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into (heart) Flashcards

1
Q

The cardiovascular system (CV) consists of:

A
  • Blood
  • Heart
  • Blood vessels
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2
Q

is the pump that circulates the blood through
an estimated
- 60,000 miles of BV
- HR 100,000 times/day
- 35 millions times/year
- Pumps 5 L/minute, 14,000 L/day, 10 million L/year

A
  • The heart
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3
Q

Anatomy of the Heart

A

Located in the mediastinum – anatomical region
extending from the sternum to the vertebral column, the
first rib and between the lungs
• Apex at tip of left ventricle
• Base is posterior surface
• Anterior surface deep to sternum and ribs
• Inferior surface between apex and right border
• Right border faces right lung
• Left border (pulmonary border) faces left lung

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4
Q 
Because heart is situated between two
rigid structure (vertebral column and
sternum) external pressure on the chest
can be used to force blood out of the
heart and into the circulation
A

cpr

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5
Q

Membrane surrounding and protecting the heart

– Confines while still allowing free movement

A

Pericardium

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6
Q

tough, inelastic, dense irregular
connective tissue – prevents overstretching, protection,
anchorage

A

Fibrous pericardium

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7
Q

thinner, more delicate membrane
– double layer (parietal layer fused to fibrous
pericardium, visceral layer also called epicardium)

A

Serous pericardium

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8
Q

Pericardial fluid reduces friction – secreted into ____

A

pericardial cavity

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9
Q

Visceral layer of serous pericardium

– Smooth, slippery texture to outermost surface

A

Epicardium (external layer)

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10
Q

95% of heart is cardiac muscle

A

Myocardium

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11
Q

Smooth lining for chambers of heart, valves and

continuous with lining of large blood vessels

A

Endocardium (inner layer)

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12
Q

receiving chambers

A

2 atria-Auricles increase capacity

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13
Q

– pumping chambers

A

– 2 ventricles

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14
Q
  • Contain coronary blood vessels
  • Coronary sulcus
  • Anterior interventricular sulcus
  • Posterior interventricular sulcus
A

Sulci – grooves

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15
Q 
– Receives blood from
• Superior vena cava
• Inferior vena cava
• Coronary sinus
– Interatrial septum has fossa ovalis
• Remnant of foramen ovale
– Blood passes through tricuspid valve (right
atrioventricular valve) into right ventricle
A

Right Atrium

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16
Q

Forms anterior surface of heart
– Trabeculae carneae – ridges formed by raised
bundles of cardiac muscle fiber
• Part of conduction system of the heart
– Tricuspid valve connected to chordae tendinae
connected to papillary muscles
– Interventricular septum
– Blood leaves through pulmonary valve (pulmonary
semilunar valve) into pulmonary trunk and then
right and left pulmonary arteries

A

Right Ventricle

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17
Q

About the same thickness as right atrium
– Receives blood from the lungs through pulmonary
veins
– Passes through bicuspid/ mitral/ left
atrioventricular valve into left ventricle

A

Left Atrium

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18
Q

Thickest chamber of the heart
– Forms apex
– Blood passes through aortic valve (aortic
semilunar valve) into ascending aorta
– Some blood flows into coronary arteries,
remainder to body

A

Left Ventricle

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19
Q

attached to papillary muscles

A

Chordae tendinae

left ventriclde

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20
Q

During fetal life ductus arteriosus shunts blood
from pulmonary trunk to aorta (lung bypass)
closes after birth with remnant

A

– called ligamentum

arteriosum(left venticle)

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21
Q

Thin-walled atria deliver blood under less pressure

to ventricles

A

Myocardial thickness

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22
Q

pumps blood to lungs

• Shorter distance, lower pressure, less resistance

A

– Right ventricle

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23
Q

pumps blood to body
works harder to maintain same rate of blood flow as right ventricle
• Longer distance, higher pressure, more resistance

A

Left ventricle

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24
Q

that forms a structural foundation for
the heart valves, prevents overstretching valves, forms point of insertion for muscle bundles, and is electrical insulator between atria and ventricles

