Skeletal Muscles and Connective Tissues Quiz
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Questions and Answers

What is the name of the delicate connective tissue membrane covering specialized skeletal muscle fibers?

Endomysium

What is the name of the tough connective tissue that binds together fascicles (bundles of muscle fibers)?

Perimysium

What is the name of the coarse sheath that covers the muscle as a whole?

Epimysium

What is the fibrous component that may become a tendon?

<p>Epimysium</p> Signup and view all the answers

What is the fibrous component that may become an aponeurosis?

<p>Epimysium</p> Signup and view all the answers

What is the approximate percentage of body weight made up by skeletal muscle?

<p>40% - 50% (A)</p> Signup and view all the answers

Skeletal muscles can vary significantly in shape, size, and fiber arrangement.

<p>True (A)</p> Signup and view all the answers

What is the point of attachment of a muscle that does not move when the muscle contracts?

<p>Origin</p> Signup and view all the answers

What is the point of attachment of a muscle that moves when the muscle contracts?

<p>Insertion</p> Signup and view all the answers

What is the name for a muscle or group of muscles that directly performs a specific movement?

<p>Prime mover (agonist)</p> Signup and view all the answers

What is the name for muscles that oppose the action of prime movers?

<p>Antagonists</p> Signup and view all the answers

What is the name for muscles that contract at the same time as prime movers, facilitating their actions?

<p>Synergists</p> Signup and view all the answers

What is the name for muscles that stabilize joints, preventing unwanted movements?

<p>Fixator muscles</p> Signup and view all the answers

What are the four components of a lever system?

<p>Rigid bar (bone), Fulcrum (F) around which the rod moves (joint), Load (L) that is moved, Pull (P) that produces movement (muscle contraction)</p> Signup and view all the answers

In which class of lever does the fulcrum lie between the pull and the load?

<p>First-class levers</p> Signup and view all the answers

In which class of lever does the load lie between the fulcrum and the joint at which the pull is exerted?

<p>Second-class levers</p> Signup and view all the answers

In which class of lever does the pull is exerted between the fulcrum and load?

<p>Third-class levers</p> Signup and view all the answers

Which of the following is NOT a feature used in muscle naming?

<p>Color (B)</p> Signup and view all the answers

Muscles of facial expression are unique in that they attach to the deep layers of the skin.

<p>True (A)</p> Signup and view all the answers

What are the muscles responsible for chewing movements called?

<p>Muscles of mastication</p> Signup and view all the answers

What is the name for the paired muscles on either side of the neck responsible for head movements?

<p>Muscles that move the head</p> Signup and view all the answers

What muscles play a critical role in respiration?

<p>Muscles of the thorax</p> Signup and view all the answers

What are the muscles of the abdominal wall arranged in?

<p>Three layers</p> Signup and view all the answers

What is the function of the muscles of the pelvic floor?

<p>Support the structures in the pelvic cavity</p> Signup and view all the answers

What are the muscles that attach the upper extremity to the torso called?

<p>Muscles acting on the shoulder girdle</p> Signup and view all the answers

What is the name for the muscles that move the upper arm?

<p>Muscles that move the upper arm</p> Signup and view all the answers

Where are the muscles that move the forearm located?

<p>Proximally to the elbow and attach to the ulna and radius</p> Signup and view all the answers

Where are the muscles that move the wrist, hand, and fingers located?

<p>On the anterior or posterior surfaces of the forearm</p> Signup and view all the answers

What is the main function of the pelvic girdle and lower extremity?

<p>Locomotion and maintenance of stability</p> Signup and view all the answers

What are the two types of muscles responsible for ankle and foot movements?

<p>Extrinsic and intrinsic muscles</p> Signup and view all the answers

What are the muscles located in the leg that pull on tendons to move the ankle and foot called?

<p>Extrinsic foot muscles</p> Signup and view all the answers

What are the muscles located within the foot that control toe movements called?

<p>Intrinsic foot muscles</p> Signup and view all the answers

Maintaining posture is one of the major roles muscles play.

<p>True (A)</p> Signup and view all the answers

What is the term for body alignment that favors function, requires the least muscular work, and keeps the body's center of gravity over its base?

