Download Anatomy of the Heart

Anatomy of the Heart
 Located in the _____________________ – anatomical region extending from the
sternum to the vertebral column, the first rib and between the lungs
 _________ at tip of left ventricle
 ___________ is posterior surface
 Anterior surface deep to sternum and ribs
 Inferior surface between apex and right border
 Right border faces right lung
 Left border (pulmonary border) faces left lung
__________________________
 Membrane surrounding and protecting the heart
 Confines while still allowing free movement
 2 main parts
 __________________ pericardium – tough, inelastic, dense
irregular connective tissue – prevents overstretching, protection,
anchorage
 ______________ pericardium – thinner, more delicate membrane
– double layer (parietal layer fused to fibrous pericardium, visceral
layer also called epicardium)
 Pericardial fluid reduces ____________ – secreted into pericardial
cavity
Layers of the Heart Wall
1. ________________________ (external layer)
 Visceral layer of serous pericardium
 Smooth, slippery texture to outermost surface
2. _______________________
 95% of heart is ____________________
3. _______________________ (inner layer)
 Smooth lining for chambers of heart, valves and continuous with lining of
large blood vessels
Chambers of the Heart
 2 ____________ – receiving chambers
 Auricles increase capacity
 2 ____________ – pumping chambers
 Sulci – grooves
 Contain coronary blood vessels
 Coronary sulcus
 Anterior interventricular sulcus
 Posterior interventricular sulcus
Right Atrium
 Receives blood from
 ________________ vena cava
 _________________ vena cava
 Coronary sinus
 Interatrial septum has _________________
 Remnant of foramen _____________
 Blood passes through __________________ valve (right atrioventricular
valve) into __________________ ventricle
Right Ventricle
 Forms anterior surface of heart
 ____________________________ – ridges formed by raised bundles of
cardiac muscle fiber
 Part of conduction system of the heart
 ______________________ valve connected to
_________________________ connected to _________________muscles
 _______________________ septum
 Blood leaves through __________________ valve (pulmonary
__________________valve) into pulmonary trunk and then right and left
pulmonary arteries
Left Atrium
 About the same thickness as right atrium
 Receives blood from the ______________ through
___________________ veins
 Passes through _____________/ ___________/ left ________________
valve into left ventricle
Left Ventricle
 ____________________ chamber of the heart
 Forms apex
 ______________________ attached to _________________ muscles
 Blood passes through _____________valve (aortic ______________
valve) into ascending aorta
 Some blood flows into coronary arteries, remainder to body
 During fetal life ______________________ shunts blood from pulmonary
trunk to aorta (lung bypass) closes after birth with remnant called
_____________________________
Myocardial thickness
 Thin-walled atria deliver blood under _____________pressure to
ventricles
 Right ventricle pumps blood to _______________
 ____________ distance, _________ pressure, __________
resistance
 Left ventricle pumps blood to body
 _____________ distance, ______________ pressure,
___________ resistance
 Left ventricle works _____________ to maintain same rate of blood flow
as right ventricle
Heart Valves and Circulation of Blood
 Atrioventricular valves
 Tricuspid and bicuspid valves
 Atria ___________/ _______________ relaxed
 AV valve _________, cusps project into ventricle
 In ventricle, papillary muscles are relaxed and chordae tendinae
_____________
 Atria _________/ ___________ contracts
 Pressure drives cusps _____________ until edges meet and close
opening
 Papillary muscles ___________ tightening chordae tendinae
 Prevents regurgitation
Semilunar valves
 Aortic and pulmonary valves
 Valves __________when pressure in ventricle __________ pressure in
arteries
 As ventricles relax, some backflow permitted but blood fills valve cusps
______________them tightly
 No valves guarding entrance to atria
 As atria contracts, compresses and closes opening
Systemic and pulmonary circulation - 2 circuits in series
 Systemic circuit
 ________ side of heart
 Receives blood from ____________
 Ejects blood into ___________
 ______________ arteries, arterioles
 Gas and nutrient exchange in systemic capillaries
 Systemic venules and veins lead back to right atrium
 Pulmonary circuit
 ____________side of heart
 Receives blood from _____________ circulation
 Ejects blood into ________________ then pulmonary arteries
 Gas exchange in pulmonary capillaries
 Pulmonary veins takes blood to __________ atrium
Cardiac Muscle Tissue and the Cardiac Conduction System
 Histology
 Shorter and less circular than skeletal muscle fibers
 ________________ gives “stair-step” appearance
 Usually _______ centrally located nucleus
 Ends of fibers connected by _______________________
 Discs contain __________________ (hold fibers together) and gap
junctions (allow action potential conduction from one fiber to the next)
 Mitochondria are ____________ and more _______________ than
skeletal muscle
 Same arrangement of actin and myosin
Autorhythmic Fibers
 Specialized cardiac muscle fibers
 Self-excitable
 Repeatedly generate action potentials that trigger heart contractions
 2 important functions
1. Act as ______________
2. Form _______________ system
Conduction system
1. Begins in __________ (SA) node in right _________ wall
 Propagates through atria via gap junctions
 Atria contact
2. Reaches ____________________ (AV) node in
________________________
3. Enters __________________ (AV) bundle (_________________)
 Only site where action potentials can conduct from atria to
ventricles due to fibrous skeleton
4. Enters right and left bundle branches which extends through
_______________________septum toward apex
5. Finally, large diameter Purkinje fibers conduct action potential to
remainder of ventricular myocardium
 Ventricles contract
Action Potentials and Contraction
1. Action potential initiated by ____ node spreads out to excite “working”
fibers called contractile fibers
2. __________________
3. Plateau
4. ___________________
Electrocardiogram
 Composite record of action potentials produced by all the heart muscle
fibers
 Compare tracings from different leads with one another and with normal
records
 3 recognizable waves
 ____, ________, and ____
Correlation of ECG Waves and Systole
1. ___________ – contraction/ diastole – ______________
2. Cardiac action potential arises in SA node
 ___ wave appears
3. Atrial contraction/ atrial ___________
4. Action potential enters ___ bundle and out over ventricles
 QRS complex
 ____________ atrial repolarization
5. Contraction of ventricles/ ventricular _____________
 Begins shortly after QRS complex appears and continues during ST segment
6. Repolarization of ventricular fibers
 ___ wave
7. Ventricular relaxation/ diastole
Cardiac Cycle
 All events associated with one heartbeat
 Systole and diastole of atria and ventricles
 In each cycle, atria and ventricles alternately contract and relax
 During atrial systole, ventricles are ____________
 During ventricle systole, atria are _______________
 Forces blood from ___________ pressure to ________________ pressure
 During relaxation period, both atria and ventricles are relaxed
 The faster the heart beats, the shorter the relaxation period
 Systole and diastole lengths shorten slightly
Heart Sounds
 ___________________________
 Sound of heartbeat comes primarily from _________________ caused by
________ of _____________________
 4 heart sounds in each cardiac cycle – only 2 loud enough to be heard
 Lubb – ____ valves close
 Dupp – _____ valves close
Cardiac Output
 CO = volume of blood __________ from left (or right) ventricle into aorta (or
pulmonary trunk) each minute
 CO = stroke volume (SV) x heart rate (HR)
 In typical resting male
 5.25L/min = 70mL/beat x 75 beats/min
 Entire blood volume flows through pulmonary and systemic circuits each minute
 Cardiac reserve – difference between maximum CO and CO at rest
 Average cardiac reserve 4-5 times resting value