Heart Anatomy

where is the heart positioned? [2]

mid-mediastinum

behind sternum

approximately how much of the heart lies left of midline of sternum

2/3

Approximately two-thirds of the heart lies to the left of the midline of the sternum between what ribs [2]

2nd

6th

the apex lies above the diaphragm at the level of what intercostal space to the left

5th intercostal space

base of the heart projects what direction

right

base of heart lies below what rib

2nd rib

posteriorly, the heart rests at the level of what vertebrae?

5-8th thoracic vertebrae

this location of the heart is responsible for allowing to maintain blood flow during CPR

between sternum & spine

these are external grooves that mark boundaries of the heart

sulci

The heart is enclosed in a sac called

peicardium

Support for the four interior chambers and valves of the heart is provided by

4 atrioventricular rings

these support for the 4 interior chambers & valves of heart form fibrous skeleton

AV rings

these chambers of the heart are are thin-walled “cups” of myocardial tissue that contribute little to the total pumping activity of the heart.

atria

these chambers of the heart make up the bulk of the heart’s muscle mass and do most of the pumping that circulates the blood

ventricles

how much larger is the mass of left ventricle compared to right ventricle

2/3 larger

this ventricle has a thinner wall

right ventricle

flaps of fibrous tissue

valves of heart

valves of the heart are flaps of fibrous tissue firmly anchored to

annulus fibrosus cordis

bicuspid valve is also called

mitral valve

this valve closes during systole, preventing backflow into atria

AV valve

this occurs during contraction of ventricles

systole

The free ends of the AV valves are anchored to papillary muscles of the endocardium by the

chordae tendinae

these valves prevent backflow of blood into the ventricles during diastole

semilunar valves

this is when chambers of the heart fill with blood

diastole

the heart has its own circulatory system, which is called

coronary circulation

when does blood flow through the coronary arteries?

only during when SL valves closed

what veins gather together into a large vessel coronary sinus

coronary veins

coronary veins gather into a large vessel called

coronary sinus

this unique ability of the heart initiates depolarization and repolarization

inherent rhythmicity

systole means

contract

diastole means

to relax

When the electrical signals of a depolarization wave reach the contractile cells; systole or diastole

systole

When the repolarization signals reach the myocardial cells they; systole / diastole

diastole

refractory period lasts nearly as long as?

systole

these cells are short, fat, branched and interconnected.

cardiac cells

Individual cardiac fibers are enclosed in a membrane called

sarcolemma

this membrane is surrounded by rich capillary network

sarcolemma

what separates cardiac fibers

intercalated discs

these are irregular transverse thickenings of the sarcolemma

intercalated discs

these provide structural support and aid in electrical conduction between fibers

intercalated discs