Podcast
Questions and Answers
Most of the muscle tissue in the body is ______ muscle.
Most of the muscle tissue in the body is ______ muscle.
skeletal
Smooth muscle regulates the size of ______ within organs.
Smooth muscle regulates the size of ______ within organs.
lumen
The muscle that makes up the heart is known as ______ muscle.
The muscle that makes up the heart is known as ______ muscle.
cardiac
Skeletal muscles are also referred to as ______ muscle.
Skeletal muscles are also referred to as ______ muscle.
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Each muscle fiber is surrounded by a connective tissue sheath called ______.
Each muscle fiber is surrounded by a connective tissue sheath called ______.
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Bundles of muscle fibers are referred to as ______.
Bundles of muscle fibers are referred to as ______.
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Each muscle fiber is made up of smaller structures called ______.
Each muscle fiber is made up of smaller structures called ______.
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The tubal system that surrounds each myofibril is known as the ______.
The tubal system that surrounds each myofibril is known as the ______.
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These muscles mainly originate from the axial skeleton or shoulder ______.
These muscles mainly originate from the axial skeleton or shoulder ______.
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These muscles control movements like flexion, extension, ______, and supination.
These muscles control movements like flexion, extension, ______, and supination.
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Muscles that form the main muscles of the forearm cross the ______ and attach to the fingers.
Muscles that form the main muscles of the forearm cross the ______ and attach to the fingers.
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An action potential travels down a motor neuron to the ______ terminal.
An action potential travels down a motor neuron to the ______ terminal.
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Calcium enters the ______, starting a series of events that lead to muscle contraction.
Calcium enters the ______, starting a series of events that lead to muscle contraction.
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The three layers of connective tissue include endomysium, perimysium, and ______.
The three layers of connective tissue include endomysium, perimysium, and ______.
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A muscle fiber either fully contracts or doesn’t contract at all—this is known as the ______ principle.
A muscle fiber either fully contracts or doesn’t contract at all—this is known as the ______ principle.
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The more movable attachment point of a muscle is called its ______.
The more movable attachment point of a muscle is called its ______.
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Muscles that oppose or reverse a movement are referred to as ______.
Muscles that oppose or reverse a movement are referred to as ______.
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A ______ stimulus is strong enough to make the muscle fiber contract.
A ______ stimulus is strong enough to make the muscle fiber contract.
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When stimulated, the sarcolemma becomes temporarily more permeable to ______.
When stimulated, the sarcolemma becomes temporarily more permeable to ______.
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Synergists assist the action of agonists by either assisting with the movement or reducing ______.
Synergists assist the action of agonists by either assisting with the movement or reducing ______.
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As we age, the mass of muscle fiber decreases while the amount of ______ increases.
As we age, the mass of muscle fiber decreases while the amount of ______ increases.
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Muscles that cross two or more joints require ______ to stabilize those joints during movement.
Muscles that cross two or more joints require ______ to stabilize those joints during movement.
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Fixators are specialized synergists that immobilize the origin of a prime mover so that all the tension is at the ______.
Fixators are specialized synergists that immobilize the origin of a prime mover so that all the tension is at the ______.
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Muscles in the upper limb are divided into three groups including muscles that move the arm, muscles that move the forearm, and muscles that move the ______ and fingers.
Muscles in the upper limb are divided into three groups including muscles that move the arm, muscles that move the forearm, and muscles that move the ______ and fingers.
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The ______ effect demonstrates that repeated contractions grow stronger with the same stimulus.
The ______ effect demonstrates that repeated contractions grow stronger with the same stimulus.
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The ______ phase is the delay before the muscle starts contracting.
The ______ phase is the delay before the muscle starts contracting.
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In wave summation, overlapping contractions result in increased overall ______.
In wave summation, overlapping contractions result in increased overall ______.
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Muscles convert chemical energy into ______ energy to enable movement.
Muscles convert chemical energy into ______ energy to enable movement.
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Somatic motor ______ send signals from the brain or spinal cord to stimulate muscle contractions.
Somatic motor ______ send signals from the brain or spinal cord to stimulate muscle contractions.
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The smallest stimulus strong enough to make all the muscle fibers in a muscle contract is called the ______.
The smallest stimulus strong enough to make all the muscle fibers in a muscle contract is called the ______.
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When more motor units are recruited, it results in ______ of muscle strength.
When more motor units are recruited, it results in ______ of muscle strength.
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A single, brief contraction of a muscle is known as a muscle ______.
A single, brief contraction of a muscle is known as a muscle ______.
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The ______ phase is the time between the stimulus and when the muscle starts contracting.
The ______ phase is the time between the stimulus and when the muscle starts contracting.
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The phenomenon where muscle contractions become stronger with repeated stimuli is referred to as ______.
