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BIO 241: Anatomy & Physiology II > The Heart > Flashcards

Flashcards in The Heart Deck (42):

What does the term "double pump" mean?

Each heartbeat pumps blood to the lungs and to the body

  • Pulmonary circulation: send blood to lungs
  • Systemic circulation: send blood to body


In what cavity is the heart located in the body?

In the Middle Mediastinum

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What is the pericardium?  What does it consist of?

Sac containing the heart


Consists of two layers:

  1. Outer Fibrous: anchor and protect heart
  2. Inner Serous
    1. Parietal layer: outermost layer
    2. Visceral layer (epicardium): surface of heart

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What is the pericardial cavity?

The parietal and visceral layers of the Inner Serous pericardium have epithelial cells that produce pericardial fluid that fills the pericardial cavity

  • This reduces friction

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What does the heart wall consist of?

  1. Epicardium (visceral layer)
  2. Myocardium
  3. Endocardium


What are the characteristics of the heart muscle, Myocardium, which is part of the heart wall?

  1. Involuntary and striated muscle
  2. Intercalated discs
    • Gap junctions to carry action potentials
  3. Ventricular muscle mass larger than atrial muscle mass
    • Ventricular muscle mass pumps blood out of heart and needs to have a stronger contraction
  4. Cardiac skeleton
    • collagen connective tissue separates atria and ventricle
    • no action potentials between two sides except through two openings causing millisecond delay

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What are the chambers of the heart?

Right and Left Aria

  • Atria have appendages called auricles
  • Larger space to expand and receive extra blood during exercise

Right and Left Ventricles

  • Coronary Sulcus: "crown" indentation that separates Atria from Ventricle
  • Intraventricular Sulci: Anterior and Posterior that separate the two ventricles

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What is the septum of the heart?

A Septum is a wall.  There is:

  • Interatrial septum: separates atria
    • Open as fetus for fetal gas exchange
    • Closed as adult
  • Interventricular septum – always closed

    • Part membranous, part muscle. 

      • Muscle part contracts.

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Walk through Blood Flow through the heart

  1. Right Atrium
    • receives deoxygenated bloods from:
      • Superior vena cava
      • Inferior vena cava
      • Coronary Sinus
  2. Right Ventricle
    • Passes through Tricuspid Valve
  3. Pulmonary Trunk
    • Passes through Pulmonary Semilunar-Valve
  4. Lungs
    • Gas exchange
  5. Pulmonary Veins
  6. Left Atrium
  7. Left Ventricle
    • Passes through the Bicuspid Valve
  8. Aorta
    • Passes through the Aortic Semlunar-Valve

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What are the Great Vessels?

  1. Aorta
  2. Superior/Inferior Vena Cava



What are the Atrioventricular Valves (AV) and how do they work?

  1. Tricuspid and bicuspid
  • right vs. left side, respectively


Chordae tendineae attach to Papillary muscles which control the opening and closing of the valves

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What are the semilunar valves?

The Pulmonary Semilunar Valve in trunk and Aortic Semilunar Valve


Arranged as 3 half-moon cusps (pockets)

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What arteries are involved in Coronary Circulation in the heart?

Left Coronary Artery

  • Anterior Interventricular Artery (widowmaker)
  • Circumflex Artery

Right Coronary Artery

  • Posterior Interventricular Artery
  • Marginal Artery

Both arteries are fused (anastomoses)

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What veins are involved in coronary circulation of the heart?

  • Great cardiac vein
  • Middle cardiac vein
  • Small cardiac vein


The coronary sinus ultimately receives all cardiac venous blood and returns it to the right atrium

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What makes up the conduction system of the heart?

Autorhythmic cells stimulates heart, generating hearbeat by starting action potentials


The ANS can modify heart rhythm but not establish the rhythm


All cardiac muscle cells are autorhythmic but 1% lose ability to contract

  • These cells form the pacemakers and conduction system


What components make up the conduction system of the heart?

Sinoatrial (SA) Node

  • Primary Pacemaker (fastest ap/min)

Atrioventricular (AV) Node

  • Secondary Pacemaker (slower ap/min)


  1. SA Node
  2. AV Node
  3. AV Bundle
  4. Split into Left and Right Bundle Branches
  5. Purkinje Fibers loop around


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  • Where does the cardiac muscle contract first? Last? 
  • Why is there a 0.12 sec delay across the AV node?
  • What separates the atrial muscle mass from the ventricular muscle mass?
  • Why does the interventricular septum begin to contract before the apex?

  • Atrial Cardiac muscle contract first and Upper Regions of the Ventricular Wall conduct last
  • 0.12 sec delay due to the AV Node not firing as fast as SA
  • Cardiac Skeleton separates the atrial and ventricular muscle masses
  • Interventricular Septum contracts first b/c AP reaches there first


What are the different Waves and intervals in the EKG?

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  1. P Wave: Atrial Depolarization
  2. QRS Complex: Ventricular Depolarization
  3. T Wave: Ventricular Repolarization

P-Q Interval: Atria depolarizes and contracts

P-R Interval: Atri and Ventricles Depolarize +contract

Q-T Interval: 

S-T Segment: Blood Gone

Quiescent Period: Time between cycles

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What does an EKG or ECG measure?

Measures electrical impulses sent down each chamber


What heart rate changes what actually changes in the conduction cycle?

