Ch. 9 Muscle Tissue Flashcards
Which is the correct description of Deep Fascia?
1) Surrounds the entire muscle
2) Lies between neighboring muscle
3) Surrounds each fiber
4) Surrounds each bundle (fascicle)
Lies between neighboring muscles
Which of the following is not a characteristic of skeletal muscle?
1) It can contract for long periods without tiring
2) It can exert tremendous power
3) It contracts rapidly
4) It is voluntary
It can contract for long periods of time without tiring
Ability of a muscle to resume its resting length after being stretched.
Elasticity
What is the sheet-like indirect attachment that anchors a muscle?
Aponeurosis
Which describes Endomysium?
1) Surrounds each bundle (fascicle)
2) Surrounds each muscle fiber
3) Binds muscles to other muscles
4) Surrounds an entire muscle
Surrounds each muscle fiber
Which describes Perimysium?
1) Surrounds each bundle (fascicle)
2) Surrounds each muscle fiber
3) Binds muscles to other muscles
4) Surrounds an entire muscle
Surrounds each bundle (fascicle)
Which of the following is a special adaptation present in skeletal muscle cells, but absent in most other cells?
1) Muscle cells have myoglobin
2) Muscle cells have mitochondria
3) Muscle cells have a nucleus
4) Muscle cells use ATP
Muscle cells have myoglobin; most other cells do not
Myofibrils are composed of repeating contractile elements called ?
Sarcomeres
The linking of thick and thin filaments together is called ?
Forming a cross bridge
What is the area of the sarcomere with overlapping thick and thin filaments?
A band
The thin myofilaments of skeletal muscle are composed chiefly of ?
Actin
What is the oxygen storage molecule in skeletal muscle?
Myoglobin
A sarcomere is part of a ?
Myofibril
Which of the following allows recoil of the muscle fiber when contraction ends?
1) Elastic filament (titin)
2) Thin filament (actin)
3) Thin filament (tropomyosin)
4) Thin filament (troponin)
5) Thick filament (myosin)
Titin
“Cross bridges” that link between the thick and thin filaments directly involve ?
Myosin
In the sliding filament model of contraction, what occurs when the muscle cell shortens?
The distance between successive Z discs shortens.
What is the rod-like contractile element within a muscle fiber containing myofilaments.
Myofibril
What is the plasma membrane of skeletal muscle fiber?
Sarcolemma
In the sliding filament model of muscle contraction, the myofilaments slide over each other, resulting in the overlapping of actin and ?
Myosin
The functional unit of contraction in a skeletal muscle fiber is the ?
Sarcomere
What is the area in the center of the A band containing only thick filaments?
H zone
What is the description of ion movement at the neuromuscular junction that produces the end plate potential?
More sodium enters the muscle fiber than potassium leaves the muscle fiber.
What is End Plate Potential?
Depolarization occurring only at the neuromuscular junction
Give the description of the voltage-gated ion channels for a region of sarcolemma that is undergoing repolarization.
Sodium channels close and potassium channels open
Give the description of the voltage-gated ion channels for a region of sarcolemma that is undergoing depolarization.
Sodium channels are open and potassium channels are closed
What is the action of Troponin?
Binds Ca2+ and starts the contraction cycle
Which of the following is an autoimmune disease that destroys acetylcholine receptors?
Myasthenia gravis
Does calcium bind to myosin heads during muscle contraction?
False; ATP binds to myosin heads
What ion combines with troponin, causing troponin to change shape which removes the blocking action of tropomyosin, allowing cross bridges to form.
Ca++
What best describes the composition of the structure known as a triad in a skeletal muscle fiber?
Terminal cisterna, transverse tubule, and terminal cisterna
The type of muscle contraction in which the muscle fibers produce increased tension although the muscle neither shortens nor lengthens is called ______.
Isometric
Smooth muscle fibers appear ___ shaped.
Spindle
What substance increases in quantity during repetitive muscle contraction during oxygen deficit?
Lactic acid
What substances all decrease during muscle contraction?
ATP, Creatine phosphate, Glucose, and Oxygen
Which one of the following binds calcium ions in a smooth muscle, causing contraction?
