Physiology - Cv System

Front 1

Describe events of systole

Back 1

Increasing pressure makes AV valves snap shut (= 1st heart sound)

Contraction of ventricle against fixed volume of blood increaes LV pressure until reaches Paortic

Semi-lunar valves open

Ejection of blood into arteries, max pressure = systolic pressure

As LV pressure falls below Paortic, aortic valve snaps shut, then pulmonic valve shuts (closing = 2nd heart sound)

Front 2

Describe events of diastole

Back 2

Semi-lunar & AV valves closed, ventricular pressure falls as muscle relaxes @ constant V

LV pressure falls to below atrial pressure and AV valves open

Ventricle refills almost entirely
Atrial contraction provides final portion of ventricular filling

Elastic recoil of arteries smooths out pressure pulse & help maintain pressure (min pressure = diastolic pressure)

Front 3

components of systemic circulation

Back 3

left heart and systemic vasculature

Front 4

components of pulmonary circulation

Back 4

right heart and pulmonary vasculature

Front 5

What does "R & L heart are coupled" mean?

Back 5

output of one = input of the other

Front 6

What controls the amt of blood flow to each organ?

Back 6

contraction & dilation of arterioles leading to each organ

Front 7

dicrotic notch or incisura marks what in the graph?

Back 7

end of systole/beginning of diastole

Front 8

Formula for cardiac output

Back 8

CO = SV x HR

Cardiac output = stroke volume x heart rate

Front 9

What is the relationship between central venous pressure & right atrial pressure?

Back 9

they are equal

Front 10

How is the LV free wall different from RV free wall in terms of pressure?

Back 10

LV free wall (and IV septum) are thick b/c LV pumps blood into high pressure aorta

RV free wall is thinner, much lower pressure will open the pulm. valve than the aortic valve

Front 11

What is the order in which the following are activated by electrical impulse:

AV node
SA node
His Purkinje system
atria
ventricles

Back 11

SA node
atria
AV node
His-Purkinje system
ventricles

Front 12

Arteriole diameter is regulated by ____ (3 things)

Back 12

autonomics, circulating vasoactive hormones, local metabolites

Front 13

3 main components of thin filaments in the sarcomere

Back 13

g-actin, troponin, tropomyosin

Front 14

How long are thin filaments?

Back 14

1.0 um

Front 15

how long are thick filaments?

Back 15

1.6 um

Front 16

component of thick filaments

Back 16

myosin

Front 17

what is the function of titin?

Back 17

connects z-line to actin and actin to myosin

Front 18

Compare sarcoplasmic reticulum & mitochondria in skeletal vs. cardiac muscles

Back 18

Cardiac SR has smaller volume than skeletal SR, but cardiac muscle has more mitochondria

Front 19

Compare junction of SR & sarcolemma in cardiac muscles vs skeletal muscles

Back 19

Cardiac - cisterna of SR form diads w/ limited SR/T-tubule contact

Skeletal - SR forms triads that envelope T-tubules

Front 20

Ca-induced-Ca-release is grades by what 2 factors

Back 20

1) size of the trigger (=amt of Ca influx vi ICa

2) amount of Ca stored in SR

Front 21

Describe the events in the Ca-induced-Ca-release

Back 21

A small amt of Ca influx (Ica) via DHP receptors triggers release of large amt Ca from the SR via Ryanodine receptors

Front 22

What does Ca binding to TnC cause?

Back 22

causes tropomyosin to unblock the myosin binding site on the thin filament and allow weak binding of actin --> A-M complexes hydrolyze ATP --> generate force

Front 23

What structures are responsible for Ca efflux out of the cell?

Back 23

1) Na-Ca exchanger (primary)
2) Sarcolemmal Ca pump

Front 24

How are the Na-Ca exchanger & Sarcolemmal Ca pump different in terms of capacity & affinity?

Back 24

Na-Ca exchanger is high capacity, low affinity ( moves lots of Ca but cannot get Ca to low resting level)

Sarcolemmal Ca Pump is low capacity, high affinity (works when Ca is relatively low, pumps out small amt to return to resting level)

Front 25

2 factors that influence # of cycling cross-bridges

Back 25

1) # strong actin-myosin complexes (this depends on sarcomere length)

2) fraction of TnC bound to Ca++

Front 26

Amt of Ca released from SR depends on: (2 things)

Back 26

1) size of trigger/magnitude of Ica

2) amt Ca in SR

Front 27

Amt of Ca stored in SR depends on: (3 things)

Back 27

1) rate of Ca uptake of SR from cytoplasm
2) rate of Ca influx into cell (Ica)
3) rate of Ca extrusion from cell (Na-Ca exchanger, sarcolemma Ca pump)

Front 28

How do norepinephrine & acetylcholine alter contractility? (increase/decrease)

Back 28

NE has a + inotropic effect
Ach has a - inotropic effect

Front 29

how does norepinephrine alter contractility? 2 ways

Back 29

1) Increases rate of SR Ca uptake by phosphorylation of phospholamban

2) decreases the Ca affinity of troponin, allowing faster release of Ca & its reaccumulation of Ca by the SR

Front 30

what is rest potentiation?

Back 30

after a longer than normal interval between beats, the 1st beat will exhibit greater than normal contractile force (reflects kinetics of SR Ca accumulation/cycling)

Front 31

what is the relationship between resting tension, total tension, active tension?

Back 31

resting + active = total

resting is determined by preload, total is measured during an isometric contraction, active is determined by subtracting resting from total

Front 32

what 3 factors shift the force-velocity curve upward & to the right?

Back 32

1. increased initial length
2. increased contractility
3. increased heart rate