Muscle Tissue Flashcards by Dalton Ridley

Key feature of muscle tissue

Contractility

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Muscle tissue components

Structural/Microfibrillar proteins: Actin and myosin

Sarcolemma: the muscle cell membrane and sarcoplasm is the cytoplasm.

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Muscle fiber is synonymous with _____

Muscle cell

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Types of muscle tissue

Skeletal muscle, Cardiac muscle, Smooth muscle

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Skeletal muscle

Large, elongated, multinucleated fibers.

Strong, quick, voluntary contractions.

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Cardiac muscle

Irregular branched cells bound together
longitudinally by intercalated discs.

Strong, involuntary contractions.

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Smooth muscle

Grouped, fusiform cells.

Weak, involuntary contractions.

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Skeletal muscle fibers, striations, and location of nuclei

Fibers: Single multinucleated cells

Striations: Present

Location of nuclei: Peripheral, adjacent to sarcolemma

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Cardiac muscle fibers, striations, and location of nuclei

Fibers: Aligned cells in branching arrangement

Striations: Present

Location of nuclei: Central

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Smooth muscle fibers, striations, and location of nuclei

Fibers: Single small, closely packed fusiform cells

Striations: Absent

Location of nuclei: Central, at widest part of cell

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Skeletal muscle connective tissue organization, major locations, and key function

Connective tissue organization: Endomysium, perimysium, and epimysium

Major locations: Skeletal muscles, tongue, diaphragm, eyes, and upper esophagus

Function: Voluntary movements

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Cardiac muscle connective tissue organization, major locations, and key function

Connective tissue organization: Endomysium; subendocardial and subpericardial CT layers

Major locations: Heart

Function: Automatic (involuntary) pumping of blood

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Smooth muscle connective tissue organization, major locations, and key function

Connective tissue organization: Endomysium and less-organized CT sheaths

Major locations: Blood vessels, digestive and respiratory tracts, uterus, bladder, and other organs

Function: Involuntary movements

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Skeletal muscle efferent innervation, contractions, cell response to increased load, and capacity for regeneration

Innervation: Motor

Contractions: All-or-none, triggered at motor end plates

Response to increased load: Hypertrophy

Regeneration: Limited, involving satellite cells mainly

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Cardiac muscle efferent innervation, contractions, cell response to increased load, and capacity for regeneration

Innervation: Autonomic

Contractions: All-or-none, intrinsic (beginning at nodes of conducting fibers)

Response to increased load: Hypertrophy

Regeneration: Very poor

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Smooth muscle efferent innervation, contractions, cell response to increased load, and capacity for regeneration

Innervation: Autonomic

Contractions: Partial, slow, often spontaneous, wavelike, and rhythmic

Response to increased load: Hypertrophy and hyperplasia

Regeneration: Good, involving mitotic activity of muscle cells

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Epimysium

The dense connective tissue that encloses the entire skeletal muscle. It is continuous with fascia and the tendon binding muscle to bone

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Perimysium

A thin but dense connective tissue layer that surrounds a fascicle

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Endomysium

Delicate connective tissue that surrounds individual muscle fibers

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Skeletal muscle development

Skeletal muscle begins to
differentiate when mesenchymal cells
called myoblasts fuse to make longer, multinucleated tubes called
myotubes. They synthesize proteins that make up myofilaments.

As myotubes continue differentiating, the nuclei are moved outward against
the sarcolemma.

Some of the cells do not fuse and differentiate but remain as a group of mesenchymal cells called muscle satellite cells located on the external
surface of muscle fibers. These cells proliferate and produce new muscle
fibers following muscle injury.

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Hypertrophy

Tissue growth by an increase in the diameter of individual muscle fibers (muscle cells)

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Hyperplasia

Tissue growth by increase in the number of
cells. Common in smooth muscle, whose cells have not lost the ability to divide by mitosis.

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Myotendinous junctions

The site of connection between tendon and muscle.

The connective tissue layers (epimysium, perimysium, and endomysium) are continuous with the connective tissue of a tendon at this junction

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Myoblasts

Mesenchymal cells that eventually become skeletal muscle.

These fuse to make longer, multinucleated tubes called myotubes

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Myofibrils

Cylindrical bundles of thick and thin myofilaments that fill the sarcoplasm (most of each muscle fiber). Thick myofilaments: Myosin Thin myofilaments: Actin & two others

Striations

Alternating light and dark bands of the skeletal muscle fibers.

A bands

The dark bands on the myofibrils Overlap between actin and myosin

I bands

The light bands on the myofibrils. Contains actin and titin

H zone

a lighter region in the middle that bisects the A band. No overlap between actin and myosin

Z disc

A dark transverse line that bisects each I band.

