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Questions and Answers
Which of the following properties enables muscle tissue to return to its original length after being stretched?
Which of the following properties enables muscle tissue to return to its original length after being stretched?
- Elasticity (correct)
- Extensibility
- Contractility
- Excitability
Which type of striated muscle is restricted to soft tissues and plays a role in speech, breathing, and swallowing?
Which type of striated muscle is restricted to soft tissues and plays a role in speech, breathing, and swallowing?
- Visceral striated muscle (correct)
- Skeletal muscle
- Smooth muscle
- Cardiac muscle
What is the functional significance of the extensive network of sarcoplasmic reticulum in muscle fibers?
What is the functional significance of the extensive network of sarcoplasmic reticulum in muscle fibers?
- To provide structural support to the myofibrils
- To transmit action potentials from the sarcolemma to the myofibrils
- To regulate calcium ion concentration for muscle contraction (correct)
- To synthesize ATP for energy during muscle activity
Which of the following is the key characteristic that distinguishes striated muscle from smooth muscle at the microscopic level?
Which of the following is the key characteristic that distinguishes striated muscle from smooth muscle at the microscopic level?
Which of the following best describes the primary role of skeletal muscle?
Which of the following best describes the primary role of skeletal muscle?
Muscle cells contain which of the following?
Muscle cells contain which of the following?
Which of the following describes the arrangement within a skeletal muscle from largest to smallest?
Which of the following describes the arrangement within a skeletal muscle from largest to smallest?
What is the significance of the arrangement of myofibrils within a muscle fiber?
What is the significance of the arrangement of myofibrils within a muscle fiber?
According to the classification of muscles based on location, which type is found in the wall of the heart and in the base of large veins that empty into the heart?
According to the classification of muscles based on location, which type is found in the wall of the heart and in the base of large veins that empty into the heart?
Which of the following does NOT describe thick myofilaments?
Which of the following does NOT describe thick myofilaments?
What regulatory proteins are associated with thin myofilaments?
What regulatory proteins are associated with thin myofilaments?
What is the function of desmin in the structure of a sarcomere?
What is the function of desmin in the structure of a sarcomere?
What is the significance of the hinge region in the structure of thick myofilaments?
What is the significance of the hinge region in the structure of thick myofilaments?
Which of the following connective tissue layers surrounds individual muscle fibers?
Which of the following connective tissue layers surrounds individual muscle fibers?
What is the role of M line proteins (myomesin, M-protein, obscurin) in the structure of a sarcomere?
What is the role of M line proteins (myomesin, M-protein, obscurin) in the structure of a sarcomere?
Which of the following best exemplifies the function of muscles in 'constriction of organs and vessels'?
Which of the following best exemplifies the function of muscles in 'constriction of organs and vessels'?
How does excitability contribute to the function of muscle tissue?
How does excitability contribute to the function of muscle tissue?
Which of the following is the functional significance of the extensive network of T-tubules in muscle fibers?
Which of the following is the functional significance of the extensive network of T-tubules in muscle fibers?
Following an injury, how do satellite cells contribute to the regeneration of skeletal muscle tissue?
Following an injury, how do satellite cells contribute to the regeneration of skeletal muscle tissue?
Which structure is responsible for relaying a muscle impulse to release calcium ions into the sarcoplasm?
Which structure is responsible for relaying a muscle impulse to release calcium ions into the sarcoplasm?
Which of the following would be the most immediate effect of the actively transporting of calcium ions into the sarcoplasmic reticulum?
Which of the following would be the most immediate effect of the actively transporting of calcium ions into the sarcoplasmic reticulum?
Which of the following connective tissue layers surrounds a bundle of skeletal muscle fibers (fascicle)?
Which of the following connective tissue layers surrounds a bundle of skeletal muscle fibers (fascicle)?
What causes troponin to change shape, moving tropomyosin on the actin and exposing active sites on actin molecules?
What causes troponin to change shape, moving tropomyosin on the actin and exposing active sites on actin molecules?
The major role and function of slow-oxidative type I fibers include what?
The major role and function of slow-oxidative type I fibers include what?
Which part of the sarcomere contains only thick filaments?
Which part of the sarcomere contains only thick filaments?
What is the primary function of titin within the sarcomere?
What is the primary function of titin within the sarcomere?
