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Anatomy & Physiology 2 > Chapter #20: The Heart > Flashcards

Chapter #20: The Heart Flashcards

1
Q

Systems involved in the heart

A

-Cardiovascular system
-Pulmonary circuit
-Systemic circuit

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2
Q

Parts of the cardiovascular system

A

-Heart
-Blood
-Blood vessels

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3
Q

Types of blood vessels

A

-arteries
-veins
-capillaries (exchange vessels)

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4
Q

Arteries

A

Carry blood away from heart (carries oxygen rich blood away from the heart and to the organs)

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5
Q

Veins

A

Return blood to heart (carries deoxygenated blood toward the heart)

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6
Q

Capillaries (exchange vessels)

A

-Interconnect smallest arteries and smallest veins
-Exchange dissolved gases, nutrients, and wastes between blood and surrounding tissues

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7
Q

Anatomy of the heart

A

-Great vessels connect at base (superior)
-Pointed tip is apex (inferior)
-Sits between two pleural cavities in mediastinum
**look at diagram on slide 5

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8
Q

Pericardium

A

-Surrounds heart
-Outer fibrous pericardium
-Inner serous pericardium
–Outer parietal layer
–Inner visceral layer (epicardium)

-Pericardial cavity
–Between parietal and visceral layers
–Contains pericardial fluid
**look at diagram on slide 7

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9
Q

Heart wall consists of three distinct layers

A
  1. Epicardium (outer layer)
  2. Myocardium (middle layer)
  3. Endocardium (inner layer)
    **know diagram on slide 10
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10
Q

Epicardium

A

-Covers surface of heart
-Covered by parietal layer of serous pericardium

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11
Q

Myocardium

A

Cardiac muscle tissue

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12
Q

Endocardium

A

Covers inner surfaces of heart

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13
Q

What direction does blood flow?

A

Blood flows from right atrium to right ventricle

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14
Q

What is the tricupid valve (right atrioventricular valve)

A

-Has three cusps
-Prevents backflow of blood

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15
Q

Compared to left ventricle, the right ventricle

A

-Holds and pumps the same amount of blood
-Has thinner walls
-Develops less pressure
-right side of the heart is weaker & thinner because it is only pumping blood to the lungs, while the left side is thicker because it is pumping blood to the body
**know diagram on slide 13

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16
Q

What is the pathway of blood?

A

Right atrium –> right ventricle –> lungs –> left atrium –> left ventricle –> body

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17
Q

How does contraction and relaxation work?

A

-atrial contraction –> ventricle relaxation
-ventricle contraction –> atrial relaxation

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18
Q

Function of Heart Valves

A

Prevent backflow of blood

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19
Q

Atrioventricular (AV) valves

A

-Between atria and ventricles
-When ventricles contract,
–Blood pressure closes valves
–Papillary muscles contract and tense chordae tendineae
—Prevents regurgitation (backflow) of blood into atria

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20
Q

Semilunar valves

A

-Pulmonary and aortic valves
-Prevent backflow of blood into ventricles

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21
Q

Heartbeat

A

-A single cardiac contraction
-All heart chambers contract in series
–First the atria
–Then the ventricles

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22
Q

Two types of cardiac muscle cells

A
  1. Autorhythmic cells: Control and coordinate heartbeat
  2. Contractile cells: Produce contractions that propel blood
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23
Q

Conducting system

A

-electrical impulses that stimulate contraction

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24
Q

Autorhythmicity

A

Cardiac muscle tissue contracts without neural or hormonal stimulation

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25
Q

Components of the conducting system

A

-Pacemaker cells found in
–Sinoatrial (SA) node—in wall of right atrium
–Atrioventricular (AV) node—at junction between atria and ventricles

-Conducting cells found in
–Atrioventricular (AV) bundle, bundle branches, and Purkinje fibers of ventricles

26
Q

What are the steps to the conducting system?

A
  1. SA node depolarizes and atrial activity begins
  2. Stimulus spreads across the atrial surfaces and reaches the AV node
  3. There is a 100-msec delay at the AV node and atrial contraction begins
  4. The impulse travels along the interventricular septum within the AV bundle and the bundle branches to the Purkinje fibers to the papillary muscles of the right and left ventricles
  5. The impulse is distributed by Purkinje fibers and relayed throughout the ventricular myocardium. Atrial contraction is completed and ventricular contraction begins
    **look at diagrams on slides 25-29
27
Q

Step 1 of the conducting system

A

-SA node depolarizes first
-establishing sinus rhythm (pattern of heart beat)
-parasympathetic stimulation slows heart rate
-beginning line on graph

28
Q

Step 2 in conducting system

A

-P wave: atrial depolarization

29
Q

Step 3 in conducting system

A
  • P-R interval: conduction through AV node & AV bundle
30
Q

Step 4 in conducting system

A

-Q wave: beginning of ventricular depolarization

31
Q

Step 5 in conducting system

A
  • QRS complex: completion of ventricular depolarization
32
Q

What is an EKG?

A

-Electrocardiogram (ECG or EKG)
-captures the heart in 3 dimensions
-a recording of electrical events int he heart
-obtained by placing electrodes at specific location on body surface
-abnormal patterns are used to diagnose damage

33
Q

Features of an EKG

A

-P wave: depolarization of atria
-QRS complex: depolarization of ventricles and ventricles begin contracting shortly after R wave
-T wave: repolarization of ventricles

34
Q

Time intervals between EKG waves

A
  • P–R interval:
    –From start of atrial depolarization
    –To start of QRS complex

-Q–T interval
–Time required for ventricles to undergo a single cycle of depolarization and repolarization

35
Q

What segment shows a heart attack?

