Muscle Flashcards
Epimysium
surrounds the entire muscle and forms tendons
Perimysium
surrounds the fasicles
Endomysium
surrounds individual muscle cells
What is the functional unit of a myofibril
A sarcomere
Is skeletal muscle multinucleate?connected by gap junctions?
They are formed by the fusion of what
Multinucleate bc they are formed by the fusion of many myoblasts, not connected by gap jxns
What are satellite cells in muscle
residual myoblasts in mature muscle. can creat new muscle if there is damage
, where do you see the nuclei in skeletal muscle
periphery
Z disks
mark the boundaries of a sarcomere, contains actin and myosin
I band
Contains only actin filaments (thin)–looks light
A band
has actin and myosin –looks dark.
H Zone
Only has myosin (thick) filaments
How do the lengths of I, A and H change during contraction
I gets smaller, H gets smaller, A does not change
What protein is at the end of z disks
Desmin
Which protein is associated with actin? myosin?
Actin: alpha actinin, nebulin
Myosin: Titin
What neurotransmitter is at the synapse between a motor nerve axon and a skeletal muscle cell
Acetylcholine
Is ATP attached to myosin during contraction?
No, when Adp is attached to Myosin there is no binding/contraction. When released there is a conformational change that lets them attach and drags actin twoard center of sarcomere
What specific protein does Calcium cause a conformational change in to allow contraction?
Troponin which is bound to tropomyosin on actin. With Calcium it moves to allow contraction
Where is calcium stored in muscle
sarcoplasmic reticulum
What is the Sarcoplasmic Reticulum receptor that leads to the release of calcium? What leads to the uptake
ryanodine receptor leads to release, Ca@+ ATPase leads to uptake
What is a triad
Action potential to release Ca travels down transverse tubule. A triad is where the t tubule has a sarcoplasmic reticulum on either side initiating release.
What is type 1 skeletal muscle
Red/Slow Twitch -oxidative
What is type 2B skeletal muscle
White/Fast Twitch -Glycolytic
Does type 1 or 2 skeletal muscle have a richer vascular supply
1
Does type 1 or 2 skeletal muscle have a larger fiber diameter?
2B- larger, stronger contraction.
Does type 1 or 2 skeletal muscle have a larger contraction speed? which one fatigues easier?
type 2
Does type 1 or 2 skeletal muscle have more myoglobin?
type 1
Does type 1 or 2 skeletal muscle have more mitochondria?
type 1
Does type 1 or 2 skeletal muscle have oxidative enzymes?
type 1
Does type 1 or 2 skeletal muscle have extensive sarcoplasmic reticulum
type 2
Does type 1 or 2 skeletal muscle have large diameter nerve fibers?
type 2
Is ADP or ATP bound during treadmilling
No myosin cannot bind to Actin with ADP attached when it is hydrolysed it moves along. When ATP/ADP bound they have low affinity for each other
What is troponin attached to
Attached to tropomyosin protein between actin filaments.
What do you stain for to see the difference between type 1 and 2B muscle? what is the difference
succinate dehydrogenase
1 is darker
What causes Duchenne Muscular Dystrpohy? what does it look like on a slide
it causes an inability to make dystrophin (a protein that binds actin to cytoskeleton)
- replacement of degenerative skeletal muscle cells by fatty and fibrous connective tissue
- in stains see evidence of muscle damage (nuclei in center because they are new nuclei being made)
What kind of innervation do extrafusal fibers get
motor
Do extrafusal or intrafusal fibers serve as proprioceptors
Intrafusal
What are the twi types of intrafusal fibers
nuclear bag and nuclear chain (based on where the nuclei are)
-they both receive sensory and gamma motor neurons
Is cardiac muscle uninucleated or multinucleated?
does it regenerate?
does it store glycogen?
uninucleated
no it does not regenerate
yes it stores glycogen
What are the three components of the intercalated disks
-fascia adherens, dsemosomes, gap junctions
Where does the actin bind in cardiac muscle cells
fascia adherens
Do cardiac muscles have triads
No they have diads, there is only SR on one side of the t tubule
What is the pacemaker of the heart
the SA node. it has the smallest myocytes so it beats at the highest frequency
What is the special kind of fibers in the AV Node
Purkinje fibers
What is special about purkinje fibers
they are specialized for conduction, contain few peripheral myofibrils, they are large cells rich in glycogen and mitochondria
What is inside atrial granules
atrial natriuretic peptide
What does atrial natriuretic peptide do
it lowers blood pressue by increasing sodium excretion and relaxing blood vessel smooth muscle.
-serves regualtory endocrine function
Do smooth muscles go in all directions
yes, in a slide see them going longitudinally and cross
Where are the nuclei for smooth muscle
central
Where do you find smooth muscle
walls of hollow organs like th gut, blood vessels, ducts, uterus.
Which kind of muscle has dense bodies
smooth
what are dense bodies
netowrks of actin demisn and vimentin filaments that distribute strain during contraction
