Chapter 5 The Heart and Blood Vessels

Interstitial fluid

The thing layer of fluid which surrounds the body's cells.

Lymph

Excess tissue fluid carried by lymphatic vessels.

Artery

A blood vessel that carries blood away from the heart.

Arteriole

A branch off of an artery that leads to a capillary; regulates blood pressure.

Capillary

A microscopic vessel between an arteriole and a venule, where gas exchange occurs.

Capillary bed

A network of capillaries, completing gas exchange with tissues.

Precapillary sphincters

Regulate blood flow through the capillary beds

Vein

A blood vessel that carries blood back towards the heart.

Venule

Small branch of a vein that receives blood from a capillary bed and send it on to a vein.

Valve

A flap of tissue in the heart or a vein that closes to prevent blood from flowing backwards, and opens to allow blood to flow forwards.

Pericardium

Membranous sac enclosing the heart

Pericardial fluid

A fluid between the pericardium and heart that prevents friction when the heart beats.

Heart

A hollow, muscular organ that generates the force needed to pump blood throughout the body.

Myocardium

Muscular, middle layer of the heart

Cardiac muscle

Involuntary muscle tissue found only in the heart; branched, striated, one nucleus per cell.

Intercalated disks

Specialized cell junctions in the myocardium where one heart cardiac muscle cell connects to the next, and is full of gap junctions.

Gap junction

A type of intercellular junction in animal cells, consisting of proteins surrounding a pore that allows the passage of materials between cells.

Septum

A thick wall that divides the heart into right and left sides; blood never crosses it.

Atria

Upper chambers of the heart

Ventricles

Lower chambers of the heart

Atrioventricular valves (tricuspid and bicuspid)

Valves that are located between the atria and the ventricles that keep blood moving forward in the pathway.

Semilunar valves (pulmonary and aortic)

Valves that separate ventricles from greater vessels and help keep blood moving forward in the pathway.

Coronary arteries/veins

Bring nutrients and blood to the heart; removes waste products; the heart does not use oxygen from the blood as it flows through the chambers and needs its own supply sent to its cells!

Myocardial infarction

The blockage of one or more coronary arteries caused by plaque buildup (heart attack)

Superior and inferior vena cava

Return unoxygenated blood to the right atrium of the heart; largest veins of the body.

Aorta

The largest artery in the body; carries blood from the heart to be distributed by branch arteries through the body.

Diastole

Relaxation phase of the heartbeat

Systole

Contraction phase of the heartbeat; first atria contract together, then relax while the ventricles contract together

SA node

The pacemaker of the heart, located in the right atrium, initiates the heartbeat by sending out an electrical signal at regular intervals.

AV node

Region of the heart between the right atrium and right ventricle from which electrical impulses spread to the ventricles during a heartbeat

Electrocardiogram (ECG)

A recording of the electrical activity of the heart

Ventricular fibrillation

Disorganized, ineffective twitching of the ventricles, resulting in no blood flow and a state of cardiac arrest.

Defibrillation

Application of an electric shock to the myocardium through the chest wall to reset the cardiac cycle

Pulse

Rhythmic expansion and recoil of an arterial wall; occurs whenever the left ventricle contracts so is a measure of heart rate.

slide 39