What are the three types of muscles? - ANSWER skeletal, smooth, cardiac
Muscles make up how much of your weight? - ANSWER about 1/2
Muscles are specialized to convert ____ energy to ____ energy. - ANSWER chemical, me-
chanical
How many skeletal muscles are in the human body? - ANSWER more than 600
Skeletal muscle includes: - ANSWER skeletal muscle tissue, connective tissues, nerves and
blood vessels
Skeletal muscles do not contract until what occurs? - ANSWER They are stimulated by a
nerve to do so. This is different from cardiac and smooth muscle.
What are the connective tissues of muscles? - ANSWER endomysium, perimysium, epi-
mysium, fascia
Skeletal muscle cells are also called - ANSWER muscle fibers
Endomysium - ANSWER Thin sleeve that surrounds each muscle fiber, creates room for
capillaries and nerve fibers to reach every muscle cell.
Perimysium - ANSWER Sheath that bundles muscle fibers into units called fascicles.
Larger blood vessels, nerves, and stretch receptors will be found within this sheath.
1
,Epimysium - ANSWER Fibrous sheath that surrounds the entire muscle and bundles mul-
tiple fascicles together.
Fascia - ANSWER Sheet of connective tissue outside of the epimysium that separates
muscles from one another.
What is direct vs indirect attachment? - ANSWER Direct: looks like directly attached, but
is not, short connection of collagen fibers.
Indirect: attaches by tendon, obvious band.
Is skeletal muscle voluntary or involuntary? - ANSWER voluntary
What are the characteristics of muscle? - ANSWER excitability: muscle cells can become
excited electrically
conductivity: electrical signals will travel along the cell
contractility: muscle cells and shorten when stimulated
extensibility: muscle cells can stretch between contractions
elasticity: when a muscle cell is stretched and then released, it recoils to a shorter length.
Why are there striations in muscle fibers (skeletal muscle)? - ANSWER Due to the over-
lapping arrangement of contractile proteins.
Structure of skeletal muscle fibers - ANSWER Sarcolemma: plasma membrane with T tu-
bules (infoldings).
Sarcoplasm: cytoplasm. Made of long proteins called myofibrils/myofilaments. Myoglobin,
glycogen strorage.
Sarcoplasmic reticulum: smooth endoplasmic reticulum, surround each myofibril. High
amounts of calcium, which is important for contraction, are stored there.
2
, Sacrolemma - ANSWER Plasma membrane of a muscle fiber that forms T tubules (tubular
infoldings).
Sarcoplasm - ANSWER Cytoplasm of a muscle cell. Made of long proteins called myofi-
brils. Contains a large amount of glycogen as well as myoglobin (an oxygen binding protein).
Sarcoplasmic reticulum - ANSWER Smooth endoplasmic reticulum, surround each myofi-
bril. High amounts of calcium, which is important for contraction, are stored there.
What are the three kinds of myofilaments? - ANSWER thick, thin, elastic
What is the structure of thin, thick, and elastic myofilaments? - ANSWER Thick: consists
of many molecules of protein myosin
Thin: is made of two intertwined strands of actin. Each bead of the actin has an active site
that can bind to the head of a myosin molecule. Also includes the protein tropomyosin,
which covers these active sites at rest. Each tropomyosin has troponin bound to it.
Elastic: composed of titin, anchors the ends of thick filaments to the Z line.
Overall structure of striations and sarcomere - ANSWER ~ Striated muscle has dark A
bands (thick filaments side by side, part of the A band is where thick and thin filaments over-
lap) alternating with lighter I bands
~ In the middle of an A band, there is a H band, where thin filaments do not reach
~ In the middle of the H band, the M line links thick filaments together
~ I bands have thin filaments, not thick filaments. Each I band is bisected by the Z line, which
provides anchorage for thin and elastic filaments
~ Sarcomere: z line to z line, functional contractile unit of muscle fiber
What are Z lines and what is anchored to them? - ANSWER Z line provides anchorage for
thin and the elastic filaments. Thin filaments are anchored to Z lines.