Sarcomere

The repetitive functional subunit of the fiber, which extends from Z disc to Z disc.

Myosin filaments

Thick; they occupy the A band at the middle region of the sarcomere.

Actin filaments

Thin and helical, and run between the thick filaments. The thin filaments have two associated regulatory proteins: Tropomyosin Troponin

Sarcoplasmic Reticulum

Skeletal muscle fibers are composed mainly of myofibrils. Each myofibril extends the length of the fiber and is surrounded by parts of the sarcoplasmic reticulum. The main function of the sarcoplasmic reticulum is to store Ca2+. The sarcolemma has deep invaginations called T-tubules

Nerve bundle

The terminal axonal twigs, and the motor end plates on striated muscle fibers

Muscle contraction steps

1. Nerve impulse stimulates acetylcholine release across the synapse, which causes a muscle impulse (membrane depolarization), 2. Ca2+ release from terminal cisternae into the sarcoplasm 3. Ca2+ binding to troponin causes tropomyosin to change shape and allow the myosin heads to bind the actin subunits, forming cross bridges between thick and thin filaments. 4. The myosin heads then pivot as ATP releases energy, which pulls the thin filaments along the thick filaments. - As long as Ca2+ and ATP are present, a contraction cycle ensues in which myosin heads repeatedly attach, pivot, detach, and return, causing the filaments to slide past one another, shortening the sarcomere. 5. When the membrane depolarization ends, Ca2+ is again sequestered, ending contraction and allowing the sarcomeres to lengthen as the muscle relaxes.

Which region "disappears" during contraction?

I band and H zone

Myasthenia gravis

an autoimmune disorder that involves circulating antibodies against proteins of acetylcholine receptors. This interferes with acetylcholine activation of their receptors, leading to periods of skeletal muscle weakness. The extraocular muscles of the eyes are commonly the first affected.

Dystrophin

A large actin-binding protein located inside the sarcolemma that is involved in the functional organization of myofibrils.

Muscle spindles

Functions the stretch receptors Have afferent sensory and efferent motor nerve fibers associated with the intrafusal fibers, which are modified muscle fibers.

Slow, Oxidative Fibers (Type 1) mitochondria, capillaries, myoglobin content, and glycogen content

Mitochondria: Numerous Capillaries: Numerous Myoglobin content: High (red fibers) Glycogen content: Low

Fast, Oxidative-Glycolytic Fibers (Type 2a) mitochondria, capillaries, myoglobin content, and glycogen content

Mitochondria: Numerous Capillaries: Numerous Myoglobin content: High (red fibers) Glycogen content: Intermediate

Fast, Glycolytic Fibers (Type 2b) mitochondria, capillaries, myoglobin content, and glycogen content

Mitochondria: Sparse Capillaries: Sparse Myoglobin content: Low (white fibers) Glycogen content: High

Slow, Oxidative Fibers (Type 1) rate of fatigue, speed of contraction, and major locations

Rate of fatigue: Slow Speed of contraction: Slow Major location: Postural muscles of back

Fast, Oxidative-Glycolytic Fibers (Type 2a) rate of fatigue, speed of contraction, and major locations

Rate of fatigue: Intermediate Speed of contraction: Fast Major location: Major muscles of legs

Fast, Glycolytic Fibers (Type 2b) rate of fatigue, speed of contraction, and major locations

Rate of fatigue: Fast Speed of contraction: Fast Major location: Extraocular muscles

Myoglobin

A reddish, globular sarcoplasmic protein, similar to hemoglobin, which contains iron atoms and allows for O2 storage.

The darker region of the sarcomere, as seen in TEM, is where the thick and thin filaments overlap. This region is called the

A band

Which ion triggers contraction of the sarcomere?

Ca++

What is the name of the sheath of dense irregular connective tissue that completely surrounds a muscle?

Epimysium

In a sarcomere, the I band is bisected by a

Z-disk

The dilated terminal end of an axon that contacts the muscle cell is called the

Motor end plate

A skeletal muscle cell is multinucleate because

During development, uninuclear myoblasts fuse to form a larger cell.

The function of muscle spindles is

Stretch detection

The long cylindrical protein filament bundles in the sarcoplasm are called

Myofibrils

Which of these are found associated with the endomysium and perimysium connective tissue layers?

Nerves and blood vessels

The sensation of the position of the muscles and bones is called

Proprioception

The repeated functional units of a myofibril, arranged end to end, are called

Sarcomeres

The cytoplasm of muscle cells is called

Sarcoplasm

What is the role of titin in muscle contraction?

