week 6 muscular system Flashcards
Muscle cells are filed with _________
myofibrils
Myofibrils are filled with
sarcomeres
The ryanodine receptor releases __
calcium
The ryanodine receptor opens when the _______ receptor opens (depolarizes)
dihydropyridine receptor
Troponin & Tropomyosin bound together as one _______ that is found around actin molecules.
protein
long fibrous protein like rope:
tropomyosin
Globular protein made up of 3 subunits
troponin
What are the three subunit of troponin
Tc, Ti, Tt
Tt stands for
Troponin-tropomyosin
Ti stands for
Troponin – interaction
Tc stands for
Troponin – calcium
Tc component allows ____ to bind
calcium
What is the TTC function
to cover the myosin binding sites on actin
The ATP that is attached to the Myosin head can be found in two different format:
ATP form, and ADP Pi form
The ATP format of the myosin head is considered
low energy configuration
The ADP and Pi format of the myosin head is considered
high energy configuration
Skeletal Muscle Activation requires ______ of a nerve
innervation
___ permits contraction & its absence ______ contraction
Ca, prevents
Neuromuscular Junction Process is the ______ of neurotransmitter and _____ of the muscle
release, innervation
Excitation Contraction Coupling is the Release of _____ and ________.
calcium , cross bridge formation
Sliding Filament Theory is the ________ aka _____ ______
contraction, power stroke
Steps to Neuromuscular junction :
Arrival of action potential -> Opening of voltage gated calcium channel->
Entry of calcium->
Exocytosis of neurotransmitter->
Diffusion of the neurotransmitter across the neuromuscular junction ->
Binding of the neurotransmitter to the receptors on the postsynaptic membrane
In the neuromuscular junction the neurotransmitter will ALWAYS be ___________.
Acetylcholine (ACh)
The receptor that acetylcholine binds to in the neuromuscular junction is always
Nicotinic Cholinergic Receptor
The receptor that acetylcholine binds to in the neuromuscular junction is always
Nicotinic Cholinergic Receptor
Steps in E-C coupling :
- Net entry of Na causes postsynaptic membrane (muscle) to reach threshold.
- Reaching threshold generates action potential on the postsynaptic membrane.
- Action potential travels down T-tubules causing the Dihydropyridine receptor to depolarize.
- The depolarization of the dihydropyridine receptor causes the Ryanodine receptor to open.
- Calcium is released from the SR and binds to troponin.
- Binding of calcium to “Tc” portion of Troponin causes the tropomyosin to shift over.
- Shifting of Troponin-Tropomyocin complex causes myosin binding sites on actin to be exposed.
- Myosin bind actin (cross bridges form between thick and thin filaments)
Sliding filament theory steps:
- Release of ATP (ADP & Pi)-> causes the myosin head to bend -> power (working) stroke occurs
- A new ATP molecule comes in and bind myosin head -> causes the thick & thin filaments to detach->
Myosin is in low energy state. - Rearrangement / Hydrolysis of ATP into ADP & Pi occurs -> myosin head straightens up (cocked position). Myosin is in high energy state now.
- If calcium present Thick and Thin filaments form cross bridges again and sliding filament theory occurs again, if Ca not present muscle will relax
Smooth muscle contains 3 inactive proteins called ________, ________, & ________
myosin light chain Kinase, calmodulin, & myosin
Steps to smooth muscle contraction :
- Calcium ions enter via voltage dependent/ voltage independent Ca2+ channels and SR (calcium induced calcium release)2. Calcium then binds to calmodulin and activates it. 3. The activated calmodulin activated the myosin light chain kinase enzymes 4. The kinase enzymes then takes ATP and converts it to ADP and Pi 5. The ADP and Pi then attach to the myosin activating it, then cross bridges form and shortening begins
Steps to smooth muscle contraction :
- Calcium ions enter via voltage dependent/ voltage independent Ca2+ channels and SR (calcium induced calcium release)2. Calcium then binds to calmodulin and activates it. 3. The activated calmodulin activated the myosin light chain kinase enzymes 4. The kinase enzymes then takes ATP and converts it to ADP and Pi 5. The ADP and Pi then attach to the myosin activating it, then cross bridges form with actin and shortening begins