Ch. 9 Muscles and Muscle Tissues Flashcards
Skeletal muscle
A type of muscle tissue made up of muscle fibers, nerves, blood vessels, and connective tissues
How are muscle fibers stimulated to contract?
By events that occur at the neuromuscular junction
Motor unit
A motor neuron and all the muscle fibers it innervates
What are the two types of muscle contractions?
Isometric and isotonic contractions
EPOC (Excess Post-exercise Oxygen Consumption)
The amount of oxygen required to restore muscle to its resting state after exercise
Smooth muscle
Nonstriated, involuntary muscle found in the walls of hollow organs
What type of muscle tissue is responsible for overall body mobility?
Skeletal muscle
Which type of muscle tissue is found only in the heart?
Cardiac muscle
Which type of muscle tissue is non-striated and involuntary?
Smooth muscle
Which muscle tissue type has the ability to contract without nervous system stimulation?
Cardiac muscle
What characteristic of muscle tissue allows it to return to its original length after stretching?
Elasticity
What is the role of smooth muscle in the body?
Forcing fluids and other substances through internal body channels
What is the ability of a muscle cell to receive and respond to a stimulus called?
Excitability
What are the three types of muscle tissue?
Skeletal, cardiac, and smooth
Which type of muscle tissue is voluntary?
Skeletal muscle
What are the key characteristics of skeletal muscle?
Skeletal, striated, and voluntary
Where is cardiac muscle tissue found?
In the heart
What are the key characteristics of cardiac muscle?
Cardiac, striated, and involuntary
What are the key characteristics of smooth muscle?
Visceral, nonstriated, and involuntary
What is the ability of muscle tissue to shorten forcibly when stimulated?
Contractility
What is the ability of muscle tissue to stretch called?
Extensibility
What are the four important functions of muscle tissue?
Produce movement, maintain posture and body position, stabilize joints, generate heat
Sarcolemma
The plasma membrane of muscle cells
Sarcoplasm
The cytoplasm of muscle cells
Muscle fibers
Elongated cells found in skeletal and smooth muscle
What is the primary function of the epimysium in skeletal muscles?
Surrounds the whole muscle
Which connective tissue sheath surrounds individual muscle fibers?
Endomysium
What type of attachment involves the epimysium fusing directly to the periosteum of a bone?
Direct attachment
Which of the following is NOT found within a skeletal muscle?
Osseous tissue
What structure serves each muscle with nerve and blood supply?
One nerve, one artery, and one or more veins
What is the role of capillaries in skeletal muscles?
Accommodate changes in muscle length
What is the primary function of the perimysium?
Surrounds fascicles
What structure is described as a ‘wispy sheath of connective tissue’?
Endomysium
Which connective tissue sheath is described as an ‘overcoat’?
Epimysium
What is the primary function of skeletal muscle fibers?
Contract to produce movement
What are the main components of a skeletal muscle?
Muscle fibers, nerves, blood vessels, and connective tissues
How do skeletal muscles receive oxygen and nutrients?
Through a rich blood supply via arteries
What is the difference between direct and indirect muscle attachments?
Direct attachments involve the epimysium fusing to bone or cartilage, while indirect attachments involve tendons or aponeuroses.
Epimysium
A dense irregular connective tissue that surrounds the entire muscle.
Perimysium
A layer of dense irregular connective tissue that surrounds each fascicle within a muscle.
Endomysium
A wispy sheath of connective tissue that surrounds each individual muscle fiber.
Fascicle
A discrete bundle of muscle cells surrounded by perimysium.
Sarcomere
The contractile unit of a muscle fiber, composed of myofilaments.
Myofibrils
Rodlike structures within muscle fibers that contain the contractile elements of the muscle, including sarcomeres.
Sarcoplasmic Reticulum (SR)
An elaborate smooth endoplasmic reticulum in muscle fibers that stores and releases calcium ions to regulate muscle contraction.
T Tubules
Extensions of the sarcolemma that penetrate into the cell’s interior, helping to transmit electrical impulses and coordinate muscle contractions.
Sliding Filament Model of Contraction
A model describing how muscle contraction occurs by the sliding of thin filaments past thick filaments, increasing their overlap.
Troponin
A regulatory protein in thin filaments that binds calcium ions and helps control the interaction between actin and myosin during muscle contraction.
Neuromuscular Junction
The region where a motor neuron contacts a skeletal muscle fiber.
Action Potential (AP)
A large change in membrane potential that spreads rapidly over long distances within a cell.
Chemically Gated Ion Channels
Ion channels that open in response to binding of a chemical messenger, such as a neurotransmitter.
Voltage-Gated Ion Channels
Ion channels that open or close in response to changes in membrane potential.
