The Heart

1
Circulatory System

• The Heart

2
Overview

• Gross anatomy
• cardiovascular system
• Cardiac conduction system and ____________________
  
• ____________________- activity of heart
• Blood flow, heart sounds, and cardiac cycle
• Cardiac output

3
Circulatory System The Heart

• Circulatory system
• _____________________________
• Cardiovascular system
• heart, arteries, veins and capillaries
• Two major divisions
• __________________________
• ______________ side of heart
• carries blood to lungs
• _______________ circuit
• ____________ side of heart
• supplies blood to the body

4
Position, Size, and Shape

• ___________________________, between lungs
• ________________ - broad superior portion of
  heart
• ____________ - inferior end, tilts to the left,
  tapers to point
• 3.5 in. wide at base, 5 in. long and 2.5 in.
  wide weighs 10 oz

5
Membranes

• Allow smooth movement (serous membranes)
• ______________ pericardium
• outer, tough, fibrous layer
• Pericardial cavity
• filled with pericardial fluid (5-30 mL)
• Visceral pericardium (____________________)
• inner, thin, smooth, moist serous layer
• covers heart surface
• _______________________
• Lines inside of heart and major vessels

6
Heart Wall

• ____________________
• thick cardiac muscle layer
• fibrous skeleton - collagenous and elastic fibers
• support and attachment for muscles
• electrical nonconductor, coordinates contraction

7
Heart Chambers

• 4 chambers
• right and left ________
• superior
• blood returning to heart
• __________________ circulation
• right and left ventricles
• inferior chambers
• pump blood into arteries
• ____________ circulation

• _______________________ sulcus- separates atria,
  ventricles
• Anterior and posterior sulci - grooves separate
  ventricles

8
Heart Chambers - Internal

• ___________septum
• separate atria
• Pectinate muscles
• ridges of myocardium in right atrium and both
  auricles
• ______________________ septum
• separates ventricles
• ____________________________
• ridges in both ventricles

9
Heart Valves

• Atrioventricular (AV) valves
• right AV valve
• 3 cusps _______________________________
• _____________ AV valve
• 2 cusps _______________________________
• ______________________ ?valves to papillary
  muscles
• Semilunar valves
• control flow into great arteries
• ____________________________
• right ventricle into pulmonary trunk
• Aortic
• left ventricle into aorta

10

• Bicuspid valve
• Interventricular septum
• Papillary muscle
• Superior vena cava
• Mitral valve
• Pulmonary semilunar valve
• Left ventricle
• Heart apex

11
AV Valve Mechanics

• Ventricles relax
• _____________drops
• semilunar valves close
• AV valves open
• ______________________________________________
• Ventricles __________
• AV valves close
• pressure rises
• semilunar valves open
• blood flows into great vessels

12
Blood Flow Through Heart
13
Coronary Circulation

• _____________________ (LCA)
• Ant. interventricular branch
• supplies septum and anterior walls of ventricles
• ___________ branch
• around left side in sulcus, supplies left atrium
  and posterior wall of left ventricle
• _________________ artery (RCA)
• ______________ branch
• supplies lateral R atrium and ventricle
• posterior interventricular branch
• supplies posterior walls of ventricles

14
Angina and Heart Attack

• ____________________________
• partial obstruction of coronary blood flow
• chest pain
• caused by ischemia, activity dependent
• ____________________________
• complete obstruction
• death of cardiac cells in affected area
• Pain/pressure in chest that radiates down left arm

15
Venous Drainage of Heart

• 20 drains directly into right atrium
• 80 returns via
• _____________________
• blood from anterior interventricular sulcus
• middle cardiac vein
• from posterior sulcus
• left marginal vein
• _____________________
• collects blood and empties into right atrium

16
Nerve Supply to Heart

• Properties
• _____________ - heartbeat originates within heart
• autorhythmic
• Sympathetic nerves from
• can raise heart rate to 230 bpm
• Parasympathetic nerves
• right /left vagal nerve to SA/AV node
• ___________ slows heart rate to 70 - 80 bpm

17

• Rosey the red blood cell was trying to find her
  friend Robert. She was
• circulating in the lower leg when she was swept
  back to the heart. She
• traveled in the ________________________ (vessel)
  and entered the
• ______________. She didnt see Robert as she
  passed the
• _______________valve and fell into the
  ______________. Ever so
• quickly, she got squeezed through the
  ___________________ (valve)
• and entered the _____________________ (vessel).
  Swish, she had been
• feeling a little blue but now as she entered the
  __________, she was
• feeling much brighter. Just as quickly she was on
  her way back to the
• heart via the ___________________. She quickly
  entered the
• __________________ and then passed by the
  _________________ as she
• entered the left ventricle. One last squeeze and
  she was zipping past
• the _____________________, out of the ventricle,
  and into the
• ____________________ on her way to the rest of
  the body. Sadly, she
• didnt find Robert.

