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biology 121 > heart anatomy and physiology > Flashcards

heart anatomy and physiology Flashcards

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1
Q

where is the sinoatrial node located?

A

in the posterior wall of the right atrium

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2
Q

what does the moderator band do?

A

conducts the impulse from the bundle branches to the anterior papillary muscle of the right ventricle

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3
Q

what does the QRS complex on an ECG represent?

A

ventricular depolarisation

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4
Q

trace the path of an action potential through the conducting system

A

sinoatrial node → internodal pathways → atrioventricular node → AV bundle → bundle branches → purkinje fibres

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5
Q

where is the heart positioned in the body?

A

posterior to the sternum, in the mediastinum between the two pleural cavities, in the pericardial sac

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6
Q

what is the role of connective tissue fibres in the epicardium?

A

physical support
distributes contractile forces
prevents overexpansion
elasticity - helps heart return to its original size and shape

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7
Q

how long does the cardiac cycle last?

A

about 0.8 seconds

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8
Q

what are three ways to diagnose MI?

A

ECG

troponin levels (Tn I) - more troponin, more damage

creatine kinase (non specific)

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9
Q

what are the symptoms of MI?

A 
severe, prolonged, crushing pain
dyspnoea
cool, clammy skin
sweating
pallor
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10
Q

what is the difference between STEMI and non STEMI MIs?

A

STEMI - complete blockage of coronary artery

non STEMI - partial obstruction - tissue damage not as bad

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11
Q

what is the formula for measuring BMI?

A

weight divided by (height squared)

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12
Q

where is the atrioventricular node located?

A

in the floor of the right atrium, near the septum

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13
Q

what is the left AV valve also know as?

A

bicuspid valve or mitral valve

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14
Q

what is isovolumetric contraction?

A

all valves are closed, ventricles contracting (same volume).

like squeezing a bottle with the lid on - pressure increases, but volume remains the same

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15
Q

what are the two types of cardiac muscle cell and what do they do?

A

conducting system cells: control and coordinate the heartbeat

contractile cells: produce contraction that propel blood

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16
Q

what do width and height equal on an ECG?

A

height equals voltage

width equals time

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17
Q

what effect would an increase in venous return have on stroke volume?

A

increased venous return = more stretch in heart muscle = greater force of contraction = higher stroke volume

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18
Q

what effect would an increase in sympathetic stimulation of the heart have on end-systolic volume?

A

increased heart rate and increased force of contraction leads to higher stroke volume = lower end-systolic volume

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19
Q

define end-diastolic volume (EDV) and end-systolic volume (ESV)

A

EDV - amount of blood in left in the ventricle at the end of relaxation

ESV - amount of blood left in the ventricle at the end of contraction

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20
Q

list the phases of the cardiac cycle

A

atrial systole
atrial diastole
ventricular systole
ventricular diastole

21
Q

what is stroke volume?

what is it measured in

A

the amount of blood that leaves the heart with each beat

ml/beat

22
Q

which blood vessels supply the heart with oxygenated blood?

A

coronary arteries

23
Q

describe the pericardium

A

pericardial sac - visceral and parietal layers with pericardial cavity containing pericardial fluid in between

serous membrane!

24
Q

what are the characteristics of cardiac muscle cells?

A

small
branched
single nucleus
intercalated discs

25
Q

what are the three layers of the heart wall, from inner to outer?

A

endocardium
myocardium
epicardium

26
Q

describe the tissue layers of the epicardium

A

serous membrane

exposed mesothelium and underlying layer of areolar tissue

areolar layer is attached to the myocardium

27
Q

what is hypertrophy

A

increase in size of cell

ie cardiac muscle hypertrophy due to increased workload

28
Q

what is contractility?

what is necessary for increased contractility?

A

the strength of contraction

more calcium from sympathetic innervation and/or hormonal stimulation from adrenaline/noradrenaline

29
Q

how much of the cardiac cycle is spent in diastole compared to systole?

A

two thirds diastole

one third systole

30
Q

what effect would hypertension have on afterload, and what would this mean for the ventricles?

A

afterload would be increased

ventricle would have to pump harder to open SL valve, would probably pump out less blood per stroke

increased arterial pressure = increased ventricular contraction = ventricle more tired = increased ESV, decreased SV

31
Q

how is stroke volume measured?

A

SV = EDV - ESV

32
Q

what is ejection fraction?

A

the percentage of EDV that is ejected with each contraction

so 100% = very efficient

33
Q

at what part of the conducting system does a slight delay occur?

what happens during this delay, and how long is it?

A

AV node

100 msec delay allows atrial contraction to occur

34
Q

which layer of the pericardium forms part of the heart wall?

A

the visceral pericardium is also the epicardium

35
Q

what are the resting potentials of atrial and ventricular cardiac cells?

A

ventricular - about -90 mV

atrial - about -80 mV

36
Q

what are the three layers of the heart wall called?

what sort of tissue is each made of?

A

epicardium - epithelium and connective tissue

myocardium - muscle

endocardium - simple squamous epithelium

37
Q

what is afterload?

A

the arterial pressure in the aorta that the ventricle must overcome to force open the SL valve

38
Q

what accounts for internal regulation of HR?

A

the cardiac conduction system

39
Q

what is the function of intercalated discs?

A

in cardiac muscles, gap junctions at the intercalated discs allow the cardiac muscle tissue to behave like a single enormous muscle cell

40
Q

what is the “lubb” sound of the heartbeat in the stethescope?

A

AV valves closing

41
Q

what is the “dupp” sound of the heartbeat in the stethescope?

A

SL valves closing

42
Q

what stops the heart’s valves from prolapsing?

A

chordae tendinae attached to papillary muscles

43
Q

what happens to BP as HR and SV increase?

A

BP increases

44
Q

what is preload?

A

what occurs before the ventricle contracts (stretch in muscle fibres)

the more a muscle is stretched, the more strongly it will contract

45
Q

what is cardiac reserve, and how much is it?

A

difference between resting output and maximum possible

4-5 times on average
7-8 times in top endurance athletes

in disease there is little or no reserve

46
Q

what is the main function of the heart?

A

to circulate blood through the body

47
Q

what factors influence heart rate?

A

SNS stimulation increases HR
PNS stimulation decreases HR
hormones increase HR

48
Q

what factors influence SV?

A

SNS increases force of contraction
preload
afterload

biology 121 (14 decks)

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