1) Troponin
2) Calmodulin
3) Myosin
4) Actin
Calmodulin
____ is the ability of a muscle to shorten forcibly when adequately stimulated.
Contractility
During the phase of excitation-contraction coupling of skeletal muscle, what occurs immediately after the action potential spreads down the T tubule?
The sarcoplasmic reticulum releases calcium.
Glycogen stores are abundant in ____ ____ fibers.
Fast glycolytic
Myofilament cross bridges form when which two structures bond?
Myosin heads and globular actin
What is the cause of rigor mortis?
Calcium influx into the sarcoplasm after death
____ is the term used to describe the squeezing action produced when opposing layers of smooth muscle alternate contraction and relaxation.
Peristalsis
One T tubule lies between two ?
Terminal cisternae
The _______ are inward invaginations of the sarcolemma that run deep into the cell and ensure that every myofibril in the muscle fiber contracts at virtually the same time.
T tubules
The thin myofilaments of skeletal muscle are composed chiefly of _______.
Actin
If a muscle is applied to a load that exceeds the muscle’s maximum tension, _______.
The muscle length will not change during contraction
Properly controlled skeletal muscle contractions produced by changing the frequency of stimulation and the strength of stimulation are referred to as _______.
Graded muscle responses
What would occur if a contracting muscle became totally depleted of ATP?
The muscle would remain in a contracted state because of an inability to break actin-myosin cross bridges.
True/False
Once damaged, smooth muscle is unable to regenerate.
False
Smooth muscle depends on the ? system to regulate contraction, while skeletal muscle relies on the ? system to regulate contraction.
calcium-calmodulin; calcium-troponin
Duchenne muscular dystrophy is inherited as an X-linked recessive trait. Does the disease affect males or females more frequently?
Males
The connective tissue that encloses the sarcolemma of an individual muscle fiber is called the ?
Endomysium
A fascicle is a ?
Bundle of muscle fibers enclosed by a connective tissue sheath
The function of the T tubules in muscle contraction is to ?
Transmit the action potential deep into the muscle cells
The sites where the motor nerve impulse is transmitted from the nerve endings to the skeletal membranes are the ?
Neuromuscular junctions
Contraction elicited by a single brief stimulus is called a ?
Twitch
A smooth, sustained contraction resulting from very rapid stimulation of the muscle, in which no evidence is seen, is called ?
Fused tetanus
Characteristics of isometric contractions include all but ?
1) Shortening
2) Increased muscle tension throughout contraction
3) Absence of shortening
4) Used in resistance training
Shortening
What provides ATP the fastest?
A coupled reaction of creatine phosphate with ADP
What provides the highest yield of ATP per glucose molecule?
Aerobic respiration of glucose
What results in the formation of lactic acid?
Anaerobic glycolysis
The contractile unit of muscle is called ?
Sarcomere
What is a long, filamentous organelle found within muscle cells that has a banded appearance?
Myofibril
What is an actin or myosin containing structure?
Myofilament
A discrete bundle of muscle cells is called?
Fascicle
___ is a continuous contraction that shows no evidence of relaxation.
Fused tetanus
An ___ contraction is one in which the muscle shortens and work is done.
Isotonic
To accomplish a strong contraction, ___ are stimulated at a rapid rate.
Many motor units
When a weak but smooth muscle contraction is desired, ___ are stimulated at a rapid rate.
Few motor units
An ___ contraction is one in which the muscle does not shorten, but tension in the muscle keeps increasing.
Isometric
What are 4 functions of muscles?
Produce movement, maintain posture, stabilize joints, & generate heat
Myasthenia gravis is an autoimmune disease that destroys ?
ACh receptors
Skeletal and smooth muscle cells (not cardiac) are called ?
Muscle fibers
The moveable bone is also called the muscle’s ?
Insertion
The immoveable bone is also called the muscle’s ?
Origin
The origin typically lies ? to the insertion.
Proximal
In what kind of attachments do the epimysium fuse to the periosteum of a bone?
Direct, or fleshy
In what kind of attachments do the muscle’s connective wrappings extend beyond the muscle as ropes (tendons) or sheets (aponeuroses)?