A

Dense connective tissue

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25
Q

– Atria contracts/ ventricle relaxed

A

• AV valve opens, cusps project into ventricle
• In ventricle, papillary muscles are relaxed and chordae
tendinae slack

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26
Q

– Atria relaxed/ ventricle contracts

A

• Pressure drives cusps upward until edges meet and
close opening
• Papillary muscles contract tightening chordae tendinae
– Prevents regurgitation

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27
Q

Atrioventricular valves

A

Tricuspid and bicuspid valves

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28
Q

Heart valves and circulation of blood
-Valves open and close in response to ___________________as the heart contracts
and relaxes to ensure a one way flow of blood.

A

pressure changes

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29
Q

– Aortic and pulmonary valves
– Valves open when pressure in ventricle exceeds
pressure in arteries
– As ventricles relax, some backflow permitted but
blood fills valve cusps closing them tightly

A

Semilunar valves

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30
Q
  • Left side of heart
  • Receives blood from lungs
  • Ejects blood into aorta
  • Systemic arteries, arterioles
  • Gas and nutrient exchange in systemic capillaries
  • Systemic venules and veins lead back to right atrium
A

– Systemic circuit

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31
Q

Right side of heart
• Receives blood from systemic circulation
• Ejects blood into pulmonary trunk then pulmonary arteries
• Gas exchange in pulmonary capillaries
• Pulmonary veins takes blood to left atrium

A

– Pulmonary circuit

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32
Q

No valves guarding entrance to atria

– As atria contracts, compresses and closes opening (t/f)

A

true

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33
Q

steps of blood flow

A
  1. right atrium(deoxygenated blood)
  2. tricuspid valve-right ventricle
  3. pulmonanry valve-pulmonary blood and arteries
  4. in pulmonary capillaries-blood loses c02 and gains oxygen
  5. pulmonary veins-oxygenated blood
  6. left atrium
  7. bicuspid valve-left atrium
  8. aortic valve-aorta and systematic arteries
  9. systematic capillaries blood loses 02 and gains co2
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34
Q

has its own network of blood vessels

A

Myocardium

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35
Q

branch from ascending aorta

A

– Coronary arteries

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36
Q

provide alternate routes or collateral
circuits
• Allows heart muscle to receive sufficient oxygen even if an artery is partially blocked

A

Anastomoses

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37
Q

Collects in coronary sinus

• Empties into right atrium

A

Coronary veins

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38
Q

• Histology
– Shorter and less circular than skeletal muscle fibers
– Branching gives “stair-step” appearance
– Usually one centrally located nucleus
– Ends of fibers connected by intercalated discs
– Discs contain desmosomes (hold fibers together) and gap
junctions (allow action potential conduction from one fiber to
the next)
– Mitochondria are larger and more numerous than skeletal
muscle
– Same arrangement of actin and myosin

A

Cardiac Muscle Tissue and the Cardiac

Conduction System

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39
Q

Specialized cardiac muscle fibers
– Self-excitable
– Repeatedly generate action potentials that trigger
heart contractions

A

Autorhythmic Fibers

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40
Q

Autorhythmic Fibers 2 important functions

A
  1. Act as pacemaker

2. Form conduction system

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41
Q

Conduction system

A
  1. Begins in sinoatrial (SA) node in right atrial wall
    • Propagates through atria via gap junctions
    • Atria contact
  2. Reaches atrioventricular (AV) node in interatrial septum
  3. Enters atrioventricular (AV) bundle (Bundle of His)
    • Only site where action potentials can conduct from atria to
    ventricles due to fibrous skeleton
  4. Enters right and left bundle branches which extends through
    interventricular septum toward apex
  5. Finally, large diameter Purkinje fibers conduct action potential
    to remainder of ventricular myocardium
    • Ventricles contract
42
Q

