Which of the following protein(s) is/are found in thin filaments? (check all that apply) (0.25pts)
One nerve fiber and all the muscle fibers innervated by it are a: (0.25pts)
The contractile unit of a muscle fiber is the: (0.25pts)
Which of the following is a neurotransmitter that fills synaptic vesicles and is used to signal between the nerve and muscle? (0.25pts)
Which type of muscle contraction produces a change in muscle tension but no change in muscle length? (0.25pts)
Fast glycolytic muscle fibers have which of the following characteristics? (check all that apply) (0.5pts)
anaerobic ATP synthesis
slow ATP hydrolysis
high myoglobin content
poor fatigue resistance
few capillaries making the tissue white in color
many large mitochondria
poor fatigue resistance few capillaries making the tissue white in color
Which of the following causes muscle fatigue? (check all that apply) (0.5pts)
lactic acid inhibits protein function
motor nerve fibers use up all the Ca2+ in the ECF
less ATP synthesis
accumulation of Na+ ions in the ECF
less signal input to the muscle by the central nervous system
lactic acid inhibits protein function less ATP synthesis less signal input to the muscle by the central nervous system
In smooth muscle, the calcium for contraction comes mainly from: (0.5pts)
In muscle metabolism, the phosphagen system is used for: (0.25pts)
Repayment of oxygen debt
Long-term energy (for prolonged exercise)
Immediate energy (the first 10 seconds of intense exercise)
Short-term energy (the first 1 minute of intense exercise)
Immediate energy ( the first 10 seconds of intense exercise)
The plasma membrane in the muscle fiber is referred to as:
the protein filled cytoplasm of the muscle fibers is referred to as:
The contractile proteins in a muscle fiber that are organized into enlongated bundles are referred to as:
the verticle plate of proteins that supports the thin filaments is known as:
the portion of the myofibril located between the two z discs is known as:
the ______ is a reservoir of calcium ions; it has gated channels in its membrane that open at the right times to release a flood of calcium into the cytostol.
the plasma membrane of a msucle fiber is called its ______ and its cytoplasm is called its _____.
List the three things that are contained in the sarcoplasm:
myofibrils glycogen: carbohydrate provides energy myoglobin: stores oxygen for muscle activity
the sarcolemma has tubular infoldings called ___, which penetrate through the cell from one side to the other.
what is its fxn?
T tubules (transverse) Fxn: signals the SR when to release calcium bursts
The protein found in thick filaments is called:
The thick filaments are ____ in the sarcromeres, while the thin filaments ___ in and out towards the z line
True/False: Myofilaments are arragned into sacromeres.
False: myofibrils are arragned into sacromeres
True/False: A muscle cell can also be referred to as a muscle cell.
the proteins found in thin filaments are called:
when a muscle fiber is relaxed, each ____ blocks the binding sites on actin and prevents myosin from binding to them.
the protein of a thin filament that covers actin is called:
List the three components of thin filaments:
Dark bands formed by parallel thick filaments that partly overlap the thin filaments is called the
A band ( think "dArk")
A lighter region in the middle of an A band that contains thick filaments only; thin filaments do not reach this far into the A band in relaxed msucle is called:
A dark line in the middle of an H band, where thick filaments are linked is called:
A light band composed of thin filaments only is called:
I Band (think lIght)
A protein disc to wich thin fialments and elastic filaments are anchored at each end of a sarcomere is called
the Z disc
The distance from one Z disc to the next; the contractile unit of a muscle fiber is called:
In terms of skeletal muscle organization, _____ are made up of myofilaments which form a ____ ____ , which then makes up a Fasicle which combind to make a __________.
myofibrils muscle fiber msucle group
What is the fxn of Smooth ER in a muscle?
used to store Ca2+ contraction
What is the repeating fxnal unit of a muscle tissue called?
During a muscle contraction, the _____ shortens by pulling the _____ closer together.
One nerve fiber and all the msucle fibers innervated by it is called:
Describe the # of fibers, location, and fxn of a small motor unit:
# of fibers: 3 - 6 fibers Location: fingers, eyes Fxn: Fine motor control
Describe the # of fibers, location, and fxn of a large motor unit:
# of fibers: 1000 muscle fibers fxn: strength location: gluteal or quadricep muscles
What are the fxn of motor units:
Strength control work in shifts/sustain long term contraction
Describe the structure of a motor unit:
cell bodies are in the brainstem/spinal cord axons (somatic motor fibers) lead to skeletal muscles each single nerve fiber branches out to a number of muscle fibers terminal branches spreads out and stiumulates all msucle fibers supplied by the nerve fiber muscle fibers of a single motor unit are not clustered together, but dispersed throught a muscle.
