All Cards Flashcards
In the graded muscle contraction recruitment controls what?
Controls the force of contraction more precisely
In graded muscle contraction, the maximal stimulus is the strongest stimulus that does what?
Increases contractile force
ATP supplies the energy for what?
For muscle contraction
ATP is regenerated by what?
Direct phosphorylation of ADP by creatine phosphate, anaerobic, glycolysis, and aerobic respiration
Aerobic glycolysis occurs in what
The absence of oxygen
What does anaerobic glycolysis do?
It breaks down glucose to two pyruvic acid molecules, releasing enough energy to form small amounts of ATP and producing lactic acid
Aerobic respiration requires what
Requires oxygen and mitochondria
Aerobic respiration generates what
Large amount of ATP
Muscle fatigue is a state of what
Physiological inability to contract
Chemical changes involved in muscle fatigue include what?
Include ionic and balances, in organic phosphate, decreased ATP, increased magnesium, and decrease glycogen
In muscle fatigue, the extra amount of oxygen that the body must take in for restorative process is called what?
The Excess postexercise, oxygen consumption
The force of muscle contraction depends on what?
It depends on the frequency of stimulation the number of muscle fibers required, and the size of muscle fibers and the degree of muscle stretch
The velocity and duration of muscle contraction are influenced by what?
They are influenced by muscle fibertype, load, and recruitment
What do slow oxidative fibers do?
Contract slowly, depend on oxygen, Resist fatigue, and have high endurance.
What do fast Glycolytic fibers do?
Contract rapidly, use little oxygen, tire quickly, and are suited for short term, rapid movements
Fast oxidative fibers are what and have characteristics of what?
They are intermediate and have characteristics of both Glycolytic and slow oxidative fibers
Aerobic exercise results in what?
It results in the increase of the number of capillaries, mitochondria, and myogoblin within the muscle fibers. It also increases endurance, strength, and resistance to fatigue.
What is the function of the deep fascia?
It supports protects and provides roots for nerves and blood vessels
What is the function of the epimysium?
It covers the entire skeletal muscle
Describe what a myofibril is
It is a cylindrical structure within my muscle fibers
What is the function of a myofibril?
It performs contractions
Describe the sarcoplasmic reticulum
It is specialized, smooth endoplasmic reticulum in muscle cells
What is the function of the Sarcoplasmic Reticulum?
Stores and releases calcium critical for contraction
What is the function of a T tubule
To ensure uniform contraction across the fiber
Describe what a terminal cisternae is
It is enlarged areas of the SR
Where is the terminal cisternae found in?
Adjacent to the T tubules
What is the function of actin?
it is the primary protein that forms the backbone of thin filaments
what is the function of the troponin?
binds calcium, by moving tropomyosin to allow contraction
describe what myosin is?
it is a motor protein with heads that form cross bridges by attaching to actin
what is acetylcholinesterase?
it is an enzyme that breaks down Ach, stopping contraction signals
what does Myasthenia Gravis do?
The Ach receptors receptors are attacked
describe what the latent phase do?
It is a delay between the stimulation and the start of contraction
describe what unfused tetanus is
it is incomplete relaxation between stimuli
Shivering is an example of what?
Unfused tetnus
Describe what fused tetnus is?
Sustained contraction without relaxation
ATP sources Anerobic Respiration what does that do?
Produces ATP without oxygen; lactic acid builds up leading to fatigue
Neural controls in the cardiac muscle allow the heart to do what?
Allow the heart to speed up for brief periods
Where is smooth muscle tissue found in?
It is found in the walls of hollow visceral organs.
What is the smooth muscles role?
Their role is to force, fluids and other substances through internal body channels
What is extensibility?
It is the ability of a cell to receive and respond to a stimulus by changing its membrane potential
What happens when the muscle cells are relaxed?
They can be stretched even beyond their resting length
What does it mean when the muscle attachments are direct?
The epimysium is fused to the periosteum of a bone
What does a muscle cell contain?
Myofibrils, sarcoplasmic reticulum, and T tubules
What are myofibrils?
They are rod like structures that run parallel to the length of the muscle fiber
What is a Sarcomere composed of?
Myofilaments and contractile proteins
What are striations made out of?
A repeating series of dark, (A) bands and light( I) bands
Where are stations found in?
They are evident along the length of each myofibril
What does a myosin molecule consist of?
Six polypeptide chains with a rod like tail and globular heads attached via a flexible hinge
What does globular Actin have?
Myosin binding site
G Acton, sub units polymerize Into what?
Long actin filaments called filamentous
Elastic filaments extends from what to what?
The Z disc to the thick filament
What is the role of elastic filaments?
Maintains the organization of the A band
What does dystrophin link?
The thin filament to the integral proteins of the sarcolemma
When does the sarcoplasmic rectum release the calcium?