A

-an elevated S-T segment shows a heart attack

36
Q

Which segment can be affected by certain medications?

A
  • Q-T interval
    -certain medications prolong this interval and slow your heart rate
37
Q

Cardiac contractile cells

A

-Form bulk of atrial and ventricular walls
-Receive stimulus from Purkinje fibers

38
Q

Intercalated discs

A

-Interconnect cardiac contractile cells
-Membranes of adjacent cells are
–Held together by desmosomes
–Linked by gap junctions

-Transfer force of contraction from cell to cell
-Propagate action potentials

39
Q

Events in an action potential in a ventricular contractile cell

A
  1. Rapid depolarization
  2. the plateau
  3. Repolarization
    **know diagram on slide 39
40
Q

Rapid Depolarization of an action potential in a ventricular contractile cell

A

-Cause: Na+ entry
-Ends with: Closure of voltage-gated fast sodium channels

41
Q

The plateau of an action potential in a ventricular contractile cell

A

-Cause: Ca2+ entry
-Ends with: Closure of slow calcium channels

42
Q

Repolarization of an action potential in a ventricular contractile cell

A

-Cause: K+ loss
-Ends with: Closure of slow potassium channels

43
Q

Cardiac Cycle

A

-From start of one heartbeat to beginning of next
-Includes alternating periods of contraction and relaxation

44
Q

Phases of the cardiac cycle within each chamber

A

-Systole (contraction)
-Diastole (relaxation)

45
Q

Blood pressure in each chamber of the cardiac cycle

A

-Rises during systole
-Falls during diastole

-Blood flows from higher pressure to lower pressure
–Controlled by timing of contractions
–Directed by one-way valves

46
Q

What is the average heart rate?

A

-75 bpm
-smaller people have a higher heart rate
-larger people have a slower heart rate

47
Q

Phases of the cardiac cycle

A
  1. Atrial systole
  2. Atrial diastole
  3. Ventricular systole
  4. Ventricular diastole
    ** know diagram on slide 43
48
Q

Steps of the cardiac cycle

A
  1. Atrial systole begins: Atrial contraction forces the blood into relaxed ventricles
  2. Atrial systole ends, atrial diastole begins
  3. Ventricular systole - first phase: Ventricular contraction, AV valve closes
  4. Ventricular systole - second phase: as ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected
  5. Ventricular diastole - early: as ventricles relax, pressure in ventricles drops; blood flows back against cusps of semilunar valves
    and forces them closed. Blood
    flows into the relaxed atria
  6. Ventricular diastole—late: All chambers are relaxed. Ventricles fill passively
49
Q

Ventricular systole

A

-Ventricular ejection
–Ventricular pressure exceeds arterial pressure
–Opens semilunar valves, allowing blood to exit
–Amount of blood ejected = stroke volume

-Semilunar valves close
–As ventricular pressure falls
–Ventricles contain end-systolic volume (ESV) (at the end of contraction, what volume of blood is left)
—-About 40 percent of end-diastolic volume

50
Q

Atrial damage vs. Ventricular damage

A

-individuals can survive severe atrial damage
-ventricular damage can lead to heart failure

51
Q

Cardiac output (CO)

A

-Volume pumped by left ventricle in one minute
-CO = HR × SV

CO = cardiac output (mL/min)
HR = heart rate (beats/min)
SV = stroke volume (mL/beat)

52
Q

Ejection fraction

A
  • (blood left)/(total blood initially there)
    -great measure of how healthy your heart is, especially after a heart attack
  • Percentage of EDV ejected during contraction
53
Q

factors affecting heart rate (HR)

A
  1. Autonomic innervation (vagus nerve)
  2. Hormones (epinephrine & norepinephrine)
54
Q

Factors affecting stroke volume (SV)

A
  1. End-diastolic volume (EDV)
  2. End-systolic volume (ESV)
    -Stroke volume (SV) = EDV - ESV
55
Q

End-diastolic volume (EDV)

A

Amount of blood in each ventricle at end of ventricular diastole

56
Q

End-systolic volume (ESV)

A

Amount of blood remaining in each ventricle at end of ventricular systole

57
Q

How to measure cardiac reflexes

A

-cardiac centers
-monitor:
1. blood pressure (baroreceptors)
2. oxygen
3. carbon dioxide (chemoreceptors)

-adjust cardiac activity

58
Q

Autonomic Tone

A

-Maintained by dual innervation and release of ACh and NE
-Fine adjustments meet needs of other systems

59
Q

Hormonal effects on heart rate

A

-Heart rate is increased by:
1. Epinephrine (E)
2. Norepinephrine (NE)
3. Thyroid hormone (T3)

60
Q

Effects of autonomic activity on contractility

A

-Sympathetic stimulation
–NE released by cardiac nerves
–E and NE released by adrenal medullae
–Causes ventricles to contract with more force
–Increases ejection fraction, decreases ESV

-Parasympathetic stimulation
–ACh released by vagus nerves
–reduces force of cardiac contractions

61
Q

Summary: the control of cardiac output

A

-Heart rate control factors
-Autonomic nervous system
-Sympathetic and parasympathetic
-Circulating hormones
-Venous return and stretch receptors

Anatomy & Physiology 2 (8 decks)

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