Excitation-Contraction Coupling
The sequence of events by which transmission of an action potential along the sarcolemma leads to muscle contraction.
Cross Bridge Cycle
The series of events during which myosin heads pull thin filaments toward the center of the sarcomere.
Action Potential
A rapid rise and subsequent fall in voltage or membrane potential across a cellular membrane.
End Plate Potential
A local change in membrane potential at the neuromuscular junction due to the influx of sodium ions and efflux of potassium ions.
Excitation-Contraction Coupling
The process by which an action potential in a muscle fiber triggers a contraction by causing the release of calcium ions.
Sarcoplasmic Reticulum
A specialized type of smooth endoplasmic reticulum that stores and releases calcium ions in muscle cells.
Tropomyosin
A protein that blocks myosin-binding sites on actin molecules, preventing muscle contraction in the absence of calcium.
Troponin
A protein that binds to calcium ions and moves tropomyosin away from myosin-binding sites on actin filaments, allowing muscle contraction.
What conditions are necessary for the cross bridge cycle to continue?
ATP must be available and Ca2+ must be bound to troponin.
Cross Bridge
The connection formed when the energized myosin head attaches to an actin myofilament.
Rigor Mortis
The muscle rigidity that occurs after death due to the inability of myosin heads to detach from actin in the absence of ATP.
Temporal summation
An increase in the frequency of stimulation that results in greater strength of contraction of a given motor unit.
Recruitment
The process of increasing the number of activated motor units to produce a stronger muscle contraction.
Muscle tone
A state of slight contraction in relaxed muscles, keeping them firm, healthy, and ready to respond to stimulation.
Isometric contraction
A type of muscle contraction where muscle tension increases but the muscle does not change length.
Isotonic contraction
A type of muscle contraction where the muscle changes length while the tension remains constant.
Direct phosphorylation
A pathway where creatine phosphate donates a phosphate to ADP to form ATP, catalyzed by creatine kinase.
Anaerobic glycolysis
A process that breaks down glucose to lactic acid, producing ATP without the use of oxygen.
Aerobic respiration
A process that uses oxygen to break down glucose, fatty acids, and amino acids to produce ATP, carbon dioxide, and water.
EPOC (Excess Postexercise Oxygen Consumption)
The extra amount of oxygen that the body must take in for restorative processes after exercise.
Creatine kinase
The enzyme that catalyzes the transfer of a phosphate group from creatine phosphate to ADP to form ATP.
Temporal summation
The process where muscle contractions are summed due to frequent stimulation.
Hypertrophy
The increase in muscle cell size due to regular resistance exercise.
Length-tension relationship
The relationship between the length of a muscle and the tension it can produce during an isometric contraction.
Slow oxidative fibers
Muscle fibers that contract slowly, rely on aerobic metabolism, and are fatigue-resistant.
Fast glycolytic fibers
Muscle fibers that contract quickly, rely on anaerobic glycolysis, and fatigue rapidly.
Fast oxidative fibers
Muscle fibers that contract quickly, rely on both aerobic and anaerobic metabolism, and have intermediate fatigue resistance.
Aerobic (Endurance) Exercise
Exercise such as swimming, running, fast walking, and biking that increases capillaries, mitochondria, and myoglobin in muscle fibers, enhancing endurance, strength, and resistance to fatigue.
Resistance Exercise
High-intensity exercise such as weight lifting that leads to muscle hypertrophy by increasing the size of individual muscle fibers and enhancing muscle strength.
Disuse Atrophy
The degeneration and loss of muscle mass due to inactivity, immobilization, or loss of neural stimulation.
Unitary Smooth Muscle
Smooth muscle found in the walls of hollow organs, characterized by rhythmic spontaneous action potentials and electrical coupling by gap junctions
Multi Unit Smooth Muscle
Smooth muscle found in large airways, large arteries, arrector pili muscles, and internal eye muscles, characterized by structurally independent fibers and absence of gap junctions
Calmodulin
A cytoplasmic calcium-binding protein that activates myosin light chain kinase in smooth muscle
Varicosities
Bulbous swellings of autonomic nerve fibers that release neurotransmitters in the general area of smooth muscle cells
Myoblast
Embryonic cells that develop into muscle tissue.
Myotube
A structure formed by the fusion of several myoblasts, which matures into a skeletal muscle fiber.
Satellite cell
Myoblast-like cells associated with skeletal muscle that help repair injured fibers.
Sarcopenia
The gradual loss of muscle mass that begins around age 30.
Intermittent claudication
A condition that restricts blood delivery to the legs, causing pain during walking.
What are anabolic steroids?
Variants of the male sex hormone testosterone used to enhance performance.
When were anabolic steroids introduced and for what initial purposes?