What term describes the cytoplasm of a muscle cell?
What term describes the cytoplasm of a muscle cell?
What type of muscle assists in respiration?
What type of muscle assists in respiration?
What is the primary component of thick filaments in a sarcomere?
What is the primary component of thick filaments in a sarcomere?
What is the main characteristic of skeletal muscle fibers?
What is the main characteristic of skeletal muscle fibers?
Which of the following is a unique characteristic of intrafusal muscle fibers compared to extrafusal muscle fibers?
Which of the following is a unique characteristic of intrafusal muscle fibers compared to extrafusal muscle fibers?
Which event directly triggers the pivoting of the myosin head during muscle contraction?
Which event directly triggers the pivoting of the myosin head during muscle contraction?
What is the role of acetylcholinesterase (AChE) at the neuromuscular junction?
What is the role of acetylcholinesterase (AChE) at the neuromuscular junction?
What is the functional significance of the triad structure formed by the T-tubule and sarcoplasmic reticulum?
What is the functional significance of the triad structure formed by the T-tubule and sarcoplasmic reticulum?
Which of the following represents the proper sequence of events leading to skeletal muscle contraction?
Which of the following represents the proper sequence of events leading to skeletal muscle contraction?
A muscle that is described as skeletal must also be described as:
A muscle that is described as skeletal must also be described as:
Which of the following properties of muscle tissue provides the ability to shorten forcibly?
Which of the following properties of muscle tissue provides the ability to shorten forcibly?
What is the function of an ATP molecule in muscle contraction?
What is the function of an ATP molecule in muscle contraction?
If a muscle cell were experimentally stripped of its sarcolemma but otherwise kept intact, which immediate effect would be most likely observed?
If a muscle cell were experimentally stripped of its sarcolemma but otherwise kept intact, which immediate effect would be most likely observed?
Which property of muscle tissue is most directly responsible for enabling a person to maintain an upright posture against the force of gravity?
Which property of muscle tissue is most directly responsible for enabling a person to maintain an upright posture against the force of gravity?
A researcher discovers a new muscle cell type with an abundance of mitochondria, small diameter, and high myoglobin content. Predict the most likely functional characteristic of this muscle cell.
A researcher discovers a new muscle cell type with an abundance of mitochondria, small diameter, and high myoglobin content. Predict the most likely functional characteristic of this muscle cell.
How would the absence of the M line proteins (myomesin, M-protein, obscurin) most immediately affect the structure and function of a sarcomere?
How would the absence of the M line proteins (myomesin, M-protein, obscurin) most immediately affect the structure and function of a sarcomere?
Consider a hypothetical scenario where the enzyme acetylcholinesterase (AChE) is completely non-functional. What immediate effect would this have on muscle contraction?
Consider a hypothetical scenario where the enzyme acetylcholinesterase (AChE) is completely non-functional. What immediate effect would this have on muscle contraction?
Which structural feature is most responsible for the efficient and rapid transmission of electrical signals deep into the muscle fiber, ensuring coordinated contraction?
Which structural feature is most responsible for the efficient and rapid transmission of electrical signals deep into the muscle fiber, ensuring coordinated contraction?
If a muscle is stretched beyond its normal physiological range, which property of muscle tissue is most crucial in preventing damage and facilitating its return to its original length?
If a muscle is stretched beyond its normal physiological range, which property of muscle tissue is most crucial in preventing damage and facilitating its return to its original length?
Which type of muscle lacks striations?
Which type of muscle lacks striations?
Damage to which of the following structures would most directly impair the storage and release of calcium ions necessary for muscle contraction?
Damage to which of the following structures would most directly impair the storage and release of calcium ions necessary for muscle contraction?
Considering the role of muscles in communication, which of the following actions would be most directly affected by impaired muscle function?
Considering the role of muscles in communication, which of the following actions would be most directly affected by impaired muscle function?
Flashcards
Muscle Tissue
Muscle Tissue
Tissue made of contractile cells, responsible for movement.
Muscle cells origin
Muscle cells origin
The origin of muscle cells.
Striated muscle
Striated muscle
Muscle cells that exhibit cross-striations under a light microscope.