Lable the sacrolemma, snyaptic knbo, snyaptic cleft, snyaptic vesicles, junctional folds
the _____ of NMJ is irregualry indented, a little like a handprint pressed into soft clay, outside the synaptic cleft is called:
the nerve fiber ends in a bulbous swelling, where action potential is discharged is called the:
the knob doesnt directly touch the muscle fiber but is separated from it by a narrow space called:
the synaptic knob contains spheroidal organelles _______ which contain ACh
to respond to ACh the mucles fiber has about 50 million ______ that occur directly across from the synaptic knobs.
to maximize the # of ACh receptors and the sensitivity to the ACh the sarcolemma has ________ which increase the surface area of teh ACh senesitive membrane.
Explain the role of the synaptic vesicels:
the electrical signal ( nerve impulse) cannot jump across the synaptic cleft like a spark, so the nerve impulse casues the snypatic vesicles to undergo
exocytosis, releasing ACh into the cleft.
Describe the role of ACh:
to excite the muscle fibers
Describe the role of the ACh receptors:
connection between the neuron and the muscle
Describe the role of the Acetylcholinesterase:
Why is it important?
the enzyme breaks down ACh after the ACh has stimulated the muscle
important: turns off muscle contraction, allows it to relax
List three types of flaccid paralysis:
Botulism Myasthenia gravis Curare
the state in which muscles are limp and cannot contract is called:
one cause of flaccid paralysis, considered a poison in which competes with ACh for receptors but does not stimulate the muscle is called:
the cause of flaccid paralysis in which ACh release is blocked is called:
the cause of flaccid paralysis that is a result in an autoimmune disorder, in which there is a defiecency of ACh receptors is called:
a state in which muscles contract and cannot relax is called:
List two examples of spastic paralysis:
sarin nerve gas rigor mortis
Described the polarized plasma membrane in a cell at rest
ECF: excess of Na+ ions, electropositive ICF: excess of K+, and anions of proteins, nucleic acids, and phosphates making it more electronegative
the separation of charge between the ECF and the ICF in the sarcolemma establishes the:
Resting membrane potentional (RMP)
The RMP of a muscle cells is:
-90 mv (millivolts)
the ion channels in the plasms membrane of an excited muscle opens and Na+ diffused down the concentration gradient, so that the inside of the cell is slightly postive is known as:
Immediately when the ICF becomes slightly positive the Na+ channels close and open K+ channels and the K+ rushs out turing the ICF back to slightly negative again is called:
the quick voltage shift from negative RMP to a postive value and then back down again is called:
Describe the importance of action potential:
it is the point in which Ca2+ is release, and the muscle contracts
Outline the sequence of events in muscle contraction:
1. action potential generate by the nerve travels down the t tubels, electrical potentional acts on the SR and releases Ca2+ into the cytostol 2. Ca2+ binds to troponin, causes troponin to change shape, which pulls troypomyosin, exposing myosin binding sites 3. myosin binds to the binding sites, this causes ADP, P to leave the myosin head, and causes the myosin to move and pull actin towards the sacromere 4. a new ATP attaches to the mysoin head, causing it to detach from actin, the ATP hydrolizaes into ADP, P and is ready to start the cyle again.
Outline the sequence of events in muscle relaxation:
1. myosin must first detach from actin, happens when ATP attaches to myosin to break the cross brigde. 2. nerve impusles stop, ACh is broken down by AChE 3. Ca2+ leaves the troponin, and is absorbed back into the SR via active transport ( requires ATP) 4. causes troypomyosin to curl around on the binding sites
Describe the role of Ca2+ in muscle relaxation:
Ca2+ leaves the troponin, absorbed back into the SR via active transport ( requires ATP) and causes the tropomyosin to cover the binding sites again
Describe the three roles of ATP in muscles:
1. Break cross bridges - between myosin and actin 2. Active transport - to get Ca2+ back into the SR, and to depolarization by the NA+ K+ pump 3. Muscle Metabolism
Define Rigor Mortis:
Explain the causes:
Definition: harding of muscles and stiffening of the body 3 - 4 hours after death
Causes: deterioration SR releases Ca2+, Ca2+ activates myosin-actin cross bridges, myosin can't release w/o ATP and no ATP is available in a dead body
Describe the role of ATP in Rigor Mortis:
myosin cant release from the myosin-actin cross bridge w/o ATP, and no more ATP is available in a dead body
What are the three ways to vary muscle tension?
