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Questions and Answers
What does the 'staircase effect' refer to in muscle contractions?
What does the 'staircase effect' refer to in muscle contractions?
Wave summation results in a decrease of overall contraction strength.
Wave summation results in a decrease of overall contraction strength.
False
What is the function of somatic motor nerves in muscle contraction?
What is the function of somatic motor nerves in muscle contraction?
They send signals from the brain or spinal cord to trigger muscle contractions.
During the __________ phase, the muscle relaxes and returns to its resting state.
During the __________ phase, the muscle relaxes and returns to its resting state.
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Match the terms related to muscle contraction with their definitions:
Match the terms related to muscle contraction with their definitions:
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What is the primary characteristic of skeletal muscle?
What is the primary characteristic of skeletal muscle?
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Smooth muscle is not found in the walls of hollow organs.
Smooth muscle is not found in the walls of hollow organs.
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What structure surrounds each muscle fiber?
What structure surrounds each muscle fiber?
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Each bundle of muscle fibers wrapped in the perimysium is called a __________.
Each bundle of muscle fibers wrapped in the perimysium is called a __________.
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Which muscle type constitutes the heart muscle?
Which muscle type constitutes the heart muscle?
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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Each muscle cell is known as a muscle fiber.
Each muscle cell is known as a muscle fiber.
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What surrounds the myofibrils within muscle fibers?
What surrounds the myofibrils within muscle fibers?
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What is the primary function of tendons?
What is the primary function of tendons?
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The origin of a muscle is its more movable attachment point.
The origin of a muscle is its more movable attachment point.
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What are muscles that assist the prime movers in a movement called?
What are muscles that assist the prime movers in a movement called?
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The connective tissues that surround muscle fibers are called __________.
The connective tissues that surround muscle fibers are called __________.
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Which of the following describes fixators?
Which of the following describes fixators?
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As a person ages, the mass of muscle fibers generally increases.
As a person ages, the mass of muscle fibers generally increases.
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Match the roles of muscles with their descriptions:
Match the roles of muscles with their descriptions:
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What type of muscle connects muscles to other muscles or bones?
What type of muscle connects muscles to other muscles or bones?
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Which group of muscles mainly originates from the axial skeleton or shoulder girdle?
Which group of muscles mainly originates from the axial skeleton or shoulder girdle?
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Muscles that control flexion and extension of the forearm are part of the first group of muscles.
Muscles that control flexion and extension of the forearm are part of the first group of muscles.
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What is released by motor neurons to trigger muscle contraction?
What is released by motor neurons to trigger muscle contraction?
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When a muscle fiber is stimulated, the sarcolemma becomes temporarily more permeable to ______.
When a muscle fiber is stimulated, the sarcolemma becomes temporarily more permeable to ______.
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Match the following processes with their descriptions:
Match the following processes with their descriptions:
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What is the main role of muscles that cross the wrist?
What is the main role of muscles that cross the wrist?
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A subthreshold stimulus is strong enough to make a muscle fiber contract.
A subthreshold stimulus is strong enough to make a muscle fiber contract.
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The resting membrane potential is particularly important in ______ cells.
The resting membrane potential is particularly important in ______ cells.
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What is maximal stimulus?
What is maximal stimulus?
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A muscle twitch has four phases.
A muscle twitch has four phases.
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What happens during the contraction phase of a muscle twitch?
What happens during the contraction phase of a muscle twitch?
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Muscle fatigue occurs when a muscle runs out of ________.
Muscle fatigue occurs when a muscle runs out of ________.
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What does multiple motor unit summation (recruitment) allow a muscle to do?
What does multiple motor unit summation (recruitment) allow a muscle to do?
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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Wave summation occurs when stimuli are applied after the muscle has fully relaxed.
Wave summation occurs when stimuli are applied after the muscle has fully relaxed.
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During treppe, the efficiency of contractions improves due to increased ________ and calcium levels in the muscle.
During treppe, the efficiency of contractions improves due to increased ________ and calcium levels in the muscle.
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Study Notes
Muscle Tissue Types
- Skeletal muscle is the most prevalent muscle type in the body.
- Smooth muscle forms the walls of internal organs and regulates lumen size.
- Cardiac muscle makes up the heart walls.
Skeletal Muscle Characteristics
- Skeletal muscles are voluntary, striated, multinucleated, and cylindrical.
- Skeletal muscle fibers (cells) range from 10 to 100 μm in length.
- Hundreds of embryonic cells fuse to form one muscle cell.
- Muscle cells are also called muscle fibers.
Myofilaments & Sarcomeres
- Myofilaments are made of actin and myosin proteins.
- Sarcomeres are the functional contractile units of a muscle cell.
- Each thin filament is surrounded by three thick filaments.
- Each thick filament is surrounded by six thin filaments.
Connective Tissue Components
- Endomysium: A layer of connective tissue that surrounds each muscle fiber.
- Perimysium: Another layer that bundles multiple fibers into fascicles.
- Epimysium: A thicker layer that encloses the entire muscle.
- Tendons and aponeuroses are formed by the convergence of these connective tissue layers, attaching muscles to bones.
Neuromuscular Junction
- The neuromuscular junction is where a motor neuron connects to a muscle fiber.
- Axon terminals release acetylcholine (ACh) into the synaptic cleft, initiating muscle contraction.
- Calcium ions (Ca2+) play a crucial role in releasing ACh.
Muscle Contraction Steps
- Electrical excitation of the muscle fiber.
- Excitation-contraction coupling.
- Shortening of the muscle fiber.
Muscle Fatigue
- Muscle fatigue occurs when the muscle can't contract due to factors like oxygen debt, lactic acid buildup, or depletion of ATP.
Muscle Activity Types
- Isometric contraction: Muscle contracts without changing length; maintaining tension, e.g., holding a weight.
- Isotonic contraction: Muscle changes length while maintaining force; e.g., walking or lifting.
Muscle Stimulation and Response
- Multiple motor unit summation: Increasing force of contraction by recruiting more motor units.
- Wave summation: Stronger contraction with repeated stimuli.
- Tetanus (complete): Sustained/strong contraction without relaxation.
Muscle Fiber Types
- A muscle twitch is a single contraction and relaxation cycle. It has three phases: latent, contraction, and relaxation.
- Treppe (staircase effect): Increased strength of contraction with repeated stimuli.
- As you use muscles more, heat and calcium will increase the efficiency of the muscle.
Primary Function of Muscles
- Muscles convert chemical energy to mechanical energy for movement.
- Somatic motor neurons signal muscle contractions.
How Skeletal Muscle Contraction is Controlled
- The brain recruits particular motor units based on strength demands.
- Impulse frequency is controlled by the brain to ensure desired levels of strength and sustained contractions
- The body can adjust the strength of muscle contraction by adjusting the number of recruited motor units or the rate at which they are stimulated.
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Description
Explore the different types of muscle tissue, including skeletal, smooth, and cardiac muscle. This quiz covers key characteristics of skeletal muscles, the structure of myofilaments and sarcomeres, as well as connective tissue components such as endomysium, perimysium, and epimysium. Test your knowledge and understanding of muscle tissue anatomy and function.