Muscle Types, Structure and Contraction Flashcards
Striated muscle associated with voluntary movement
Contraction regulated by Somatic NS
Skeletal muscle
Striated muscle in the heart
Contraction regulated by Autonomic NS
Cardiac muscle
Muscle in blood vessels, visceral tissues
Contraction regulated by Autonomic NS
Smooth muscle
Three layers of connective tissue surrounding the skeletal muscle:
- ) Epimysium - layer of cells encasing entire muscle
- ) Perimysium - layer of cells encasing bundle of muscle fibers (cells)
- ) Endomysium - layer of cells encasing individual muscle fibers
Cell membrane of individual muscle fibers (plasma membrane)
Sarcolemma
Muscle fibers….(4)
- Sarcolemma
- Each cell has more than one nucleus
- Contain myofibrils made up of protein
- SR - surround myofibrils
Repeating unit that forms the myofibrils (contractile unit)
Sarcomere
Thick filaments
Myosin
Thin filaments
Actin
Troponin
Tropomyosin
I band, A band, H zone of Skeletal muscle contraction
I band = only thin filaments
A band = contains entire thick filament
H zone = only thick filaments
During skeletal muscle contraction, what happens to each band/zone?
I band = gets smaller
A band = stays the same length (thick does not change)
H zone = gets smaller
During skeletal muscle contraction, the sarcomere _____ due to a/an _____ of _______.
Shortens due to an overlap of thick and thin filaments
-NONE of the filaments themselves change length
What do muscle contractions need? (3)
- ATP
- Nerve impulse (Acetylcholine)
- Calcium
Attached to actin filaments and tropomysin and BINDS calcium
Troponin
NO Calcium = blocks myosin binding site
Calcium = moves off the myosin binding site on the actin
Tropomysin
Differences of smooth muscle from skeletal muscle (5)
- Smaller
- Spindle-shaped
- Single nuclei, no t-tubules, poorly developed SR
- more THIN filaments than skeletal, no troponin
- Not organized into sarcomeres
Smooth Muscle Myofibrils (3)
- ) Thick filament through the sarcoplasm
- ) Thin filament anchored to dense bodies and membrane
- ) During contraction, thin filaments pulled together (from football-shaped –> globular)
Smooth muscle contraction dependent on…
Ca2+ concentrations
-Processes more time-consuming than in skeletal muscle - slower contraction
Single-unit Smooth muscle
“Joined” by gap junctions
Coordinated contraction
Multi-unit Smooth muscle
Cells as individual units
More direct than neural control
ex: Eyes, arteries, hair erectors
- Striated (has sarcomeres)
- Cells joined together with intercalated disks: gap junctions and desmosomes
- Regions with pacemaker activity
- Long contraction - relatively slow
Cardiac muscle
Sliding Filament Theory
During muscle contraction, the thick and thin filaments slide over each other, increasing the degree of overlap, shortening each sarcomere
The gap junctions of cardiac muscles allow for…
Beating of the heart
The desmosomes of cardiac muscles allow for…
Muscle to generate a great deal of force
Which of the following terms refers to the name of the plasma membrane of a muscle
fiber?
Sarcolemma
Which of the following terms refers to the name of the connective tissue layer that
surrounds each muscle fiber?
Endomysium
Which of the following proteins is not part of the thin filament in skeletal muscle?
Myosin
What is the name of the repeating contractile unit that makes up the myofibril?
Sarcomere
In the skeletal muscle, calcium binds to which of the following proteins?
Troponin
During skeletal muscle contraction, ATP binds to which of the following proteins?
Myosin
In which of the following types of muscle does calcium cause muscle contraction by
increasing the phosphorylation of myosin?
Smooth muscle
What is the name of the neurotransmitter involved in signaling skeletal muscle
contraction?
Acetylcholine
From what muscle fiber organelle is calcium released during muscle contraction?
Sarcoplasmic reticulum
