KIN 223 Chapter 10, KIN 223 Chapter 10 Assessment, Ch. 10: Muscle Tissue, Chapter 10 A&P
The vascular supply to slow-twitch muscle fibers is ______ the network of capillaries around fast-twitch muscle fibers.
more extensive than
In a motor unit, a single ______ neuron typically controls numerous muscle fibers in a muscle
motor
Skeletal muscle contraction is controlled by _____ neurons.
motor
The iris of the eye contains
multiunit smooth muscle
The iris of the eye contains skeletal muscle. multiunit smooth muscle. single-unit smooth muscle. cardiac muscle.
multiunit smooth muscle
The branch of the nervous system that helps govern smooth muscle contraction is the _______ nervous system.
! autonomic
Muscles of the eye and hand have a high percentage of _______ fibers.
! fast twitch
The multiple nuclei in skeletal muscle cells are the result of the: ! fusion of myoblasts. cytokinesis of embryonic satellite cells. spontaneous development of nuclei in embryonic cells. stimulation of fibroblasts by hormones. action of testosterone on mesenchyme cell.
! fusion of myoblasts.
A skeletal muscle cell contains hundreds to thousands of _________, which are complex organelles; they are cylindrical in shape--about 2 micrometers in diameter and as long as the cell. ! myofibrils microfilaments sarcomeres T-tubules sarcolemma
! myofibrils
Oxidative fibers are:
! red and fatigue-resistant.
The most abundant form of smooth muscle is:
! single-unit, which is also known as visceral smooth muscle.
Select all that are true when a muscle fiber is at rest.
- ACh receptors are open - Calcium is stored in the sarcoplasm
Which of the following proteins are found within a sarcomere
- actin - connectin
Thin filaments in smooth muscle cells contain which proteins
- actin - tropomyosin
Smooth muscle is found in which of the following locations?
- in the wall of the small intestine - around blood vessels - in wall of the uterus
Multiunit smooth muscle is found in which of the following locations
- iris of the eye - arrestor pili muscles in the skin
Smooth muscle shows a different length-tension relationship than skeletal muscle because _____
- it lacks Z discs but has dense bodies - the arrangement of the thick and thin filaments allows for contraction even when stretched
A neuromuscular junction contains a
- motor end plate - synaptic cleft - synaptic knob
Which may occur as a result of muscle atrophy?
- reduction in muscle size - fibers become weaker - muscle loses tone - fibers waste away and die
In which activities are muscles in an isometric contraction
- sitting up very straight - holding a yoga pose - pushing on a locked door
phosphate
ATP is generated when the enzyme creatine kinase transfers Pi from creatine ______________ to ADP.
length-tension
In order to predict how much tension a muscle can produce when contracting, it is important to consider the _____________________ relationship of thick and thin filaments.
greater
In the gluteus maximus, each motor unit controls a _____________ amount of muscle fibers than a motor unit in the eye muscles. Lesser/Greater
Hypertrophy
Increase in muscle size.
fatigue
Intermediate fibers have a high resistance to _______________.
sliding
The _____________ filament theory explains how muscle fibers shorten during contraction.
oxygen debt
The amount of additional oxygen that must be inhaled following exercise to restore pre-exercise conditions is called ________________________.
transverse tubule
The component of a muscle fiber that quickly transports a muscle impulse from the sarcolemma throughout the entire muscle fiber is called the ________________________________.
sarcomere
The contractile unit of a myofibril is called the ___________________.
slowly
Type I muscle fiber contracts more ___________ than type IIa and IIb muscle fibers.
Isometric Contraction
When skeletal muscle tension is insufficient to overcome the resistance, there is no movement of the muscle.
Isotonic Contraction
When skeletal muscle tension results in movement of the muscle.
C
Which of the following muscle characteristics characterize an effect of aging? A. Increase capacity to recover from disease B. Increase in muscle fiber diameter C. Slow, progressive loss of muscle mass D. Increase in myoglobin content in muscle
What part of a myosin molecule does ATP bind to?
head
Relaxation is facilitated by the release of passive tension that developed in cablelike __________ proteins that were compressed during contraction.
connectin
Which contraction occurs when you try (unsuccessfully) to move a wall?
isometric
Acetylcholine moves across the synaptic cleft by _____
diffusion
A sarcomere is defined as the distance from one _____ to the next
disc
The spring-like property that returns muscle to its original length after a contraction ends is
elasticity
The epimysium of a muscle surrounds the ______
entire skeletal muscle
Muscle cells are said to have what characteristic because they can respond to stimulation from the nervous system
excitability
During which phase of the crossbridge cycle is ATP split into ADP and Pi? Immediately preceding the detachment of the myosin head → Immediately preceding the resetting of the myosin head Immediately preceding the power stroke
→ Immediately preceding the resetting of the myosin head
Which are the reservoirs that store the calcium required for muscle contraction? Synaptic vesicles Synaptic clefts → Terminal cisternae Peroxisomes Mitochondria
→ Terminal cisternae
Glycolysis is an:
→ anaerobic process that occurs in the cytosol.
