Exam1Lec8Muscle Flashcards
What are the striated muscles?
skeletal and cardiac
Which muscles are voluntary and what are involuntary?
- voluntary: skeletal
- involuntary: smooth and cardiac
What does the endomysium surround?
each single muscle fiber
What does the perimysium surround?
each fasicle
What does the epimysium surround?
the entire muscle
What are the 3 connective tissue layers of muscle (outside to in)?
epimysium> perimysium> endomysium
Which connective tissue layers are made from dense irregular tissue?
epimysium and perimysium
Which connective tissue layers are made from reticular connective tissue?
endomysium
What band stays consistent with its length during a contraction?
A band (actin + myosin)
Which bands get smaller during a contraction?
I (actin) and H (myosin) bands
What is the triad of a muscle fiber? What does it align with?
2 profiles of of SR, and 1 profile of T-tubules. It aligns with the A-I junction
for cardiac. it aligns with z-line
What is needed to have the muscle relax after each stroke?
ATP
Where are the nuclei located in skeletal muscle?
on both sides of the fiber (periphery)
What is myomesin?
cross-links thick filaments that are next to each other at M line
What is titin?
forms elastic lattice that anchors thicK filaments to Z disks
What is troponin?
- binds Ca
- binds to tropomyosin
- binds to actin (inhibitibg actin-mysosin interact)
What is tropomyosin?
occupies grooves of the thin filaments
What is C protein?
binds thick filaments at the M line
(anchors thick @M)
What are the 2 types of muscle fibers?
red and white muscle fibers
What is a muscle spindle?
sense what the contraction level is of a muscle
What occurs during Ca depolarization?
- membrane depolarizes
- L-type Ca channel located in transverse tubule changes conformation
- ryanodine-sensitive Ca channel becomes present in sarcoplasmic reticulum to open and release Ca
- ryanodine channel releases Ca into sarcomere
- released Ca binds to troponin C and initiates contraction
What is rigor mortis?
continued contraction of muscle due to lack of ATP
What is the process of a contraction?
- need ATP for muscle contraction
- ATP broken down to ADP
- release of phosphate group
- release ADP to bind ATP for muscle relaxation
What is a powerstroke in regards to a contraction?
conformation change leads to the release of ADP
What is the vascularization of red and white muscle fibers?
- red: rich vascular supply
- white: poor vascular supply
What is the contractiontion of red and white muscle fibers?
- red: slow but repetitive; NOT easily fatigued; weaker contraction
- white: fast but easily fatigued; stronger contraction
What is the mitochondria composition in red and white muscle fibers?
- red: numerous
- white: few
What is the myoglobin composition of red and white muscle fibers?
- red: rich
- white: poor
What is the relationship between intrafusal and extrafusal fibers?
when intrafusal contracts, extrafusal relaxes
when intrafusal relaxes, extrfusal contracts
What is needed to stimulate a skeletal muscle contraction?
Ach release at NMJ
What is myasthenia gravis?
autoimmune disease where antibodies are produced against Ach receptors
Where are intercalated disks located?
between cardiac muscle cells
What are the components of the intercalated disk?
fascia adherens, desmosomes, and gap junctions
What type of muscle has the least amount of sarcoplasmic reticulum?
smooth muscle
What regulates the smooth muscle contraction?
Ca/calmodulin
What is the smooth muscle contraction system bound to?
the membrane and dense bodies made of alpha-actinin
What are the 2 things unique to smooth muscle for a contraction?
- myosin lightchain kinase (MLCK)
- calmodulin
What is the purpose of the calveola?
brings in Ca via pinocytosis to initiate contraction
What are the 3 layers of smooth muscles?
- muscularis mucosa
- muscularis externa inner circular
- muscularis externa outer longitudinal
