Chapter 38 Musculoskeletal System Flashcards
The powerstroke in muscle cells occurs when ___.
inorganic phosphate is released from myosin
True or False: Skeletal muscle cells produce action potentials.
True
When a muscle cell is stimulated to contract, the sarcoplasmic reticulum releases ____.
calcium ions
____ is the protein that physically blocks the myosin binding sites on the thin filaments.
trompomyosin
Which of the following types of muscles has(have) contractile proteins organized into sarcomeres and are striated muscles?
cardiac and skeletal
The “tubes of protein” that are bundles of the contractile proteins found in striated muscle are called ____.
thin filaments
How do muscle fibers shorten during contraction?
Two types of protein filaments overlap and slide past each other.
What muscle type is voluntary?
skeletal
Skeletal systems are important for ___.
movement
The striated appearance of muscle is due to the ____.
organization of the sarcoplasmic reticulum
True or False: Muscles can contract and relax.
True
What needs to happen with muscles in order for movement to occur?
they need something to pull on
What are bone and cartilage part of?
endoskeletons
3 Types of Skeletons
- hydrostatic
- exoskeleton
- endoskeleton
Hydrostatic Skeleton
formed by a fluid-filled compartment within the body
Exoskeleton
external skeleton on the surface of the animal
Example of an Animal with an Exoskeleton
arthropods (spiders)
Endoskeleton
hard mineralized structures within soft tissues
Primitive endoskeletons include spicules of ___.
sponges
coelom
fluid-filled body cavity
What are muscles responsible for?
tissue movement
True or False: All animals have muscle.
False
What animals do NOT have muscle?
sponges and cnidarians
3 Types of Muscle
- skeletal
- cardiac
- smooth
Characteristics of Skeletal Muscle
- voluntary and involuntary movement of breathing
- contain sarcomeres
- multinucleated
Characteristics of Cardiac Muscle
- heart contraction; involuntary
- contains sarcomeres and intercalated discs
- branched
Characteristics of Smooth Muscle
- involuntary
- movement in gut, bladder, and blood vessels
- do not contain sarcomeres
How do non-striated muscles differ from striated muscles?
the presence of sarcomeres
Myofibril
tightly packed filament bundles
Myocyte
muscle cell
Muscle fiber
muscle cell
Are skeletal muscle cells multinucleated?
YES
Characteristics of a Sarcomere
- unit of contraction
- these units repeat
What are thick filaments made of?
myosin
What are thin filaments made of?
actin
2 Types of Contractile Proteins
actin and myosin
Sliding Filament Theory
filaments slide past each other whenever contraction occurs
The length of the sarcomere is related to ___.
how much force can be produced
Is length related to overlap in the sarcomere?
YES
Too much overlap ___.
nowhere for the myosin to move the actin
Too little overlap ___.
myosin can’t grab actin
Neuromuscular Junction
point of contact between a motor neuron and a skeletal muscle cell
Motor Unit
a motor neuron and all of the muscle fibers it innervates
Motor Neuron
a neuron that sends an impulse to a muscle
Can a motor neuron terminate on multiple muscle cells?
YES
Sarcoplasmic Reticulum
endoplasmic reticulum inside a muscle cell
Sarcoplasmic reticulum stores ___.
calcium
Where does depolarization start in muscle cells?
ligand gated channels
What ion enters into a skeletal muscle cell to create and action potential?
Na+ (sodium)
What does the action potential in a muscle cell cause to be released from the sarcoplasmic reticulum?
calcium
Characteristics of Myosin
- multiple subunits
- place of ATPase activity
Characteristics of Actin Filament
- actin monomers
- myosin binding site
2 Types of Regulatory Proteins in Muscles
tropomyosin and troponin
Characteristics of Troponin
- binds calcium ions
- interacts with tropomyosin
Tropomyosin
blocks myosin binding site
What is released to cause a powerstroke in muscle contraction?
phosphate
What is rigor?
stiffening due to death of muscle
What does calcium bind to?
troponin
When calcium bind to troponin, what does troponin do?
the troponin reveals the myosin binding site by removing tropomyosin
What causes myosin to release actin?
ATP binding to the myosin
What causes the myosin head to cock forward?
ATP being broken down into ADP
Characteristics of Slow-Twitch Muscle Cells
- red, oxidative fibers
- aerobic
- has many mitochondria
- contains myoglobin
Characteristics of Fast-Twitch Muscle Cells
- white, glycolytic fibers
- anaerobic
- fewer mitochondria
- do NOT contain myoglobin
The neurotransmitter _____ binds to receptors in plasma membrane of a muscle cell to stimulate contraction.
Acetylcholine
What is the role of calcium ions in the control of muscle contraction?
it bind to troponin to stimulate contraction
Which muscle protein hydrolyzes ATP to stimulate muscle contraction?
myosin
A pair of closely related bird species includes one that migrates long distances that takes months and another that has evolved near-flightlessness on its island home, with the exception of short flights to escape its predators. What might you expect to find when comparing the breast muscles that are used for flight of these two species?
The migratory species would have relatively higher levels of myoglobin.
When animals die, the lack of ATP causes muscles to stiffen in rigor mortis because ____.
Actin and myosin cannot separate from each other without ATP
Examine the picture below. This capillary could be in a____. This is because ___.
skeletal muscle…. carbon dioxide is diffusing from the tissue labeled 1 into the plasma
True or False: When a muscle cell shortens, the amount of overlap between the thick and thin filament decreases.
False
