human anatomy and physiology > cardiovascular system - cardiac function and dysfunction > Flashcards

cardiovascular system - cardiac function and dysfunction Flashcards

(47 cards)

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1
Q

all events of the cardiac cycle associate with what

A

1 heartbeat (800msec)

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2
Q

what happens normally in the cardiac cycle

A

2 atria contract while 2 ventricles relax, then while 2 ventricles contract, the 2 atria relax

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3
Q

define systole

A

contract

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4
Q

define diastole

A

relax

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5
Q

name the 3 phases of cardia cycle

A

P
QRS
T

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6
Q

summarise the relaxation period occurs after T-wave

A

ventricular & atrial diastole/relaxation

  • Ventricular pressure drops below atrial & AV valves open, so ventricular filling occurs
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7
Q

summarise what happens after the P wave

A

atrial systole/contraction and ventricular diastole

  • Ventricles fill with remaining blood (~25%)
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8
Q

summarise what happens after QRS wave

A

ventricular systole and atria diastole

  • Pressure pushes AV valves closed
  • Pushes semilunar valves open and ejection occurs
  • Ejection until ventricle relaxes enough for arterial pressure to close semilunar valves
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9
Q

name the divisions of the cardiac cycle

A
  1. atrial systole
  2. early ventricular systole
  3. late ventricular systole
  4. early ventricular diastole
  5. late ventricular diastole
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10
Q

explain the atrial systole division of cardiac cycle

A

atria contract, AV valves open, semilunar valves closed

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11
Q

explain the early ventricular systole division of cardiac cycle

A

atrial relax, ventricles contact, AV valves forced closed, semilunar valves forced open

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12
Q

explain the late ventricular systole division of cardiac cycle

A

atria relax, ventricles contract, AV valves remain closed, semilunar valves forced open

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13
Q

explain the early ventricular diastole division of cardiac cycle

A

atria and ventricles relax, AV valves and semilunar valves closed, atria begin passively filling with blood

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14
Q

explain the late ventricular diastole division of cardiac cycle

A

atria and ventricles relax, atria passively fill with blood as AV valves open, semilunar valves closed

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15
Q

how do heart sounds occur

A

From blood turbulence caused by closing of heart valves

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16
Q

which heart sounds are heard through a stethoscope

A

During each cardiac cycle only the 2 loudest of 4 heart sounds

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17
Q

explain the 4 heart sounds

A

S1 = ‘lub’ louder, longer, closure of AV valves soon after ventricular systole

S2 = ‘dub’ quieter, shorter, closure of semilunar valves at beginning of ventricular diastole

S3 = rapid ventricular filling

S4 = atrial contraction

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18
Q

what is a heart murmur

A

Abnormal sound (rushing/gurgling) before, between, after or masking normal sounds

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19
Q

what does a heart murmur indicate and explain this

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A

Indicates valve disorder e.g.,

  • mitral/aortic stenosis (narrowing)
  • mitral valve prolapse (MVP) – protrude into L atrium during ventricular contraction
    = not always serious
    = occurs in 10-15% of population - 65% of which are females
20
Q

what is cardiac output

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A

CO = Volume of blood ejected from L (or R) ventricle into aorta (or pulmonary trunk) each minute

21
Q

how is cardiac output calculated

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A

CO (ml/min) = stroke volume (SV)(ml/beat) x heart rate (beats/min)

SV- volume ejected by ventricle with each contraction

22
Q

Entire blood volume flows through what and when

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A

the pulmonary & systemic circulation each minute

23
Q

what happens to cardiac output when we exercise

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A

it increases by about double during mild exercise and by almost 4 times as much during intense exercise

