chapter 20: the heart Flashcards Preview

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Flashcards in chapter 20: the heart Deck (102):
1

Right side of the heart carries blood

to pulmonary circuit

2

Left side of the heart carries blood to

systematic circuit

3

Pulmonary circuit

carries blood to and from gas exchange surfaces of the lungs

4

systematic circuit

transports blood to and from the rest of the body

5

location of the heart
-cavity
-near
-posterior to
-extends from
-___ of heart is to the left of the midline

-throacic
-anterior chest wall
-sternum
-T5 to T9
-2/3

6

Base of heart location

~3rd costal cartilage

7

Apex of heart
-definition
-location

-inferior pointed tip
-~5th intercostal space

8

Mediasteum
-definition
-what does it contain (5)

region between two pleural cavities
-contains heart, great vessels, thymus, esophagus and trachea

9

Tissues of the heart

pericardium

10

pericardium
-definition
-2 layers

-lining of the pericardial cavity
-1. fibrous pericardium
2. serous pericardium

11

fibrous pericardium
-location
-definition
-function

-outer most portion
-dense network of collagen fibers
-stabilizes position of heart and associated vessels

12

serous pericardium
-definition
-2 components

-inner "double" serous membrane; fluid secreting layer
-provides lubrication
-1. visceral pericardium
2. parietal pericardium

13

visceral pericardium
-location
-what does it do
-known as

-inner most layer
-covers and adheres close to outer surface of heart
-epicardium

14

Parietal pericardium
-definition
-location

-lines inner surface of pericardium
-adjacent to fibrous pericardium

15

The heart wall
-3 components

1. epicardium
2. myocardium
3. endocardium

16

epicardium
-known as
-2 components

-visceral pericardium
-1. mesothelium
2. areolar tissue (connective tissue)

17

mesothelium

fluid secreting cells

18

myocardium
--definition
-what are the cardiac muscle cells called

-cardiac muscle tissue; muscular wall of heart
-cardiomyocytes

19

endocardium
-2 components
-what type of epithelium
-function

-1. areolar tissue
2. endothelium
-simple squamous epithelium
-covers all inner surfaces of heart

20

Cardiac muscle cells
-3 general characteristics
-1 special feature

-1. striated
2. small
3. branched with a single nucleus
-intercalated discs

21

Intercalated discs
-definition
-contains
-function

-specialized membranes b/n adjacent cells
-gap junctions
-allows all cells of the heart to become excited at the same time = heart contracts as a unit

22

Auricle of right atrium

expands to fill with blood

23

left pulmonary artery

carries deoxygenated blood to lungs

24

Pathway of blood through heart
-right side (9 steps)

1. superior vena cava
2. fossa ovalis (l atrium)
3. coronary sinus (l atrium)
4. right atrioventricular valve (r AV valve, tricuspid valve) (r ventricle)
5. inferior vena cava (r ventricle)
6. papillary muscle
7. pulmonary semilunar valve
8. left and right pulmonary arteries
9. to lungs

25

pathway of blood through heart
-left side (7 steps)

1. Left and right pulmonary arteries
2. left atrium
3. left atrioventicular valve (left AV valve, bicuspid valve)
4. left ventricle
5. aortic semilunar valve
6. aorta
7. to body

26

Superior vena cava

delivers blood from upper extremities

27

coronary sinus

opening of coronary circulation

28

right atrioventricular valve
-2 other names
-function

-1. right AV valve
2. tricuspid valve
-prevents backflow

29

inferior vena cava

delivers blood from lower body

30

papillary muscle
-1 component
-definition of that component

-chordae tendinae
-cords attached to valves and anchored to papillary muscle

31

Left pulmonary arteries
-carries what type of blood

oxygen poor blood to lungs

32

left pulmonary veins
-carries what type of blood

oxygen rich blood to heart

33

left atrioventricular valve
-3 other names

1. left AV valve
2. bicuspid valve
3. mitral valve

34

coronary circulation
-definition
-function
-what happens if it becomes partially or completely blocked?

-supplies blood to heart muscle
-penetrates myocardium -delivers O2 and nutrients
-myocardial infarction - heart attack!

