Sherwood Cardiac Physiology

Chapter 9 Cardiac Physiology

Cir!ulatory System # Three basi! !omponents  $ %eart # Ser&es as pump that establishes the pressure gradient needed 'or blood to 'low to tissues

 $ Blood &essels # "assageways through whi!h blood is distributed 'rom heart to all parts o' body and ba!k to heart

 $ Blood # Transport medium within whi!h materials being transported are dissol&ed or suspended

Chapter  Cardia! "hysiology

Cir!ulatory System # Three basi! !omponents  $ %eart # Ser&es as pump that establishes the pressure gradient needed 'or blood to 'low to tissues

 $ Blood &essels # "assageways through whi!h blood is distributed 'rom heart to all parts o' body and ba!k to heart

 $ Blood # Transport medium within whi!h materials being transported are dissol&ed or suspended

Chapter  Cardia! "hysiology

Cir!ulatory System # "ulmonary !ir!ulation  $ Closed loop o' &essels !arrying blood between heart and lungs # Systemi! !ir!ulation  $ Cir!uit o' &essels !arrying blood between heart and other body systems

Chapter  Cardia! "hysiology

Cir!ulatory System #  (natomy o' the heart  $ %ollow) %ollow) mus!ular organ about the si*e si* e o' a !len!hed 'ist  $ "ositioned between two bony stru!tures $ sternum and &ertebrae # "osition makes it physi!ally possible to manually dri&e blood 'rom heart when it is not pumping e''e!ti&ely +C",

Chapter  Cardia! "hysiology

Cir!ulatory System # %eart # .ual pump  $ ,ight and le't sides o' heart 'un!tion as two separate pumps  $ .i&ided into right and le't hal&es and has 'our !hambers #  (tria  $ pper !hambers  $ ,e!ei&e blood returning to heart and trans'er it to lower !hambers

# entri!les  $ Lower !hambers whi!h pump blood 'rom heart Chapter  Cardia! "hysiology

Cir!ulatory System # %eart  $  (rteries # Carry blood away 'rom &entri!les to tissues

 $ eins # essels that return blood 'rom tissues to the atria

 $ Septum # Continuous mus!ular partition that pre&ents mi1ture o' blood 'rom the two sides o' heart

Chapter  Cardia! "hysiology

Cir!uit o' Blood low • The venae cavae are veins returning blood to the right atrium. Oxygen has been extracted from this blood. Carbon dioxide has been added to it. This blood is pumped from the right ventricle through the pulmonary artery to the lungs. • The lungs add oxygen to this blood received from the right side of the heart. Carbon dioxide is removed from this blood. This blood flows through pulmonary veins to the left atrium of the heart. This oxygen rich blood is pumped from the left ventricle through the aorta, a large artery. Chapter  Cardia! "hysiology

Blood low Through and "ump (!tion o' the %eart

Chapter  Cardia! "hysiology

%eart al&es #  (trio&entri!ular +( &al&es  $ ,ight and le't ( &al&es are positioned between atrium and &entri!le on right and le't sides  $ "re&ent ba!k'low o' blood 'rom &entri!les into atria during &entri!ular emptying  $ ,ight ( &al&e #  (lso !alled tri!uspid &al&e

 $ Le't ( &al&e #  (lso !alled bi!uspid &al&e or mitral &al&e

 $ Chordae tendinae # ibrous !ords whi!h pre&ent &al&es 'rom being e&erted # "apillary mus!les Chapter  Cardia! "hysiology

%eart al&es # Semilunar &al&es  $  (orti! and pulmonary &al&es  $ Lie at 3un!ture where ma3or arteries lea&e &entri!les  $ "re&ented 'rom e&erting by anatomi! stru!ture and positioning o' !usps # 4o &al&es between atria and &eins  $ ,easons #  (trial pressures usually are not mu!h higher than &enous pressures # Sites where &enae !a&ae enter atria are partially !ompressed during atrial !ontra!tion Chapter  Cardia! "hysiology

%eart al&es

Chapter  Cardia! "hysiology

%eart 5all # Consists o' three distin!t layers  $ 6ndothelium # Thin inner tissue # 6pithelial tissue whi!h lines entire !ir!ulatory system

 $ yo!ardium # iddle layer  # Composed o' !ardia! mus!le # Constitutes bulk o' heart wall

 $ 6pi!ardium # Thin e1ternal layer whi!h !o&ers the heart

Chapter  Cardia! "hysiology

Cardia! us!le ibers # 8nter!onne!ted by inter!alated dis!s and 'orm 'un!tional syn!ytia # 5ithin inter!alated dis!s $ two kinds o' membrane  3un!tions  $ .esmosomes  $ 9ap 3un!tions

Chapter  Cardia! "hysiology

# %eart is en!losed by peri!ardial sa! # "eri!ardial sa! has two layers  $ Tough) 'ibrous !o&ering  $ Se!retory lining # Se!retes peri!ardial 'luid  $ "ro&ides lubri!ation to pre&ent 'ri!tion between peri!ardial layers

# "eri!arditis  $ 8n'lammation o' peri!ardial sa!

Chapter  Cardia! "hysiology

6le!tri!al (!ti&ity o' %eart # %eart beats rhythmi!ally as result o' a!tion potentials it generates by itsel' +autorhythmi!ity # Two spe!iali*ed types o' !ardia! mus!le !ells  $ Contra!tile !ells # : o' !ardia! mus!le !ells # .o me!hani!al work o' pumping # 4ormally do not initiate own a!tion potentials