5 sequence of conduction system

A
  1. sinoatrial node
  2. atrioventricle node
  3. atrioventricle bundle
  4. r/l bundle branches(right ventricle
  5. purkinge fibers
43
Q

node acts as natural pacemaker
– Faster than other autorhythmic fibers
– Initiates 100 times per second

A

sinoatrial node

44
Q

Nerve impulses from ___modify timing
and strength of each heartbeat
– Do not establish fundamental rhythm

A

autonomic nervous

system (ANS) and hormones

45
Q

3 steps Action potential initiated by SA node spreads out to excite “working” fibers called contractile fibers

A
  1. Depolarization
  2. Plateau
  3. Repolarization
46
Q 
– contractile fibers have stable
resting membrane potential
• Voltage-gated fast Na+ channels open – Na+ flows in
• Then deactivate and Na+
inflow decreases
A
  1. Depolarization
47
Q

period of maintained depolarization
• Due in part to opening of voltage-gated slow Ca2+
channels – Ca2+ moves from interstitial fluid into cytosol
• Ultimately triggers contraction
• Depolarization sustained due to voltage-gated K+
channels balancing Ca2+ inflow with K+ outflow

A

Plateau

48
Q

– recovery of resting membrane potential
❑ Resembles that in other excitable cells
❑ Additional voltage-gated K+ channels open
❑ Outflow K+ of restores negative resting membrane potential
❑ Calcium channels closing

A

Repolarization

49
Q 
time interval during which second
contraction cannot be triggered
– Lasts longer than contraction itself
– Tetanus (maintained contraction) cannot occur
❑ Blood flow would cease
A

Refractory period

50
Q

Composite record of action potentials produced by all the heart
muscle fibers
– Compare tracings from different leads with one another and with
normal records
– 3 recognizable waves
• P, QRS, and T

A

Electrocardiogram

51
Q

6 Correlation of ECG Waves and Systole

A

– Systole – contraction/ diastole – relaxation
1. Cardiac action potential arises in SA node
• P wave appears
2. Atrial contraction/ atrial systole
3. Action potential enters AV bundle and out over ventricles
• QRS complex
• Masks atrial repolarization
4. Contraction of ventricles/ ventricular systole
• Begins shortly after QRS complex appears and continues during S-T
segment
5. Repolarization of ventricular fibers
• T wave
6. Ventricular relaxation/ diastole

52
Q

contraction phase

A

Systole

53
Q

relaxation phase

A

Diastole

54
Q 
consists of the SYSTOLE
and DIASTOLE of both atria, rapidly
followed by the SYSTOLE and DIASTOLE
of both ventricles.
- PRESSURE and VOLUME changes during
the cardiac cycle
- during a cardiac cycle ATRIA and
VENTRICLES alternately contract and
relax forcing BLOOD from areas of
HIGH pressure to areas of LOW
pressure
A

cardiac cycle

55
Q

During, atrial systole ___ are relaxed

A

ventricles

56
Q

– During ventricle systole ___ are relaxed

A

atria

57
Q

All events associated with one heartbeat
• Systole and diastole of atria and ventricles
• In each cycle, atria and ventricles alternately contract
and relax
– During atrial systole, ventricles are relaxed
– During ventricle systole, atria are relaxed
• Forces blood from higher pressure to lower pressure
• During relaxation period, both atria and ventricles are
relaxed
– The faster the heart beats, the shorter the relaxation period
– Systole and diastole lengths shorten slightly

A

Cardiac Cycle

58
Q 
Auscultation
• Sound of  \_\_\_ comes
primarily from blood
turbulence caused by closing
of heart valves
• 4 heart sounds in each cardiac
cycle – only 2 loud enough to
be heard
– Lubb – AV valves close
– Dupp – SL valves close
A

heartbeat

59
Q

volume of blood ejected from left (or right)
ventricle into aorta (or pulmonary trunk) each minute
___stroke volume (SV) x heart rate (HR)
• In typical resting male
– 5.25L/min = 70mL/beat x 75 beats/min
• Entire blood volume flows through pulmonary and
systemic circuits each minute