35

5 major arteries of the coronary circulation

1. right coronary artery
2. left coronary artery
3. anterior interventricular artery
4. posterior interventricular artery
5. circumflex artery

36

3 veins of the coronary circualtion

1. coronary sinus
2. great cardiac vein
3. middle cardiac vein

37

origin of the heart beat
-3 things
-2 types of cells

-1. the heart beats (contracts) 60-80 times per min. (~75 bpm average)
2. the heart is "self excitatory"- stimulates itself; "automaticity"
3. the conducting system of the heart initiates and distributes the stimulus
-1. contractile cells
2. conducting cells

38

contractile cells

produce contraction that propel blood

39

conducting cells
-function
-smaller or bigger than contractile cells
-lacks 2 things
-do they contract

-initiate and spread electrical impulses
-smaller
-lacks actin and myosin
-no

40

Action potentials
-3 steps
-2 periods

-1. resting
2. depolarization
3. repolarization
-1. absolute refractory period
2. relative refractory period

41

threshold mV

-60 mV

42

resting phase
-cause
-mV

-lots of protein inside and leakage of K+ out of cell
- -70mV

43

depolarization
-cause

-movement of Na+ in through open channels

44

repolarization
-cause

Na+ channels close, K+ channels are fully open and K+ exits

45

absolute refractory period
-occurs when
-definition

-between depolarization and repolarization
-cannot have another action potential during this time

46

relative refractory period
-occurs when
-definition

-occurs after an action potential
-can get another action potential but it takes more energy

47

when does contraction of a skeletal muscle occur

after action potential

48

action potential in a cardiac myocyte
-conducting cells
-contractile cells
-3 phases

-initiate and conduct action potentials
-conduct action potentials and contract
-1. depolarization
2. plateau
3. repolarization

49

depolarization in a cardiac myocyte
-cause

-Na+ entry through open channels

50

plateau phase in a cardiac myocyte
-cause
-what moves
-what does this maintain

-opening of slow Ca++ channels, closing of Na+ channels
-ca2+ ions move from outside to inside and from inside SR into sarcoplasm
-maintains a slightly positive membrane potential

51

repolarization of cardiac myocyte
-cause

closing of Ca++ channels; opening of K+ channels

52

absolute refractory period in cardiac myocyte
-long or short
-continues until
-when can it initiate another action potential

-long
-relaxation is underway
-when the heart has already relaxed

53

the conducting system of the heart
-6 steps

1. Sinoatrial (SA) node
2. intermodal pathways
3. atrioventricular (AV) node
4. AV bundle
5. Bundle branches (R and L)
6. Purkinjie fibers

54

Sinoatrial node
-function

initiates the action potential- "pacemaker"

55

Purkinjie fibers

small branches that penetrate the myocardium and deliver action potential

56

when does the pacemaker (SA node) spontaneously depolarizes

about every 0.8 secs

57

which node is faster? SA node or AV node?

SA node

58

what mV is the threshold at for the SA node

-40 mV

59

Electrocardiogram
-known as
-definition
-3 steps
-6 components

-"EKG" or "ECG"
-Action potentials passing through the conducting system are strong enough to be detected by electrodes on the body surface
-1. atrial excitation begins
2. impulse delayed at AV node - Atria contract
3. impulse travels toward purkjinie fibers
4. ventricular contraction begins
-P wave, Q, R, S, QRS complex, T wave

60

P wave

depolarization of atria

61

QRS complex

depolarization of ventricles

62

T wave

repolarization of ventricles

63

What is not seen in the electrocardiogram?

atrial repolarization (masked behind QRS complex)

64

The cardiac cycle
-definition
-2 stages

Period between start of one heart beat and beginning of the next
-1.systole
2. diastole

65

Systole
-definition
-2 types
-pressure

-contraction
-1. atrial systole
2. ventricular systole
-increase pressure

66

Diastole
-definition
-2 types
-pressure

-relaxation
-1. atrial diastole
2. ventricular diastole
-decrease pressure

67

overview of the cycle
-3 steps
-how many sec for each heart beat

1. Atria contract (atrial systole); ventricles relax (ventricular diastole) - 0.1 sec
2. Atria relax (atrial diastole); ventricles contract (ventricular systole) - 0.3 sec
3. Atria relax (atrial diastole); ventricles relax (ventricular diastole) (when heart rate increases this phase gets alot shorter)- 0.4 sec
-0.8 sec

68

4 phases of the cardiac cycle

1. Late Diastole
2. Atrial Systole
3. Ventricular systole
4. ventricular diastole

69

Late diastole
-definition
-AV valves
-Semilunar valves
-Blood flow right side
-blood flow left side
-period of passive filling

-atria and ventricles are relaxed
-open
-closed
-Blood will enter the RA and flow into the RV through the open AV valve
-Blood will enter the LA and flow into the LV through the open AV valve
-~70% of the ventricular volume enters this way

70

Atrial systole
-definition
-conducting system (3)
-ECG
-ventricles are in systole and diastole
-Blood pumped right side
-blood pumped left side

-atria contract
-1. Action potentials initiated as SA node
2. Travels through internodal branches to AV node
3. Atria are depolarized
-diastole
-RA pumps blood through open AV valve to RV
-LA pumps blood through open AV valve to LV