<p>Good posture</p> Signup and view all the answers

How is posture maintained by muscles?

<p>Muscles exert a continual pull on bones in the opposite direction from gravity</p> Signup and view all the answers

What is the nervous system's role in maintaining posture?

<p>Responsible for the existence of muscle tone and regulation and coordination of the amount of pull exerted by individual muscles</p> Signup and view all the answers

Only the muscular system is responsible for maintaining posture.

<p>False (B)</p> Signup and view all the answers

Muscle cells can increase or decrease in number, size, and ability to shorten at different periods.

<p>True (A)</p> Signup and view all the answers

What are the conditions that can affect the muscular system?

<p>Pathological conditions</p> Signup and view all the answers

Life cycle changes do not affect the muscular system.

<p>False (B)</p> Signup and view all the answers

What is the term for the replacement of muscle cells with nonfunctional connective tissue that occurs with aging?

<p>Degenerative changes of aging</p> Signup and view all the answers

Which of the following is NOT a general function of the muscular system?

<p>Digestion of food (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic of skeletal muscle cells?

<p>Conductivity (C)</p> Signup and view all the answers

What is the name for muscle fibers due to their threadlike shape?

<p>Muscle fibers</p> Signup and view all the answers

What is the plasma membrane of muscle fibers called?

<p>Sarcolemma</p> Signup and view all the answers

What is the network of tubules and sacs found within muscle fibers that pumps and stores calcium ions called?

<p>Sarcoplasmic reticulum</p> Signup and view all the answers

What are the numerous fine fibers packed close together in sarcoplasm called?

<p>Myofibrils</p> Signup and view all the answers

What is the segment of a myofibril between two successive Z lines called?

<p>Sarcomere</p> Signup and view all the answers

What is the name for the dark stripes called A bands and light H zones, as well as light stripes called I bands, that characterize striated muscle?

<p>Striated muscle</p> Signup and view all the answers

What are the transverse tubules that extend across the sarcoplasm at right angles to the long axis of the muscle fiber called?

<p>T tubules</p> Signup and view all the answers

What is the name for the triplet of tubules consisting of a T tubule sandwiched between two sacs of sarcoplasmic reticulum?

<p>Triad</p> Signup and view all the answers

What are the thick and thin filaments found in myofibrils called?

<p>Myofilaments</p> Signup and view all the answers

What protein makes up almost all of the thick filament?

<p>Myosin</p> Signup and view all the answers

What are the myosin 'heads' called?

<p>Cross bridges</p> Signup and view all the answers

What globular protein forms two fibrous strands twisted around each other to form the bulk of the thin filament?

<p>Actin</p> Signup and view all the answers

What protein blocks the active sites on the actin molecules?

<p>Tropomyosin</p> Signup and view all the answers

What protein holds tropomyosin molecules in place?

<p>Troponin</p> Signup and view all the answers

What is the point where motor neurons connect to the sarcolemma called?

<p>Neuromuscular junction</p> Signup and view all the answers

What is the neurotransmitter released into the synaptic cleft that stimulates receptors and initiates an impulse in the sarcolemma called?

<p>Acetylcholine (ACh)</p> Signup and view all the answers

What triggers the release of calcium ions that bind to troponin, causing tropomyosin to shift and expose active sites on actin?

<p>Calcium ions (Ca++)</p> Signup and view all the answers

What theory describes the mechanism of muscle contraction, where thin filaments slide past thick filaments?

<p>Sliding Filament Theory</p> Signup and view all the answers

What is the process of actively pumping calcium ions back into the sarcoplasmic reticulum, which leads to muscle relaxation called?

<p>Relaxation</p> Signup and view all the answers

What provides the energy required for muscular contraction?

<p>Hydrolysis of ATP</p> Signup and view all the answers

What molecule binds to the myosin cross bridge and transfers its energy to the cross bridge to pull the thin filament during contraction?

<p>Adenosine triphosphate (ATP)</p> Signup and view all the answers

What molecule is used by muscle fibers to continually resynthesize ATP?

<p>Creatine phosphate</p> Signup and view all the answers

What type of respiration occurs when adequate oxygen is available?

