Muscles and Movement Flashcards
What are the three types of muscle tissue in the body?
Skeletal, Cardiac, and Smooth muscle
which type of muscle is responsible for voluntary movement
skeletal
where is the cardiac muscle found
found in the heart and moves blood through thecirculatory system
what is the main function of smooth muscle
controls movement of substance in internal organs and tubes, such as blood vessels and the digestive system
which types f muscle are under involuntary control
cardiac and smooth m
what is the basic structural unit of skeletal muscle
The sarcomere
which two proteins are responsible for muscle contraction
actin and myosin
What are the names of the three connective tissue layers surrounding muscle fibers?
Epimysium, Perimysium, and Endomysium
what is the function of the sarcoplasmic reticulum in muscle cells
stores and releases calcium ions for muscle contraction
what is the role of transverse tubules (t-tubules)
allows action potentials to penetrate into the muscle fibers
what is the name of the model that describes how muscles contract
sliding filament theory
What happens to the sarcomere during contraction?
It shortens as actin filaments slide past myosin filaments
Which regulatory proteins control muscle contraction?
Troponin and Tropomyosin
What causes the myosin binding sites on actin to be exposed?
Calcium ions bind to troponin, moving tropomyosin
What is the function of ATP in muscle contraction?
ATP provides energy for cross-bridge cycling and detachment of myosin from actin
what is the neuromuscular junction
the synapse between the motor neuro and the muscle fiber
Which neurotransmitter is released at the neuromuscular junction?
Acetylcholine
How does calcium trigger muscle contraction?
Calcium binds to troponin, shifting tropomyosin to expose myosin-binding sites on actin
what ion is essential for muscle relaxation
Calcium must be pumped back into the sarcoplasmic reticulum for relaxation to occur
What enzyme breaks down acetylcholine to stop muscle contraction?
Acetylcholinesterase
in cardiac muscle what are intercalated discs
gap junctions allowing electrical signals to pass between cardiac cells
How does cardiac muscle differ from skeletal muscle in contraction?
Cardiac muscle has pacemaker cells and is myogenic, meaning it contracts without neural input
What is the role of calcium-induced calcium release in cardiac muscle?
Extracellular calcium enters through DHP receptors, triggering additional calcium release from the sarcoplasmic reticulum
Why does cardiac muscle have a longer refractory period?
To prevent tetanus and allow the heart to fill with blood between beats
What are the two types of smooth muscle, and how do they differ?
Single-unit smooth muscle contracts as a syncytium via gap junctions, while multi-unit smooth muscle contracts independently
how is smooth muscle contraction regulated differently from skeletal muscle
smooth muscle uses calmodulin instead of tropine to regulate contraction
which enzyme activates myosin in smooth muscle
myosin light chain kinase
which type of muscle contraction generates force without shortening the muscle
isometric contraction
what adaptations do frogs have that allow them to jump long distances
powerful skeletal muscles and tendon storage of elastic energy
what can hummingbirds fly backwards and hover
they have unique wing muscle adaptations and high frequency wings beats
which muscle types can contract the fastest
skeletal
which muscle type contracts the slowest but can retain force for long durations
smooth muscle
Why do cardiac muscle cells have a longer refractory period than skeletal muscle cells?
To prevent sustained contractions that would stop the heart from pumping
What role does acetylcholinesterase play in muscle contraction?
Breaks down acetylcholine to stop the signal for contraction
What would happen if T-tubules were absent in muscle fibers?
Action potentials would not efficiently reach deep muscle fibers, reducing contraction efficiency
How does the recruitment of motor units affect muscle force generation?
More motor units activated = greater force production
What is the difference between neurogenic and myogenic muscle contraction?