18
Conduction System

• SA node
• ________________
• __________________
• sets heart rate
• _________________
• gateway to ventricles
• AV bundle
• pathway from AV node
• Right and left bundle branches
• divisions of AV bundle enter interventricular
  septum
• _______________________
• from apex spread through ventricular myocardium
• fibrous skeleton insulates atria from ventricles

19
Structure of Cardiac Muscle

• Short, branched cells, _____________________
• ________________ join myocytes end to end
• mechanical junctions tightly join myocytes
• electrical junctions - gap junctions allow ions
  to flow
• _________________________

20
Cardiac Rhythm

• _______________ ventricular contraction
• Diastole - ventricular __________________
• Sinus rhythm
• set by SA node at 60 100 bpm
• at rest .8 sec ? 75 bpm
• adult at rest is 70 to 80 bpm
• ________________________________ (PVC)
• caused by hypoxia, electrolyte imbalance,
  stimulants, stress, etc.

21
Cardiac Rhythm

• __________________ - region of spontaneous firing
  (not SA)
• nodal rhythm - set by AV node, 40 to 50 bpm
• intrinsic ventricular rhythm - 20 to 40 bpm
• ____________ - abnormal cardiac rhythm
• _____________ failure of conduction system
• bundle branch block
• total heart block (damage to AV node)

22
Impulse Conduction to Myocardium

• SA node signal travels at 1 m/sec through atria
• AV node slows signal to 0.05 m/sec
• AV bundle and purkinje fibers
• speeds signal along at 4 m/sec to ventricles
• Ventricular systole begins at apex, progresses up
• spiral arrangement of myocytes twists ventricles
  slightly

23
Electrocardiogram (ECG)

• Composite of action potentials
• detected, amplified and recorded by electrodes on
  arms, legs and chest
• Diagnose abnormalities in conduction pathways,
  MI, heart enlargement and electrolyte and hormone
  imbalances

24
ECG

• _____________________ atrial systole
• SA node fires, atrial depolarization
• ______________ complex - ventricular
  depolarization
• (atrial repolarization and diastole - signal
  obscured)
• ST segment - ventricular systole
• __________________ - ventricular repolarization

25
Electrical Activity of Myocardium

• 1) _______________________ begins
• 2) atrial depolarization complete (atria
  contract)
• 3) ______________________
• _____________________ atria repolarize (atria
  relax)
• 4) ventricular depolarization complete
  (ventricles contract)
• 5) ventricles begin to repolarize at apex
• 6) ventricular repolarization complete
  (ventricles relax)

26
Cardiac Cycle

• One complete contraction and relaxation of all 4
  chambers of the heart
• Atrial systole, Ventricle diastole
• Atrial diastole, Ventricle systole
• __________________________

27
Principles of Pressure and Flow

• Pressure causes a fluid to flow
• pressure gradient - pressure difference between
  two points

• Resistance opposes flow
• great vessels have positive blood pressure
• ventricular pressure must rise above this
  resistance for blood to flow into great vessels

28
Heart Sounds

• _________________ - listening to body sounds
• First heart sound (S1), louder and longer
  _____________, closure of ______ valves
• Second heart sound (S2), softer and sharper
  __________ occurs with _________________________
  __________
• S3 - rarely heard in people 30

29
Major Events of Cardiac Cycle

• Quiescent period
• Ventricular filling
• ________________ contraction
• Ventricular ejection
• ________________________________

30
Phases of Cardiac Cycle

• __________________ period
• all chambers relaxed
• AV valves open and blood flowing into ventricles
• ___________________
• SA node fires, depolarize
• atria contract, force additional blood into
  ventricles
• ventricles now contain _____________________
  (EDV) of about 130 ml of blood

31
Isovolumetric Contraction of Ventricles

• Atria repolarize and relax
• Ventricles depolarize
• Ventricles contract
• Rising pressure closes AV valves -
  __________________________________________
• No ejection of blood yet (no change in volume)

32
Ventricular Ejection

• Pressure opens semilunar valves
• Blood ejected
• _________________ amount ejected, 70 ml at rest
• SV/EDV _______________________
• at rest 54
• vigorous exercise ? 90
• diseased heart
• ______________________ volume amount left in
  heart