rest - 5.25L/min
mild exercise - 10L/min
intense exercise- 19L/min

24
Q

what is cardiac reserve

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A

ratio between max CO & rest CO

  • Average = 4 - 5x
  • Top endurance athlete = 7-8x
  • Severe heart disease = None (thus daily living tasks limiting)
25
what is the regulation of stroke volume
volume ejected by ventricle
26
name the 3 important factors related to regulation of stroke volume
preload contractility afterload
27
explain preload in terms of stroke volume regulation
degree of stretch Frank-Starling Law of the Heart: - Increase diastolic volume increases strength of contraction which increased stroke volume
27
explain contractility in terms of stroke volume regulation
forcefulness of contraction of individual ventricular muscle fibres
27
explain afterload in terms of stroke volume regulation
pressure to exceed to eject ventricular blood i.e., to open semilunar valve; - Increased by elevated BP (hypertension) & narrowing of arteries by atherosclerosis.
28
explain the homeostasis and control in the regulation of heart rate
During exercise - CO rises to supply working tissues with more O2 & nutrients Stroke Volume may fall - if ventricular myocardium damaged or blood volume reduced by bleeding Homeostatic mechanisms - act to maintain adequate CO by increasing heart rate & contractility.
29
name the most important factors that regulate heart rate
automimic nervous system Hormones, released by adrenal medulla - * epinephrine & norepinephrine
30
Autonomic Regulation of Heart Rate originates where
in cardiovascular centre in medulla oblongata
31
name and explain the 2 ways the nervous system controls the heart
Input to CV centre - From higher brain centres (e.g., hypothalamus) - From sensory receptors: Proprioceptors Chemoreceptors Baroreceptors Output to heart - Increased depolarisation in SA node: increases heart rate - Increased contractility of A & V: increases stroke volume - Decreased depolarisation in SA node: decreases heart rate
32
explain chemical regulation of the heart
Hormones – released with exercise, stress & excitement - epinephrine & norepinephrine, these increase both heart rate & contractility - thyroid hormones (do same as above) Ions - increase in K+ or Na+ decreases heart contraction & rate - high conc of Na+ blocks Ca2+ influx during cardiac AP, so contraction decreased - high conc K+ blocks generation of AP - increase Ca2+ speeds heart rate & strengthens heart
33
name 4 other factors that regulate heart rate
age gender physical fitness body temp
34
explain how age and gender regulate heart rate
Age As you grow older, pulse rate is about same as before. But upon exercise, it may take longer for pulse to increase & longer to slow down afterward. Highest heart rate with exercise is also lower than when younger. Gender (female resting > male resting) i.e., female resting heart rate is faster than the male resting heart rate (on average)
35
explain how physical fitness regulates heart rate
Over time, with chronic cardio training, resting heart rate drops because each beat delivers a bigger burst of blood, so fewer beats needed. This takes work off your heart and is why cardio exercise is recommended for heart health.
36
explain how body temp regulates heart rate
(>temp > rate) i.e., the higher the body temperature the faster the heart rate
37
explain Long Q-T Syndrome
Conduction disorder Rare, genetic problem Repolarisation abnormality Prone to very rapid heartbeats - Poor supply to brain, lack of O2 May cause fainting, fits, seizures
38
name the 2 forms of treatment for long Q-T syndrome
beta blockers defibrillator
39
explain how beta blockers are a treatment for long Q-T syndrome
Block b adrenoceptors Decrease electrical impulse that passes through AV node Prevents sudden increase in heart rate
40
explain how defibrillators are a treatment for long Q-T syndrome
Depolarises entire myocardium simultaneously With luck, after repolarisation, the SA node will be the 1st to reach threshold.
41
what is arrhythmia
Irregular heart rhythm due to defect in conduction system of heart
42
name the causes of arrhythmia
drugs (caffeine, nicotine, alcohol etc.,) anxiety Hyperthyroidism K+ deficiency certain heart diseases.
43
name and explain some examples of arrhythmia
Heart block - serious; conduction system slowed or blocked, commonly at AV node Atrial flutter - abnormal rapid atrial contraction (300x/min) Atrial fibrillation - asynchronous contraction of atrial fibres (400-600x/min), thus chamber fails to pump blood as effectively (reduces by 20-30% in strong heart, so person still lives) Ventricular fibrillation - quick death as blood not ejected from ventricles
44
Representative Heart Conditions Detectable through what
ECGs tachycardia = very regular and high spikes extrasystole (beat) - large and wide dip and then increase within the normal heart beat ventricular fibrillation - flatter line so few peaks complete heart block - large gaps between heart beats myocardial infraction - wide R wave Asystole - almost flat line
45
heart disease is caused by the build up of what
Atherosclerotic Plaque lumen of blood vessel becomes smaller due to the presence (build up) of the plaque.
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