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BIOL 1190 > Ch. 20 - The Heart > Flashcards

Ch. 20 - The Heart Flashcards

1
Q

Where is the heart located?

A

mediastinum; mostly left of midline

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2
Q

C/C fibrous and serous pericardium

A

F - protects and anchors heart; prevents overstretching

S - parietal layer fuses with F percardium; visceral layer in direct contact with heart

*serous fluid found in between parietal and visceral pericardia

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3
Q

What are the layers of the heart wall?

A

epicardium, myocardium, endocardium

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4
Q

What are sulci?

A

grooves on outside of heart that separate chambers; contain BV and fat

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5
Q

What is an auricle?

A

pouch-like structure on anterior surface of each atrium; helps atria hold greater vol of blood

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6
Q

Which chambers receive?

A

atria

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7
Q

Which chambers pump?

A

ventricles

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8
Q

Where does the R atrium receive blood from? Where does it pump blood to?

A

superior/inferior vena cava, coronary sinus; right ventricle via tricuspid valve (right AV)

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9
Q

Where does the R ventricle receive blood from? Where does it pump blood to?

A

right atrium; into pulmonary trunk via right semilunar valve (pulmonary valve)

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10
Q

Where does the L atrium receive blood from? Where does it pump blood to?

A

oxygenated blood from lungs; left ventricle via bicuspid valve (left AV)

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11
Q

Where does the L ventricle receive blood from? Where does it pump blood to?

A

left atrium; aorta via left semilunar valve (aortic valve)

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12
Q

AV valves prevent back flow from…

A

…ventricles into atria

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13
Q

Semilunar valves prevent back flow from…

A

….arteries into ventricles

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14
Q

What triggers the opening and closing of heart valves?

A

pressure changes; not neurons/AP!

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15
Q

What are valves composed of?

A

dense irregular CT covered with endocardium

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16
Q

How do AV valves prevent back flow?

A

papillary muscles attached to valve cusps by chordae tendinae; chordae prevent valve cusps from opening into atrium

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17
Q

What are semilunar valves composed of?

A

3 moon-shaped cusps

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18
Q

When do semilunar valves open?

A

when pressure in ventricles exceed pressure in arteries

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19
Q

What is the function of coronary arteries?

A

supply myocardium cells with fresh nutrients and O2; branch off aorta

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20
Q

What is the function of coronary veins?

A

collect waste from cardiac muscle and drain into coronary sinus, which then empties into R atrium

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21
Q

What is systole and diastole?

A

S - contraction

D - relaxation

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22
Q

What does the cardiac cycle consist of?

A

systole + diastole of both atria followed by systole + diastole of both ventricles

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23
Q

What are characteristics of cardiac muscle?

A

branched, intercalated discs connected by gap junctions and desmosomes, involuntary, striated, single central nucleus

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24
Q

How do cardiac muscle sarcomeres differ form skeletal muscle?

A
  • more mitochondria (25% of cell vol)
  • T-tubules wider but less abundaent
  • SR less prominent; need Ca2+ from outside cell
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25
Q

How do cardiac muscles produce ATP?

A
  • aerobic cellular resp
    a. at rest: use FA, glucose
    b. during exercise; use lactic acid
  • creatine phosphate when something is wrong!
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26
Q

What are the role of autorhythmic fibers?

A
  • generate spontaneous AP that trigger heart contractions
  1. act as pacemaker, setting baseline rhythm of electrical excitation that causes contraction
  2. form conduction system; propagates AP through heart muscle
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27
Q

What is the sinoatrial (SA) node?

A
  • cluster of cells in wall of R atrium
  • repeated spontaneous depolarization; no stable resting potential
  • triggers contraction of both atria
28
Q

What is the atrioventricular (AV) node?

A
  • located in b/t 2 atria (atrial septum)

- signal is slightly delayed at AV node

29
Q

Why is the delay of the signal at AV node important?

A

atria have to contract then relax; ventricles have to contract then relax

30
Q

What is AV bundle?

A
  • where signal can be transmitted from atria and ventricles
  • send signal down ventricular septum to apex
  • Purkinje fibers conduct signal up ventricle wall
  • triggers contraction of ventricles
31
Q

What are the 3 phases of an AP in a ventricular contractile fiber?