A

cardiac output

60
Q

difference between maximum CO and
CO at rest
– Average cardiac reserve 4-5 times resting value

A

• Cardiac reserve –

61
Q

Regulation of stroke volume

– 3 factors ensure left and right ventricles pump equal volumes of blood

A
  1. Preload
  2. Contractility
  3. Afterload
62
Q

Degree of stretch on the heart before it contracts
– Greater preload increases the force of contraction

• Preload proportional to end-diastolic volume (EDV)

A
  1. Preload
63
Q

the more the heart fills with blood during diastole, the greater the force of contraction during systole

A

Frank-Starling law of the heart

64
Q

– 2 factors determine EDV

A
  1. Duration of ventricular diastole
  2. Venous return – volume of blood returning to right
    ventricle
65
Q 
increase contractility
• Often promote Ca2+ inflow during cardiac action
potential
• Increases stroke volume
• Epinephrine, norepinephrine, digitalis
A

– Positive inotropic agents

66
Q

decrease contractility
• Anoxia, acidosis, some anesthetics, and increased K+
in interstitial fluid

A

Negative inotropic agents

67
Q

– Pressure that must be overcome before a
semilunar valve can open
– Increase in ___ causes stroke volume to
decrease
• Blood remains in ventricle at the end of systole
– Hypertension and atherosclerosis increase
afterload

A

afterload

68
Q

Cardiac output depends on heart rate and stroke volume
– Adjustments in heart rate important in short-term control of cardiac output and blood pressure
– Autonomic nervous system and epinephrine/ norepinephrine most important

A

Regulation of Heart Beat

69
Q

Originates in cardiovascular center of medulla oblongata

– Increases or decreases frequency of nerve impulses in both sympathetic and parasympathetic branches of ANS

A

Autonomic regulation

70
Q

Noreprinephrine has 2 separate effects

A
  • In SA and AV node speeds rate of spontaneous depolarization
  • In contractile fibers enhances Ca2+ entry increasing contractility
71
Q

release acetylcholine which decreases

heart rate by slowing rate of spontaneous depolarization

A

Parasympathetic nerves

72
Q

Chemical regulation of heart rate

A

Hormones
• Epinephrine and norepinephrine increase heart rate and contractility
• Thyroid hormones also increase heart rate and contractility
– Cations
• Ionic imbalance can compromise pumping effectiveness
• Relative concentration of K+
, Ca2+ and Na+ important

73
Q

Heart develops from mesodermal cells called the

A

cardiogenic area

74
Q

Heart develops from mesodermal cells called the cardiogenic area which in turn forms a pair of elongated
strands

A

cardiogenic cords.

75
Q

The cords will eventually
form the and they in turn form the
primitive heart tube

A

endocardial tubes

76
Q

The cords will eventually

form the endocardial tubes and they in turn form the ____

A

primitive heart tube

77
Q

The primitive heart tube develops into 5 distinct regions including: (from tail end to
head end)

A
  1. Sinus venosus: forms part of the R. atrium, coronary sinus and SA node.
  2. Atrium: forms a part of the R. & L. atria and auricles.
  3. Ventricle: forms the L. ventricle and a part of the R. ventricle.
  4. Bulbus cordis: forms a part of the R. ventricle
  5. Truncus arteriosus: forms the pulmonary trunk and ascending aorta.
78
Q

(t/f) There is also a bending during the heart development that brings the primitive heart tube to the adult heart position.

