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

The Heart Flashcards

1
Q

What does the term “double pump” mean?

A

Each heartbeat pumps blood to the lungs and to the body

  • Pulmonary circulation: send blood to lungs
  • Systemic circulation: send blood to body
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2
Q

In what cavity is the heart located in the body?

A

In the Middle Mediastinum

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3
Q

What is the pericardium? What does it consist of?

A

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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4
Q

What is the pericardial cavity?

A

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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5
Q

What does the heart wall consist of?

A
  1. Epicardium (visceral layer)
  2. Myocardium
  3. Endocardium
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6
Q

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

A
  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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7
Q

What are the chambers of the heart?

A

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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8
Q

What is the septum of the heart?

A

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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9
Q

Walk through Blood Flow through the heart

A
  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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10
Q

What are the Great Vessels?

A
  1. Aorta
  2. Superior/Inferior Vena Cava
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11
Q

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

A
  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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12
Q

What are the semilunar valves?

A

The Pulmonary Semilunar Valve in trunk and Aortic Semilunar Valve

Arranged as 3 half-moon cusps (pockets)

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13
Q

What arteries are involved in Coronary Circulation in the heart?

A

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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14
Q

What veins are involved in coronary circulation of the heart?

A
  • 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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15
Q

What makes up the conduction system of the heart?

A

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
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16
Q

What components make up the conduction system of the heart?

A

Sinoatrial (SA) Node

  • Primary Pacemaker (fastest ap/min)

Atrioventricular (AV) Node

  • Secondary Pacemaker (slower ap/min)

ORDER:

  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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17
Q
  • 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?
A
  • 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
18
Q

What are the different Waves and intervals in the EKG?

A
  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

19
Q

What does an EKG or ECG measure?

A

Measures electrical impulses sent down each chamber

20
Q

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

A

The Quiescent period gets longer or shorter

21
Q

What phenomena control blood flow through the heart?

A

Contraction and Relaxation of the

  1. Atrioventricular (AV) Valves
  2. Semilunar (SL) Valves
22
Q

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

A

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*
23
Q

How do the chambers behave during a normal cardiac cycle?

A

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

  • Systole: Contraction
  • Diastole: Relaxation
24
Q

What are the phases of the cardiac cycle?

A
  1. Ventricular Filling
  2. Isovolumetric Contraction
  3. Ventricular ejection
  4. Isovolumetric relaxation
25
Q

What occurs during Ventricular Filling?

A

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

END DIASTOLIC VOLUME = 130 mL

26
Q

What is Isovolumetric Contraction?

A

Same Volume Contraction:

  • Brief moment during contraction when Ventricle Pr>Atria Pr but Vent Pr<arterial></arterial>
  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
27
Q

What occurs during Ventricular Ejection?

A

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

28
Q

What occurs during Isovolumetric Relaxation?

A

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
29
Q

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

A

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

30
Q

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

A
31
Q

What is cardiac output?

A

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

32
Q

What is cardiac ouput determined by?

A

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

33
Q

What is cardiac reserve?

A

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

34
Q

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

A

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

35
Q

How is Stroke volume regulated?

A
  1. Preload
  2. Contractility
  3. Afterload
36
Q

What is Preload?

A

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
37
Q

What is contractility?

A

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

38
Q

What is Afterload?

A

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
39
Q

What will affect cardiac output?

A

Heartrate (HR) or Stroke Volume (SV)

40
Q

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

A

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

41
Q

How does the automic nervous system regulate heart rate?

A

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
42
Q

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

A

Hormones

  • epinephrine, norepinephrine, thyroxine, glucagon

Ions

BIO 241: Anatomy & Physiology II (11 decks)

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