33
Ventricles- Isovolumetric Relaxation

• Ventricles repolarize and relax (begin to expand)
• Semilunar valves close - heart sound S2 occurs
• AV valves remain closed
• __________________________________ (no change in
  volume)

34
Ventricular Filling - 3 phases

• Rapid ventricular filling
• AV valves first open
• ______________
• sustained lower pressure, venous return
• ________________
• filling completed

35
Rate of Cardiac Cycle

• Atrial systole, 0.1 sec
• Ventricular systole, 0.3 sec
• Quiescent period, 0.4 sec
• Total 0.8 sec, heart rate ___________

36
Ventricular Volume Changes at Rest

• End-systolic volume (ESV) 60 ml
• Passively added to ventricle during atrial
  diastole 30 ml
• Added by atrial systole 40 ml
• End-diastolic volume (EDV) 130 ml
• Stroke volume (SV) ejected by ventricular
  systole -70 ml
• End-systolic volume (ESV) 60 ml
• Both ventricles must eject same amount of blood

37
Cardiac Output (CO)

• Amount ejected in 1 minute
• Cardiac Output _______________ x
  ________________________
• 4 to 6L/min at rest
• vigorous exercise ? CO to 21 L/min - 35 L/min
• _________________ difference between a persons
  maximum and resting CO
• ? with fitness, ? with disease

38
Heart Rate

• _____________ surge of pressure in artery
• infants have HR of 120 bpm
• young adult females avg. 72 - 80 bpm
• young adult males avg. 64 to 72 bpm
• HR rises in the elderly
• ________________ resting HR above 100
• stress, anxiety, drugs, heart disease or ? body
  temp.
• ____________________ resting HR
• in sleep and endurance trained athletes

39
Chronotropic Effects

• _____________________ agents ? HR
• Negative chronotropic agents _________
• Cardiac center of ____________________
• autonomic control center
• cardioacceleratory center (sympathetic)
• cardioinhibitory center (parasympathetic)

40
Chronotropic Chemicals

• Electrolytes
• K has greatest effect
• __________________________
• myocardium less excitable, HR slow and irregular
• hypokalemia
• _______________________________________________
• Calcium
• hypercalcemia
• ________________________
• _______________________
• increases HR

41
Sympathetic Nervous System

• _______________________ center
• stimulates SA node, AV node and myocardium
• secrete _________________________
• CO peaks at HR of 160 to 180 bpm
• can ? HR up to 230 bpm, but SV and CO ? (less
  filling time)

42
Parasympathetic Nervous System

• _______________________ center
• right vagus (SA)
• left vagus (AV)
• secretes ACH, nodal cells hyperpolarized, HR
  slows
• ______________ background firing rate holds HR
  to sinus rhythm of 70 to 80 bpm
• maximum vagal stimulation ? HR as low as 20 bpm

43
Inputs to Cardiac Center

• Higher brain centers affect HR
• cerebral cortex, limbic system, hypothalamus
• sensory or emotional stimuli (rollercoaster, IRS
  audit)
• _________________________
• changes in activity, HR ? before metabolic
  demands arise
• _________________________
• aorta and internal carotid arteries
• pressure ?, signal rate drops, cardiac center ?
  HR
• if pressure ?, signal rate rises, cardiac center
  ? HR

44
Inputs to Cardiac Center

• _______________________
• sensitive to blood pH, CO2 and oxygen
• aortic arch, carotid arteries and medulla
  oblongata
• ? CO2 (hypercapnia) causes ? H levels, may
  create acidosis (pH
• Hypercapnia and acidosis ? HR

45
Stroke Volume (SV)

• Governed by three factors
• _______________________
• _______________________
• _______________________
• Example
• ? preload or contractility causes ? SV
• ? afterload causes ? SV

46
Preload

• Tension in ventricular myocardium
• _______________ causes __________________
• exercise ? venous return, stretches myocardium (?
  preload) , ? CO matches ? venous return
• ____________________________ - SV? EDV
• ventricles eject as much blood as they receive
• more they are stretched (? preload) the harder
  they contract

47
Contractility

• Contraction force for a given preload
• Positive inotropic agents
• factors that _____________________
• hypercalcemia, catecholamines, glucagon,
  digitalis
• Negative inotropic agents
• factors that ? contractility are
• ________________________________

48
Afterload

• Pressure in arteries above semilunar valves
  opposes opening of valves
• _________________________
• any impedance in arterial circulation ? afterload
  
• Continuous ? in afterload (lung disease,
  atherosclerosis, etc.) causes hypertrophy of
  myocardium, may lead it to weaken and fail