The phenomenon where muscle contractions become stronger with repeated stimuli is referred to as ______.
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In ______, if stimuli are applied before the muscle fully relaxes, contractions build on each other.
In ______, if stimuli are applied before the muscle fully relaxes, contractions build on each other.
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When stimuli come very quickly, and there is no time for relaxation, the muscle experiences ______.
When stimuli come very quickly, and there is no time for relaxation, the muscle experiences ______.
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Muscle ______ occurs when it can no longer contract due to energy depletion.
Muscle ______ occurs when it can no longer contract due to energy depletion.
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Study Notes
Muscle Tissue Types
- Most muscle tissue is skeletal muscle.
- Remaining muscle is smooth muscle, found in hollow organs and cardiac muscle, which forms the heart walls.
- Smooth muscle regulates lumen size.
- Cardiac muscle forms the heart muscle(myocardium).
Skeletal Muscle Characteristics
- Skeletal muscle is voluntary, striated, multinucleated, and cylindrical.
- Skeletal muscle moves materials within the body.
- Skeletal muscle fibers range from 10 to 100 µm.
Muscle Fiber Structure
- Hundreds of embryonic cells fuse to form each muscle fiber.
- The plasma membrane is the sarcolemma.
- The nucleus is beneath the sarcolemma.
- Myofilaments, composed of actin and myosin, form sarcomeres (the muscle's functional contractile unit). Six thin filaments surround each thick filament, and each thick filament is surrounded by three thin filaments.
- Myofibrils are bundled myofilaments.
- Muscle fibers are bundled and surrounded by connective tissue to create organs, like skeletal muscles.
- Endomysium surrounds each muscle fiber.
- Perimysium surrounds fascicles (bundles of muscle fibers), creating bundles of muscle fibers called fascicles.
- Sarcoplasmic reticulum surrounds myofibrils and contains calcium.
Muscle Organization
- Muscle fibers are delicate and easily damaged.
- They're bundled with connective tissue to form skeletal muscles.
- Each muscle fiber is covered by endomysium.
- Several muscle fibers bundled together are covered by perimysium.
- Multiple fascicles form a whole muscle and are covered by epimysium.
- These cover layers form tendons or aponeuroses, and connect muscles to bones or other muscles.
Neuro-Muscle Interactions
- The neuromuscular junction is where a motor neuron meets a muscle fiber.
- The terminal branches of a motor axon reach muscle fibers.
- Each terminal branch ends in axon terminals that form junctions with muscle fibers.
- A motor unit consists of one motor neuron and all the muscle fibers it controls.
- The synaptic cleft separates the neuron's axon terminal and muscle fiber.
- Neuron signals trigger acetylcholine (ACh) release, binding on sarcolemma, causing ion channels to open, and depolarization.
- Calcium ion release is triggered, initiating muscle contraction.
Muscle Contraction
- Muscle contraction involves stimulation, excitation-contraction coupling, and actual contraction.
- Resting membrane potential maintains an electrical difference across the membrane.
- Ion balance relies on the Na+-K+ pump.
- Action potential travels, releasing acetylcholine.
- Calcium is released, enabling muscle fiber contraction.
Muscle Contraction Types
- All-or-none Principle: A muscle fiber contracts fully or not at all.
- Graded Response: A muscle's overall contraction strength varies based on the number of recruited fibers and the frequency of stimulation.
Muscle Fatigue
- Muscle fatigue occurs due to issues with oxygen, lactate buildup, potassium, and ATP.
- Muscle weakness decreases, and contractions weaken when fatigued.
Muscle Activity Summary
- Repeated stimulation increases heat/calcium and muscle efficiency (think warm-up).
- Wave summation happens when subsequent stimuli occur before relaxation, leading to stronger contractions.
- Tetanus is continuous sustained contraction with no relaxation.
- Muscle fatigue happens when muscles can't further contract due to energy depletion.
- Twitch graph shows a single contraction (latent, contraction, relaxation).
- Treppe/staircase effect shows increasing contraction strength with repeated stimuli.
- Maximal stimulus is the weakest signal that activates all muscle fibers.
Additional Points
- Synergists assist prime movers, reducing unwanted movement.
- Fixators stabilize origins, allowing prime movers to produce force.
- Muscles are categorized by their roles in arm, forearm, and finger/hand movements.
- Isometric contractions hold objects at constant length.
- Isotonic contractions cause object movement.
- Muscles convert chemical energy to mechanical energy via somatic motor neurons.
- Motor unit recruitment and impulse frequencies control contraction strength.
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Description
This quiz covers the various types of muscle tissue, including skeletal, smooth, and cardiac muscles. It delves into the characteristics of skeletal muscle and the structure of muscle fibers, highlighting the roles each muscle type plays in the body. Test your knowledge on anatomy and physiology related to muscle tissues!