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Muscles make up how much of your weight? - ANSWER about 1/2
Muscles are specialized to convert ____ energy to ____ energy. - ANSWER chemical, me-
chanical
How many skeletal muscles are in the human body? - ANSWER more than 600
Skeletal muscle includes: - ANSWER skeletal muscle tissue, connective tissues, nerves and
blood vessels
Skeletal muscles do not contract until what occurs? - ANSWER They are stimulated by a
nerve to do so. This is different from cardiac and smooth muscle.
What are the connective tissues of muscles? - ANSWER endomysium, perimysium, epi-
mysium, fascia
Skeletal muscle cells are also called - ANSWER muscle fibers
Endomysium - ANSWER Thin sleeve that surrounds each muscle fiber, creates room for
capillaries and nerve fibers to reach every muscle cell.
Perimysium - ANSWER Sheath that bundles muscle fibers into units called fascicles.
Larger blood vessels, nerves, and stretch receptors will be found within this sheath.
1
,Epimysium - ANSWER Fibrous sheath that surrounds the entire muscle and bundles mul-
tiple fascicles together.
Fascia - ANSWER Sheet of connective tissue outside of the epimysium that separates
muscles from one another.
What is direct vs indirect attachment? - ANSWER Direct: looks like directly attached, but
is not, short connection of collagen fibers.
Indirect: attaches by tendon, obvious band.
Is skeletal muscle voluntary or involuntary? - ANSWER voluntary
What are the characteristics of muscle? - ANSWER excitability: muscle cells can become
excited electrically
conductivity: electrical signals will travel along the cell
contractility: muscle cells and shorten when stimulated
extensibility: muscle cells can stretch between contractions
elasticity: when a muscle cell is stretched and then released, it recoils to a shorter length.
Why are there striations in muscle fibers (skeletal muscle)? - ANSWER Due to the over-
lapping arrangement of contractile proteins.
Structure of skeletal muscle fibers - ANSWER Sarcolemma: plasma membrane with T tu-
bules (infoldings).
Sarcoplasm: cytoplasm. Made of long proteins called myofibrils/myofilaments. Myoglobin,
glycogen strorage.
Sarcoplasmic reticulum: smooth endoplasmic reticulum, surround each myofibril. High
amounts of calcium, which is important for contraction, are stored there.
2
, Sacrolemma - ANSWER Plasma membrane of a muscle fiber that forms T tubules (tubular
infoldings).
Sarcoplasm - ANSWER Cytoplasm of a muscle cell. Made of long proteins called myofi-
brils. Contains a large amount of glycogen as well as myoglobin (an oxygen binding protein).
Sarcoplasmic reticulum - ANSWER Smooth endoplasmic reticulum, surround each myofi-
bril. High amounts of calcium, which is important for contraction, are stored there.
What are the three kinds of myofilaments? - ANSWER thick, thin, elastic
What is the structure of thin, thick, and elastic myofilaments? - ANSWER Thick: consists
of many molecules of protein myosin
Thin: is made of two intertwined strands of actin. Each bead of the actin has an active site
that can bind to the head of a myosin molecule. Also includes the protein tropomyosin,
which covers these active sites at rest. Each tropomyosin has troponin bound to it.
Elastic: composed of titin, anchors the ends of thick filaments to the Z line.
Overall structure of striations and sarcomere - ANSWER ~ Striated muscle has dark A
bands (thick filaments side by side, part of the A band is where thick and thin filaments over-
lap) alternating with lighter I bands
~ In the middle of an A band, there is a H band, where thin filaments do not reach
~ In the middle of the H band, the M line links thick filaments together
~ I bands have thin filaments, not thick filaments. Each I band is bisected by the Z line, which
provides anchorage for thin and elastic filaments
~ Sarcomere: z line to z line, functional contractile unit of muscle fiber
What are Z lines and what is anchored to them? - ANSWER Z line provides anchorage for
thin and the elastic filaments. Thin filaments are anchored to Z lines.
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