Flashcards in Normal Structure And function Deck (305)
Cardiac muscle is unstriated - TRUE OR FALSE
False - it is striated
Cardiac myocytes are electrically coupled by...
Desmosomes have what function within cardiac muscle?
Provide mechanical adhesion between adjacent cardiac cells
Contractile unit of muscle
Actin filaments form the light/dark appearance of myofibrils?
Within each myofibril, actin and myosin are arranged into....
Muscle tension is produced by ___ of actin filaments over myosin filaments
Force generation depends upon ________ interaction between myosin and actin filaments
Requirements for muscle contraction (2)
Role of calcium in muscle contraction
Binds to troponin, moving the tropomyosin away from the actin myosin binding site
Calcium is released from the _______ _______ in cardiac muscle
TRUE OR FALSE - the release of calcium from the sarcoplasmic reticulum is dependent on the presence of extra cellular calcium
Calcium induced calcium release is
The release of calcium in response to the release of calcium
Where does the CIcR start in cardiac muscle?
The calcium influx during ventricular muscle action potential through L-type calcium channels - travels down T-tubules increasing the release from SR
Channel that removes calcium from the cell back to the SR
Excitation of the heart normally originations in the ________ cells of the ___ ____ ____
pacemaker cells of the SAN
The heart is normally under the control of the ___
TRUE or FALSE - the cells in the SAN have a resting membrane potential
The SAN constantly drifts towards depolarisation
The pacemaker potential is due to what 3 ion currents?
Na influx and K influx (funny current)
Transient Ca influx
Decreased K efflux
Ion channel responsible for the rising phase of the action potential in the SAN?
Ion channel responsible for the falling phase of the action potential in the SAN?
K channel --> K efflux
Why is conduction is delayed within the AVN?
to allow for atrial systole
Phase 0 of ventricular AP
Phase 1 of ventricular AP
closure of Na, transient K efflux
Phase 2 of ventricular AP
LTCC balanced with transient K efflux
Phase 3 of ventricular AP
Ca channels close but delayed rectifier K channels remain open
Phase 4 of ventricular AP
resting membrane potential
Nerve which exerts continuous control over the heart?
Autonomic predominant control over the heart?