Cardiac3

Front 1

the coupling of electrical stimulation with mechanical force happens via:

Back 1

calcium

Front 2

calcium enters the myocyte during Phase__ depolarization

Back 2

2

Front 3

L-type voltage-dependent calcium channels located in ____ and ____

Back 3

sarcolemma and T tubules

Front 4

L-type voltage-gated calcium channels open in response to local ____

Back 4

AP. Thus, calcium diffuses into cytosol from ECF across T-tubule membrane during cardiac AP.

Front 5

calcium binds to troponin and initiates:

Back 5

a contraction

Front 6

in cardiac contractile cells, the L-type calcium channels are located primarily in the _________. these voltage gated channels are opened in response to a local AP.

Back 6

T-tubules.

Front 7

Calcium diffused into the cytosol from the ECF across the T tubule mumbrane during a cardiac AP.

Back 7

this small amount of entering calcium triggers the opening of nearby calcium release channels in the adjacent lateral sacs of the sarcoplasmic reticulum. in this way, calcium entering the cytosol from the ECF induces a much larger release of calcium into the cytosol from the intracellular stores.

Front 8

the resultant local bursts of calcium from the sarcoplasmic reticulum collectively increase the cytosolic calcium pool sufficiently to turn on the contractile machinery.

Back 8

this extra supply of calcium from the sarcoplasmic reticulum is responsible for the long period of cardiac contraction. this increased contractile time ensures adequate time to eject the blood.

Front 9

the role of calcium within the cytosol is to bind with the troponin-tropomyosin complex and physically pull it aside so that the cross-bridge cycling and contraction can take place.

Back 9

in cardiac muscle, the exent of cross bridge activity varies with the amount of cytosolic calcium. various regulatory factors can alter the amount of cytosolic calcium.

Front 10

removal of calcium from the cytosol by energy dependent mechanisms in both the plasma membrane and sarcoplasmic reticulum restores the blocking action of troponin and tropomyosin, so that:

Back 10

contraction ceases and the heart muscle relaxes.

Front 11

some drugs alter cardiac function by:

Back 11

changing calcium movement across myocardial cell membranes

Front 12

inotrophy=

Back 12

force of contractions

Front 13

rise in ECF calcium levels:

Back 13

prolongs plateau of AP

Front 14

the more calcium released:

Back 14

the stronger the contraction (to a certain extent)

Front 15

tetany=

Back 15

involuntary contraction of muscle

Front 16

refractory period:

Back 16

the time after AP during which excitable tissue's membrane is unresponsive

Front 17

cardiac tissue must contract in a responsive, controlled, and reliable manner to create the pressure difference that drives blood thru the cardiovascular system.

Back 17

the cardiac cycle is the time period from the start of one ventricular contraction to the beginning of the next.

Front 18

mechanical events of the cardiac cycle include:

Back 18

contraction, relaxation, and the resultant changes in blood flow. these result from rhythmic changes in cardiac electrical activity.

Front 19

the cardiac cycle =

Back 19

alternate periods of systole and diastole

Front 20

systole=

Back 20

contraction and emptying

Front 21

diastole=

Back 21

relaxation and filling

Front 22

heart murmurs are:

Back 22

abnormal heart sounds

Front 23

heart murmurs are usually assoc. with:

Back 23

heart disease. murmurs in young people that are not assoc with heart disease are called functional murmurs.

Front 24

heart murmurs result from:

Back 24

turbulent flow rather than laminar flow.

Front 25

the turbulent flow of heart murmurs is caused by:

Back 25

1. stenotic valves: stiff, narrowed valve; doesnt open sufficiently
2. insufficient, leaky valves: valve that doesnt close completely; usually scarring of valve edges-> dont fit together properly

rheumatic fever is often a culprit for both