Focus 6 Flashcards
Muscle cell membrane
Sarcolemma
Thick filament of the sarcomere
Myosin
Thin filament of the sarcomere
Actin
What are the levels of organization of skeletal mm (simple-complex)
- myofilament
- sarcomere
- myofibril
- mm fiber
- fascicle
- muscle
Thick filament
Myosin
Series of events linking excitation to mm contraction. (Cross-bridge activity)
Excitation Contraction Coupling
Functional unit of mm cells
Sarcomere
Regulatory proteins (accessory proteins)
Troponin/tropomyosin
Similar to EPSP but much greater. Potential change=
EPP (End Plate Potential)
Part of mm cell containing Ca++
Sarcoplasmic reticulum
Carries the AP deep into the mm cell itself
T-tubules
Changes shape, sliding tropomyosin out of the way freeing up binding sites
Troponin
Thin filament
Actin
Ca++ binds with _________ causing ________ to change shape allowing myosin to bind with actin
Troponin
Tropomyosin
ATP is required to:
-
- form cross bridge
- break cross bridge
- pump Ca++ (active transport pump) back into sarcoplasmic reticulum
ATP is generated by:
-
- creative phosphate
- anaerobic glycolysis
- aerobic respiration
Glycogen broken down into glucose. Lactic acid released
Anaerobic glycolysis
This happens so we don’t run out of ATP
Muscle fatigue
Oxygen required to replace depleted muscle energy stores (return to homeostatic levels)
Oxygen debt
A lot of ACh + a lot of receptors =
No summation required
Myosin heads have two sites
Actin-binding site
Myosin ATPase site
Made up of sarcomere -> thick/thin filament
Myofibril
Forms the neuromuscular junction. Fits into depression in mm fiber
Terminal buttons
Each mm fiber contracts all the way
All or nothing law
Allows mm contraction with varying force. Innervation of more or less cells of a mm
Recruitment
Allows fine control movement
Small motor unit
Allows for powerful contractions
Large motor unit