 $  (utorhythmi! !ells # .o not !ontra!t # Spe!iali*ed 'or initiating and !ondu!ting a!tion potentials responsible 'or !ontra!tion o' working !ells

Chapter  Cardia! "hysiology

6le!tri!al (!ti&ity o' %eart # Lo!ations o' non!ontra!tile !ells !apable o' autorhymi!ity  $ Sinoatrial node +S( node # Spe!iali*ed region in right atrial wall near opening o' superior &ena !a&a # "a!emaker o' the heart

 $  (trio&entri!ular node +( node # Small bundle o' spe!iali*ed !ardia! !ells lo!ated at base o' right atrium near septum

 $ Bundle o' %is +atrio&entri!ular bundle # Cells originate at ( node and enters inter&entri!ular septum # .i&ides to 'orm right and le't bundle bran!hes whi!h tra&el down septum) !ur&e around tip o' &entri!ular !hambers) tra&el ba!k toward atria along outer walls

 $ "urkin3e 'ibers # Small) terminal 'ibers that e1tend 'rom bundle o' %is and spread throughout &entri!ular myo!ardium

Chapter  Cardia! "hysiology

Spe!iali*ed Condu!tion System o' %eart

Chapter  Cardia! "hysiology

6le!tri!al (!ti&ity o' %eart # Cardia! impulse originates at S( node #  (!tion potential spreads throughout right and le't atria # 8mpulse passes 'rom atria into &entri!les through ( node +only point o' ele!tri!al !onta!t between !hambers #  (!tion potential brie'ly delayed at ( node +ensures atrial !ontra!tion pre!edes &entri!ular !ontra!tion to allow !omplete &entri!ular 'illing # 8mpulse tra&els rapidly down inter&entri!ular septum by means o' bundle o' %is # 8mpulse rapidly disperses throughout myo!ardium by means o' "urkin3e 'ibers # ,est o' &entri!ular !ells a!ti&ated by !ell-to-!ell spread o' impulse through gap 3un!tions Chapter  Cardia! "hysiology

Spread o' Cardia! 61!itation

Chapter  Cardia! "hysiology

6le!tri!al (!ti&ity o' %eart #  (tria !ontra!t as single unit 'ollowed a'ter brie' delay by a syn!hroni*ed &entri!ular !ontra!tion #  (!tion potentials o' !ardia! !ontra!tile !ells e1hibit prolonged positi&e phase +plateau a!!ompanied by prolonged period o' !ontra!tion  $ 6nsures ade;uate e3e!tion time  $ "lateau primarily due to a!ti&ation o' slow L-type Ca20 beats per minute

Chapter  Cardia! "hysiology

 (bnormalities in ,hythm # ,hythm  $ ,egularity or spa!ing o' 6C9 wa&es #  (rrhythmia  $ ariation 'rom normal rhythm and se;uen!e o' e1!itation o' the heart  $ 61amples #  (trial 'lutter  #  (trial 'ibrillation # entri!ular 'ibrillation # %eart blo!k

Chapter  Cardia! "hysiology

Cardia! yopathies # .amage o' the heart mus!le  $ yo!ardial is!hemia # 8nade;uate deli&ery o' o1ygenated blood to heart tissue

 $ 4e!rosis # .eath o' heart mus!le !ells

 $  (!ute myo!ardial in'ar!tion +heart atta!k # ?!!urs when blood &essel supplying area o' heart be!omes blo!ked or ruptured

Chapter  Cardia! "hysiology

,epresentati&e %eart Conditions .ete!table Through 6C9

Chapter  Cardia! "hysiology

Cardia! ?utput # olume o' blood e3e!ted by ea!h &entri!le ea!h minute # .etermined by heart rate times stroke &olume

Chapter  Cardia! "hysiology

Cardia! ?utput # %eart rate is &aried by altering balan!e o' parasympatheti! and sympatheti! in'luen!e on S( node  $ "arasympatheti! stimulation slows heart rate  $ Sympatheti! stimulation speeds it up

Chapter  Cardia! "hysiology

Cardia! ?utput # Stroke &olume  $ .etermined by e1tent o' &enous return and by sympatheti! a!ti&ity  $ 8n'luen!ed by two types o' !ontrols # 8ntrinsi! !ontrol # 61trinsi! !ontrol

 $ Both 'a!tors in!rease stroke &olume by in!reasing strength o' heart !ontra!tion

Chapter  Cardia! "hysiology

rank-Starling Law o' the %eart # States that heart normally pumps out during systole the &olume o' blood returned to it during diastole

Chapter  Cardia! "hysiology

4ourishing the %eart us!le # us!le is supplied with o1ygen and nutrients by blood deli&ered to it by !oronary !ir!ulation) not 'rom blood within heart !hambers # %eart re!ei&es most o' its own blood supply that o!!urs during diastole  $ .uring systole) !oronary &essels are !ompressed by !ontra!ting heart mus!le # Coronary blood 'low normally &aries to keep pa!e with !ardia! o1ygen needs

Chapter  Cardia! "hysiology

Coronary (rtery .isease +C(. # "athologi!al !hanges within !oronary artery walls that diminish blood 'low through the &essels # Leading !ause o' death in nited States # Can !ause myo!ardial is!hemia and possibly lead to a!ute myo!ardial in'ar!tion  $ Three me!hanisms # "ro'ound &as!ular spasm o' !oronary arteries # ormation o' atheros!leroti! pla;ues # Thromboembolism

Chapter  Cardia! "hysiology

"ossible ?ut!omes o' (!ute yo!ardial 8n'ar!tion +%eart (tta!k

Chapter  Cardia! "hysiology

Cardiac Anatomy

Cardiac Cycle