20-1: The heart is a four-chambered organ that pumps blood through the systemic and pulmonary circuits

right atrium

receives blood from the systemic circuit and passes it to the right ventricle

vein

returns blood to the heart

pulmonary circuit

Carries blood to and from gas exchange surfaces of lungs

great vessels

the largest veins and arteries in the body

pericardial cavity

between parietal and visceral layers contains pericardial fluid

myocardium

cardiac muscle tissue that forms the atria and ventricles

artery

carries blood away from the heart

pulmonary circulation

carries oxygen-poor blood from the heart's lower right chamber (right ventricle), through the pulmonary arteries, to the lungs, and oxygen-rich blood back through the pulmonary veins to the heart's upper left chamber (left atrium)

systemic circulation

carries oxygen-rich blood from the heart's lower left chamber (left ventricle), through the systemic arteries, and oxygen-poor blood through the systemic coins back to the heart's upper right chamber (right atrium)

left atrium

collects blood from the pulmonary circuit and empties it into the left ventricle

endocardium

covers inner surfaces of heart simple squamous epithelium and areolar tissue

epicardium

covers surface of heart covered by parietal layer of serous pericardium

The layers of the heart wall from superficial to deep are:

epicardium myocardium endocardium

auricle

external visible flap formed by the collapse of the outer wall of a relaxed atrium

cardiac skeleton

four bands of elastic tissue around heart valves and bases of pulmonary trunk and aorta stabilize positions of valves and ventricular muscle cells electrically insulate ventricular cells from atrial cells

coronary sulcus

groove that marks border between atria and ventricles

heart

has four muscular chambers, two associated with each circuit

apex of heart

inferior pointed tip

pericarditis

inflamed pericardial surfaces rub against one another caused by pathogens in pericardium may cause cardiac tamponade

capillary (aka exchange vessel)

interconnect the smallest arteries and smallest veins exchange of nutrients, dissolved gases (aka gas exchange), and wastes between the blood and surrounding tissues

semilunar valves

pulmonary and aortic valves prevent back flow of blood into ventricles

right ventricle

pumps blood into the pulmonary circuit

left ventricle

pumps blood into the systemic circuit

blood flows from

right atrium to right ventricle

anterior & posterior interventricular sulci

separate left and right ventricles contain blood vessels of cardiac muscle

interatrial septum

separates atria

interventricular septum

separates ventricles much thicker than interatrial septum

base of heart

superior great vessels connect here

right atrium receives blood from

superior vena cava (carries blood from head, neck, upper limbs, and chest) and inferior vena cava (carries blood from trunk, viscera, and lower limbs)

pericardium

surrounds the heart consists of fibrous (outer) pericardium and serous (inner) pericardium

systemic circuit

transports blood to and from the rest of the body

atrioventircular valves

tricuspid and mitral valves folds of fibrous tissue that extend into the openings between the atria and ventricles permit blood flow in one direction: from right atrium to right ventricle from left atrium to left ventricle

serous pericardium

two-layered membrane composed of parietal (outer) layer and visceral (inner) layer [epicardium]