A

true

79
Q

divide the primitive
atrioventricular canal into R. & L. atrioventricular canals separating the R. &. L.
atria from R. & L. ventricles respectively

A

Mesodermal thickenings known as endocardial cushions

80
Q

Interatrial septum partitions the primitive atrium and forms the R. & L. atria but
initially a ___
forms in this septum that before birth
allows most blood entering the R. atrium to pass into the L. atrium

A

foramen ovale

81
Q

Interatrial septum partitions the primitive atrium and forms the R. & L. atria but
initially a foramen called foramen ovale forms in this septum that before birth
allows most blood entering the R. atrium to pass into the L. atrium. It will be closed
after birth but it remnants forms the _______

A

fossa ovalis on interatrial septum

82
Q

lungs

  • pump pulmonary circulation- blood from heart and go up to each lung
  • it receives deoxygenated (superior /inferior vena cava,coronary sinus)blood from the body and send it to the lungs for oxygenation.

path of blood/diagram of blood flow

A

Right side of the heart-

83
Q

pump for the systemic circulation. it pumps oxygenated blood from the lungs out into the vessels of the body.
left atrium-receive red, oxygenated blood from the lungs via the pulmonary veins.

A

Left side of the heart-

84
Q
  1. right atrium- deoxygenated- superior/inferior vena cava,coronary sinus
    -tricuspid valve to close prevent backflow into the right atrium
    -beginning of pulmonary circulation
    1. right ventricle-deoxygenated- contraction
      3.pulmonary trunk- semilunar valve close- prevent back flow into right ventricle
    2. Right / Left pulmonary capillaries of the right/ left lung
      right side of pulmonary circulation- deoxygenated
A

5.pulmonary veins-left atrium-oxygenated- end of pulmonary circulation
-bicuspid valve/mitral valve open/left atrioventricular valve
6.left ventricle- full of blood - begining of systemetic circulation
-bicuspid valve is close prevent backflow left atrium
-contraction
7.2 semilunar valves to open and push to the aorta- aorta and beggining of pulmonary trunk
8. aorta goes to the body
right atrium- end of systemic the circulation
9. in systemic capillaries loses oxygen and gains co2

85
Q

• Fibers within the network are connected by thickening of sarclomma called ___ which hold the fibers and gap junction that allows action potention to conduct from one muscle fibre to another.

A

intercalated

86
Q

because they are self-excitable. they repeatedly generate spontaneous action potential that then trigger heart contraction.
These cells act as a pace maker to set the rhythm of electrical excitation for the contraction of the entire heart
they form the conduction sysytem the route for propogating action potential through the heart muscle. This specific pathway of conduction ensures that cardiac chambers become stimulated to contract in the coordinated manner.

A

Autorhythmic cells

87
Q

atrial depolarization - spread impulse from SA node over atria.

A

p wave-

88
Q

rapid venticular depolarization- spread of impulse through ventricles

A

QRS complex-

89
Q

ventricular repolarization

A

t wave-

90
Q

represent the time when ventricular contractile fibers are depolarized during the plateau phase of the action potential

A

s-t segment end of s to the beginning of T

91
Q
  • represent the time from venticular depolarization end of ventricular repolarization.
    correlation of ecg waves with atrial and ventricular systole
A

The Q- T segment

92
Q
  1. depolarization of the sa node causes atrial depolarization
    1. atrial depolarization results in atrial systole. as the atria contrract the increase pressyre on the blood forces it through the open av valves int the ventricles
    2. atrial systole contributes a final 25 ml of blood to the volume already in each ventricle (105 ml. the end of atrial systole is also the end of diastole is end diastolic volume at this point each ventricle contains 130 ml of blood
    3. The qrs complex marks the onset of ventricular depolarization
    4. vetricukar depolarization causes ventricular systole
      contraction of the ventricles rises the pressure on the blood forcing it up against the av valves to push tem closed.
      For 0.05 seconds cusps of the valves all four av and sl valves are closed.this is isovolumetric contraction.
A
  1. cotinued contraction causes the ventricular pressure to exceed aortic pressure and the SL valves open allowing blood to flow out in the aorta- same for pulmonanry side. this is the ventricular ejection phase.
    1. the Left and right ventricles each eject about 70 ml of blood into aorta/pulmonary arterty which leaves 60 ml remaining in each ventricle-end systolic volume
    2. t wave in ecg marks onset of ventricular repolarization.
    3. ventricular repolarization causes ventricular diastole. as pressure in ventricles falls blood will flow back to area of lower pressure pushing the sl valves closed. rebound off the closed cusps of the aortic valve produce the dicrotic wave on the aortic pressure curve. After Sl valve close there is brief interval where ventricular blood volume does not change because all 4 valves are closed. -isovolumentric relaxation phase.
    4. as the ventricles relax falls below atrial pressure and the av valves open marking the beginning of ventricular filling. The major part of the filling occurs right after the Av nvalves ope. prior to this blood has been flowing into and collecting in the relaxed into and collecting in the relaxed atria and as soon as the valves open, it is dumped into ventricles-
      at the end of relaxation period the ventricles are 3/4 full. then we get a P wave amd it all starts again.
93
Q

