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

cardiovascular system - cardiac function and dysfunction Flashcards

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

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

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

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

A

the pulmonary & systemic circulation each minute

23
Q

what happens to cardiac output when we exercise

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

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
Q

what is the regulation of stroke volume

A

volume ejected by ventricle

26
Q

name the 3 important factors related to regulation of stroke volume

A

preload
contractility
afterload

27
Q

explain preload in terms of stroke volume regulation

A

degree of stretch Frank-Starling Law of the Heart:

  • Increase diastolic volume increases strength of contraction which increased stroke volume
27
Q

explain contractility in terms of stroke volume regulation

A

forcefulness of contraction of individual ventricular muscle fibres

27
Q

explain afterload in terms of stroke volume regulation

A

pressure to exceed to eject ventricular blood i.e., to open semilunar valve;

  • Increased by elevated BP (hypertension) & narrowing of arteries by atherosclerosis.
28
Q

explain the homeostasis and control in the regulation of heart rate

A

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
Q

name the most important factors that regulate heart rate

A

automimic nervous system

Hormones, released by adrenal medulla
- * epinephrine & norepinephrine

30
Q

Autonomic Regulation of Heart Rate originates where

A

in cardiovascular centre in medulla oblongata

31
Q

name and explain the 2 ways the nervous system controls the heart

A

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
Q

explain chemical regulation of the heart

A

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
Q

name 4 other factors that regulate heart rate

A

age
gender
physical fitness
body temp

34
Q

explain how age and gender regulate heart rate

A

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
Q

explain how physical fitness regulates heart rate

A

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
Q

explain how body temp regulates heart rate

A

(>temp > rate)
i.e., the higher the body temperature the faster the heart rate

37
Q

explain Long Q-T Syndrome

A

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
Q

name the 2 forms of treatment for long Q-T syndrome

A

beta blockers
defibrillator

39
Q

explain how beta blockers are a treatment for long Q-T syndrome

A

Block b adrenoceptors

Decrease electrical impulse that passes through AV node

Prevents sudden increase in heart rate

40
Q

explain how defibrillators are a treatment for long Q-T syndrome

A

Depolarises entire myocardium simultaneously

With luck, after repolarisation, the SA node will be the 1st to reach threshold.

41
Q

what is arrhythmia

A

Irregular heart rhythm due to defect in conduction system of heart

42
Q

name the causes of arrhythmia

A

drugs (caffeine, nicotine, alcohol etc.,)
anxiety
Hyperthyroidism
K+ deficiency
certain heart diseases.

43
Q

name and explain some examples of arrhythmia

A

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
Q

Representative Heart Conditions Detectable through what

A

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
Q

heart disease is caused by the build up of what

A

Atherosclerotic Plaque
lumen of blood vessel becomes smaller due to the presence (build up) of the plaque.

human anatomy and physiology (52 decks)

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