Neurogenic contraction requires nervous system input, while myogenic contraction is self-initiated by pacemaker cells)
how do muscles generate movement in vertebrates
they contract and pull on bones via tendons
what are the three types of skeletal support systems in animals
endoskeleton, exoskeleton and hydrostatic
what are the three main energy systems that supply ATP for muscle contraction
immediate, glycolic and oxidative systems
which type of muscle fiber is best suited for endurance and which is best for power
type 1=endurance type11b= power
what is the main difference between muscle strength and power
strength is ,maximum force and power is force exerted rapidly
what factors contribute to muscle fatigue
exercise intensity, metabolism type, muscle composition and fitness level
how does motor unit requirement affect muscle force
the more motor units recruited= greater force generated
what is the length-tension relationship in muscle contraction
force generation depends on the muscles initial length before contraction
how does cross-sectional area affect muscle strength
larger muscle fibers generate more force
What is the difference between fusiform and pennate muscle architecture?
Fusiform = parallel fibers, optimized for speed; Pennate = angled fibers, optimized for force
Which type of muscle architecture produces the greatest force?
Pennate muscles
What is a lever system in biomechanics?
A system where bones and muscles work together to move a load
Which class of lever is most common in the human body, and what is its function?
Class III lever; allows for greater range and speed of motion
Why do sprinters and marathon runners have different muscle fiber compositions?
Sprinters have more fast-twitch fibers for power, marathon runners have more slow-twitch fibers for endurance
How do tendons contribute to efficient movement?
Store and release elastic energy to enhance force production
How does calcium trigger muscle contraction?
Binds to troponin, shifting tropomyosin to expose myosin-binding sites on actin
Why is ATP required for both muscle contraction and relaxation?
Powers cross-bridge cycling and calcium reuptake into the sarcoplasmic reticulum
What is a lever system in biomechanics?
A system where bones and muscles work together to move a load
What are the three muscles types in vertebrates?
Skeletal
Cardiac
Smooth
What are the primary muscle types in invertebrates?
transversely striated
obliquely striated
smooth muscles
what is the role of calcium ions in muscle contraction?
they regulate the binding of myosin to actin filaments
how do midges achieve 1000Hz wing beats?
they use asynchronous flight muscles, maintaining constant intracellular calcium levels.
how do birds and bats differ in flight mechanisms?
birds use large pectoral muscles, while bats rely on elastic skin and smaller muscles for control.
what adaption allows hummingbirds to hover and fly backwards?
large pectoral muscles
rapid metabolism
unique wing angles
elongated wings
how do squids achieve jet proulsion?
by contracting circumferential muscles in their mantle to expel water forcefully
why do crabs move sideways?
their exoskeleton and hinge joints allow lateral movement
what is the relationship between locomotion and energy cost?
swimming is the most efficient, followed by flying, and running is most costly.
when did the first version of myosin appear and what was its function?
over 2 billion years ago and was to keep intracellular fluids separate from the environment.
How did cnidarian and bilaterian muscles evolve independently?
By adding novel proteins to a pre-existing contractile apparatus, resulting in similar muscle structures.
What are the two main types of muscle fibers?
Slow-twitch (Type I) for endurance and Fast-twitch (Type II) for rapid force generation.
What factors affect the force of muscle contraction?
Cross-sectional area, neural stimulation, muscle fiber type, and energy availability.
how does the catch state in mullusks work?
Twitchin protein binds myosin filaments, allowing tension to be maintained with minimal energy use
what is the difference between synchronous and asynchronous flight muscles?
Synchronous: One contraction per nerve impulse.
Asynchronous: Constant Ca²⁺ levels allow muscles to contract multiple times per impulse.
why is asynchronous muscle flight more efficient?
Fewer nerve impulses are needed, and Ca²⁺ pumps are minimised, reducing energy cost.
how do hummingbirds rains support their flight activities?
They have a large hippocampus for spatial memory and an enlarged nucleus lentiformis mesencephali for visual processing.
what is a hydrostatic skeleton and how does it aid movement?
a fluid filled cavity that muscles contract against enabling motion in worms and other invertebrates
why is swimming and flying more energy efficient than running?
gliding and air currents helps reduce energy needed and water supports body weight again reducing energy needed.