A term that describes the change in muscle following a lack of exercise is:
→ atrophy.
Which is the correct order of the connective tissue layers of a skeletal muscle, beginning with the outermost first? a: Endomysium b: Epimysium c: Perimysium
→ b, c, a
Acetylcholine exerts its effect by: stimulating the motor neuron's synaptic knob. → binding to receptors at the motor end plate. activating acetylcholinesterase. allowing calcium to enter the cell.
→ binding to receptors at the motor end plate.
Growth of the uterus during pregnancy is accomplished by _________ of its smooth muscle.
→ both hypertrophy and hyperplasia
Rather than tightly coupled synapses between neurons and muscle cells, single-unit smooth muscle contains:
→ diffuse junctions where neuron varicosities are responsible for neurotransmitter release.
When a muscle is isometrically contracted, its length _______ change.
→ does not
The most prevalent of skeletal muscle fibers in the body are _____ fibers.
→ fast twitch
During development, many groups of ____ fuse to form single skeletal muscle fibers.
myoblasts
Thick filaments are assembled from bundles of the protein called
myosin
Release of crossbridges and a decline in muscle tension characterize the _______ period of a twitch.
relaxation
Approximately 40-50% of your body weight is _____ muscle.
skeletal
Match the muscle tissue with its appearance or shape.
skeletal - long, cylindrical fiber cardiac - short, branched cell smooth - fusiform-shaped cell
Which is not a connective tissue component of a muscle
skeletal muscle fibers
The _______ filament theory explains how muscle fibers shorten during contraction
sliding
Which fibers dominate many of the back and calf muscles that contract almost continually to maintain posture?
slow twitch
The force generated when a skeletal muscle is stimulated to contract is muscle ______
tension
Most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic.
true
True or False: A single myofibril runs the length of the muscle fiber
true
True or false: a byproduct of anaerobic respiration is lactic acid
true
A single contraction and relaxation of a muscle fiber is referred to as a muscle ______
twitch
within a synaptic knob, synaptic ______ contain the neurotransmitter ACh
vesicles
A typical skeletal muscle cell contains approximately _____ mitochondria. 3 30 → 300 3000
→ 300
What is the letter associated with the dark bands in a sarcomere? I → A Z M H
→ A
Which is the neurotransmitter that causes the release of calcium ions from reservoirs within the muscle cell and thereby initiates the steps of contraction? Acetylcholinesterase Rubitussin → Acetylcholine Serotonin Norepinephrine
→ Acetylcholine
Which may occur as a result of muscle atrophy?
→ All choices are correct
Which letter is associated with a zone (in a relaxed muscle) that is a little more lightly shaded because only thick filaments are present? I A M Z → H
→ H
Muscle Fiber
Elongated, multinucleated, cylindrical cell.
True
Embryonic myoblasts fuse to form single muscle fibers during development; thus skeletal muscle cells are multinucleated. True/False
ATP
Energy to drive the myosin movement in the sliding filament process is provided in the form of ______.
A term that describes the change in muscle following a lack of exercise is
atrophy
The wall of the heart is composed of ____ muscle.
cardiac
If a skeletal muscle is injured, surrounding _____ cells may be stimulated to differentiate and assist in its repair and regeneration.
satellite
In an isotonic contraction, the muscle fibers ______, resulting in movement.
shorten or lengthen
Place the steps of cross-bridge cycling in order:
1. Cross-bridge formation 2. Power stroke 3. Release of myosin head 4. Reset myosin head
fascicle
A bundle of muscle fibers is known as a ___________.
Which is the neurotransmitter that causes the release of calcium ions from reservoirs within the muscle cell and thereby initiates the steps of contraction?
Acetylcholine
ACh
Acetylcholinestrase in the synaptic cleft is needed so that ________ will not continuously stimulate the cell to contract.
elasticity
After a contraction, muscle returns to its original relaxed position due to its normal ____________________.