In the 1950s to treat anemia, certain muscle-wasting diseases, and to prevent muscle atrophy after surgery.
What physical changes does testosterone cause during puberty in males?
Increase in muscle and bone mass.
Which famous athletes have been revealed to use anabolic steroids?
Barry Bonds, Mark McGwire, Marion Jones, and Lance Armstrong.
What are some of the claimed benefits of anabolic steroids for athletes?
Enhanced muscle mass and strength, and increased oxygen-carrying capability due to a greater volume of red blood cells.
What are some of the physical side effects of anabolic steroid use?
Bloated faces, acne, hair loss, shriveled testes, infertility, liver damage, and changes in blood cholesterol levels.
What are some of the psychiatric hazards of anabolic steroid use?
Depression, delusions, manic behavior, and ‘roid rage’.
Roid rage
Extreme violent behavior and personality swings caused by anabolic steroid use.
Cushingoid sign
A symptom of steroid excess characterized by a bloated face.
Anabolic steroids
Drugs that are variants of the male sex hormone testosterone, used to enhance athletic performance.
Which hormone promotes increased skeletal muscle?
Testicular androgen.
Cardiac hypertrophy
An increase in the size of the heart’s muscle cells, often due to exercise.
Gastrointestinal motility
The movement of the digestive system’s muscles that aids in the digestion and passage of food.
What are the three types of muscle tissue?
Skeletal, cardiac, and smooth muscle.
Which type of muscle tissue is striated and controlled involuntarily?
Cardiac muscle.
What are the special functional characteristics of muscle tissue?
Excitability, contractility, extensibility, and elasticity.
From what embryonic cells does muscle tissue develop?
Myoblasts.
What is the role of the sarcoplasmic reticulum (SR) in muscle fibers?
To release and sequester calcium ions.
What is a motor unit?
One motor neuron and all the muscle cells it innervates.
What is the energy source for muscle contraction?
ATP.
What are the three types of muscle fibers?
Fast glycolytic (fatigable), slow oxidative (fatigue-resistant), and fast oxidative (fatigue-resistant) fibers.
What happens to skeletal muscles during regular aerobic exercise?
They increase in efficiency, endurance, strength, and resistance to fatigue.
What is the main difference between smooth and skeletal muscle fibers?
Smooth muscle fibers are nonstriated and involuntary, while skeletal muscle fibers are striated and voluntary.
Myofibrils
Contractile elements in muscle fibers that occupy most of the cell volume and have a banded appearance due to the arrangement of myofilaments.
T tubules
Invaginations of the sarcolemma that allow electrical stimuli to be delivered quickly deep into the muscle cell.
Excitation-contraction coupling
The process by which an action potential in the sarcolemma leads to the release of calcium ions from the sarcoplasmic reticulum, triggering muscle contraction.
Motor unit recruitment
The process of activating more motor units to increase muscle strength.
Excess postexercise oxygen consumption (EPOC)
The amount of oxygen required to restore muscle cells to their resting state after exercise.
What is nemaline myopathy?
A muscle disorder caused by mutations in one of 11 different genes related to thin filaments, leading to muscle weakness.
What is the primary diagnostic method for nemaline myopathy?
Muscle biopsy.
What are the characteristic symptoms of nemaline myopathy in children?
Symptoms can include waddling walk, difficulty standing, problems swallowing, pneumonia, progressive weakness, and foot drop.
Actin
A protein that forms thin filaments in muscle cells and is essential for muscle contraction.
What consequences would you expect from an abnormality in actin?
Muscle weakness and impaired muscle contraction.
Troponin
A protein that binds to calcium and helps regulate muscle contraction by moving tropomyosin off the myosin-binding sites on actin filaments.
How could abnormal troponin cause muscle weakness?
It could impair the regulation of muscle contraction, leading to reduced muscle strength.
What is the role of calcium in skeletal muscle contraction?
Calcium released from the sarcoplasmic reticulum binds to troponin to initiate muscle contraction.
Sarcoplasmic Reticulum
An organelle in muscle cells that stores and releases calcium to trigger muscle contraction.
What might happen if a child with malignant hyperthermia is given the wrong anesthetic?
Continuous cross bridge cycling causes the muscle to contract too much, leading to a life-threatening reaction.
How can resistance training benefit children with nemaline myopathy?
It can strengthen their respiratory muscles, improving their breathing and overall muscle function.
Myoglobin
Oxygen-binding pigment in muscle.
Androgen
A hormone such as testosterone that controls male secondary sex characteristics.
Lactic acid
Product of anaerobic metabolism, especially in muscle.
Excess postexercise oxygen consumption (EPOC)
The volume of oxygen required after exercise to replenish stores of O2, ATP, creatine phosphate, and glycogen and oxidize the lactic acid formed during exercise. Also called oxygen debt.
