VSCI100 Introduction to the Cardiovascular System

Flashcards covering the gross anatomy of the thorax, lung lobes, heart chambers, valves, cardiac cycle phases, heart sounds, and electrical conduction pathway.

Cardiovascular System

The system responsible for the delivery of oxygen, nutrients, hormones, and enzymes to body tissues and the removal of waste products and heat.

Thoracic Inlet

The cranial boundary of the thorax.

Thoracic Vertebrae

The dorsal boundary of the thorax; there are $13$ in the normal dog.

Costochondral Junction

The junction between the dorsal bony portion ($2/3$) and the ventral cartilaginous portion ($1/3$) of a rib.

Floating Rib

The last rib which is not connected ventrally to the costal arch.

Sternebrae

The $8$ small bones that make up the sternum.

Manubrium

The first sternebra, which is palpable cranially.

Xiphoid Process

The last sternebra, palpable caudally, which has a cartilaginous extension called the xiphoid cartilage.

Diaphragm

A sheet of skeletal muscle forming the caudal boundary of the thorax, extending from the sternum, ribs, and vertebrae to a central aponeurotic tendon.

Hilus

The root of the lungs, located dorsal to the heart.

Visceral Pleura

The serous membrane that invests the lungs.

Parietal Pleura

The serous membrane lining the thorax, consisting of the mediastinal, diaphragmatic, and costal pleura.

Heart Base

The dorsal and cranial portion of the heart where main vessels enter and exit.

Heart Apex

The caudoventral portion of the heart, which has a slight left deviation.

Pericardium

An outpouching of the pleura consisting of visceral and parietal layers separated by serous fluid that encapsulates the heart.

Endocardium

The innermost layer of the heart body.

Myocardium

The muscular middle layer of the heart body.

Epicardium

The outer serosal layer of the heart, confluent with the visceral pericardium.

Mitral Valve

The left atrioventricular (AV) valve, also known as the bicuspid valve, which has $2$ cusps in most species.

Tricuspid Valve

The right atrioventricular (AV) valve, which typically has $3$ cusps.

Interventricular Septum

The muscular wall separating the ventricles, containing a proximal membranous portion.

Auricle

An additional outpouching of an atrium, also known as an atrial appendage.

Semilunar Valves

A collective term for the aortic and pulmonic valves.

Systole

The contraction phase of the cardiac cycle when blood is pushed out of the chambers.

Diastole

The relaxation phase of the cardiac cycle when chambers fill with blood.

Isovolumetric Contraction

The phase of the cardiac cycle starting after the AV valves close but before the semilunar valves open, where volume remains constant as pressure increases.

Isovolumetric Relaxation

The phase starting after the semilunar valves close but before the AV valves open, where volume remains constant as pressure drops.

$$S1$$

The first heart sound caused by the closure of AV valves and rebound of blood at the start of isovolumetric contraction.

$$S2$$

The second heart sound caused by the closure of the pulmonary and aortic valves, marking the end of systole.

Gallop Rhythm

The term used in dogs and cats when $S3$ and/or $S4$ heart sounds are audible on auscultation.

Heart Murmur

Abnormal sounds generated by turbulence in the blood within the heart or great vessels.

Sinoatrial (SA) node

A specialized area of cardiac muscle cells in the right atrium wall that generates the initial electrical impulse.

Atrioventricular (AV) node

Specialized tissue in the distal interatrial septum that provides the only electrical communication between the atria and ventricles.

Annulus Fibrosus

A fibrous plate that supports the valves and electrically isolates the atria from the ventricles.

Bundle of His

Also known as the atrioventricular bundle; it passes the electrical impulse from the AV node through the annulus fibrosus to the interventricular septum.

Purkinje Fibres

The branches of the bundle branches that supply the electrical impulse to the ventricular muscle.

Septomarginal Band

A band of tissue where part of the right bundle branch crosses to the free wall of the right ventricle.