True
An action potential causes depolarization of the T-tubule membrane. True/False
Intermediate Filaments
Cytoskeleton network.
Atrophy
Decrease in the skeletal muscle fiber size.
Similar to skeletal muscle cells, all smooth muscle cells are excited by ACh.
False
Concentric Contraction
Shortening of muscle length; occurs because the muscle tension is greater than the resistance.
sarcomere
The functional contractile unit of a skeletal muscle fiber is known as a _________________.
The ______ discs that anchor the sarcomere on either end in skeletal muscle are absent from smooth muscle cells
Z
To start a muscle contraction, a nerve impulse causes ______ release at a neuromuscular junction.
acetylcholine
Contraction of a muscle fiber requires that the myosin heads in the thick filament bind to active sites on ____ molecules within the thin filaments
actin
Multiunit smooth muscle cells are stimulated
individually
Which of the following structures anchor adjacent cardiac muscle cells together?
intercalated disc
Cardiac muscle cells form Y-shaped branches and join to adjacent muscle cells at junctions called ____________ _____
intercalated discs
Smooth muscle contraction is under ____ control of the nervous system
involuntary
The type of fibers specialized to continue contracting for extended periods of time, as would be required in running a marathon, for example, are _____ fibers.
→ slow twitch
The net energy yield from one glucose molecule through the process of glycolysis is:
! 2 ATP.
Each thick filament contains about ______ protein molecules (each molecule has two heads and two braided tails).
! 200
Which of the myofilaments of a muscle fiber has the active sites to which the heads of the thick filaments will bind? ! Actin Troponin Tropomyosin Myosin Sarcoplasm
! Actin
Which sequence correctly lists the changes that allow the thick and thin filaments to slide past one another in skeletal muscle contraction? ! Attach - pivot - detach - return Pivot - attach - return - detach Attach - detach - pivot - return Return - pivot - attach - detach Pivot - attach - detach - return
! Attach - pivot - detach - return
Which letter is associated with the light band and contains thin filaments only? ! I A M Z H
! I
Which contraction occurs when you try (unsuccessfully) to move a wall?
! Isometric
Which protein makes up the thick filaments? ! Myosin Actin Tropomyosin Troponin Myopathy
! Myosin
Which fibers dominate many of the back and calf muscles that contract almost continually to maintain posture?
! Slow twitch
Which structures are reservoirs that store acetylcholine? ! Synaptic vesicles Synaptic clefts Terminal cisternae Lysosomes Sarcomeres
! Synaptic vesicles
Invaginations of the muscle cell membrane that extend deep into the cell are known as the: ! T-tubules. terminal cisternae. titin complexes. Z-discs. end plates.
! T-tubules.
A sarcomere is defined as the distance from one _____ to the next adjacent ____ . (The same answer fills in both spaces.) ! Z disc I band H zone A band M line
! Z disc
With increased age, skeletal muscles show:
! a decrease in the number of myofibrils.
The top long distance runners probably have _______ proportion of slow muscle fibers in their leg muscles.
! a higher
Which is a correct listing of the hierarchy of a skeletal muscle's components, beginning with the smallest? a: Myofibrils b: Muscle fiber c: Fascicle d: Skeletal muscle
! a, b, c, d
The presence of mitochondria and myoglobin facilitate _________ respiration in muscle cells. ! aerobic anaerobic
! aerobic
A flat, thin structure made of dense connective tissue that serves to attach a muscle to a bone (or to another muscle) is a(n): ! aponeurosis. tendon. perimysium. myolemma. superficial fascia.
! aponeurosis.
Muscle tone is a result of _________ nervous system activity, and it acts to _________ joint position.
! involuntary, stabilize
The vascular supply to slow muscle fibers is ______ the network of capillaries around fast muscle fibers.
! more extensive than
Consider the difference between lifting a light pad of paper versus a heavy text book. The primary way the level of force of muscle contraction is controlled is by:
! recruiting a different number of motor units.
The increase in muscle tension that occurs with an increase in the intensity (voltage) of a stimulus is called:
! recruitment.
Which can cause muscle fatigue?
- build up of intracellular Pi - insufficient Ca 2+ - Na+ of K+ imbalances
Match each property of a muscle cell with its description
- excitability: response to stimuli - contractibility: stimulation of muscle cells generates tension within the cell - elastic: a contracted muscle cell recalls to its resting length when the applied tension is removed - extensibility: a muscle cell is capable o extending in length in response to the contraction of opposing muscle cells
The skeletal muscles arranged in layers along the walls of the abdominal cavity and the floor of the pelvic cavity perform what function?
