Integration of Cardiac Function

Question 1

intrinsic mechanisms

Answer 1

• local to the heart
• mechanical/muscular
• starlings
• contractility
• electrical/ionic, ionic concentrations`

Question 2

extrinsic mechanisms

Answer 2

• SNS- NE, B1 receptor, increases cAMP, tachy and increased contractility
• PNS-Ach, M2 receptors, decrease cAMP, brady, decreased contractility
• neuronal and hormonal signaling pathwats

Question 3

CO

Answer 3

-proportional to oxygen consumption

Question 4

increase CO

Answer 4

• exercise
• fever
• anxiety
• body weigh
• pregnancy
• hyperthyroidism
• compensatory increases-chronic anemia, histotoxic hypoxia, pulmonary disease with hypoxemia
• mild inspiratory hypoxia

Question 5

decrease CO

Answer 5

• sleep
• aging
• severe anoxia
• acute hemorrhage
• heart disease-acute MI, rheumatic fever, CHF

Question 6

steady states

Answer 6

• try and keep CO around 5
• increase volume shifts venous function curve to the right
• increase SNS shifts cardiac function curve to up, inc HR or SV

Question 7

response to exercise

Answer 7

-mechanical and chemical

Question 8

mechanical response to exercise

Answer 8

• muscle pump increases venous return
• increase in RAP
• increase in end diastolic pressure
• increase in SV
• inc in CO

Question 9

chemical response to exercise

Answer 9

• increase CO2, dec O2, decrease pH
• local vasodilation of active muscle increases venous return (which increases RAP)
• also decreases arterial pressure
• activates arterial baroreceptors (decrease AP- less PNS, more SNS)
• increase in HR and SV, increase CO
• vasoconstriction of inactive muscle, splanchnic, cutaneous, renal

Question 10

SNS

Answer 10

• heart stronger pump

- increases MSFP due to venoconstriction- same volume in smaller vessel

Question 11

SNS

Answer 11

• heart weaker pump

- decreases MSFP

Question 12

phases of the cardiac cycle

Answer 12

1. filling
2. isovolumetric contraction phase
3. ejection phase
4. isovolumetric relaxation phase
   - mechanical and electrical events that occur during a heart beat

Question 13

P

Answer 13

-atrial depolarization

Question 14

QRS

Answer 14

• ventricular depol
• phase 0 upstroke
• R onset of ventricular contraction

Question 15

T wave

Answer 15

• ventricular repolarization

- phase 3

Question 16

ST segment

Answer 16

-plateau in AP

Question 17

TP

Answer 17

-ventricular diastole

Question 18

point 1 on cardiac cycle

Answer 18

during ejection the volume in the left ventricle falls from 120 mL to 50
-SV is 70
fraction is 70/120 58%

Question 19

point 2

Answer 19

• ventricular filling occurs during early diastole when mitral and tricuspid valves open
• atrial contraction occurs at the end of diastole and produces only a small rise in the pressure for both the right and left hearts, small increase in vent volume
• atrial diastole during ventricular systole, atrial pressure rises, falls when mitral valves open

Question 20

point 3

Answer 20

• diastole begins at the dichrotic notch when the aortic valve closes
• left vent pressure falls when volume is increasing
• forward momentum of blood entering ventricles distends the ventricles and drops pressure even though volume is increasing

Question 21

point 4

Answer 21

• during systole, left ventricle pressure starts bigger to drive blood but then aortic pressure is higher
• blood flows because forward momentum but flow is decreased

Question 22

filling phase

Answer 22

• ventricles at relatively low pressure
• AV valves open (tricuspid and mitral
• ventricles fill with blood (50-120 ml)
• P wave of EKG precedes atrial contraction

Question 23

jugular pressure

Answer 23

• follows R atrial pressure
• A -atrial contraction
• C- closure of tricuspid valve
• V- atrial filling and emptying

Question 24

isovolumetric contraction phase

Answer 24

• QRS complex occurs
• ventricular depolarization
• ventricular muscles contract, no immediate volume change
• ventricular pressure rapidly increase until reach aortic pressure AV valves rapidly close
• pulmonary and aortic valves open

Question 25

ejection phase

Answer 25

- once ventricular pressure exceeds that of the aorta and pulmonary artery - blood ejected from ventricles - dominant event of systole - T wave of EKG at half of outflow phase - at end of outflow phase, ventricular pressure decreases leading to isovolumetric relaxation

Question 26

isovolumetric relaxation

Answer 26

- pressure rapidly drops in both ventricles - pulmonary and aortic valves close at the beginning of diastole - when ventricular pressure drops below that of the atria - mitral and tricuspid valves open - a new inflow phase begins

Question 27

SV

Answer 27

- affected by changes in EDV and ESV - atrial filling pressure-increase impedes venous return decreases EDV and SV - ventricular filling time- increase increases EDV - ventricular compliance increase increases EDV - HR- increase-decreases diastole time, dec EDV - increase preload, increase EDV, increases SV (starling-more stretch increases sensitivity) - after load increase decreases ejection and increases ESV, less Sv

Question 28

rhythmicity

Answer 28

provided by intrinsic mechanisms of SA node

Question 29

atria

Answer 29

-contraction is a relatively minor component, | right before left

Question 30

ventricles

Answer 30

- left before right - left like squeezing toothpaste - right contraction like bellows, approx same volume from both

Question 31

valves

Answer 31

- mitral closes slightly before tricuspid because left ventricle contracts first - pulmonary pressure less than aortic so that opens first - aortic valve closes first too - tricuspid opens first - right sided valves open first - left sided valves close first

Question 32

S1

Answer 32

Lub

Question 33

S2

Answer 33

Dub

Question 34

s3

Answer 34

diastolic filling gallop | -recoil of ventricles with low compliance

Question 35

s4

Answer 35

atrial contraction gallop | -usually pathologic