Muscular System Flashcards
Know the three types of muscle tissue
Skeletal Tissue: organs that are attached to bones and skin ( voluntary muscle: consciously controlled and striated )
Cardiac Tissue: found only in the heart ( makes up bulk of heart walls ) ( striated, involuntary, and includes intercalated discs )
Smooth Tissue: found in walls of hallow organs ( ex. stomach, urinary bladder, and airways ) ( not striated and involuntary )
Understand/know the structure of Myofibrils
Myofibrils: densely packed, rodlike elements ( single muscle fiber can contain 1000s and accounts for 80% of muscle cell volume )
What are the proteins + their function that make up myofibrils?
Myosin: thick filaments ( connected at M line )
Actin: thin filaments ( anchored to Z discs )
Know the function of sacroplasmic reticulum and t-tubules
Sacroplasmic reticulum: run longitudinally along myofibrils and stores and releases Ca2+
T-tubules: increase muscle fiber’s surface area greatly and allows electrical nerve transmissions to reach deep into inferior of each muscle fiber
Describe the silding filament mechanism of muscular contraction
myosin heads attach to and “ walk “ along the thin filaments at both ends of a sacromere, z-disc come closer together and the sacromere shortens, resulting in shortening of the entire of muscle
Know/understand the steps of the contraction cycle
- ATP Hydrolysis: hydrolysis of the ATP reorients and energizes the myosin head
- Formation of cross-bridges: myosin head attaches the myosin-binding site on actin
- Power Stroke: during the power stroke, the cross bridges rotates, sliding the thin filaments in toward the M line
- Detachment of the myosin from actin: as the next ATP is binding to the myosin head, the myosin head detaches from actin
What structures comprise the NMJ?
axon terminals, synaptic clefts, and junctional folds
Know/understand the summary of events at the NMJ
- AP arrives at axon terminal
- voltage-gated calcium channels open, calcium enters axon terminal
- calcium entry causes release of ACh neurotransmitter into synaptic cleft
- ACh diffuses across to ACh receptors ( Na+ chemical gates ) on sacrolemma
- ACh binding to receptors, open gates, allowing Na+ to enter resulting in a change in membrane potential
- Acetylcholinesterase degrades ACh
Isometric types of contraction vs. isotonic
Isotonic contractions: muscle changes in length and moves load ( concentric contractions: muscles shorten and does work ex. biceps contract to pick up a book ) ( eccentric contractions: muscle lengthens and generates force ex. laying a book down causes biceps to lengthen while generating a force )
Isometric contractions: load is greater than the maximum tension muscle can generate, so muscle neither shortens nor lengths ( stays the same )
What are the three ways ATP can be generated to supply muscular contraction? How much fuel can each one offer?
- creatine phosphate ( 15 seconds of fuel )
- anaerobic pathway ( glycolysis -> lactic acid ) ( no fuel )
- aerobic respiration ( fuels used include glucose from glycogen stored in muscle fiber, then bloodborne glucose, and free fatty acids )
Example from Test: which of the following muscle tissue types are involuntary?
Smooth and Cardiac
Example from Test: ____ & _____ are regulatory proteins which help switch the contraction process on and off?
Troponin & Tropomyosin
Example from Test: thick filaments are made up by the protein ____?
Myosin
Example from Test: during the sliding filament moment of muscular contraction, which of the following are true?
Thin filaments slide over thick filaments and the sacromere shortens
Example from Test: True or False; a contraction in which the muscle does not shorten but its tension increases is called isometric contraction?
True