- protection - contraction - support
Which are characteristics of oxidative fibers?
- red - good for endurance - high concentration of myoglobin - use aerobic respiration
Place the following events in the correct order of occurrence once ACh diffuses across the synaptic cleft of a NMJ:
1. ACh binds to receptors on the motor end plate 2. The resulting action potential moves down the sarcolemma 3. The action potential moves down the t-tubules 4. The action potential reaches the terminal cisternae of the SR 5. Calcium ions are released into the sarcoplams
Place the events at a neuromuscular junction in order
1. Arrival of nerve signal at synaptic knob 2. Calcium entry into synaptic knob 3. Exocytosis of ACh into synaptic cleft 4. Binding of ACh to motor end plate
Place the events in the diagram in order
1. Nerve impulses arrive at synaptic knob 2. Ca2+ enters and binds synaptic vesicles 3. ACh is released into synaptic cleft 4. ACh binds receptors on the motor end plate
Place the stages of cross-bridge cycling in order
1. calcium binds troponin; myosin binding site uncovered 2. cross-bridge formation 3. power stroke 4. release of myosin head by ATP 5. reset of myosin head
The net energy yield from one glucose molecule through the process of glycolysis is
2 ATP
tendon
A cord-like structure that attaches muscle to bone is a ____________.
twitch
A single contraction and relaxation of a muscle fiber is referred to as a muscle ____________.
Tetanus
A sustained muscle contraction.
The arrival of a nerve impulse at the synaptic knob of a motor neuron causes synaptic vesicles to release ______ into the synaptic cleft
ACh
Blood vessels deliver nutrients and oxygen to the muscle fibers so that they can produce the molecule ____ (the currency of energy) needed for contraction.
ATP
Energy to drive them myosin movement in the sliding filament process is provided in the form or
ATP
Skeletal muscle contraction requires large amounts of energy in the form of ___________ in order to complete the sequence of cyclic events that lead to sarcomere shortening.
ATP
Match the thin filament protein and thing filament associated protein names with its functions
Actin - two intertwined strands each band has a myosin binding sites Tropomyosin - two intertwined strands cover myosin binding sites Troponin - bound to troponmyosin can bind calcium ions
striations
Although smooth muscle cells have both thick and then filaments, they are not precisely aligned, so no visible _____________ are present.
perimysium
An extensive network of blood vessels and nerve fibers extends through both the epimysium and the __________________ of a muscle.
hyperplasia
An increase in muscle fiber number is called ___________________.
Dense Plaque
Anchoring point between intermediate filaments and the sarcolemma.
Dense Body
Anchoring point between intermediate filaments and the sarcoplasm.
Calmodulin
Binds calcium.
Match each function of skeletal muscle with its description.
Body Movement - muscles contract and pull on the tendons that attach the muscles to the bones. Posture - Contraction of specific skeletal muscles stabilizes joints. Temperature regulation - heat is produced as a waste product of energy usage Storage and movement of materials - Voluntary sphincter muscles of the gastrointestinal and urinary tracts can be kept closed or opened.
Match the structures with their functions.
Cytoskeleton network - intermediate filaments Anchoring point between intermediate filaments and the sarcoplasm - Dense body Anchoring point between intermediate filaments and the sarcolemma - Dense plaque
MLCP
Dephosphorylates myosin.
Match each property of a muscle cell with its description.
Excitability - Cell is responsive to stimuli Contractility - Stimulation of muscle cells generates tension within the cell Elasticity - A contracted muscle cell recoils to its resting length when the applied tension is removed Extensibility - A muscle cell is capable of extending in length in response to the contraction of opposing muscle cells
Smooth muscle cells tend to be shorter but thicker than skeletal muscle cell.
False
In a sarcomere, the ____ zone (or band) is the light central region of the A band.
H
The act of shivering is an example of skeletal muscle performing what function?
Heat production
When viewed under a light microscope, the light bands, called ____ bands, contain only ____ filaments
I;thin
Isometric
If you strain to push on a wall that does not move, your muscles are in what type of contraction?
During which phase of the crossbridge cycle is ATP split into ADP and Pi?
Immediately preceding the resetting of the myosin head.
A
In a 1500-meter run, an event that may take about 5 to 6 minutes, ATP is supplied by which energy sources? A. Phosphagen, anaerobic, and aerobic sources B. Phosphagens only C. Phosphagens and anaerobic sources D. Aerobic sources
Hyperplasia
Increase in the number of muscle fibers.