Smooth muscle
Smooth muscle
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Skeletal muscle function
Skeletal muscle function
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Visceral striated muscle
Visceral striated muscle
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Cardiac muscle location
Cardiac muscle location
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Fibers
Fibers
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Cytoplasm
Cytoplasm
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Sarcoplasmic reticulum
Sarcoplasmic reticulum
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Cell membrane
Cell membrane
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Skeletal muscle composition
Skeletal muscle composition
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Epimysium
Epimysium
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Perimysium
Perimysium
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Endomysium
Endomysium
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Sarcomere
Sarcomere
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Myofilaments
Myofilaments
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Thick myofilaments
Thick myofilaments
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Thin myofilaments
Thin myofilaments
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Study Notes
- Human Histology (Lecture) MT120225, Unit 3 focuses on muscular tissue.
- The unit aims to identify different types of muscular tissues and their functions.
- Course content includes overview and classification of muscle, skeletal, cardiac, and smooth muscle, as well as muscle regeneration.
Muscle Tissue
- Composed of contractile cells.
- Responsible for movement.
- Muscle cells originate from the mesoderm.
Muscle Classification by Appearance
- Striated muscle cells exhibit cross-striations under a light microscope.
- Smooth muscle cells do not exhibit cross-striations.
Muscle Classification by Location
- Skeletal muscle facilitates movement of the axial and appendicular skeleton.
- Visceral striated muscle is restricted to soft tissues.
- Visceral striated Muscle plays roles in speech, breathing, and swallowing.
- Cardiac muscle is located in the heart wall and the base of large veins emptying into the heart.
Muscle Tissue Terminology
- Muscle cells are referred to as fibers.
- Cytoplasm is termed sarcoplasm.
- Smooth endoplasmic reticulum is known as sarcoplasmic reticulum.
- Cell membrane is called sarcolemma.
- Mitochondria are referred to as sarcosomes.
Functions of Muscles
- Movement of the body
- Maintenance of posture
- Respiration
- Production of body heat
- Communication
- Constriction of organs and vessels
- Contraction of heart
Properties of Muscle Tissue
- Contractility
- Excitability
- Extensibility
- Elasticity
Skeletal Muscle
- Composed of long, multinucleated muscle cells.
Connective Tissue Coverings
- Epimysium: A thick, dense, irregular connective tissue that surrounds the entire skeletal muscle, containing large nerves, blood vessels, and lymphatics.
- Perimysium: A thin connective tissue that surrounds each bundle of muscle fibers, known as a fascicle, and contains nerves, blood vessels, and lymphatics.
- Endomysium: Consists of very thin reticular fibers that surround individual muscle fibers, containing nerve fibers, capillaries, and scattered fibroblasts.
Myofibril
- There are between 5,000 to 10,000 myofibrils per muscle fiber.
- Spans the length of the muscle fiber.
- Diameter is 1-2 um.
- Arranged parallel to the long axis of the cell.
- Exhibit transverse striations of alternating light and dark bands.
- Composed of repeating units of sarcomeres.
Sarcomere
- It's the region of a myofibril that spans two Z-lines.
- It is 1.5-2 um in length in a resting muscle.
- It is the smallest repetitive subunit of the contractile apparatus in muscle fiber.
- Composed of filaments.
Myofilaments
- 1,000 - 2,000 arranged parallel to the long axis of the sarcomere.
- Two types are thick and thin.
Thick Myofilaments
- Located in the midzone of sarcomere.
- Span the region of A-band.
- Diameter is 15 nm.
- Length 1.5 um.
- They contain myosin.
- Two myosin heavy chains
- Two myosin heads.
- Bind to active sites on actin molecules to form cross-bridges.
- Attached to the rod portion by a hinge region that bends and straightens during contractions.
- Heads are ATPase enzymes
Thin Myofilaments
- Run between thick filaments, spanning the region of the A-band.
- Diameter is 8 nm and length is 1um.
- Contain actin.
- Associated with tropomyosin and troponin.
- Globular (G) actin contains receptor sites for myosin head.
- Tropomyosin in relaxed muscle covers the active sites on the G-actin subunits.
- Troponin attaches to tropomyosin, binds to calcium, and regulates interaction between actin and myosin.
Muscle Contraction
- It is the mechanical component.
- Depends on myofibril and myofilament activity.
- It's an electrical component.
- Three muscle fiber components respond to and transmit electrical signals.
- Those components are sarcolemma, transverse tubules, and sarcoplasmic reticulum.
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