Muscle Physiology Flashcards
Structural Proteins
- titin, desmin, vimentin, alpha actin
- hold actin & myosin & myofilaments in place
Contractile Proteins
- Actin & myosin
- actually cause muscle contraction
I band
region of sarcomere with thin filaments only
H Zone
-region of sarcomere containing myosin only
Muscle cell
Muscle Fiber
T Tubule
- continuation of sarcolemma that protrudes into the sarcoplasm
- allows action potential to get to deeper into cell to release Ca++
- between 2 lateral sacs to make a triad
Epimysium
Covers entire Mm
Sarcomere
- made of protein filaments
- structural unit of muscle, separated by Z lines
Endomysium
-covers each muscle fiber
Each actin is surrounded by
3 myosin
Sarcoplasmic Reticulum
- Ca++ storage in lateral sacs, close to T tubules
- Wraps longitudinally around myofibril
Regulatory Proteins
- tropomyosin & troponin
- prevent/cause muscle contraction
TnT
(troponin)
binds to tropomyosin
3 classifications of Sarcomere Proteins
- regulatory
- contractile
- structural
Z Line
- marks boundary of sarcomere
- connect 1 sarcomere to next
- (actin attached here)
M Line
- Extends through the center of the H zone
- represents proteins that serve to hold together the adjoining myosin molecules
Muscle Connective Tissue
- Epimysium
- Perimysium
- Endomysium
Troponin
- complex of 3 units (mickey mouse ears)
- TnC
- TnT
- TnI
Perimysium
covers a fasiculus
A Band
-region of sarcomere containing all of the myosin and the actin that overlaps it
The myosin is cocked when:
it has ADP + Pi bound to it’s head
& a high energy form of myosin
Actin
- Spherical molecules joined in 2 helical strands
- each sphere has binding site for myosin
Mm connective tissue fuses at ends of muscles to:
form tendons to attach to bones
Fasciculus
- bundle of muscle fibers in parallel
- separated by perimysium
Myofibrils
- contractile unit of Mm where tension is generated
- one segment is a sarcomere
Myosin
thick filament
2 head of myosin
- 1 site to bind with actin
- 1 site to bind ATP
Thick Filaments
-made up of myosin
Each myosin is surrounded by_____
6 different actin
Thin Filaments
-made of actin, troponin, tropomyosin
Tropomyosin
-long threadlike protein runs along groove made by actin
molecule strings
-Covers binding sites while resting
Tnc
troponin that binds to Ca++
TnI
troponin that binds to actin and inhibits binding of tropomyosin to actin