Match each stage of a muscle twitch with the amount of tension generated.
Latent period - there is no tension Contraction period - tension increases Relaxation period - tension decreases
Eccentric Contraction
Lengthening of muscle length; the muscle exerts less force than that needed to move the load, and the muscle lengthens.
Myofibril
Long, cylindrical contractile element within muscle cell.
The _____ line is a thin, transverse, protein meshwork structure in the center of the H zone of a sarcomere
M
Match each protein with its function.
MLCK - phosphorylates myosin Calmodulin - binds calcium MLCP - dephosphorylates myosin
Muscle
Multiple bundles housing many muscle fibers.
individually
Multiunit muscle cells contract _________________.
Which type of smooth muscle is innervated most similar to skeletal muscle, with muscle cells arranged as motor units and each cell stimulated by a single motor neuron?
Multiunit smooth muscle
False
Multiunit smooth muscle cells are stimulated to contract in unison, whereas single-unit smooth muscle cells receive stimulation to contract individually. True/False
False
Multiunit smooth muscle is characterized by the use of gap junctions between cell membranes. True/False
Match the name of the muscle cell component with its function.
Muscle fiber - metabolic activities; contraction Sarcolemma - regulates entry and exit of materials Sarcoplasm - site of metabolic processes for normal muscle fiber activities Sarcoplasmic reticulum - stores calcium ions needed for muscle contraction T-tubule - transports the action potential from the sarcolemma throughout the entire muscle fiber
True
Myofibrils are composed of protein filaments called actin and myosin. True/False
Match the component of a muscle cell with its description
Myofilbrils- cylindrical organelles specialized for contraction Thick filament- composed of myosin Thin filament- composed of actin, troponin, and tropomyosin Actin- double stranded contracille protein Tropomyosin- double stranded regulatory protein
False
Myoglobin provides muscle fibers with a means of supplying ATP anaerobically. True/False
Relaxation Period
Period where tension decreases.
Contraction Period
Period where tension increases.
Latent Period
Period where there is no tension.
MLCK
Phosphorylates myosin.
acetylcholine
Receptors in the motor end plate bind with the neurotransmitter, _____________________, released from the synaptic knob.
True
Rising sarcoplasmic calcium levels results in contraction in both smooth muscle fibers and skeletal muscle fibers. True/False
together
Single-unit muscle cells contract ________________.
True
Smooth muscle cells lack transverse tubules. True/False
multiunit
Smooth muscle found in both the iris and ciliary muscle of the eye and arrector pili muscles in the skin is __________ smooth muscle.
fusiform
Smooth muscle is composed of short cells that have a __________ shape.
wave summation
Stimulation of muscle fibers at a rate of 20 to 50 stimuli per second does not allow for complete relaxation of the fibers before the next stimulatory event. This results in _____________________ and can lead to incomplete tetany.
True
T-tubules are invaginations of the sarcolemma of a muscle cell. True/False
Which are the reservoirs that store the calcium required for muscle contraction?
Terminal cristernae
thick
The H-zone is more lightly shaded because only ___________ filaments are present.
caveolae
The invaginations of sarcolemma on the smooth muscle cell are called ______________.
fast glycolytic
The majority of skeletal muscle fibers in the body are ________________________ fibers.
sarcolemma
The plasma membrane of a skeletal muscle fiber is called the ___________________.
acetylcholine
The primary neurotransmitter at the neuromuscular junction is __________________________.
calcium
The sarcoplasmic reticulum stores ______________ ions needed to initiate muscle contraction.
same length
Thick and thin filaments maintain their ____________________, whether the muscle is relaxed or contracted.
Actin, Tropomyosin
Thin filaments in smooth muscle cells contain which proteins?
A
Which of the following statements is true concerning calcium ions? A. In smooth muscle, it binds with calmodulin B. In skeletal muscle, it binds with calmodulin C. In smooth muscle, it binds with troponin D. In skeletal muscle, it binds with tropomyosin
Cardiac muscle cells use ____ respiration almost exclusively
aerobic
Ten minutes into a marathon, your body is relying on ______ cellular respiration for ATP
aerobic
For longer contractions, muscle cells obtain ATP by which process?
aerobic respiration
Lifting weights will cause muscles to enlarge. This is primarily due to
an increase in the size of muscle cells
Lifting weights will cause muscles to enlarge. This is primarily due to
an increase in the size of muscle cells.