Motor unit recruitment length-tension relationship temporal summination
Explain what happens during each phase of a muscle twitch:
latent period: delay of about 2 millseconds b/w onset of stimulis and the onset of the twitch contraction phase: the muscle begins to produce external tension and move a resisting object or load, short - lived relaxation phase: SR quickly reabsorbs Ca2+ before muscle develops maximal force, ca2+ leaves, myosin releases, tension declines
Describe what factors vary the strength of a muscle twitch:
frequency in which stiumlation takes place: closer together - stronger the Ca2+ concentration in the sarcoplasm how stretched the muscle was before situmation took place Temp, pH, and Hydration
Describe how the length - tension relationship determines the strength of muscle contraction:
overly contracted: thick filaments butt against the Z disc and the muscle fiber cant contract much more overly stretched: too little overlap b/w the thick and thin myofilaments that few cross-bridges are made ideal: max # of cross bridges can be made
True/False: all muscle contractions are considered all or nothing - the # of nerve firings has no impact on the strength of the contraction
False - the # of firings does have impact on strenght of contraction and are considered all or nothing
Describe motor unit recruitment:
Subthreshold stimuli: produces no muscle contraction threshold and above: excites more and more nerve fibers and motor units, stronger contractions maximum: all nerve fibers are stimulated, no further increase in muscle tension
Describe the effect of temoral summation:
Each new stimulus arrives before the previous twitch is over, generates higher tension, and the muscle relaxes only partially between stimuli Treppe: moderate freq. of stimulation, muscle relaxes fully b/w contractions Incomplete teanus: higher freq., muscle does not have time to relax between contraction twitchs Complete teanus: high freq., muscle does not have time to relax at all, continual contraction, muscle fatigues, tension declines
Describe the contracted sacromere:
Z line: moves in A band: does not move I band: shortens (actin is pulled) H band: reduced in space
a contraction in which there is a change in tension, without change in length is called:
"iso" - same "metric"- measure, length
Example: Holding a weight, muscle devlopes tension, but doesnt change length
a contraction in which there is a change in length at constant tension is called:
"iso" same t - tonic - tension
muscle shortening is known as:
concentric contraction Ex: Flexing your arm to bring a weight up
muscle lengthening is known as:
eccentric contraction: Ex: extending your arm down to bring down a weight during a bicep curl
Describe how muscle get ATP for immediate energy, the phosphage system:
List the 2 enzymes involved:
a. gets most of its ATP needs from borrowing phosphate groups from other molecules and transfering them to ADP
Enzymes: myokinase, Creatine(not a standard source)
**buying time until other systems kick in**
Describe how muscles get ATP for short term energy, anaerobic fermenation, and glycolysis:
glycolysis: break down glucose, generating ATP, glucose is converted to lactic acid anaerobic (no oxygen): lactic acid builds up, crystals
*doesnt last long, still buying time until long term energy*
Describe how mucles get ATP for long term energy from aerobic respiration:
Glycogen is broken down (2 atp) into pyruvic acid, Pyruvid acid goes into citric acid cycle, then finally the electron transport chain for 36 ATP.
glucose comes from glycogen and fatty acids
State factors that contribute to muscle fatiuge:
No more glycogen ( fuel depletion) latic acid build up - more acidic, enzymes dont work as effiecently K+ in ECF builds up - no xchange of Na+ and K+ is less exictiability of fibers ADP, P accumilation Electrolyte loss Central nervous system fatigue - mental fatigue ACh deficit - decrease excitablilty
List the three modes of ATP systhesis in msucle metabolism:
Immediate Energy: phosphagen system Short term Energy: glycogen-lactic acid system (glycolysis, anaerobic ferementation) Long term: aerobic respiration
Compare Slow oxidative and Fast glycolytic fibers:
SlowATP: aerobic Myoglobin: abundant glyocgen: low mitochondria: abundant and large capillaries: abundant color red
F ast ATP: anaerobic Myoglobin: low glycogen: abundant mitochondria: few and small capillaries: few color: white
List three ways in which smooth muscle is similar to skeletal muscle:
1. filaments slide 2. Ca2+ for contractions 3. use ATP
Liste the cellular structure, location, source of stimulation, source of calcium and level of control of smooth muscle:
Smoothcellular structure: single nucli, no striations, no sacromere, no t tubules, no troponin location: lines hollow organs, intestines, lungs, piloerector source of stimiulation: autonomic nervous system, how acidic, stretch, and pace maker activity level of control: involuntary source of calcium: ECF
which type of energy ( muscle metabolism) would you use to for a few yards chase after a soccer ball? _____ or _____
immediate or short term
which is NOT a cause of muscle fatigue?
A. lack of a "will to win"
B. atp deficit
C. decrease exciteability caused by excessive calcium in the ECF
D. decreased excitability caused by ACh deficit
which of the following is NOT a mode of sitmulating smooth muscle?
B. anxiety level
C. amount of stretch
D. autonomic nervous system
in a slow wocidative muscle how abundant are the following substances:
glycogen: low capillaries: abundant myoglobin: abundant
which of the following is not a fxn of muscle tissue:
A. produce body heat
B. conduct electrical impulses
C. store the majority of the body's calcium
D. conversion of chemical energy to mechanical energy
what is the opposing force of an isometric contraction?
C. muscle strength ability
the sacromere is the repeating ____ __
__ of the myofibril and has the organizational order
which of the terms refers to a "muscle cell"
D. muscle fiber
which part of actin does calcium bind to to uncover tropomyosin from the myosin binding sites?
a. myosin heads
c. distal troyomyosin
d. thin filament
e. synaptic vesicles
true/false: each muscle is innervated by many neurons
true/false: during a msucle contraction the distance between the z discs and the h band both shorten
true/fasle: one muscle fiber action potential causes only one muscle fiber twitch