The titin molecule prevent overstretching of the sarcomere and also acts like a spring to recoil the sarcomere after it is stretched.

A group of mesenchymal satellite cells help to repair skeletal muscle cells after injury. They do this by

Differentiating to produce new muscle cells that fuse with existing muscle cells.

# Reversed prompt Contractility

Key feature of muscle tissue

# Reversed prompt Structural/Microfibrillar proteins: Actin and myosin Sarcolemma: the muscle cell membrane and sarcoplasm is the cytoplasm.

Muscle tissue components

# Reversed prompt Muscle cell

Muscle fiber is synonymous with \_\_\_\_\_

# Reversed prompt Skeletal muscle, Cardiac muscle, Smooth muscle

Types of muscle tissue

# Reversed prompt Large, elongated, multinucleated fibers. Strong, quick, voluntary contractions.

Skeletal muscle

# Reversed prompt Irregular branched cells bound together longitudinally by intercalated discs. Strong, involuntary contractions.

Cardiac muscle

# Reversed prompt Grouped, fusiform cells. Weak, involuntary contractions.

Smooth muscle

# Reversed prompt Fibers: Single multinucleated cells Striations: Present Location of nuclei: Peripheral, adjacent to sarcolemma

Skeletal muscle fibers, striations, and location of nuclei

# Reversed prompt Fibers: Aligned cells in branching arrangement Striations: Present Location of nuclei: Central

Cardiac muscle fibers, striations, and location of nuclei

# Reversed prompt Fibers: Single small, closely packed fusiform cells Striations: Absent Location of nuclei: Central, at widest part of cell

Smooth muscle fibers, striations, and location of nuclei

# Reversed prompt Connective tissue organization: Endomysium, perimysium, and epimysium Major locations: Skeletal muscles, tongue, diaphragm, eyes, and upper esophagus Function: Voluntary movements

Skeletal muscle connective tissue organization, major locations, and key function

# Reversed prompt Connective tissue organization: Endomysium; subendocardial and subpericardial CT layers Major locations: Heart Function: Automatic (involuntary) pumping of blood

Cardiac muscle connective tissue organization, major locations, and key function

# Reversed prompt Connective tissue organization: Endomysium and less-organized CT sheaths Major locations: Blood vessels, digestive and respiratory tracts, uterus, bladder, and other organs Function: Involuntary movements

Smooth muscle connective tissue organization, major locations, and key function

# Reversed prompt Innervation: Motor Contractions: All-or-none, triggered at motor end plates Response to increased load: Hypertrophy Regeneration: Limited, involving satellite cells mainly

Skeletal muscle efferent innervation, contractions, cell response to increased load, and capacity for regeneration

# Reversed prompt Innervation: Autonomic Contractions: All-or-none, intrinsic (beginning at nodes of conducting fibers) Response to increased load: Hypertrophy Regeneration: Very poor

Cardiac muscle efferent innervation, contractions, cell response to increased load, and capacity for regeneration

# Reversed prompt Innervation: Autonomic Contractions: Partial, slow, often spontaneous, wavelike, and rhythmic Response to increased load: Hypertrophy and hyperplasia Regeneration: Good, involving mitotic activity of muscle cells

Smooth muscle efferent innervation, contractions, cell response to increased load, and capacity for regeneration

# Reversed prompt The dense connective tissue that encloses the entire skeletal muscle. It is continuous with fascia and the tendon binding muscle to bone

Epimysium

# Reversed prompt A thin but dense connective tissue layer that surrounds a fascicle

Perimysium

# Reversed prompt Delicate connective tissue that surrounds individual muscle fibers

Endomysium

# Reversed prompt Skeletal muscle begins to differentiate when mesenchymal cells called myoblasts fuse to make longer, multinucleated tubes called myotubes. They synthesize proteins that make up myofilaments. As myotubes continue differentiating, the nuclei are moved outward against the sarcolemma. Some of the cells do not fuse and differentiate but remain as a group of mesenchymal cells called muscle satellite cells located on the external surface of muscle fibers. These cells proliferate and produce new muscle fibers following muscle injury.

Skeletal muscle development

# Reversed prompt Tissue growth by an increase in the diameter of individual muscle fibers (muscle cells)

Hypertrophy

# Reversed prompt Tissue growth by increase in the number of cells. Common in smooth muscle, whose cells have not lost the ability to divide by mitosis.

