muscle Flashcards
What are the muscle functions?
Producing movement, maintaining posture and body position, stabilizing joints, generating heat
What is a sacromere?
It is the smallest contractile unite of a muscle fiber- the functional unit of skeletal muscle.
What is tropomyosin?
polypeptide rod shaped protein, spiral about the actin core and help stiffen and stabilize it. Block myosin-binding sites on actin so that myosin heads on the thick filaments cannot bind to the thin filaments.
What is Troponin?
globular 3 polypeptide protein: (Tnl) inhibitory subunit that binds to actin (TnT) binds to tropomyosin and helps position it on actin (TnC) binds calcium ions
What is dystrophin?
protein which links thin filaments to the integral proteins of the sarcolemma- anchored to the extracellular matrix.
What are Terminal cisterns?
form larger, perpendicular cross channels at the A band - I band junctions and they always occur in pairs.
What is the Sliding Filament model of contraction?
the I bands shorten, the distance between Z discs shorten, H zones disappear, A bands move closer together but their length does not change.
What is a synaptic cleft:
gap between axon and sacrolemma filled with a gel-like extracellular substance rich in glycoproteins and collagen fibers.
What are synaptic vessels?
small membranous sacs containing the neurotransmitter acetylcholine (ACh)
What is a motor unit?
consists of one motor neuron and all the muscle fibers it innervates or supplies.
What is a muscle twitch?
a motor units response to a single action potential of its motor neuron.
What are the phases of muscle twitch?
- latent period- excitation-contraction coupling occurs- cross bridge begins to cycle.
- Contraction period - cross bridges are active 10-100ms
- Period of relaxation - 10-100ms re-entry of calcium into the SR, contractile & muscle tension decreases.
What is Isotonic contractions?
muscle length changes and moves a load, tension stabilizes after sufficient tension has developed.
What is Isometric contractions?
tension builds muscles peak tension producing capacity, but muscle neither shortens nor lengthens.
What is aerobic respiration?
occurs in the mitochondria, requires oxygen, and involves a sequence of chemical reactions that break the bonds of fuel molecules and release energy to make ATP.