Glycolysis is an
anaerobic process that occurs in the cytosol.
in a muscle cell, the short term energy is supplied by ___ respiration, while long term energy is supplied by ___
anaerobic/aerobic
A tendon that forms a thin, flattened sheet is called a/an ______
aponeurosis
After breaking your arm, you have a cast on it for three months. when the cast is removed, your arm looks much smaller than it did before. what process caused this to happen?
atrophy
The cyclic events of "attach, pivot, detach, return" continue as long as _______ ____ remain bound to the troponin
calcium ion
To initiate a smooth muscle cell contraction, calcium enters the cell and binds to
calmodulin, which then binds to and activates myosin light-chain kinase.
The type of muscle fibers that are striated, form Y-shaped branches, and are joined by intercalated discs are
cardiac
The sarcolemma of smooth muscle cells has small invaginations called
caveolae
The sarcolemma of smooth muscle cells has small invaginations called _______
caveolae
a muscle fiber is what level of organization in the body?
cellular
The enzyme acetylcholinesterase resides in the synaptic
cleft
As a result of muscle fiber contraction, thick filaments in neighboring sarcomeres move_____
closer together
The amount of additional oxygen that must be inhaled in order to restore pre-exercise levels is called oxygen ______
debt
A person's tolerance for exercise ___ with age
decreases
The synaptic knob of the neuron is an ______ of an axon.
expanded tip
The characteristic of muscle that allows it to be passively stretched is
extensibility
True or false: a muscle fiber that is partially shortened can produce a contraction stronger than the contraction it can produce when at is resting length
false
The majority of skeletal muscle fibers in the body are ____ fibers
fast glycolytic
The most prevalent of skeletal muscle fibers in the body are _____ fibers.
fast-twitch
Intermediate fibers have a high resistance to
fatigue
In a lab, wave summation is demonstrated by increasing the _________ of the stimulus.
frequency
One of the reasons you might struggle to lift a heavy object with your arm fully extended is because
full extension results in decreased overlap between thick and thin filaments in the muscle
Smooth muscle is composed of short cells that have a ________ shape
fusiform
The diameter of a muscle fiber will predict
how much power it will produce
An increase in muscle fiber size is called
hypertrophy
Muscle tone is a result of _________ nervous system activity, and it acts to _________ joint position.
involuntary, stabilize
The two types of muscle contraction are: a _______ contraction (when a muscle contracts but does not change length) and b. ________ contraction (when a muscle contracts and does change length).
isometric; isotonic
Although muscle fibers obey the all-or-none principle, the force of muscle contraction can be varied depending on how many ______ units are used
motor
When someone engages in exercise that requires more oxygen than is available, they develop a(n) _____ _______ (2 words), which results in heavy breathing for several minutes after the exercise is complete.
oxygen debt
The ______ is the connective tissue covering of a fascicle.
perimysium
ATP is generated when the enzyme creatine kinase transfers Pi from creatine ______ to ADP.
phosphate
Increased phosphate ion concentration is believed to contribute to fatigue by interfering with
phosphate release by myosin heads during crossbridge cycling.
As you hold a barbell and begin to flex your arm in a curl, your biceps brachii slowly lifts the weight by using more and more units. This phenomenon, which increases the strength of the contraction, is referred to as _____.
recruitment
The motor end plate is a specialized region of the
sarcolemma
The plasma membrane of a skeletal muscle fiber is called the ___.
sarcolemma
Match the structure with its description.
sarcomere - functional contractile unit of skeletal muscle A-band - dark band containing both actin and myosin H-zone - contains thick filaments only I-band - light band containing thin filaments only
Within a myofibril, Z discs separate the functional units known as
sarcomeres
At the end of muscle contraction, calcium ions are moved back into the _______ reticulum by ATP driven ion pumps
sarcoplasmic
At the end of contraction, when the stimulation form the nerve impulse ceases, calcium ions are pumped back into the ______
sarcoplasmic reticulum
The membranous network that wraps around myofibrils and holds relatively high concentrations of calcium is known as the
sarcoplasmic reticulum
The type of fibers specialized to continue contracting for extended periods of time, as would be required in running a marathon, for example, are _____ fibers.
slow-twitch
Smooth muscle contraction is ____, resistant to _______, and usually sustained for an extended period of time
slow; fatigue
Type I muscle fibers contract more _____ that type II and IIb muscle fibers.
slowly
The type of muscle fibers that have only a single nucleus, both thick and thin filaments, but no Z discs, are
smooth
The type of muscle that forms the majority of the walls of the digestive tract is ______ muscle.