<p>Aerobic respiration</p> Signup and view all the answers

What type of respiration occurs when low levels of oxygen are available, resulting in the formation of lactic acid?

<p>Anaerobic respiration</p> Signup and view all the answers

The all-or-none principle states that muscle fibers contract with varying degrees of force depending on the strength of the stimulus.

<p>False (B)</p> Signup and view all the answers

What is the minimum level of stimulation needed to cause a fiber to contract?

<p>Threshold stimulus</p> Signup and view all the answers

What consists of a motor neuron plus the muscle fibers to which it attaches?

<p>Motor unit</p> Signup and view all the answers

What is a quick jerk of a muscle produced as a result of a single, brief threshold stimulus called?

<p>Twitch contraction</p> Signup and view all the answers

What is the phase of a twitch contraction during which the nerve impulse travels to the SR to trigger the release of calcium ions?

<p>Latent phase</p> Signup and view all the answers

What is the phase of a twitch contraction during which calcium ions bind to troponin and sliding of filaments occurs?

<p>Contraction phase</p> Signup and view all the answers

What is the phase of a twitch contraction during which the sliding of filaments ceases and the muscle relaxes?

<p>Relaxation phase</p> Signup and view all the answers

What is the gradual, steplike increase in the strength of contraction seen in a series of twitch contractions that occur 1 second apart called?

<p>Treppe</p> Signup and view all the answers

What occurs if the relaxation phase of a twitch contraction disappears completely?

<p>Contracture</p> Signup and view all the answers

What are smooth, sustained contractions called?

<p>Tetanus</p> Signup and view all the answers

What is the phenomenon of multiple twitch waves being added together to sustain muscle tension for a longer time called?

<p>Multiple wave summation</p> Signup and view all the answers

What is the type of tetanus where very short periods of relaxation occur between peaks of tension called?

<p>Incomplete tetanus</p> Signup and view all the answers

What is the type of tetanus where the stimulation is such that twitch waves fuse into a single, sustained peak called?

<p>Complete tetanus</p> Signup and view all the answers

What is the continual, partial contraction of a muscle called?

<p>Muscle tone</p> Signup and view all the answers

What is the term for the small number of muscle fibers within a muscle that contract at any one time, producing muscle tone?

<p>Tonic contraction</p> Signup and view all the answers

What is the term for muscles with less tone than normal?

<p>Flaccid</p> Signup and view all the answers

What type of contraction is characterized by the muscle maintaining the same tone while the muscle length shortens?

<p>Isotonic contraction</p> Signup and view all the answers

What type of contraction is characterized by the muscle length remaining the same while the muscle tension increases?

<p>Isometric contraction</p> Signup and view all the answers

Skeletal muscles always contract with maximum force.

<p>False (B)</p> Signup and view all the answers

What is the relationship between the initial length of a muscle fiber and the maximal strength it can develop called?

<p>Length-tension relationship</p> Signup and view all the answers

What reflex helps the body maintain muscle length in response to increased load?

<p>Stretch reflex</p> Signup and view all the answers

What type of muscle is found only in the heart, forming the bulk of the wall of each chamber?

<p>Cardiac muscle</p> Signup and view all the answers

What type of muscle is composed of small, tapered cells with single nuclei, forming the muscular layer in walls of hollow structures?

<p>Smooth muscle</p> Signup and view all the answers

What is the most common type of smooth muscle that exhibits autorhythmicity and peristalsis?

<p>Visceral muscle</p> Signup and view all the answers

Flashcards

Skeletal Muscles

There are over 600 skeletal muscles in the body.

Skeletal Muscle Weight

Skeletal muscle makes up 40% - 50% of our body weight.

Endomysium

Delicate connective tissue covering individual skeletal muscle fibers.

Myofibrils

Fine fibers packed within muscle fibers.

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Sarcomere

Contractile unit of muscle fibers between Z lines.

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Neuromuscular Junction

Connection point between motor neurons and muscle fibers.

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Acetylcholine (ACh)

Neurotransmitter triggering muscle contraction.

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Calcium ions (Ca)

Trigger the exposure of active sites on actin.

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Sliding Filament Theory

Explains how muscle fibers contract by overlapping filaments.

