Download Unit 6- p3 heart

NOTES: UNIT 6 part 3-The Circulatory System: The Heart
The cardiovascular system _________________________________________ to tissues and
______________________________.
STRUCTURE OF THE HEART
Size: about 14 cm long and 9 cm wide
Location:
● 2/3 left of midline
● below 2nd rib and rests on diaphragm
*Location allows for CPR
Heart Covering: the heart is enclosed in a ______________________________________________;
protects against ______________________
● loosely fitting superficial part of the sac: fibrous pericardium
● deep to the fibrous pericardium: serous pericardium
*composed of 2 layers
*space between the layers = pericardial cavity (____________________________________)
Heart Wall
● ____________________ = _____________________________; in contact with pericardium (older
people= infiltrated with FAT)
● ____________________ = _________________________; thick, muscular (mainly cardiac muscle
tissue!)
● ____________________ = _________________________; has elastic and collagen fibers (lines the
heart chambers)
4 Heart Chambers: (heart is divided into right and left sides)
● RIGHT:



● LEFT:



Heart Valves: designed to prevent backflow of blood!
ATRIOVENTRICULAR VALVES:
-________________________: separates R atrium from R ventricle
-________________________ (a.k.a. _______________________):
separates L atrium from L ventricle
● Structure of AV valves:
-CHORDAE TENDINAE: _________________________________________________
Label me!
_____________________________
-PAPILLARY MUSCLES: _________________________________________________
__________________ attach to the chordae tendinae
*serve to anchor flaps in their closed position so pressure doesn’t blow them into atria like
an umbrella on a windy day
SEMILUNAR VALVES:
-________________________________: separates R ventricle from pulmonary arteries
-__________________________: separates L ventricle from aorta
*ventricle contraction forces these valves open until contraction is over; blood flow
backwards closes valves
Path of Blood Through the Heart:
● Blood _____________________________________
enters the ______________ SIDE through the vena
cava and is then pumped into pulmonary circulation
(_________________________________________)
● After blood is ________________________ in the lungs, it returns to the __________
SIDE through the pulmonary veins and is then pumped into ______________________
circulation via the aorta (_________________________)
Path of Blood Flow Through the Heart
•Right side
–Blood enters the right atrium through the superior and inferior vena cava  right atrioventricular
(tricuspid) valve  right ventricle  pulmonary semilunar valve  pulmonary artery  lungs
•Left Side
–Blood returns from the lungs through the pulmonary veins  left atrium 
left atrioventricular (bicuspid, mitral) valve  left ventricle 
aortic semilunar valve  aorta
Heart Blood Supply:
● the CORONARY ARTERIES supply blood to the myocardium
● blood returns to the R atrium through the cardiac veins and coronary sinus
**500,000 Americans die per year of coronary artery disease
**3.5 million Americans have coronary problems
Cardiac Cycle:
*______________________________
*______________________________
●Ventricular filling: blood returning to heart passively flows into atria & the open AV valves
● ATRIAL SYSTOLE: atria contract (propels residual blood) while the ventricles relax (VENTRICULAR
DIASTOLE)
● VENTRICULAR SYSTOLE: ventricles contract while the atria relax (ATRIAL DIASTOLE)
● all chambers relax for a brief period; cycle repeats!
Conduction System of the Heart
•The conduction system of the heart is composed of 4 structures
–Sinoatrial Node (___________________________)
–Atrioventricular Node
–Atrioventricular Bundle
–Purkinje Fibers
•Each of these structures is composed of modified cardiac muscle cells that only permit the rapid
conduction of an impulse through the heart
Initiation of Cardiac Cycle:
● electrical impulses originate in the SA node: stimulate the atria to contract
(_____________________)
● impulses pass slowly to the _____ node, then to the Purkinje fibers: stimulate
the ventricles to contract
ELECTROCARDIOGRAM (ECG/EKG):
● records the electrical changes in the myocardium during a cardiac cycle
● the pattern has several characteristic waves:
1) P wave: depolarization wave from SA through atria  atria contract
2) QRS complex: ventricular depolarization; precedes ventricle contraction  ventricles
contract
3) T wave: ventricular repolarization diastole
Regulation of Cardiac Cycle:
● heartbeat is affected by:
-