cardiac muscle contraction

Question 1

why is there an voltage/pd across a cell membrane

Answer 1

electrochemical potential outside cell is mainly positive and electrochemical potential in cell is mainly negative generating a voltage/pd

Question 2

what is the resting potential of a cardiac myocyte

Answer 2

-85mV

Question 3

how are nerve impulses created

Answer 3

by movement of ions creating changes in voltage

Question 4

what feature of nerve cells allow areas to be skipped, increasing speed of conduction

Answer 4

myelin

Question 5

how is an action potential generated in cardiac myocyte

Answer 5

Stimulus – A stimulus triggers an inflow of Na+ ions into the cell. This increases the potential difference from -85/90 to a value of around 30. During this period, there are some failed initiations of the action potential.

Depolarisation – Therefore Naᐩ ions rapidly diffuse in. The potential difference increases to +30mV, meaning the inside of the cell is more positive than the outside. It then hits a Platou where no more +Na enter but rather Ca+ enters (this is the contraction period)

Repolarisation – Voltage-gated potassium channels open and calcium stops entering. Kᐩ ions quickly diffuse out of the axon, repolarising the membrane.

Question 6

what is excitation contraction coupling

Answer 6

ionic movement as part of the action potential causing contraction

Question 7

how might you be able to increase the strength of cardiac contraction

Answer 7

increasing the influx of calcium or maintaining higher calcium levels in the cytosol of cardiac myocytes during an action potential.

Question 8

where in cardiac myocytes is calcium stored

Answer 8

sarcoplasmic reticulum

Question 9

what In the actin filament does calcium bind to

Answer 9

troponin (c)

Question 10

what is coronary artery atheroma

Answer 10

when buildup of fatty deposits break off and cause blockage in the heart (can lead to heart attack)