Lab 2: Cardiovascular System

Mastrangelo Lab #2

Cardiac Myocyte

The muscle cells that make up the heart

Myofibrils

Specialized organelles inside the cardiac myocyte, consist of long chains of sarcomeres

Sarcomeres

The fundamental contractile units of muscle cells

Intercalated Disk

Cardiomyocyte cell-cell junctions; composed of desmosomes and gap junctions

Desmosomes

Maintain cell-cell connection by binding to intermediate filaments

Gap Junction

Allows ions to pass between cells, allowing action potentials to spread

Pericardium

the membrane enclosing the heart, consisting of an outer fibrous layer and an inner double layer of serous membrane

Fibrous pericardium

dense connective tissue; outermost, attaches to diaphragm

Parietal pericardium

Serous membrane, lines fibrous sac

Epicardium

(visceral pericardium) serous membrane; covers surface of the heart

Myocardium

Thick cardiac muscle

Endocardium

Serous inner lining

Atria

Two upper recieving chambers

Ventricles

Two lower pumping chambers

Valves

Prevent backflow of blood

Tricuspid

Right atrioventricular valve

Bicuspid

Left atrioventricular (mitral) valve

Chordae Tendinae

FIbrous cords that attach AV valves to papillary muscle

Pulmonary Semilunar

Valve between right ventrical and pulmonary artery

Aortic Semilunar

Valve between the left ventricle and the aorta

Closing of the AV valves

“lub” - first heart sound

Closing of the semilunar valves

“dub” - second heart sound

Systole

Ventricular Contraction

Diastole

Ventricular Relaxation

Intrinsic Conduction System

Non-contractile cells within the heart that stimulate and synchronize heart rhythm

SA (Sinoatrial) node

Pacemaker

AV (Atrioventricular) node

Allows for a 0.12 second delay in signal conduction

AV bundle (HIS bundle)

Only electrical connection between the atria and ventricles

Bundle Branches

Extend through the interventricular septum

Purkinjie Fibers

Travel thru ventricular walls

Tachycardia

Persistant resting heart rate above 100 bpm

Bradycardia

Persistant resting heart rate below 60 bpm

Chronotropic agents

Drugs / factors that can change the heart rate

Autonomic Nervous System

Divided into Sympathetic and Parasympathetic

Sympathetic Nervous System

Increases the heart rate

Parasympathetic Nervous System

Decreases the heart rate

Epinephrine

Increases heart rate, contracts blood vessels

Thyroid Hormone

Increases heart rate, cardiac contraction, cardiac output, and promotes vasodilation

Calcium Sodium and Potassium

Electrolyte Balances that can control HR

Age, gender, fitness level and body temperature

Additional Controls on HR

EKG

Electrocradiogram; recording of the electrical activity of the heart

P Wave

Atrial depolarization

QRS Complex

Ventricular depolarization

T wave

Ventricular repolarization

Einthoven’s Triange

The three lead EKG

Right arm to left arm

Lead I

Right arm to left leg

Lead II

Left arm to left leg

Lead III

Electrical Axis of the Heart

Represents the direction that the electrical impulses travel through the heart

Atrial Fibrilation

Upper heart chambers beat chaotically (no P wave!)

LAD heart attack

Severve blockage in the main front artery of the heart (left anterior descending)

Wiggers diagram

Compares pressure and volume / explains heart physiology