A
  1. rapid depolarization
  2. plateau
  3. repolarization: closure of Ca2+ channels and K+ outflow when additional K+ channels open

**prolonged refractory period

32
Q

What occurs during depolarization phase?

A

Na+ inflow as Na+ channels open; resting membrane potential is -90mv

33
Q

What occurs during plateau phase?

A
  • Ca2+ inflow from outside cell/SR as Ca2+ channels open –> Ca2+ binds to troponin
  • K+ outflow as K+ channels open
34
Q

What occurs during repolarization phase?

A
  • Ca2+ channels close
  • K+ channels open to let K+ out of cell
  • muscle contraction ceases –> relaxation!
35
Q

Is tetanus possible in cardiac muscle cells?

A

no because potential is maintained

36
Q

What occurs at atrial and ventricular diastole?

A

4 chambers are relaxed; passive filling of blood into heart

37
Q

What occurs at atrial systole, ventricular diastole?

A

atria contract; blood pushes into ventricles

38
Q

What occurs at atrial diastole, ventricular systole?

A

atria relaxes; ventricles contract; blood pushes out of heart

39
Q

What does an electrocardiogram record?

A

spread of AP through heart

40
Q

What are the recognizable waves in an EKG that appear with each heartbeat?

A
  1. P wave - atrial depol (contraction!)
  2. QRS complex - rapid ventricular depol (contraction!)
  3. T wave - ventricular repol (relaxes)`
41
Q

Describe the AP propagation through the heart

A
  1. electrical impulse from SA node to walls of atria; atria contract=
  2. impulses reaches AV node; delay
  3. bundle branches carry signal from AV node to apex
  4. signal spreads through ventricle walls; ventricles contract
42
Q

What causes the sound of a heartbeat?

A

turbulence of blood flow caused by closure of valves

43
Q

What is the first heart sound?

A
  • AV valves close soon after V systole begins
44
Q

What is the second heart sound?

A
  • SL valves close near beginning of V diastole
45
Q

What does the R-R interval tell you?

A

length of time a heartbeat takes

46
Q

What kinds of information can you get from an ECG?

A

how muscles are conducting AP; can detect valve malfunction

47
Q

What is cardiac output? (CO)

A

vol of blood ejected from a ventricle each minute

48
Q

What is stroke volume? (SV)

A

vol of blood ejected by the ventricle with each contraction

49
Q

What is heart rate? (HR)

A

number of beats per minute

50
Q

What is the formula for cardiac output?

A

CO = SV x HR

51
Q

Depending on activity level, what are normal levels of cardiac output?

A

Resting - 5L/min
Mild exercise - 10L/min
Intense exercise - 19.5L/min

52
Q

How many times can the average person increase their CO resting value? How about a top endurance athlete?

A

4-5 times; 7-8 times

53
Q

What is a cardiac reserve?

A

difference between person’s max cardiac output & cardiac output at rest

54
Q

What hormones influence heart rate?

A

epinephrine, norepinephrine

55
Q

How are specific ion concentrations crucial to heart rate?

A
  1. increased K+ blocks AP generation
  2. increased Na+ blocks Ca2+
  3. increased Ca2+ speeds heart rate and force of contraction
56
Q

What other factors influence heart rate?

A

age, gender, physical fitness (athletes have lower rate), body temp (increased temp leads to increased heart rate)

57
Q

What are the 3 factors of regulation of stroke volume?

A

preload, contractility, afterload

58
Q

What is preload?

A

degree of stretching

more blood filling chamber –> more stretching –> greater force of contraction

59
Q

What is the amount of blood in chamber dependent on?

A

venous return and duration of diastole (relaxation)

60
Q

What is contractility?

A

force of contraction of myocardium

61
Q

C/C positive and negative inotropic agents

A

+ : increase contractility by increasing Ca2+ inflow

  • : decrease contractility by decreasing Ca2+ inflow/increasing K+ outflow
62
Q

What does inotropic mean?

A

drugs acting on contractility fibres

63
Q

What is afterload?

A

amount of pressure required to open semilunar valves

64
Q

What causes high afterload?

A

high BP

65
Q

What leads to increased stroke volume?

A

increased preload + contractility, decreased afterload

BIOL 1190 (18 decks)

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