Muscle cell function (M.S.)

what are the 3 types of muscle types?

skeletal, cardiac and smooth

what type of muscle do skeletal and cardiac fall under?

striated

how long is the AP duration and relative refrac period in neuronal AP?

short APD and long relative refrac. period

does cardiac AP have long or short refractory period?

long

what does a heart need to beat and why?

needs a pacemaker to generate electrical signal since heart cannot beat spontaenously

is cardiad AP long or short and why

long AP prevents tetany, and prevents arrythmia(through regular beating)

why does skeletal muscle need to be tetanised?

because it allows sustained contractions of the muscle. Allows us to stand, walk, maintain posture (basic physiological functions)

is skeletal muscle refractory period long or short?

short

what are the two types of basic excitability in smooth muscles

AP and graded depolarisation

what are graded depolarisation in terms of smooth muscle?

steady changes in membrane potential that doesn’t involve AP

what are time independent and dependent channels

time independemnmt are channels that dont have automatic closing mechanism and stay open for as long as drug/ligand or voltage charge is present.

Time dependent does have auto closing mevhanism so they close after AP

what ion is central to contraction in all muscle types?

Ca2+ ion

what was the Sydney-Ringer experiment?

When Ca was removed from the heart muscle, cardiac cells wouldnt contract, however when Ca was removed skeletal muscle would continue to contract

what is calcium induced calcium released and where is it found?

extracellular calcium causes the causes even more calcium to be released in the carduiac muscle

what is voltage induced calcium released and where is it found

no extracellular CA involved, only external voltage causes channel to open and causes CA release in skeletal muscle

why is voltage induced calicum released beneficial in skeletal muscle?

doesnt need Ca to be present at all times in order to contract

what is required for cross bridge formation?

Ca (bind to troponin C to displace tropomyosin) and ATP to provide energy

what 3 things affect CA sensitivity?

temp, pH, drugs(in body)

how is tension regulated in skeletal muscle.

Via more motor units recruited

how is tension regulated in cardiac muscle

via size of the clacium gradient

what does a larger calcium transient lead to?

more force

what are the 5 steps in smooth muscle contraction

1. calcium enters smooth muscle cell via gated channel (voltage, drug, ligand etc)

2. Ca binds to calmodulin to form calcium calmodulin

3. Ca-calmodulin activates MLCK(myosin light chain kinase)

4. activated MLCK phosphorylates myosin light chain

5. so smooth muscle contracts