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Twitch Contraction

A quick, brief contraction of muscle fibers.

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Muscle Tone

Continuous, partial contraction of muscles.

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Isometric Contraction

Muscle tension increases without changing length.

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Isotonic Contraction

Muscle shortens while maintaining constant tension.

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Cardiac Muscle

Muscle type that forms the heart wall and contracts rhythmically.

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Smooth Muscle

Involuntary muscle in hollow structures like intestines.

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Muscle Naming Features

Muscles are named based on location, shape, or function.

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Tetanus

Sustained contraction without relaxation.

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Stretch Reflex

Muscles respond to stretch to maintain length.

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Injury Recovery

Muscles adapt and repair after strain or injury.

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Prime Mover (Agonist)

Muscle that provides primary force for movement.

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Antagonist

Muscles that oppose the action of the prime mover.

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Synergists

Muscles aiding prime movers in action.

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Good Posture

Ideal body alignment requiring least energy to maintain.

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Muscle Size Variation

Muscles differ in size, shape, and fiber arrangement.

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Myosin

Thick filament protein crucial for muscle contraction.

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Actin

Thin filament protein forming part of muscle contraction.

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Tropomyosin

Blocks active sites on actin to prevent contraction.

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Troponin

Protein that holds tropomyosin in place on actin.

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Lever System

A system in muscles involving levers, fulcrum, and load.

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Origin

Fixed attachment point of a muscle that does not move.

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Insertion

Moving attachment point of a muscle.

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Study Notes

Skeletal Muscles

  • Over 600 skeletal muscles in the body.
  • Account for 40-50% of body weight.
  • Exhibit considerable variation in size, shape, and fiber arrangement.
  • Shapes include broad, narrow, long, tapering, short, blunt, triangular, quadrilateral, irregular, flat sheets, or bulky masses.
  • Fiber arrangements include parallel, convergent, oblique, pinnate, bipennate, or curved.

Connective Tissue Layers

  • Endomysium: Delicate connective tissue covering individual muscle fibers.
  • Perimysium: Tough connective tissue surrounding fascicles (bundles of muscle fibers).
  • Epimysium: Coarse sheath surrounding the entire muscle.
  • Tendon: Fibrous cord connecting muscle to bone.
  • Aponeurosis: Fibrous sheet connecting muscle to bone or other muscles.

Muscle Actions and Interactions

  • Origin: Attachment point that remains stationary during contraction.
  • Insertion: Attachment point that moves during contraction.
  • Prime Mover (Agonist): Muscle primarily responsible for a specific movement.
  • Antagonist: Muscle that opposes the action of the prime mover.
  • Synergists: Muscles that assist the prime mover.
  • Fixator Muscles: Stabilize joints during movement.

Levers and Muscle Function

  • Lever System: Composed of a rigid bar (bone), fulcrum (joint), load (weight), and pull (muscle contraction).
  • First-Class Levers: Fulcrum between load and pull.
  • Second-Class Levers: Load between fulcrum and pull.
  • Third-Class Levers: Pull between fulcrum and load (most common in the body).

Muscle Naming Conventions

  • Muscles are named based on various features, including location, function, shape, fiber direction, number of heads, points of attachment, and relative size.

Specific Muscle Groups

  • Facial Expression Muscles: Attach to skin.
  • Mastication Muscles: Involved in chewing.
  • Head Movement Muscles.
  • Thoracic Muscles: Important for respiration.
  • Abdominal Wall Muscles: Arranged in layers for strength.
  • Pelvic Floor Muscles: Support pelvic organs.
  • Shoulder Girdle Movement Muscles.
  • Upper Arm Movement Muscles.
  • Forearm Movement Muscles.
  • Wrist, Hand, and Finger Movement Muscles.
  • Lower Limb Muscles.
  • Thigh and Lower Leg Movement Muscles.
  • Ankle and Foot Movement Muscles (extrinsic and intrinsic).

Posture and Muscle Tone

  • Posture: Maintaining body alignment.
  • Good Posture: Aligns the body's center of gravity over its base for optimal function.
  • Muscle tone is achieved by the continual pull of muscles in the opposite direction of gravity.
  • The nervous system coordinates muscle contraction to maintain posture.
  • Several systems contribute to posture maintenance (respiratory, digestive, excretory, and endocrine).