71

Ventricular systole
-atria are in systole and diastole
-2 steps

-diastole
-1. isovolumetric contraction
2. ventricular ejection

72

isovolumetric contraction
-definition
-conducting system (2)
-ECG
-how do ventricles contract
-ventricular pressure increases or decreases
-when ventricular pressure is > atrial pressure
-heart sound
-blood flow

-same volume
-1. AV node to AV bundle to R and L bundle branches to Purkinjie fibers
2. ventricles are depolarizing
-isometrically
-increasing
-AV valves close on left and right
-Lubb - 1st heart sound
-No blood enters or exits - maintain same volume

73

Isometric contraction

tension of muscle without movement

74

Ventricular ejection
-ventricular pressure
-semilunar valves
-Blood pumped right side
-blood pumped left side
-volume ejected

-increasing
-open when ventricular pressure > aortic and pulmonary artery pressure
-Blood pumped through open semilunar valves into pulmonary trunk
-Blood pumped through open semilunar valves into aorta
-stroke volume: volume of blood ejected in one beat

75

ventricular diastole
-2 components

1. isovolumetric relaxation
2. ventricular filling

76

isovolumetric relaxation
-definition
-conducting system
-ECG
-ventricular pressure
-when ventricualr pressure

-same volume
-repolarization
-T wave
-decreasing
-semilunar valves close
-dubb - 2nd heart sound
-AV valves open

77

Ventricular filling
-AV valves
-semilunar valves
-blood flow

-open
-closed
-ventricles are passively filling

78

Cardiodynamics
-definition
-3 important terms

-examines the factors the effect cardio output
-1. End-diastolic volume
2. End-systolic volume
3. Stroke volume

79

cardio output (CO)
-definition
-indication of

-amount of blood pumped by left ventricle in one minute
-blood flow through tissues

80

End-diastolic volume

amount of blood in each ventricle at the end of ventricular diastole

81

End-systolic volume

amount of blood in each ventricle at the end of ventricular systole

82

Stoke volume
-definition
-formula

-amount of blood pumped out of the heart in a single heart beat
-SV= EDV-ESV

83

How do we determine cardio output?

Cardio output (CO) = heart rate (HR) x stroke volume (SV)

84

What is a normal cardiac output?

CO = 75 bpm x 80 ml/beat = 6000 ml/min

85

Factors affecting stroke volume
-5

1. Venous return (VR)
2. Filling time (FT)
3. Increased by sympathetic stimulation
4. Decreased by parasympathetic stimulation
5. Increased by E, NE, glucagon, thyroid hormone

86

3 factors that determine stroke volume

1. Preload
2. Contractility
3. after load

87

preload
-definition
-frank-starling law of the heart

-degree to which cardiac muscle cells are stretched just before contracting
-more in = more out; increased VR = increased CO
increased FT = increased CO

88

What determines the degree to which the heart is stretched?

the EDV; greater the EDV = larger the preload

89

Contractility
-definition
-example
-2 types of action

-amount of force produced during a contraction
-increased contractility = decreased ESV = increased SV
-1. positive inotropic action
2. negative inotropic action

90

positive inotropic action

increase contractility

91

negative inotropic action

decrease contractility

92

afterload
-definition
-increased afterload =

-pressure in the pulmonary trunk and aorta the heart must overcome to eject blood
-increased afterload = longer period of isovolumetric contraction = increased ESV = decreased SV

93

3 factors affecting heart rate

1. Autonomic nervous system
2. hormones and chemicals
3. other (age, sex, and temp)

94

autonomic nervous system
-definition
-2 branches

-innervated through cardiac plexus
-1. sympathetic
2. parasympathetic

95

sympathetic NS
-definition
-effect on heart rate
-effect on force

-cardioacceleratory center in medulla oblongata; sympathetic nerves supply SA node
-increase
-increase

96

parasympathetic NS
-definition
-effect on heart rate
-effect on force

-cardioinhibitory center in medulla oblogata; parasympathetic nerves supply SA node
-decrease
-decrease

97

Hormones and chemicals
-5

1. norepinephrine
2. epinephrine
3. thyroid hormones
4. calcium channel blockers
5. beta blockers

98

how does norepinephrine, epinephrine and thyroid hormones effect heart rate and contractility?

-increase heart rate
-increase contractility

99

how does calcium channel blockers and beta blockers effect heart rate and contractility?

-decrease heart rate
-decrease contractility

100

age effecting HR
-young
-old

-higher
-lower

101

sex effecting HR
-females
-male

-higher
-lower

102

temp effecting HR
-hot
-cold

-higher
-lower