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Questions and Answers
What is the role of the epimysium in muscles?
What is the role of the epimysium in muscles?
- Provides elasticity to muscles
- Absorbs shock during muscle contraction
- Allows for passage of blood vessels and nerves (correct)
- Converts muscle contractions into heat
Fascia is only visible during muscle dissection and not during cooking.
Fascia is only visible during muscle dissection and not during cooking.
False (B)
What are the bundles of muscle cells called?
What are the bundles of muscle cells called?
Fascicles
The connective tissue layer that surrounds each fascicle is called the ______.
The connective tissue layer that surrounds each fascicle is called the ______.
What connects muscle to bone?
What connects muscle to bone?
The endomysium encases individual muscle fibers.
The endomysium encases individual muscle fibers.
Match the following connective tissues with their functions:
Match the following connective tissues with their functions:
The tension created by contraction of muscle fibers is transferred through the ______ to the tendon.
The tension created by contraction of muscle fibers is transferred through the ______ to the tendon.
What is the primary functional unit of a muscle cell?
What is the primary functional unit of a muscle cell?
A sarcomere can be seen with the naked eye.
A sarcomere can be seen with the naked eye.
What are the two additional proteins associated with actin in thin filaments?
What are the two additional proteins associated with actin in thin filaments?
The thick filament is primarily made up of __________.
The thick filament is primarily made up of __________.
Match the following muscle structures with their descriptions:
Match the following muscle structures with their descriptions:
How many sarcomeres would you need to stack to equal the thickness of printer paper?
How many sarcomeres would you need to stack to equal the thickness of printer paper?
The Z disc marks the borders of a sarcomere.
The Z disc marks the borders of a sarcomere.
What is the role of the perimysium in muscle tissue?
What is the role of the perimysium in muscle tissue?
What is the term used for the plasma membrane in muscle cells?
What is the term used for the plasma membrane in muscle cells?
The term 'sarcoplasm' refers to the plasma membrane of a muscle cell.
The term 'sarcoplasm' refers to the plasma membrane of a muscle cell.
What does the term 'sarcoplasmic reticulum' refer to?
What does the term 'sarcoplasmic reticulum' refer to?
The cytoplasm of a muscle cell is known as the __________.
The cytoplasm of a muscle cell is known as the __________.
Which connective tissue layer envelops a fascicle of muscle fibers?
Which connective tissue layer envelops a fascicle of muscle fibers?
The endomysium is not continuous with the perimysium.
The endomysium is not continuous with the perimysium.
Match the muscle cell components with their definitions:
Match the muscle cell components with their definitions:
The __________ is the connective tissue that surrounds individual muscle fibers.
The __________ is the connective tissue that surrounds individual muscle fibers.
Which type of muscle tissue is primarily responsible for voluntary movements?
Which type of muscle tissue is primarily responsible for voluntary movements?
What is the main function of smooth muscle tissue?
What is the main function of smooth muscle tissue?
Cardiac muscle tissue is an involuntary muscle type found only in the heart.
Cardiac muscle tissue is an involuntary muscle type found only in the heart.
Name the three types of muscle tissues.
Name the three types of muscle tissues.
Skeletal muscle is characterized by a __________ appearance due to its striations.
Skeletal muscle is characterized by a __________ appearance due to its striations.
Match the muscle tissue with its characteristic feature:
Match the muscle tissue with its characteristic feature:
Skeletal muscle fibers are able to contract quickly but tire easily.
Skeletal muscle fibers are able to contract quickly but tire easily.
Which of the following is a characteristic of cardiac muscle tissue?
Which of the following is a characteristic of cardiac muscle tissue?
What is the primary ion that enters the muscle fiber when voltage-gated sodium channels open?
What is the primary ion that enters the muscle fiber when voltage-gated sodium channels open?
Potassium ions (K+) exit the muscle fiber when voltage-gated potassium channels open.
Potassium ions (K+) exit the muscle fiber when voltage-gated potassium channels open.
What occurs after the opening of voltage-gated sodium channels?
What occurs after the opening of voltage-gated sodium channels?
The _____ channels allow sodium ions to enter the muscle fiber.
The _____ channels allow sodium ions to enter the muscle fiber.
Match the ion with its behavior during the action potential:
Match the ion with its behavior during the action potential:
How does the egress of positive charges affect the membrane potential?
How does the egress of positive charges affect the membrane potential?
Voltage-gated potassium channels open before voltage-gated sodium channels.
Voltage-gated potassium channels open before voltage-gated sodium channels.
Describe the difference in the opening speed between sodium and potassium channels.
Describe the difference in the opening speed between sodium and potassium channels.
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Study Notes
Overview of Muscle Tissues
- Muscle tissue is one of the four basic tissue types in the human body, playing essential roles in movement, posture, and heat production.
- There are three distinct types of muscle tissue: skeletal, cardiac, and smooth muscle.
- Understanding muscle as an organ (individual muscles) versus muscle as tissue (collections of muscle cells) is crucial.
Structure and Function of Muscle Tissue
- Skeletal muscle: Voluntary, striated, multi-nucleated; attached to bones and responsible for body movements.
- Cardiac muscle: Involuntary, striated, single nucleus; found in the heart, responsible for pumping blood.
- Smooth muscle: Involuntary, non-striated, single nucleus; located in walls of hollow organs like intestines and blood vessels, controlling involuntary actions.
Muscle Organization
- Skeletal muscles are organized into bundles called fascicles, each surrounded by perimysium (connective tissue).
- Epimysium encases the entire muscle, connecting muscle fibers to tendons, which attach muscles to bones.
- Endomysium surrounds individual muscle fibers, facilitating nutrient and waste exchange.
Sarcomere Structure
- Sarcomeres are the fundamental unit of contraction in muscle fibers, composed of thick (myosin) and thin (actin, troponin, tropomyosin) filaments.
- The arrangement of filaments within sarcomeres allows muscle contraction to occur through the sliding filament mechanism.
Muscle Contraction Mechanism
- Triggered by action potentials generated from depolarization of the muscle cell membrane.
- Voltage-gated sodium channels open first, allowing Na+ ions to enter, followed by the opening of potassium channels for K+ ions to exit, leading to repolarization of the membrane.
- Contraction is facilitated by the interaction of actin and myosin filaments, which slide past each other to shorten the muscle.
Communication and Control
- The nervous system fine-tunes muscle activation by selectively stimulating subsets of fibers within fascicles.
- Blood vessels and nerves pass through the epimysium, ensuring proper function and responsiveness to stimuli.
Important Terminology
- Sarcolemma: Plasma membrane of muscle fiber.
- Sarcoplasm: Cytoplasm of muscle fiber.
- Sarcoplasmic reticulum: Specialized endoplasmic reticulum in muscle cells that stores calcium ions for contraction.
Conclusion
- Muscle tissue plays a vital role in the body’s movement systems and is characterized by unique structural and functional properties specific to each muscle type.
- Understanding muscle anatomy and physiology is fundamental to studying human movement and maintaining health.
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