The Quiescent period gets longer or shorter


What phenomena control blood flow through the heart?

Contraction and Relaxation of the

  1. Atrioventricular (AV) Valves
  2. Semilunar (SL) Valves


How does Pressure affect blood flow?  What pressures are involved in the Cardiac Cycle?

Blood always flows from an area of high pressure to an area of low pressure

  • Pressure is a result of the size of a chamber and the volume of blood within it


  1. Venous Pressure
  2. Atrial Pressure*
  3. Ventricular Pressure
  4. Aterial Pressure*


How do the chambers behave during a normal cardiac cycle?

Two Atria will contract while the Two Ventricles relax, then, Two Ventricles contract while the two Atria relax

  • Systole: Contraction
  • Diastole: Relaxation



What are the phases of the cardiac cycle?

  1. Ventricular Filling
  2. Isovolumetric Contraction
  3. Ventricular ejection
  4. Isovolumetric relaxation


What occurs during Ventricular Filling?

In diastole, ventricles expand and pressure decreases

  • AV valves open when atrial pr. >  ventricular pr.

3 Phases of Ventricular Filling:

  1. Rapid ventricular filling
  2. Diastisis
  3. Atrial systole

70% of Ventricle fills w/ Phases 1 & 2 due to pressure difference

30% of Ventricle fills w/ Phase 3 due to Atrial Contraction



What is Isovolumetric Contraction?

Same Volume Contraction:

  • Brief moment during contraction when Ventricle Pr>Atria Pr but Vent Pr


  1. Atrial Diastole Begins
  2. Ventricular Systole Begins
  3. AV Valves close when Ventricular Pr>Atrial Pr
  4. No blood ejected because Arterial Pr>Ventricular Pr


What occurs during Ventricular Ejection?

Ventricular Pr>Arterial Pr

  • SL Valves open when Ventricular Pr>Arterial Pr
  • Rapid ejection then reduced ejection

Stroke Volume = 70 mL

End-Systolic Volume = 60 mL


What occurs during Isovolumetric Relaxation?

Brief period of time where the volume remains the same but the blood has been ejected so pressure goes down

  • SL Valves are closed and AV Valves are still closed

Early Ventricular Diastole

  • Ventricles expand = pr decreases
  • SL Valves close when arterial pr>ventricular pr

Quiescent Period

  • ​Begins whe atrial pr>ventricular pr
  • AV valves will open and ventricular filling occurs to begin next cycle


What are the volume changes that occur during the cardiac cycle?

End-systolic volume                                              = 60 ml

  •  left from previous heart beat

Passively added during atrial diastole (70%)

  • rapid ventricular filling + diastasis                 = 70 ml

Atrial systole (30%)


Total  end-diastolic volume                                  = 130 ml

Stroke volume              minus                                 -  70 ml

(ejected by ventricular systole)  ___________

Leaves the end-systolic volume                            = 60 ml


What are the chamber volume and pressure changes listed in the diagram below?

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What is cardiac output?

amount of blood ejected from the left ventricle into the aorta per minute


What is cardiac ouput determined by?

Stroke volume (SV) and Heart Rate (HR)

SV x HR = Cardiac Ouput


Example:  (70 ml/beat)(75 beats/minute) = 5,250 ml/min or 5.25L/min


In 1 min all of the blood within the body cycles through once


What is cardiac reserve?

difference between maximum cardiac output and resting cardiac output

  • Resting cardiac output = 5 L/min
  • Max (exercise) cardiac ouput = 20 L/min
  • The max is 300% higher, so cardiac reserve = 300%

Exercise increases Cardiac Reserve


How do we compensate for congestive heart failure and pump more blood?

We tap into the cardiac reserve when ventricle not pumping all of the 70mL that it should


How is Stroke volume regulated?

  1. Preload
  2. Contractility
  3. Afterload


What is Preload?

More stretch in the sarcomere = more forceful contraction

  • Increased venous return + Increased length of the Diastole = Increased ventricular filling = Increased Preload = Increased Ventricular stretch
  • This results in a more forceful contraction = increased stroke volume = increased cardiac output

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What is contractility?

External factors such as epinephrine increase the contractility of the muscle resulting in increased stroke volume = increased cardiac output

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What is Afterload?

Pressure in the artery right after ventricle is higher then ventricular pressure and decreases cardiac output

  • blood pools in ventricle => leading to hypertrophy of ventricle => leads to congestive heart failure

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What will affect cardiac output?

Heartrate (HR) or Stroke Volume (SV)


What is the difference between Stroke Volume (SV) and Cardiac Output (CO)?

Stroke Volume (SV): amount of blood that moves out of heart w/ each Cardiac Cycle


Cardiac Output (CO): amount of blood that leaves the heart per minute


How does the automic nervous system regulate heart rate?

Sensory Input received from:

  • Baroreceptors: Blood Pressure
  • Chemoreceptors: Chemical concentration

Sensory Input sent to medulla oblongata. Motor output sent to:

  • Cardioacceleratory neurons - via sympathetic NS
    • release epinephrine at SA node
    • increase heart rate
  • Cardioinhibitory neurons - via parasympathetic NS
    • release acetylcholine at SA node
    • decrease heart rate


What kinds of chemicals can be used to regulate heart rate?


  • epinephrine, norepinephrine, thyroxine, glucagon