Integration of Cardiac Function Flashcards Preview

Physiology > Integration of Cardiac Function > Flashcards

Flashcards in Integration of Cardiac Function Deck (50)
Loading flashcards...
1

2 mechanisms to control CO

intrinsic - local to heart
-mechanical/muscular (Starling's law related to contractility)
-electrical/ionic (membrane potential; ionic concentrations)

extrinsic - extra-cardiac neuronal and hormonal signaling pathways
-baroreceptors and chemoreceptors related to sympathetic stimulation and parasympathetic inhibition

2

neurotransmitter, receptors, second messenger, and functional "results" for sympathetic stimulation of the heart

NE to beta1 (pacemakers and myocetes) that increase cAMP
-cause tachycardia and increased contractility

3

neurotransmitter, receptors, second messenger, and functional "results" for parasympathetic stimulation of the heart

ACh to M2 (pacemakers, minor myocete effect) that decrease cAMP
-cause bradycardia and decreased contractility

4

how does CO compare in the aorta and pulmonary artery?

CO is the same in both, b/c they are in series
-it is NOT the sum of flows into aorta and pulmonary arteries

5

how low does CO go to be defined as hypoxia?

falls below 1/3 normal

6

what is the relationship between CO, work, and O2 consumption during exercise?

positive linear relationship

7

how does mild inspiratory hypoxia change CO?

increases CO
-decreased O2 concentration in environment (like at high altitude)

8

how does chronic anemia change CO?

increases CO
-decreased O2 content in blood when RBC concentration is reduced

9

how does histotoxic hypoxia change CO?

increases CO
-tissue poisoning involves decreased ability of tissues to utilize O2 as occurs after cyanide ingestion

10

how does pulmonary disease change CO?

increases CO
-in general, resulting in hypoxemia (lowered O2 concentration in blood)

11

what are 4 compensatory diseases that increase CO?

-chronic anemia
-histotoxic hypoxia
-pulmonary disease with hypoxemia
-mild inspiratory hypoxia

12

how does hyperthyroidism change CO?

increases CO b/c increased metabolic rate

13

how does pregnancy change CO?

increases CO (by 8%) corresponding to increased metabolism

14

difference between mild anoxia and severe anoxia

mild anoxia: increases CO b/c decrease peripheral resistance
severe anoxia: decreases CO b/c O2 deprivation in heart

15

how does HTN change CO?

unaltered in most forms

16

what happens to CO during hemorrhage?

CO is less than 1/2 normal for a significant period of time
-can cause severe shock

17

what 3 heart diseases decrease CO?

acute myocardial infarction
rheumatic fever
congestive heart failure

18

effect of body size on CO

CO increases in proportion to size
-CO = k * W^(3/4)

19

cardiac index and equation

CI = CO/body surface area
-attempt to normalize CO to individuals of different sizes

20

how does CO change with age?

body metabolism slows with increasing age, as does CO, by about 30% between 20 to 45 years old
-drops from 6 to 5.25 L/min

21

effect of anxiety on CO

emotional factors increase CO

22

effect on posture on CO

if laying down to sitting up: CO decreases by 23%
if laying/sitting to standing up, CO increases b/c tensing muscles

23

effect of temperature on CO

during fever, CO rises due to effects of temperature on metabolic rates of tissue

24

4 phases of cardiac cycle

1. filling phase
2. isovolumetric contraction phase
3. ejection phase
4. isovolumetric relaxation phase

25

what does the P wave correspond to

atrial depolarization
-while the AV node, bundle of his, bundle branches, and Purkinje network are depolarized as well, they don't generate voltages large enough to be measured

26

what does the QRS complex correspond to?

ventricular depolarization (upstrokes)

27

what does the T-wave correspond to?

ventricular repolarization

28

what does the ST segment correspond to?

plateau phase (phase 2)

29

what does the TP segment correspond to?

ventricular diastole

30

ventricular volume changes in cardiac cycle

1. ejection: falls from 120 to 50 mL, corresponding to stroke volume of 70 mL, and EJ of 58%
2. filling: occurs during early diastole as mitral and tricuspid valves open
-atrial systole occurs at the end of diastole, with only a small rise in pressure for both right and left hearts, so responsible for only a small increase in ventricular volume

Decks in Physiology Class (60):