Muscle Physiology Flashcards
What makes muscles contract
Excitation - contraction coupling
What are the intermediate filaments in smooth muscle?
Desmin, the are bound together at dense bodies (oblique, transverse fibres)
Resting membrane Potential of muscles vs neurons
-90 (muscle ) vs -70 (neuron)
What maintains the -90mV resting membrane potential in muscle cells?
- sodium potassium ATPase pump (balances the leaky channels)
- passove leak channels
What are the channel proteins involved in the calcium cycling process (5 types)
Ryanodine , inositol triphosphate
SERCA, NCX, calcium-ATPase
Is L type or T type channels involved in myocardial contraction
Both but mainly refer to L type
The depolarisation of SAN is due to the L type calcium channels opening
Excitation contraction coupling process
How many calcium and sodium does the NCX transport
1 calcium per 3 sodium
NCX31
Difference in calcium ion release from SR in smooth muscle vs skeletal/heart muscles
In smooth muscle - Ryanodine (RyR) and Inositol triphosphate (IP3R)
In cardiac and skeletal muscle - RyR only
In which type of muscle does depolarisation last the longest
Smooth muscle because of the presence of Inositol triphosphate (IP3R) which can be affected by agonists. IP3R is less reliant on action potentials
What is the process of calcium induced calcium release
When the calcium enters the cell through L type channels and activate MORE calcium to be released from the SR through the Ryanodine and IP3 channels
Troponin C
troponin T
tropomyosion
C; calcium binds to this
T: binds troponin c to tropomysoin
Tropomysoin blocks the actin-myosin binding sites
How many chains does a single myosin have
6 it is a hexamer
2 heavy chains and 4 light chains
What induces the power stroke
The release of inorganic phosphate and ADP
When does the myosin head relax
When a new ATP attaches
