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Winter 2014 / Human Physiology > Lecture 3 The Heart > Flashcards

Lecture 3 The Heart Flashcards

0
Q

fibrous pericardium?

A
  • dense irregular CT

- protects and anchors the heart, prevents overstretching

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1
Q

where is the HT located?

A

in mediastinum - area from the sternum to the vertebral column and bt LU

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2
Q

what is thin, delicate membrane containing:

  • parietal layer - outer layer
  • pericardial cavity with pericardial fluid
  • visceral layer (epicardium)
A

serous pericardium

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3
Q

what are the layers of the Heart?

A

epicardium
myocardium
endocardium

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4
Q

which layer of the HT is the visceral layer of serous pericardium?

A

epicardium

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5
Q

which layer of the heart is the cardiac muscle layer and is the bulk layer of the heart?

A

myocardium

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6
Q

which layer lines the chamber and valves of the heart?

A

endocardium

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7
Q

the thickness of myocarium varies according to the function of what?

A

the function of chamber of heart

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8
Q

what is the thickness of atria wall, why?

A

Atria are thin walled, because they deliver blood to adjacent ventricles

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9
Q

what is the thickness of ventricle walls, why?

A

ventricle walls are much thicker and stronger

  • the right ventricles supplies blood to the lung (little flow resistance)
  • left ventricle wall is the thickest to supply systemic circulation
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10
Q

which chamber of the HT, receives blood from 3 sources? what are they?

A

right atrium

- superior vena cava, inferior vena cava, coronary sinus, blood flows through the tricuspid valve to the right ventricle

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11
Q

the right ventricle?

A

receives blood from right atrium, blood goes through pulmonary semilunar valve; blood flows into pulmonary trunk

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12
Q

the left atrium?

A

receives blood from lungs (through 4 pulmonary venins, 2 right and 2 left) and through the bicuspid valves blood passes through into left ventricle

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13
Q

left ventricle

A

receives blood from left atrium, sends blood through aortic semilunar valve into ascending aorta

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14
Q

the systemic circulation is on which side of the heart? and does what?

A
  • the left side of heart pumps blood through body
  • left ventricle pumps oxygenated blood into aorta
  • aorta branches into many arteries that travel to organs
  • arteries branch into many arterioles in tissue
  • arterioles branch into thin-walled capillaries for exchange of gases and nutrients
  • deoxygenated blood begins its return in venules
  • venules merge into veins and return to right atrium
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15
Q

pulmonary circulation

A
  • right side of heart pumps deoxygenated blood to lungs
  • right ventricle pumps blood to pulmonary trunk
  • pulmonary trunk branches into pulmonary arteries of gases
  • oxygenated blood returns to heart in pulmonary veins
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16
Q

what is the function of the dense CT rings surrounding the valves of the heart, and that fuses and merges with the interventricular septum?

A
  • the fibrous skeleton of the heart support structure for heart valves
  • it is an insertion pt for cardiac muscle bundles
  • it acts as an electrical insulator bt atria and ventricles (prevents direct propagation of AP’s to ventricles)
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17
Q

what is coronary circulation?

A
  • coronary circulation is blood supply to the heart
  • heart is a very active muscle and needs lot of O2
  • when heart relaxes high pressure of blood in aorta pushes blood into coronary vessels
  • there are many anastomoses in coronary circulation
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18
Q

what is anastomoses?

A
  • connection between arteries supplying blood to same region, provide alternate routes if one artery becomes occluded
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19
Q

which cells fire spontaneously, and act as pacemaker and form conduction system for the heart?

A

autorhythmic cells

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20
Q

what are cluster of cells in wall of Right Atria,

  • begins heart activity that spreads to both atria
  • pacemaker of heart (why?)
A

SA node

it’s the pacemaker, bc SA node is the fastest it sets the pace

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21
Q

what is the connection bt atria and ventricles and divides into bundle branches & purkinje fibers (large diameter fibers that conduct signals quickly)

A

AV bundle of His

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22
Q

SA nodes fires spontaneously how many times per min?

A

90-100 x/min

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23
Q

AV nodes fires how many times per min?

A

40-50 x/mins

24
Q

if both SA and AV nodes are suppressed, how many times per min does the ventricles fire by themselves?

A

20- 40 x/min

25
Q

if extra beats form at other sites, this is called?