Hyperplasia

# Reversed prompt The site of connection between tendon and muscle. The connective tissue layers (epimysium, perimysium, and endomysium) are continuous with the connective tissue of a tendon at this junction

Myotendinous junctions

# Reversed prompt Mesenchymal cells that eventually become skeletal muscle. These fuse to make longer, multinucleated tubes called myotubes

Myoblasts

# Reversed prompt Cylindrical bundles of thick and thin myofilaments that fill the sarcoplasm (most of each muscle fiber). Thick myofilaments: Myosin Thin myofilaments: Actin & two others

Myofibrils

# Reversed prompt Alternating light and dark bands of the skeletal muscle fibers.

Striations

# Reversed prompt The dark bands on the myofibrils Overlap between actin and myosin

A bands

# Reversed prompt The light bands on the myofibrils. Contains actin and titin

I bands

# Reversed prompt a lighter region in the middle that bisects the A band. No overlap between actin and myosin

H zone

# Reversed prompt A dark transverse line that bisects each I band.

Z disc

# Reversed prompt The repetitive functional subunit of the fiber, which extends from Z disc to Z disc.

Sarcomere

# Reversed prompt Thick; they occupy the A band at the middle region of the sarcomere.

Myosin filaments

# Reversed prompt Thin and helical, and run between the thick filaments. The thin filaments have two associated regulatory proteins: Tropomyosin Troponin

Actin filaments

# Reversed prompt Skeletal muscle fibers are composed mainly of myofibrils. Each myofibril extends the length of the fiber and is surrounded by parts of the sarcoplasmic reticulum. The main function of the sarcoplasmic reticulum is to store Ca2+. The sarcolemma has deep invaginations called T-tubules

Sarcoplasmic Reticulum

# Reversed prompt The terminal axonal twigs, and the motor end plates on striated muscle fibers

Nerve bundle

# Reversed prompt 1. Nerve impulse stimulates acetylcholine release across the synapse, which causes a muscle impulse (membrane depolarization), 2. Ca2+ release from terminal cisternae into the sarcoplasm 3. Ca2+ binding to troponin causes tropomyosin to change shape and allow the myosin heads to bind the actin subunits, forming cross bridges between thick and thin filaments. 4. The myosin heads then pivot as ATP releases energy, which pulls the thin filaments along the thick filaments. - As long as Ca2+ and ATP are present, a contraction cycle ensues in which myosin heads repeatedly attach, pivot, detach, and return, causing the filaments to slide past one another, shortening the sarcomere. 5. When the membrane depolarization ends, Ca2+ is again sequestered, ending contraction and allowing the sarcomeres to lengthen as the muscle relaxes.

Muscle contraction steps

# Reversed prompt I band and H zone

Which region "disappears" during contraction?

# Reversed prompt an autoimmune disorder that involves circulating antibodies against proteins of acetylcholine receptors. This interferes with acetylcholine activation of their receptors, leading to periods of skeletal muscle weakness. The extraocular muscles of the eyes are commonly the first affected.

Myasthenia gravis

# Reversed prompt A large actin-binding protein located inside the sarcolemma that is involved in the functional organization of myofibrils.

Dystrophin

# Reversed prompt Functions the stretch receptors Have afferent sensory and efferent motor nerve fibers associated with the intrafusal fibers, which are modified muscle fibers.

Muscle spindles

# Reversed prompt Mitochondria: Numerous Capillaries: Numerous Myoglobin content: High (red fibers) Glycogen content: Low

Slow, Oxidative Fibers (Type 1) mitochondria, capillaries, myoglobin content, and glycogen content

# Reversed prompt Mitochondria: Numerous Capillaries: Numerous Myoglobin content: High (red fibers) Glycogen content: Intermediate

Fast, Oxidative-Glycolytic Fibers (Type 2a) mitochondria, capillaries, myoglobin content, and glycogen content

# Reversed prompt Mitochondria: Sparse Capillaries: Sparse Myoglobin content: Low (white fibers) Glycogen content: High

Fast, Glycolytic Fibers (Type 2b) mitochondria, capillaries, myoglobin content, and glycogen content

# Reversed prompt Rate of fatigue: Slow Speed of contraction: Slow Major location: Postural muscles of back

Slow, Oxidative Fibers (Type 1) rate of fatigue, speed of contraction, and major locations

# Reversed prompt Rate of fatigue: Intermediate Speed of contraction: Fast Major location: Major muscles of legs

Fast, Oxidative-Glycolytic Fibers (Type 2a) rate of fatigue, speed of contraction, and major locations

# Reversed prompt Rate of fatigue: Fast Speed of contraction: Fast Major location: Extraocular muscles

Fast, Glycolytic Fibers (Type 2b) rate of fatigue, speed of contraction, and major locations

# Reversed prompt A reddish, globular sarcoplasmic protein, similar to hemoglobin, which contains iron atoms and allows for O2 storage.

Myoglobin

Muscle Tissue Flashcards

(108 cards)