smooth
A circular muscle band that contracts at an orifice is also known as a _______________.
sphincter
Cardiac muscle cells are ______ like skeletal muscle fibers
striated
A "step-wise" increase in the force of contraction of a single muscle fiber motor unit due to repeated stimulation is called _____
summation
An action potential travels down the sarcolemma, through the t-tubules, to the
terminal cisternae
Parts of the sarcoplasmic reticulum that appear as blind sacs perpendicular to the fiber's length are called _______
terminal cisternae
A continuous, smooth contraction of muscle in which twitches are fully fused is referred to as _________.
tetany
When calcium ions bind to troponin, which of the following then occurs?
the myosin binding sites on actin are exposed.
The point where a motor neuron meets a skeletal muscle fiber is called?
the neuromuscular junction
the striated appearance in skeletal muscle cells is due to size and density differences between ______ and ________ filaments
thick/thin
For relaxation to occur: A. Ach receptors close and Ca++ channels on the sarcoplasmic reticulum close. B. Ach receptors close and Ca++ channels on the sarcoplasmic reticulum open. C. Ach receptors open and Ca++ channels on the sarcoplasmic reticulum close. D. Ach receptors open and Ca++ channels on the sarcoplasmic reticulum open.
→ Ach receptors close and Ca++ channels on the sarcoplasmic reticulum close.
Which is not a protein found in thin filaments? Actin Troponin Tropomyosin → Sarcomyosin No exceptions; all are found in thin filaments
→ Sarcomyosin
Which letter is associated with the line that is a thin protein structure that serves as an attachment site for thin filament ends? I A → Z M H
→ Z
A power stroke involves: an actin molecule pulling a myosin molecule toward the M-line. a thin filament shortening in length and thereby shortening the sarcomere. → a myosin head pulling a thin filament toward the center of the sarcomere. a thick filament pushing an actin filament towards the nearest Z-line.
→ a myosin head pulling a thin filament toward the center of the sarcomere.
A motor unit consists of: multiple motor neurons and multiple muscle fibers. → a single motor neuron and the multiple muscle fibers it controls. multiple motor neurons and the one muscle fiber they control. one synaptic terminal button, a cleft, and an acetylcholine receptor. an end plate, T-tubule, and sarcoplasmic reticulum.
→ a single motor neuron and the multiple muscle fibers it controls.
In general, a skeletal muscle is composed of: a: connective tissue sheaths b: nerves c: arteries d: veins e: muscle fibers
→ a, b, c, d, e
Which are possible functions of skeletal muscles? a: Maintenance of posture b: Both highly coordinated and localized simple movements c: Temperature regulation d: Support of certain body organs e: Regulation of the movement of material through certain body tracts
→ a, b, c, d, e
The action potential of a muscle fiber occurs: at the end plate. → along the sarcolemma and down the T-tubules. within the sarcoplasmic reticulum. in the mitochondria.
→ along the sarcolemma and down the T-tubules.
Fibers from one motor unit: are clustered together within one fascicle of the muscle. → are dispersed throughout most of the muscle.
→ are dispersed throughout most of the muscle.
Lifting weights will cause muscles to enlarge. This is primarily due to
→ by an increase in the size of muscle cells.
To initiate a smooth muscle cell contraction, calcium enters the cell and binds to:
→ calmodulin, which then binds to and activates myosin light chain kinase.
The type of muscle fibers that are striated, form Y-shaped branches, and have junctions called intercalated discs are:
→ cardiac.
A skeletal muscle cell can be several inches long. The property of muscle tissue that allows an impulse to travel down the entire length of the cell membrane is: elasticity. conductivity. extensibility. contractility. responsibility.
→ conductivity.
When a muscle relaxes:
→ crossbridges stop forming and muscle elasticity
The spring-like property that returns muscle to its original length after a contraction ends is: extensibility. elasticity. contractility. treppe effect. conductivity.
→ elasticity.
A drug that inhibited acetylcholinesterase would result in: a failure to stimulate the muscle due to decreased Ach release. → enhanced stimulation of the muscle due to decreased Ach breakdown. enhanced stimulation of the muscle due to enhanced Ach release. poor muscle stimulation due to enhanced Ach breakdown
→ enhanced stimulation of the muscle due to decreased Ach breakdown.
When an impulse arrives at the knob of the motor neuron, calcium: enters through active transport pumps and triggers the release of transmitter. → enters through voltage-gated channels and triggers the release of transmitter. exits through active transport pumps and brings transmitter with it. exits through voltage-gated channels and triggers transmitter release. is released from synaptic vesicles.