Indirect
Which of the following is most directly associated with attachments between muscles and bones?
1) Epimysium
2) Perimysium
3) Endomysium
Epimysium
The ? regulates calcium levels in muscle cells.
Sarcoplasmic reticulum
Which of the following is the smallest unit?
1) Myofilament
2) Fascicle
3) Myofibril
4) Muscle fiber
Myofilament
? are the protein molecules that form contractile units within myofibrils.
Myofilaments
The ? is chiefly composed of the protein myosin that forms thick filaments.
A band
Which of the following does not change length during shortening resulting from muscle contraction?
1) Thin myofilament
2) Distance between Z discs
3) H zone
4) I band
Thin myofilaments
Voltage gated Na+ and K+ channels are associted most directly with which event during stimulation of muscle?
1) Propogating AP along sarcolemma
2) Release of Ach in synaptic cleft
3) Depolarization of motor end plate
4) Release of Ca from SR
Propagating AP along sarcolemma
Which of the following occurs last in cross bridge formation?
1) Binding of Ca to troponin
2) Binding of ACh to receptors
3) Depolarization of sarcolemma
4) Arrival of AP at axon terminal
Binding of Ca to troponin
Which of the following occurs during the relaxation phase of a muscle twitch?
1) Active transport of Ca into SR
2) Binding of Ca to thin filaments
3) Release of ACh into synaptic cleft
4) Depolarization of T tubules
Active transport of Ca into SR
Increased contractile force due to recruitment results from ?
Increasing numbers of activated somatic motor neurons
Ca++ is pumped back into the SR during which phase of muscle twitch?
Relaxation
Increased contractile force due to recruitment results from ?
Stimulation of a muscle by increasing numbers of activated somatic motor neurons.
Which of the following is expected to occur during the recovery period following intense exercise?
1) Glycogen formed from glucose
2) PYR-H converted to LA-H
3) O2 levels decrease
4) ATP syntehsized anaerobically
Glycogen formed from glucose
What explains the decreased contractile force generated by a stretched muscle?
Stretching of myofibrils within fibers decreases the overlap between thick and thin myofilaments.
Which of the following is NOT characteristic of fast glycolytic fibers?
1) Depends on blood for nutrients
2) Relatively large diameter
3) White appearance
4) Powerful, but quick to fatigue
Depend on blood for nutrients; they depend on glycogen stores within cell
Smooth muscle and skeletal muscle contain what kind of myofilaments?
Both thick and thin
How are smooth muscle cells arranged?
In sheets
In smooth muscle, Ca++ binds to ___ rather than troponin.
Calmodulin
What kind of muscle cells regenerate and are able to divide?
Smooth
The sequence of events that converts AP in a muscle fiber to a contraction is known as ?
E-C coupling
Where it abuts the T tubule, the SR forms sac-like bulges called?
Terminal cisternae
The cross bridge cycle begins when ___ binds to ___?
Ca++ binds to troponin
If troponin is a component of both cardiac and skeletal muscle, why is an elevated plasma troponin level useful in diagnosing myocardial damage?
The subunits of the troponin in cardiac muscle are unique to heart muscle.
What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated?
Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron.
A muscle cell runs out of ATP. Even though these are cyclic reactions, what step of the cross bridge cycle given is most directly inhibited or terminated?
Cross bridge detachment
The cross bridge cycle starts when _________.
Ca++ from the sarcoplasmic reticulum binds to troponin
What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated?
Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron.
The prefix ? means turning, change, or affinity for.
Tropo-
? is a missing protein in Duschenne 19’s muscular dystrophy.
Dystrophin
Botulism and myasthenia gravis are conditions that cause muscle weakness. Which of these statements is NOT true?
1) Botulinum toxin impairs the release of acetylcholine from the presynaptic neuron.
2) Both conditions are caused by an inability of the body to produce adequate acetylcholine.
3) Both conditions affect normal activity at the neuromuscular junction.
4) In myasthenia gravis, acetylcholine is released, but the receptors on the junctional folds of the sarcolemma cannot receive the acetylcholine.
Both conditions are caused by an inability of the body to produce adequate acetylcholine.
