Muscle And Nerve - Brauer (Completed)| Contractile Proteins - Staudinger Flashcards
What is the role of Perimysium and endomysium? 4
Perimysium surrounds muscle fiber bundles
Within Perimysium endomysium further segregates bundles of muscle fibers
Where would you find the nucleus in skeletal muscle? How many nuclei would you find? 5
Multinucleated located in the periphery
What is the basic unit of a myofibril? 6
Sarcomere
What structure increases the surface area of the sarcolemma? 6
T tubules
What makes up a sarcoplasmic triad? 6
Sarcoplasm - T tubule - Sarcoplasm
What are the lighter areas seen when viewing skeletal muscle through an electron microscope? 7
I band - thin filaments (actin)
What are the darker areas seen when viewing skeletal muscle through an electron microscope? 7
A band
What is the anchor site for actin (thin) microfilaments? 7
Z-line
What only contains actin thin filaments? 7
I-band
What is the anchor site for thick myosin filaments? 7
M-line
What contains only thick myosin filaments? 7
H-zone
What can be described as an overlap of thick and thin filaments plus the H-zone? 7
A-band
What cell(s) make up the thick filament? 9
Myosin bundles
What inhibits the binding of myosin to actin? 10
Troponin I
What binds the actin complex to tropomyosin? 10
Troponin T
What subunit of troponin binds calcium? 10
Troponin C
What is the role of ATP in muscle contraction?
It binds myosin causing the myosin to release actin and extend back to its starting position, bind another segment of actin, and contract
What are the characteristics of Type I fibers? 12
Slow oxidative, slow ATPase
Red (>[myoglobin])
Oxidative
Contract long period w/o fatigue
What are the characteristics of Type Ia fibers? 12
fast oxidative, fast ATPase
Contractions are powerful and fast
Aerobic respiration, but O2 delivery rate is low
Least numerous
Contains less myoglobin
What are the characteristics of Type IIb fibers? 12
Fast glycolytic, fast ATPase
Power and speed
Anaerobic respiration, short bursts
No myoglobin
What are neuron clusters within the PNS referred to as? What are neuron clusters within the CNS referred to as? 13
PNS - ganglia
CNS - nuclei
What are Nissl bodies? 14
refers to the stain that the RER uptakes, suggesting that a lot of protein production (neurotransmitters) must occur in a neuron
What’s the difference between a dendrite and axon in terms of signal transduction? 15
Dendrite —> electrical signals toward the cell body
Axon —> electrical signals away from the cell body
What is the most common class of neuron with many dendrites and one axon? 16
Multipolar neurons
Where is a common place you find bipolar neurons? 16
Retina
How do myelin sheaths increase the speed of signal transduction? 19
Signals are able to jump from one node of ranvier to the next
What are the three CT layers of a peripheral nerve? What do they encompass? 20
Epineurium —> contains the nerve fascicle and blood vessels
Perineurium —> encompasses nerve fascicle
Endometrium —> encompasses a single axon
What are the main neurotransmitters? 22
Acetylcholine —> primary for muscle
Noradrenaline
In terms of innervation what is a major difference between skeletal, smooth, and cardiac muscle? 23
Skeletal muscle is directly innervated (receives an axon terminal) while cardiac and smooth muscle don’t necessarily have to be
What happens when acetylcholine is release into a muscle fiber? 24
Acetylcholine stimulates an action potential that travels down T tubules and is dumped into the sarcoplasmic reticulum where it causes the sarcoplasmic reticulum to release calcium
What is the role of nuclear bag fibers? 26
Wrapped at the CENTER by type Ia nerve fibers
Detect change in length and degree of tension
What is the role of nuclear chain fibers? 26
Wrapped at the ENDS by type II nerve fibers
Detect static muscle length
What is the composition of Myosin? 12S
2 heavy chains
4 light chains
Two globular heads
What is the relation of the thin filaments (actin) to the thick filaments (Myosin)? 13S
There are 6 actin filaments to one Myosin filament 60° per thin filament
What is heavy meromyosin (HMM) and light meromyosin (LMM)? 14S
Heavy Meromyosin:
S1/S2 (includes globular heads)
This is where Papain digests
Light Meromyosin:
α-helices
This is where trypsin digests
In regards to Light Meromyosin, what allows a tight and precise bonding between the two α-helical strands? 15S
Hydrophobic interactions allow for tight bonding between four ions that meet in the middle
When looking at the heavy Meromyosin segment, what is the role of the S1 portion? 16S
Contains a P-loop that has an ATPase domain
This is where ATP binds to allow hinge movement (power stroke)
What is Myomesin? 18S
Found along the M-line
Proteins that anchor the thick filaments (myosin) together
What is Titian? 18S
One of the largest proteins on the planet
Attaches to a Z disc and then moves in between a thick filament (myosin) before attaching to the m line*
Extremely elastic allows and opposes the force of the power stroke
What kind of directionality do we see in the thin filament (actin)? 20S
Minus end —> faces the M-line
Plus end —> barbed, hooks into the Z-disc for anchoring
How does a thin filament come to together? 21S
Remember thin filaments are called Actin
G-actin subunits, single monomers are bound by ATP
The subunits come together to form F-actin and in the process ATP are converted to ADP
(+ end grows faster)
Final product is a filament full of what use to be G-actin, but is now f-actin subunits each attached to ADP
What is Tropomodulin? 22S
Caps the minus end of the thin filament (actin) preventing further polymerization
Remember minus end faces m line
What caps the positive end of the thin filament?
CapZ (β-actinin)
Associates with α-actinin at the plus end
What acts as a precise ruler for the polymerization of actin? 22S
Nebulin (precisely 6669 residues)
What does Troponin T, I, and C do?
Troponin T —> binds tropomyosin
Troponin I —> Inhibits myosin binding (binds actin)
Troponin C —> binds Ca2+ (activates)
Slide 25?
Figure out what the take away is for this in class
What holds together bundles of myofibrils?
Desmin (also synemin, but not so much)
Listen in on 30
Figure out what’s important
31
Figure out what is important from lecture
33
What’s important
34
Whats important
What is the problem in Duchenne muscular dystrophy? 36S
No detectable dystrophin
What is the problem in Becker muscular dystrophy? 36S
Dystrophins of various sizes
37
What’s important
What mobilizes glycogen to glucose in the liver? 39S
Insulin???
What causes pyruvate production from glucose-6-phosphate in the muscle? 39S
Add
What is the composition of muscle glycogen phosphorylase b? 40S
2 subunits
Each subunit is a mirror image of the other
Contains:
S catalytic site
AMP allosteric site
What directly activates glycogen phosphorylase? 40
Phosphorylase kinase
Ca2+ binds calmodulin activating it —>
Calmodulin activates phosphorylase kinase —>
Phosphorylase kinase attaches AMP to glycogen phosphorylase —>
Activity of glycogen phosphorylase increased
