Muscle Principles
Muscles have two points of attachment. What are those attachments?
An origin and insertion
What are the characteristics of slow-twitch fibers?
1. Resistant to fatigue
2. Oxidative
What is the function of the masseter muscle?
Elevates the mandible and occludes teeth
What is the small unit in muscle fibers that allows a skeletal muscle to contract?
Sarcomere
What is the theory that explains how muscles shorten?
sliding filament theory
What is Wolf's Law?
Muscle shapes the bone
What are the characteristics of fast-twitch fibers?
1. fast glycolytic
2. cause rapid fatigue
Adducts, rotates, extends, and flexes the arm
What is the thick filament in skeletal muscle called?
Myosin
The cross bridge pulls actin, which slides over the myosin – known as the ____
Power Stroke
A student says muscles exert forces to push bones to make movement.
Use muscle principles to explain why this is incorrect.
Muscles exert forces only to pull, never to push.
A soccer player suddenly sprints at maximum speed. What muscle fiber type is primarily engaged and why?
Fast-twitch muscle fibers generate quick, powerful contractions for sprinting because they're not long-endurance like slow-twitch.
A student cannot extend their arm due to an injury.
Which muscle is likely injured, and how does its action explain the loss of movement?
The triceps are responsible for elbow extension; damage to them prevents full arm extension.
What is the structure that stores and releases calcium for muscle contraction
Sarcoplasmic Reticulum
What happens to actin binding sites when calcium is released?
They become exposed.
Why do muscles usually work in antagonistic pairs instead of alone?
Because they can only pull, not push; another muscle is needed to return to its original position, allowing for efficient control and movement
Why might a marathon runner rely on slow-twitch fibers rather than fast-twitch fibers?
Fast-twitch fibers cause rapid fatigue and aren't suited for high endurance sports like running.
What is the function of the supraspinatus
Adducts the shoulder
What is the function of the striated appearance of skeletal muscle
The muscle fibers under the striated appearance go in the direction of the pull to contract effectively
How does a lack of ATP contribute to rigor mortis
(use words such as Myosin, Actin, Fibers, Oxygen)
Oxygen is needed for cellular respiration, which produces ATP. When one dies, ATP decreases, which is required for myosin to release actin. Without ATP, the myosin heads stay attached, and the muscle fibers cannot relax.
Muscles that cross many joints are for ____ and _____?
speed and agility
A basketball player practices vertical jumps and starts jumping higher over time. Which muscle fibers are improving, and how do they help with jumping power?
What are fast-twitch fibers, because they generate strong, explosive force needed for jumping?
A runner strains their gastrocnemius muscle.
How will this affect walking or jumping?
Plantar flexion is weakened, making walking, running, and jumping difficult.
If the sarcomeres in a muscle fiber shorten, what happens to the overall muscle and why?
The muscle shortens because, within muscle fibers, the filaments slide past one another, causing the sarcomeres to contract and pulling the fibers inward.
A patient has low calcium levels. Predict how the muscle contraction will change and explain your reasoning.
Low calcium levels can prevent calcium from binding to troponin. This prevents tropomyosin from shifting and exposes its active binding sites, leading to improper muscle contraction.