A

ectopic pacemaker

26
Q

what is the cardiac cell resting membrane potential?

A

-90 mv

27
Q

what happens during depolarization?

A
  • excitation spreads through gap junctions

- fast Na+ channels open for rapid depolarization

28
Q

what happens during plateau phase?

A
  • 250 msec (only 1 msec in neuron)
  • slow Ca+2 channels open, let Ca+2 enter from outside cell and from storage in sarcoplasmic reticulum, while K+ channels close
  • Ca+2 binds to troponin to allow for actin-myosin cross bridge formation & tension development
29
Q

what is repolarization?

A
  • Ca+2 channels close and K+ channels open & -90mv is restored as potassium leaves the cell
30
Q

how long is the refractory period? why?

A

very long so heart can fill

31
Q

what records action potential of all active cells?

A

EKG

32
Q

P wave

A

atrial depolarization

33
Q

P to Q interval

A

conduction time from atrial to ventricular excitation

34
Q

QRS complex

A

ventricular depolarization

35
Q

T wave

A

ventricular repolarization

36
Q

what is one cardiac cycle?

A

75 beats/min, one cycle requires .8 sec

37
Q

what is end diastole volume (EDV)?

A

volume in ventricle at end of diastole, about 130 ml

38
Q

what is end systolic volume (ESV)?

A

volume in ventricle at end of systole, about 60ml

39
Q

what is stroke volume (SV)

A

the volume ejected per beat from each ventricle, about 70 ml

SV = EDV-ESV

40
Q

what is a brief period when volume in ventricles does not change - as ventricles relax, pressure drops and AV open?

A

isovolumetric relaxation

41
Q

what are the phases of cardiac cycle?

A
  • isovolumetric relaxation
  • ventricular filling (rapid ventricular filling)
  • ventricular systole
42
Q

what happens during ventricular filling?

A
  • rapid ventricular filling: as blood flows from full atria
  • diastasis: as blood flows from atria in smaller volume
  • atrial systole pushes final 20 - 25 ml blood into ventricle
43
Q

what happens during ventricular systole?

A
  • ventricular systole
  • isovolumetric contraction: brief period, AV valves close before SL valves open
  • ventricular ejection: as SL valves open and blood is ejected out
44
Q

what is the blood pressure in aorta?

A

120 mm Hg

45
Q

what is the blood pressure in pulmonary trunk?

A

30 mm Hg

46
Q

the difference in ventricle wall thickness allows heart to do what? what is the volume of blood ejected from each ventricle?

A

pushes the same amount of blood with more force from left ventricle

  • 70 ml (stroke volume)
47
Q

the first heart sound that is created with the closing of atrioventricular valves?

A

lubb

48
Q

the second heart sound, created with closing of semilunar valves is?

A

dupp

49
Q

what is the amount of blood pushed into aorta or pulmonary trunk by ventricle?

A

cardiac output

50
Q

cardiac output is determined by?

what is the equation?

A

determined by stroke volume and heart rate

CO = SV x HR

51
Q

what influences stroke volume?

A

preload (affect stretching; Frank-Starling Law of Heart: more blood more force of contraction)
contractility (autonomic nerves, hormones, Ca+2 or K+ levels)
afterload (amount of pressure created by the blood in the way

52
Q

what are the causes of CHF?

A

coronary artery disease, hypertension, MI, valve disorders, congenital defects

53
Q

what happens in a left side heart failure?

A
  • less effective pump so more blood remains in ventricle
  • heart is overstretched & even more blood remains
  • blood backs up into lungs as pulmonary edema
  • suffocation & lack of oxygen to the tissues
54
Q

what happens in right side failure?

A
  • fluid builds up in tissues as peripheral edema
55
Q

how does the nervous control from cardiovascular center in the medulla affect heart rate?

A
  • sympathetic impulses increase heart rate and force of contraction
  • parasympathetic impulses decrease heart rate
  • baroreceptros (pressure receptors) detect change in BP and send info to cardiovascular center (located in arch of the aorta and carotid arteries)
56
Q

what hormones affect heart rate?

A
  • epinephrine, norepinephrine, thyroid hormones

- ions (Na+, K+, Ca+2)

57
Q

what is in atrial septum and transmits signal to bundle of His?

A

AV node

Winter 2014 / Human Physiology (4 decks)

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