→ enters through voltage-gated channels and triggers the release of transmitter.
The characteristic of muscle that allows it to be passively stretched is: conductivity. elasticity. excitability. extensibility. contractility.
→ extensibility.
"Intermediate fibers" is another name for:
→ fast twitch, oxidative fibers.
In a lab, wave summation is demonstrated by increasing the _________ of the stimulus.
→ frequency
One of the reasons you might struggle to lift a heavy object if you tried to lift it with your arm at a fully extended posture is that:
→ full extension results in decreased overlap between thick and thin filaments in the muscle.
A motor unit within the powerful quadriceps muscle would: contain several motor neurons. be much like those in the eye muscles. generally contain less than ten fibers. → generally contain several hundred fibers.
→ generally contain several hundred fibers.
One feature that helps provide fast energy to a muscle cell is the presence of granules containing the complex carbohydrate: creatine phosphate. myoglobin. → glycogen. nebulin. hemoglobin.
→ glycogen.
Phosphate transfer is used for
→ immediate ATP needs and is not dependent on oxygen.
Events of excitation contraction coupling, such as the release of calcium from intracellular stores, occur during the ________ period of a muscle twitch.
→ latent
The neurons that stimulate muscle contraction are called _____ neurons. sensory contractile inhibitory → motor association
→ motor
Smooth muscle tissue in which cells are individually sent signals to contract (rather than contracting in unison) is referred to as:
→ multiunit.
Myoglobin is a molecule within muscle cells that can bind: creatine phosphate. → oxygen. hemoglobin. acetylcholine. ATP
→ oxygen.
Increased phosphate ion concentration is believed to contribute to fatigue by interfering with:
→ phosphate release by myosin heads during crossbridge cycling.
An end plate potential is an event that involves a gain of: positive charge for the cell, as potassium rapidly enters. → positive charge for the cell, as sodium rapidly enters. negative charge for the cell, as potassium rapidly enters. negative charge for the cell, as sodium rapidly enters
→ positive charge for the cell, as sodium rapidly enters.
Release of crossbridges and a decline in muscle tension characterize the _______ period of a twitch.
→ relaxation
When smooth muscle is stretched for a prolonged period of time, it responds by:
→ relaxing
For relaxation to occur: calcium leaves the sarcoplasmic reticulum, troponin binds calcium and blocks the binding sites on actin. calcium enters the myofibril, it detaches from myosin, and the binding sites on myosin become inactive. → sarcoplasm calcium levels fall, calcium is removed from troponin, and tropomyosin blocks binding sites on actin. extracellular calcium levels fall, calcium is pumped into the myofibril, and tropomyosin slides away from actin.
→ sarcoplasm calcium levels fall, calcium is removed from troponin, and tropomyosin blocks binding sites on actin.
The membranous network that wraps around myofibrils and holds relatively high concentrations of calcium is known as the: sarcolemma. T-tubule. → sarcoplasmic reticulum. sarcomere. Golgi body
→ sarcoplasmic reticulum.
The latchbridge mechanism of myosin heads is a property of ________ muscle.
→ smooth
The type of muscle fibers that have only a single nucleus, both thick and thin filaments, but no Z discs, are:
→ smooth.
The narrow space that separates the motor neuron and the skeletal muscle fiber in a neuromuscular junction is called the: motor end plate. synaptic vesicle. → synaptic cleft. synaptic knob. Ach floor.
→ synaptic cleft.
The structure responsible for attaching muscle to bone is a: sphincter. ligament. fascia. → tendon. myofibril
→ tendon.
For a sprint lasting 60 seconds, ATP is supplied initially by:
→ the phosphagen system but primarily by glycolysis.
The way acetylcholine is released from a neuron is: by a primary active transport pump. by rapid diffusion when a voltage-gated ion channel opens for it. → through exocytosis when a vesicle fuses with the membrane. by conduction through a gap junction from nerve to muscle.
→ through exocytosis when a vesicle fuses with the membrane.
"Staircase" and "warm up" are alternative names for ___________, an increased muscle response to a constant stimulus.
→ treppe
The calcium ions involved in skeletal muscle contraction bind to a(n)______ subunit. myosin actin elastin tropomyosin → troponin
→ troponin
The repolarization of the action potential involves the opening of:chemically gated Na+ channels. voltage-gated Na+ channels. chemically gated K+ channels. → voltage-gated K+ channels.
→ voltage-gated K+ channels.