Sarcolemma
The plasma membrane of a muscle fiber.
Actin
A cytoskeletal element; a contractile protein of muscle.
Muscle tone
Low levels of contractile activity in relaxed muscle; keeps the muscle healthy and ready to act.
Perimysium
Connective tissue that bundles muscle fibers into fascicles.
Aerobic
Oxygen-requiring.
Excitation-contraction (E-C) coupling
Sequence of events by which transmission of an action potential along the sarcolemma leads to the sliding of myofilaments.
Graded muscle contractions
Variations in the degree of muscle contraction by changing either the frequency or strength of the stimulus.
Sarcoplasm
The cytoplasm of a muscle fiber.
Muscular dystrophy
A group of inherited muscle-destroying diseases.
Motor end plate
Neuromuscular Junction - Region where a motor neuron comes into close contact with a skeletal muscle cell.
Myoblasts
Embryonic mesoderm cells from which all muscle fibers develop.
Anaerobic threshold
The point at which muscle metabolism converts to anaerobic glycolysis.
Skeletal muscle
Muscle composed of cylindrical multinucleate cells with obvious striations; the muscle(s) attached to the body’s skeleton; voluntary muscle.
Tendon
Cord of dense regular connective tissue attaching muscle to bone.
Myosin
One of the principal contractile proteins found in muscle.
Contraction
To shorten or develop tension, an ability highly developed in muscle cells.
Myofilaments
Filament that constitutes myofibrils. Of two types: actin and myosin.
Summation
Accumulation of effects, especially those of muscular, sensory, or mental stimuli.
Contractility
Muscle cell′s ability to move by shortening.
Axon terminal
The bulbous distal endings of the terminal branches of an axon where neurotransmitters are released.
Tetanus
(1) A smooth, sustained muscle contraction resulting from high-frequency stimulation; (2) an infectious disease caused by an anaerobic bacterium.
Myogram
A graphic recording of mechanical contractile activity produced by an apparatus that measures muscle contraction.
Threshold stimulus
Weakest stimulus capable of producing a response in an excitable tissue.
Neuromuscular junction
Region where a motor neuron comes into close contact with a skeletal muscle cell; aka motor end plate.
Epimysium
Sheath of fibrous connective tissue surrounding a muscle.
Muscle tension
The force exerted by a contracting muscle on some object.
Excitability
Ability to respond to stimuli.
Visceral muscle
Type of smooth muscle; its cells are electrically coupled by gap junctions, and so they rhythmically contract as a unit. They often exhibit spontaneous action potentials. Also called unitary smooth muscle.
Sarcoplasmic reticulum (SR)
Specialized endoplasmic reticulum of muscle cells.
Motor unit
A motor neuron and all the muscle cells it stimulates.
Aerobic endurance
The length of time a muscle can continue to contract using aerobic pathways.
Isometric contraction
Contraction in which the muscle does not shorten (the load is too heavy) but its internal tension increases.
Synaptic vesicles
Small membranous sacs containing neurotransmitter.
Creatine kinase
Enzyme that catalyzes the transfer of phosphate from creatine phosphate to ADP, forming creatine and ATP; helps power muscle contraction.
Creatine phosphate (CP)
Compound that serves as an alternative energy source for muscle tissue.
Sarcomere
The smallest contractile unit of muscle; extends from one Z disc to the next.
Varicosities
Knoblike swellings of certain autonomic axons containing mitochondria and synaptic vesicles.
Hernia
Abnormal protrusion of an organ or a body part through the containing wall of its cavity.
Fascicles
Bundle of nerve or muscle fibers bound together by connective tissue.
Myofibrils
Rodlike bundle of contractile filaments (myofilaments) found in muscle fibers (cells).
Latent period
Period of time between stimulation and the onset of a response (such as muscle contraction).
T tubule
Extension of the muscle cell plasma membrane (sarcolemma) that protrudes deeply into the muscle cell.
Glycolysis
Breakdown of glucose to pyruvic acid—an anaerobic process.
Responsiveness
Ability to respond to stimuli.
Isotonic contraction
Contraction in which muscle tension remains constant at a given load, and the muscle shortens.
Aerobic respiration
Respiration in which oxygen is consumed and glucose is broken down entirely; water, carbon dioxide, and large amounts of ATP are the final products.
Endomysium
Thin connective tissue surrounding each muscle cell.
Muscle twitch
The response of a muscle to a single brief threshold stimulus.
Anaerobic
Not requiring oxygen
Muscle fibers
A muscle cell.
Aponeurosis
Fibrous or membranous sheet connecting a muscle and the part it moves.