Muscle Cell Structure and Contraction

  • Muscle Fibers: Threadlike shape.
  • Sarcolemma: Muscle fiber's cell membrane.
  • Sarcoplasmic Reticulum (SR): Stores calcium ions.
  • Myofibrils: Fine fibers within the sarcoplasm.
  • Sarcomere: Contractile unit of muscle fiber.
  • Striated Muscle: Alternating dark (A bands) and light (I bands) stripes.
  • T Tubules: Extend across the sarcoplasm, allowing rapid transmission of impulses.
  • Triad: A T tubule surrounded by two sacs of sarcoplasmic reticulum.
  • Myofilaments: Thick (myosin) and thin (actin) filaments within myofibrils.
  • Myosin: Thick filament with heads that bind to actin.
  • Cross Bridges: Myosin heads that attach to actin.
  • Actin: Thin filament containing active sites.
  • Tropomyosin: Covers active sites on actin.
  • Troponin: Holds tropomyosin in place.
  • Neuromuscular Junction: Where motor neuron connects to muscle fiber.
  • Acetylcholine (ACh): Neurotransmitter released to initiate muscle contraction.
  • Calcium Ions (Ca++): Trigger muscle contraction by binding to troponin.
  • Sliding Filament Theory: Myosin heads pull actin filaments, causing contraction.
  • Hydrolysis of ATP: Provides energy for muscle contraction.
  • Adenosine Triphosphate (ATP): Energy source for muscle contraction.
  • Creatine Phosphate: Stores energy to resynthesize ATP.
  • Aerobic Respiration: Produces ATP with sufficient oxygen.
  • Anaerobic Respiration: Produces ATP without sufficient oxygen, producing lactic acid.

Muscle Contraction Types

  • All-or-None Principle: Muscle fibers contract completely or not at all.
  • Threshold Stimulus: Minimum stimulus to cause a contraction.
  • Motor Unit: Motor neuron and the muscle fibers it controls.
  • Twitch Contraction: Single, brief contraction.
  • Latent Phase: Brief delay between stimulus and contraction.
  • Contraction Phase: Shortening of the muscle.
  • Relaxation Phase: Return of muscle to resting length.
  • Treppe: Staircase phenomenon; increasing strength of contraction in a series of twitches.
  • Contracture: Absence of relaxation phase.
  • Tetanus: Sustained contraction.
  • Multiple Wave Summation: Multiple twitches combine for greater strength.
  • Incomplete Tetanus: Brief relaxation periods between twitches.
  • Complete Tetanus: Rapid twitches fuse into a sustained contraction.
  • Muscle Tone: Continuous partial contraction of muscles.
  • Tonic Contraction: Small groups of fibers contract, maintaining muscle tone.
  • Flaccid: Reduced muscle tone.
  • Spastic: Increased muscle tone.
  • Isotonic Contraction: Contraction with change in muscle length (e.g., lifting).
  • Isometric Contraction: Contraction without change in muscle length (e.g., pushing against a wall).
  • Graded Strength Principle: Muscles contract with varying strength depending on needs.
  • Length-Tension Relationship: Muscle’s strength depends on its initial length.
  • Stretch Reflex: Maintaining muscle length in response to load.

Other Muscle Types

  • Cardiac Muscle: Found only in the heart, rhythmic contractions.
  • Smooth Muscle: Found in walls of hollow organs, involuntary contractions.
  • Visceral Muscle: Most common smooth muscle type, autorhythmic, exhibits peristalsis.

Aging and Muscle Function

  • Degenerative changes in aging cause muscle cell replacement with connective tissue, leading to a decrease in strength.

General Functions

  • Movement: Body as a whole or parts.
  • Heat Production: Maintaining body temperature.
  • Posture: Maintaining body position.

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Description

Test your knowledge on skeletal muscles, their connective tissue layers, and muscle actions. Learn about the different types of muscle fibers, their arrangements, and the functions of various tissue layers. This quiz will help reinforce your understanding of muscle anatomy and physiology.

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