Chapter 10 Muscular Tissue Flashcards
Contractive organelles of skeletal muscle?
Myofibrils
Dilated end sacs of the sarcoplasmic reticulum?
Terminal cisterns
Fluid filled system of membranous sacs?
Encircles each Myofibrils?
Sarcoplasmic Reticulum
Formed by a transverse tubule and 2 terminal cisterns on either side?
Triad
Stored by the SR. When in a relaxed muscle fiber
Calcium Ions (Ca+2)
From the terminal cisterns of the SR. Triggers muscle contraction?
Release of Ca+2
Darker middle part of a sarcomere. Extends the entire length of thick filament
A Band
Narrow plate shapes regions of dense protein. Separates one sarcomere from the next
Z discs
Basic functional unit of a myofibril
Sarcomere
Small protein structures within Myofibrils
Filaments or myofilaments
Where the thick and thin filaments lie side by side
Zone of overlap
Lighter less dense area that contains the rest of the thin filament but no thick filaments.
I band
Contains thick but not thin filaments, in the center of each A band
H zone
Formed when supporting proteins that hold the thick filaments together at the center of the H line. At the middle of the sarcomere
M line
Twisted golf club handles point towards the M line in the center of the sarcomere
Myosin tail
The 2 projections of each myosin molecule.heads project outward from the shaft in a spiraling fashion each extending toward one of the 6 thin filaments that surround each thick filament
Myosin head
3 muscle proteins
Contractile - generate force during contraction
Regulatory - help switch the contraction process off and on
Structural- keep the thick and thin filaments in the proper alignment, give myofibril elasticity and extensibility
2 contractive proteins
Myosin - main component of thick filaments and functions as motor protein
Actin- motor protein pull various cellular structures to achieve movement by converting electrical in ATP to mechanical energy
Components of sarcomere
Z discs A band I band H zone M line
Where a myosin head can attach
Myosin binding site
Main component of thin filaments anchored to Z discs. Individual actin molecules join to form an actin filament that is twisted into a helix
Actin
Thin filaments contain
Actin
Troponin
Tropomyosin
Contractile proteins can generate force during contraction
Myosin and actin
Regulatory proteins, help switch contraction on and off
Troponin and Tropomyosin
When muscle activity continues and the supply of creatinine phosphate within the muscle fiber is depleted. Glucose is catabolized to generate ATP
Anaerobic glycolysis
Pyruvic acid generated from glycolysis is converted to
Lactic acid
Muscular activity lasting more than 30 seconds. This system of ATP production involves biological oxidation
Aerobic cellular respiration
A small amino acid like molecule that is synthesized in the liver, kidneys and pancreas and then transported to muscle fibers
Creatine
Unique to muscle fibers an energy rich molecule that’s is found in muscle fiber. The enzyme Creatine kinase catalyzes the transfer of the high energy phosphate group from ATP to Creatine forming Creatine phosphate and ADP
Creatine phosphate
From Creatine phosphate. By anaerobic glycolysis. By aerobic respiration. Production of ATP in muscle fibers
Muscle metabolism
Used to diagnose certain muscle disorders . Measures the electrical activity in resting and contracting muscles
Electromyography
Acetylcholine released at the neuromuscular junction triggers a muscle action potential which leads to muscle contraction
Summary of events of the contractions and relaxation in a skeletal muscle fiber
Blocks removal of ACh from receptors so strengthens weak muscle contractions of myasthenia gravia. Also an antidote for curare after surgery is finished
Neostigmine (anticholinesterase agent)
Release of acetylcholine
Activation of ACh receptors
Production of muscle action potential
Termination of ACh activity
Events occurring after a nerve signal
Neurons that stimulate skeletal muscle fibers to contract
Somatic motor neurons
Plant poison from poison arrows . Relax muscle during surgery
Curare
Produced by the bacterium clostridium botulinum. Bl is exocytosis of synaptic vesicles at the NMJ as a result ACh is not released and muscle contraction does not occur
Botulinum toxin
Usually near the midpoint of a skeletal muscle fiber, the synapse between the somatic motor neuron and a skeletal muscle fiber
Neuromuscular Junction
Chemical messenger released when the 1st cell communicates with the second cell
Neurotransmitter
Deep groves in the motor end plate that provide a large surface area for ACh
Junction folds
All of the synaptic end bulbs in one side of he synaptic cleft plus the motor end plate of the muscle fiber on the other side
Neuromuscular junction
Ligand gates ion channels, abundant in junction folds , integral transmembrane proteins to which ACh binds
Acetylcholine receptors
The region of the sarcolemma opposite the synapse end bulbs
Motor end plate
Neurotransmitter released at the NMJ
Acetylcholine