CARDIOVASCULAR

Afterload

Pressure against which ventricles must pump blood.

Aorta

Carries blood from the left ventricle to the body.

Aortic valve

Heart valve that prevents backflow from the aorta to the left ventricle.

Apex

Pointed end of the heart, the location of the point of maximum impulse.

Atria

Upper chambers of the heart; receive blood.

Atrial diastole

Relaxation of atria.

Atrial systole

Contraction of atria.

Atrioventricular (AV) node

Group of pacemaker cells that relays impulses from the atria to the ventricles.

Atrioventricular Valves

Valves between atria and ventricles (Tricuspid and Mitral).

Atrium

Upper chamber of the heart.

Automaticity

The unique ability of the cardiac muscle to contract without nervous stimulation.

Baroreceptor Reflex

Regulates heart rate and stroke volume in response to blood pressure changes.

Baroreceptors

Pressure sensors in the aorta and carotid arteries that detect changes in blood pressure.

Base

Broadest part of the heart where great vessels enter and leave.

Bicuspid Valve

AV valve between left atrium and ventricle.

Cardiac Cycle

Repetitive pumping action which includes contraction and relaxation.

Cardiac Muscle

Contains 1 centrally located nucleus, branching cells, rich in mitochondria, striated.

Cardiac Output

Volume of blood pumped by a ventricle in 1 min (CO = HR × SV).

Chambers and Blood Vessels

Includes left atrium, right atrium, left ventricle, right ventricle.

Chemoreceptor Reflex

Mechanism where chemicals affect heart rate and stroke volume.

Chemoreceptors

Sensors that detect levels of carbon dioxide, oxygen, and pH.

Chordae Tendineae

Fibers supporting AV valve flaps.

Coronary Arteries

Supply blood to the heart wall.

Coronary Sinus

Drains blood from heart muscle to the right atrium.

Depolarization Phase

Na+ and Ca2+ channels open.

Diastole

Period of cardiac muscle relaxation.

Electrocardiogram (ECG)

Recording of electrical activity of the heart.

Endocardium

The endothelial membrane that lines the chambers of the heart.

Epicardium

The serous membrane on the surface of the myocardium.

Epinephrine

Hormone that can increase heart rate and stroke volume.

Factors Modifying Basic Heart Rate

Includes neural controls, hormones, and physical factors.

Heart Characteristics

Size of a fist, weighs less than 1 lb, located between lungs.

Heart Coverings

Pericardium: double-layered sac that protects the heart.

Heart Layers

Epicardium, myocardium, endocardium.

Heart Rate

Number of heart beats in 1 min, approximately 72 beats/min.

Heart Sounds

First sound is 'lubb,' second is 'dupp.'

Inferior Vena Cava

Drains blood from below the diaphragm.

Interatrial Septum

Wall separating right and left atria.

Interventricular Septum

Wall separating right and left ventricles.

Left Coronary Artery

Supplies blood to the anterior heart wall.

Major Blood Vessels

Includes superior vena cava, renal arteries, and pulmonary veins.

Mediastinum

Space between the lungs.

Mitral Valve

Valve regulating blood flow between left atrium and ventricle.

Murmurs

Abnormal heart sounds due to faulty valves.

Myocardium

Middle layer of the heart wall, composed of cardiac muscle.

Nervous Regulation

Mechanism of the nervous system regulating heart function.

Pacemaker Potential

Membrane changes initiating cardiac action potentials.

Parasympathetic Nervous System

Slows heart rate primarily via the vagus nerve.

Pericardial Cavity

Space around the heart containing serous fluid.

Pericardium

Membranous sac enclosing the heart.

Physical Factors

Age, gender, exercise, and body temperature affecting heart rate.

Plateau Phase

Ca2+ channels remain open, prolonging action potential.

Preload

The amount of stretch in the ventricular muscle before contraction.

Pulmonary Circuit

Carries deoxygenated blood to lungs.

Pulmonary Trunk

Splits into right and left pulmonary arteries.

Pulmonary Valve

Prevents backflow from pulmonary artery to right ventricle.

Purkinje Fibers

Distribute the impulse throughout the ventricles for contraction.

P Wave

Represents atrial depolarization.

QRS Complex

Represents ventricular depolarization.

T Wave

Represents ventricular repolarization.

Stroke Volume

Volume of blood pumped per ventricle per contraction (~70 ml).

Ventricles

The two lower chambers of the heart.

Ventricular Diastole

Relaxation of ventricles.

Ventricular Systole

Contraction of ventricles.

Cardiovascular System Functions

Regulates blood supply, generates blood pressure, routes blood, and ensures one-way blood flow.

Sinoatrial (SA) Node

The heart's natural pacemaker initiating each heartbeat.

Atrioventricular (AV) Node

Delays the electrical impulse from the atria to the ventricles.

Bundle of His (AV Bundle)

Transmits the impulse from the AV node to the ventricles.

Bundle Branches and Purkinje Fibers

Distribute the impulse throughout the ventricles for contraction.

Rhythmicity

The heart's ability to beat regularly.

Repolarization Phase

K+ channels open, Ca2+ channels close.

Coronary Artery Disease

A condition characterized by the narrowing of coronary arteries.

Hypertension

High blood pressure affecting cardiovascular health.

Heart Failure

A condition where the heart cannot pump sufficiently.

Composition of Blood

Red blood cells, white blood cells, platelets, and plasma.

Hemoglobin

Protein in red blood cells that carries oxygen.

Regulatory Mechanisms

How hormones like adrenaline and the nervous system influence heart function.