When the muscle fiber is stimulated to contract
What are T tubules?
They are investigations of the sarcolemma that run deep into the cell between the terminal cisterns
What does T tubules allow?
It allows change in the membrane potential to rapidly penetrate deep into the muscle fiber
What does contraction refer to in the sliding filament model?
It refers to the active shed of myosin cross bridges
What are cross bridges?
Force generating sites
What occurs to the thick and the thin filaments during contraction of the sliding filament model?
Neither of them change Length during contraction
What do skeletal muscle contractions require?
Requires activation of motor neurons in the spinal cord
What do motor neurons connect with?
They connect with skeletal muscles
What is an action potential?
It is a large change in a membrane potential that spreads rapidly over long distances with a cell
What do chemically gated ion channels create?
They create small local changes in membrane potential
What does the axon form as it branches?
It forms a neuromuscular junction with a single muscle fiber
What does the synaptic cleft separate?
The axon terminal and muscle fiber
Synaptic vesicles with the axon terminal contains what
Acetylcholine
What is excitation contraction coupling?
It is the sequence of events by which an action potential along the sarcolemma leads to the sliding of myofilaments
The transition of the AP along the T tubules causes what?
It causes voltage sensitive to be proteins to change shape, opening CA +2 release channels in the SR
In excitation contraction coupling, Calcium ions bind what?
Troponin
In excitation contraction coupling Calcium ions, remove what?
Removes the blocking action Of tropomyosin
In excitation contraction coupling, Myosin binding to Actin forms what and what begins?
Forms cross bridges, and contraction begins
What is the cross bridge cycling?
it is the series of events during which myosin heads pull thin filaments toward the center of the Sarcomere
How does the cross bridge cycling begin?
Epic begins when the energized myosin head attaches to an actin microfilament forming a cross bridge
In the cross bridge cycling ADP and PI released and then the myosin head does what?
The myosin head, pulls the actin filament toward the M line
In cross bridge cycling ATP attaches to myosin weakening what?
Weakening the link between myosin and actin and causing the myosin head to detach.
A muscle twitch is the response of what?
It is the response of a muscle to a single stimulation
Muscle contractions are graded in two ways describe them
An increase in the frequency of stimulation causes temporal summation, and the increase in strength of stimulation causes recruitment
In graded muscle contractions, temporal submission occurs when what happens?
When a second contraction begins before the muscle has completely relaxed
In the graded muscle contraction as the stimulation frequency increases what happens
The relaxation time between twitches becomes shorter, concentration of CA +2 in the cytosol rises, and wave summation becomes greater, progressing to unfused or incomplete tetanus
How would a drug that interferes with cross bridge formation affect muscle contraction
The contraction will not happen it blocks it and you would become paralyzed
List 3 factors that are responsible for duration of a muscle cell
1.How long stimulation lasts at NMJPresence of Ca ions in the sarcoplasmAvailability of ATP/fatigue issues
Tension rises to peak levels with brief periods of relaxation is what type of contraction?
Unfused Tetanus
Slightly higher tension results as a string of successive stimuli are received is what type of contraction?
Summation
Stimulus frequently is so rapid that relaxation is completely eliminated is what type of contraction?
Summation
How does the body produce sustained contractions? For example, posture requires back muscles to be contracted. You can stand up for many hours. Explain
You have one nerve contracting one muscle
A muscle producing peak tension during rapid cycles of contraction and no relaxation is said to be in?
Fused tetnus
What is a motor unit?
All muscle cells controlled by a single neuron – the eyeball needs extreme control, so one motor unit
communicates with 4-6 cells, while the leg muscles need only general control, so one motor unit
communicates with 1000-2000 cells.
What forms of energy reserves do resting skeletal muscle fibers contain?
CP, glycogen
What two mechanisms are used to generate ATP in a muscle cell?
Aerobic and anaerobic respiration
. List two areas of the body where you would not expect to find slow fibers.
Muscles surrounding the eyeballs and muscles of the fingers
Describe the relationship between lactic acid and fatigue.
As lactic acid levels increase, pH of the sarcoplasm drops, enzymes will not work, therefore, muscle is
fatigued and can no longer contract until homeostasis is regained.
What would happen if you were orbiting the moon for 6 months?
Disuse atrophy
What would happen to your muscles if you were in an accident and needed bed rest for 2 months
Disuse atrophy
What would happen if You have been bulking-up by drinking those gross GNC milkshakes loaded with creatine?
Hypertrophy
What would happen ifYou were in a skydiving accident where you severed the spinal cord at C-7?
Degeneration atrophy
What fibers are in a salmon?
Dark
What fibers are in a seal?
White
What is a spasm?
A sudden contraction of a single muscle in a larger muscle group
What is a cramp?
A painful spasm
What is a tremor?
Rhythmic, repeated contraction, produces shaking
