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Questions and Answers
What type of fibers primarily make up the endomysium?
What type of fibers primarily make up the endomysium?
Aponeuroses are a type of structure that connect muscles to ligaments.
Aponeuroses are a type of structure that connect muscles to ligaments.
False
What is the primary cellular process used by muscular tissue to make ATP?
What is the primary cellular process used by muscular tissue to make ATP?
Aerobic cellular respiration
The plasma membrane of myocytes is called the __________.
The plasma membrane of myocytes is called the __________.
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Match the following structures to their functions:
Match the following structures to their functions:
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What do the thick filaments in a sarcomere primarily consist of?
What do the thick filaments in a sarcomere primarily consist of?
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The I band in a sarcomere contains only thick filaments.
The I band in a sarcomere contains only thick filaments.
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What is the name of the specialized endoplasmic reticulum in muscle cells?
What is the name of the specialized endoplasmic reticulum in muscle cells?
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Muscular hypertrophy is primarily a __________ response to increased mechanical stress.
Muscular hypertrophy is primarily a __________ response to increased mechanical stress.
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Where do muscle fibers increase their volume during hypertrophy?
Where do muscle fibers increase their volume during hypertrophy?
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Which type of muscular tissue contracts to move blood through the heart?
Which type of muscular tissue contracts to move blood through the heart?
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Skeletal muscle tissue is responsible for regulating the passage of substances through the body.
Skeletal muscle tissue is responsible for regulating the passage of substances through the body.
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What is the scientific study of muscular tissue called?
What is the scientific study of muscular tissue called?
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Muscular tissue is contractile, meaning it can shorten and generate tension.
Muscular tissue is contractile, meaning it can shorten and generate tension.
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Match the following layers of fascia with their descriptions:
Match the following layers of fascia with their descriptions:
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What is responsible for producing electrical signals called muscle action potentials?
What is responsible for producing electrical signals called muscle action potentials?
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The muscles are surrounded by connective tissue layers called fascia.
The muscles are surrounded by connective tissue layers called fascia.
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Muscular tissue is not extensible and cannot be stretched without tearing.
Muscular tissue is not extensible and cannot be stretched without tearing.
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Study Notes
Muscular Tissue
- Three types of muscular tissue: skeletal, cardiac, and smooth
- Skeletal muscle contracts to move bones and stabilize body positions.
- Cardiac muscle contracts to move blood through the heart.
- Smooth muscle contracts to regulate the passage of substances through the body, for example, in the GI tract and blood vessels.
- All muscles generate heat during contraction
Properties of Muscle
- Myology is the scientific study of muscular tissue.
- Muscular tissue exhibits four special properties: electrical excitability, contractility, extensibility, and elasticity.
- Muscle action potentials stimulate contraction, which generates tension on bones, resulting in movement.
- Muscular tissue can be stretched without tearing, as seen around the stomach.
- Muscular tissue has the ability to return to its original resting length after stretching.
Skeletal Muscle Structure
- Skeletal muscle cells are called muscle fibers, which are elongated cells also known as myocytes.
- Muscle fibers are composed of bundled protein filaments called myofibrils.
- Muscle fibers + connective tissue + nerve and blood supply = muscle (an organ)
- Muscles are surrounded by connective tissue layers called fascia.
- Fascia physically groups muscles with similar functions together and provides passage for nerves and vasculature.
Fascia Layers
- Epimysium is the most superficial layer of fascia, composed of dense irregular connective tissue that wraps muscles.
- Perimysium is the intermediate layer of fascia, composed of dense irregular connective tissue wrapping fascicles, bundles of muscle fibers.
- Endomysium is the deepest layer of fascia, mostly composed of reticular fibers that wrap individual muscle fibers.
Tendons and Aponeuroses
- Fascia forms tendons, thick rope-like structures that connect muscles to bones.
- Aponeuroses are a special type of tendon forming broad sheets, such as the epicranial aponeurosis connecting the two bellies of the occipitofrontalis muscle.
Muscle Blood and Nerve Supply
- Muscular tissue requires oxygen-rich blood for its functions and is extensively vascularized.
- Skeletal muscles are extensively innervated by somatic motor neurons, regulating voluntary muscle contraction.
- Axons from the spinal cord branch to muscles, typically one branch per muscle fiber.
Skeletal Muscle Fiber Structure
- Individuals are born with all the muscle fibers they will ever have, which begin as immature cells called myoblasts in the womb.
- Myoblasts fuse as they mature, forming large multinucleate cells.
Sacrolemma and Sarcoplasm
- The plasma membrane of a myocyte is called the sarcolemma, conducting electrical signals.
- The sarcolemma folds inwards, or invaginates, to form T-tubules.
- The cytoplasm of a myocyte is called the sarcoplasm, densely packed with myofibrils.
- Sarcoplasm is rich in glycogen, a carbohydrate energy store.
Myoglobin
- Myoglobin, found only in muscle cells, binds oxygen at an iron-containing center called heme.
- This allows myocytes to receive oxygen from both inside and outside the cell.
Myofibrils
- Myofibrils are densely packed within sarcoplasm, composed of contractile protein filaments called myofilaments, approximately 2 nm in diameter.
- The regular pattern of overlapping filaments in skeletal and cardiac muscle gives them a striated appearance.
Sarcoplasmic Reticulum
- The SR is the specialized smooth endoplasmic reticulum in muscle cells, extensively folded around each myofibril.
- Membrane folds within the SR are called cisternae.
- Terminal cisternae specifically release calcium to each T-tubule.
- When two terminal cisternae meet a T-tubule, it forms a triad.
Muscle Hypertrophy
- Muscle fibers do not divide, but muscles can grow through hypertrophy, an increase in sarcoplasmic volume.
- Each muscle fiber increases its cellular contents, particularly myofibrils, mitochondria, and SR.
- Hypertrophy is a response to increased mechanical stress, hormones, and disease.
Sarcomere Structure
- Myofibrils are bundles of thread-like structures called myofilaments.
- Each myofilament is made of contractile units called sarcomeres joined end-to-end.
- Each sarcomere consists of overlapping thick and thin filaments.
- Thick filaments extend from the midline (M-line) of the sarcomere and are made of myosin.
- Thin filaments extend from the ends (Z-discs) of the sarcomere and are made of actin.
Sarcomere Zones and Bands
- The regions where thick and thin filaments overlap and everything in between is called the A band.
- Regions between the zones of overlap around the M-line are called the H zone, containing only thick filaments.
- Regions between zones of overlap around the Z-discs are called the I band, containing only thin filaments.
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Description
Explore the different types of muscular tissue, including skeletal, cardiac, and smooth muscle, and their unique functions. Learn about the properties that define muscle tissue and its role in movement and bodily functions. This quiz covers essential concepts related to myology and muscular structure.
