of the body.

Blood leaves through the aorta.

Apex is formed by the LV.

Four Valves of the Heart

Valves are one way valves that direct blood flow through the heart.

Valves that are between atria and ventricles are the atrioventricular valves.

Valves that are between ventricles and vessels are the semilunar valves.

- Right AV - Left AV- Pulmonic Valve- Aortic Valve

Path of Blood through the Heart

Systemic Circuit blood enters Right Atrium through Superior and Inferior Vena Cava

Blood goes through the Tricuspid (AV) valve into Right Ventricle.

Right Ventricle pumps blood through the Pulmonic (semilunar) valve into the pulmonary trunk.

Blood leaves divisions of pulmonary trunk to enter the lungs. (Pulmonary Circuit)

Blood returns from the lungs through the pulmonary veins to the Left Atrium.

Blood goes through the Mitral (AV) valve into the Left Ventricle.

Left Ventricle pumps blood through the Aortic (semilunar) valve to the body and back into the Systemic Circuit.

Blood Pathway

SVC/IVC RA Tricuspid RV Pulmonic Lungs Pulmonary veins LA Mitral LV Aortic Body

Coronary CirculationSupplies the heart muscle with own blood supply

Right and Left Coronary arteries are the main ones.

Encircle the heart.

Receive blood when heart relaxes.

Drains back into the RA.

Vessels affected with Heart Attacks.

Function of the Heart

Although we refer to Right and Left Heart, the heart contracts and works together.

Active phase, when contraction occurs, is called Systole.

Resting phase, when chambers are filling, is called Diastole.

One complete sequence of contraction and relaxation is called the Cardiac Cycle.

Each cardiac cycle is a single heartbeat.

Cardiac Output CO = HR x SV The volume of blood pumped out by the

ventricles in 1 minute is called cardiac output (CO)

The volume of blood ejected from ventricles with each heartbeat is called stroke volume (SV)

The number of times the heart beats within 1 minute is called the heart rate (HR)

Heart’s Conduction System

Heart is stimulated to contract by specialized tissue within the heart. The action potential is initiated here and spreads through the structure of the heart.

SA node (Pacemaker of the heart)

AV node Atrioventricular

bundle (bundle of His)

Purkinje fibers

Conduction System cont….

SA node (sinoatrial node) is located in the Right Atrium and is commonly called the Pacemaker of the Heart because it sets the rate of heart contraction

AV node (atrioventricular node) is located in the interatrial septum in Right Atrium

AV bundle (bundle of His) is located in the interventricular septum.

Purkinje fibers are located throughout the myocardium.

Control of Heart RateHeart rate can be affected by the nervous system, hormones and internal influences:

ANS plays a major role.

Hormones, ions, and drugs.

Exercise affects the heart rate by increasing amount of blood ejected with each heart beat.

There are different kinds, or variations, of heart rate.

Bradycardia – slow heart rate, usually less than 60 bpm

Tachycardia – a fast heart rate, more than 100 bpm

Sinus Arrhythmia – variation due to changes in rate and depth of breathing

Premature beat – a heart beat that comes before the normal beat

Heart Sounds

“Lub – Dub” “lub” is caused by the closing of AV

valves “dub” is caused by the closing of the

semilunar valves MURMURS : - an abnormal sound usually caused by a

faulty valve- can be caused by many things- organic and functional murmurs

Heart DiseaseThe most common cause of death in the country!

Classifications of Heart Disease

Anatomical- Endocarditis :

inflammation of the heart lining

- Myocarditis : inflammation of heart muscle

- Pericarditis : inflammation of the serous membrane on surface of heart

Causative Factors- Congenital : present at

birth- Rheumatic heart

disease: caused by rheumatic fever

- Coronary Heart Disease (CAD) : involves the vessels supplying the heart muscle

- Heart Failure : deterioration of the heart tissues

Congenital Heart DiseaseForamen Ovale (Atrial Septal Defect)

Ductus Arteriosus (Patent Ductus Arteriosus)

Coarctation of the Aorta

tetralogy of Fallot

Ventricular Septal Defect –

*** the most common SINGLE congenital heart defect

tetralogy of FallotThe most common congenital heart defect.

- It occurs as a combination of four defects.

- Includes: Pulmonary Artery Stenosis, Interventricular Septal Defects, Aortic Displacement to the Right and Right Ventricular Hypertrophy

Rheumatic Heart DiseaseCaused by a Streptoccal infection(same one that causes strep throat)

The antibodies formed to combat the disease, attack the heart valves

Most frequently the mitral valve

The incidence of rheumatic fever has decreased with the use of antibiotics

Coronary Heart DiseaseLumen may narrow because of artherosclerosis

Vessel narrowing leads to ischemia

Ischemia causes Myocardial Infarction

Angina Pectoris

Arrhythmia (Flutter/Fibrillation)

Defibrillators, AED, Thrombolytics

Angioplasty/Coronary Artery Bypass Graft

Angioplasty is a procedure used to open an occluded coronary vessel to restore blood flow to the heart.

Stents can be placed in vessel to keep it open.

Can be the only treatment for MI or pt may require CABG.

Heart FailureCondition where heart is unable to pump correctly and give enough oxygen to tissues.

Results in enlarged chambers, ventricles are not able to contract properly, blood backs up, and blood pressure increases.

CHF : Retention of fluid from heart failure. Managed with diet, drugs and managed lifestyle.

Heart Disease in the Elderly

Heredity plays a major role Environmental factors Disease Personal Habits Age alone contributes to: heart

decreasing in size, valves become less flexible, decrease strength of contraction & conduction system failure

Prevention of Heart Disease

FACTORS THAT CAN NOT BE MODIFIED…

FACTORS THAT CAN BE MODIFIED

Age Gender Heredity Body type

Smoking Physical activity Weight control Diet HTN DM and gout

Heart StudiesStethoscope tells you a lot of information

EKG/ECG

Cardiac Catheterization

Fluoroscopy

US / Echo

Treatment of Heart Disease Drugs (Digoxin, NTG, Beta-blockers,

Antiarrhythmics, Anticoagulants) Pacemakers Cardioversion (Chemical or Electric) Angioplasty Heart Surgery (CABG, Valve Replacement,

Transplant)

ReviewKnow the following: Structure/Layers of HeartHeart Divisions and ValvesHeart Blood SupplyFlow of blood through heartFunction of heart and Cardiac OutputConduction/Control of heart rate (What is this controlled by?)Heart DiseasePrevention of Heart DiseaseHeart StudiesTreatment of Heart Disease