first heart sound lubb- closing av valve after ventricular systole begins

A

dupp- closing of the sl valves- end of ventricular systole

heart murmur- foramen ovales open

94
Q

cardiac Output-is the volume of blood ejected from the left ventricle into aorta pulmonary trunk each minute
Cardiac output- equals the stroke volume the volume of vlood ejected by the ventricle woth each contaction multiply by the heart rate(beats/min) the number of beats per minute
CO=SVx HR

SV=70ml x beats per minute
Regulation of heart rate 
autonomic regulation of the heart 
central control of the cardiovascular system stems from the cardiovascular center in the medulla oblongata 
limbic system input increase HR even before activity by sending impulses to CV center
A

sympathethic impulses increase heart rate and force of contraction.parasymtpathetic impulses decreas heart rate
from thw thoracic level of spinal cord, cardiac accelerator nerves extend out to Sa node AV node and myocardium to trigger the relase of norepinephrine.

95
Q

is the ratio between the maximum cardiac output a person can achive the cardiac output

A

cardiac reserve-

96
Q

Cations (na ,K, CA also effect heart rate
elevated k and na in blood decrese heart rate and contractility because excess na blocks ca2 inflow during action potential to decrease the force of contraction. excess K blocks the generation of action potential. increased interstitial ca2 speed hr and heart contractility.

A

babies have much higher resting hear rates, women are slightly higher than men, athletes are lower than couch potaotoes.
heat (fever,exercise speds up the depolarization of sa node and increase Hr while hypothermia lower hr and slows strength of contraction reducing the tissue demands for 02
exercise and the heart
a person cv fitness can be improbed with reguar fitnes-20mins to increase co and elevates metablic rate
several weeks of training results in maximal cardiac outut and oxygen delivers to tissues.
regular exercise also decrease anxiety and depression,controls weight and increases fibrinolytic activity ( reduces blood clotting.
-sustained exercise increased oxygen demand in muscles.
tachcardia-elevated heart rate
bradycardia-decrease heart rate

97
Q

heart rate is affected hormones- epinephrine , norepinephrine and thyroid hormones. epinephrine and noreepinephrine are also released from the adrenal medulla and act as the same way as with sympathtic stimulation
thyroid hormones also enhanced heart rate and contractility

A

Norepinephrine speed the rate of spotaneous depolarization of the fibers in SA and av node to increase heart rate. it also enhances the entry of CA2 through the channels to increase contractility of the myocardium. the result is increased sv and co, this increase in contractility offsets the decrease in preload.

98
Q

Parsympathethic impulses arrive at the heart via the right and left vagus nerves(CNX and release acetycholine to decrease the heart rate by slowing the rate of spontaneous depolarization at the nodes.PArasympathetic impulses have the little effect on contractility of the venticles..

A

vagus nerves-acetycholine

99
Q

montior the position of your limbs and as you start to move them around faster with exercise, nerve impulse are sent to the CV centere to stimulate in HR at the onset of activity

A

Proprioceptors-

100
Q
  • monitor presuure changes- detect the amount of the presure of the stretching in major arteries and veins ehich relates to the presuure of blood through blood vessels. they are located in the arch of aorta and carotid sinus.
A

Barorecetors

101
Q

monitor chemical changes in the levels of O2 and Co 2 in the blood

A

chemoreceptors

ap 2 (5 decks)

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