Chapter 8: Muscle Physiology Flashcards
What is a myofibril?
Muscle fiber
What is the sarcolemma?
The membrane surrounding muscle fibers
How many nuclei do muscle fibers have?
Several nuclei
What organelle is responsible for energy production in muscle fibers?
Mitochondria
What type of energy is produced by glycogen?
Energy from glucose
What are lateral sacs also known as?
Terminal cisternae
What does the sarcoplasmic reticulum store?
Calcium ions
What is the function of T-tubules?
Bring action potential to the center of the muscle fiber
What type of muscle is striated muscle?
Smooth muscle is non-striated
What are the two types of contractile proteins in muscle fibers?
Myosin and actin
What is the role of tropomyosin in muscle contraction?
Covers binding sites on actin
What is the function of troponin?
Binds calcium and triggers tropomyosin movement
What is the function of titin in muscle fibers?
Stabilizes myosin molecules
What is the function of nebulin?
Stabilizes actin molecules
What is a sarcomere?
The striated region of a muscle fiber
What is the I band in a sarcomere?
Region with actin by itself
What is the H zone in a sarcomere?
Region with myosin by itself
What is the A band in a sarcomere?
Overlap of myosin and actin
What causes the striations in striated muscle?
The dark color of the A band
What is the role of the neuromuscular junction (NMJ)?
It facilitates the transmission of action potentials to muscle fibers.
What are T-tubules and their function?
They help transmit action potentials into the muscle fiber and trigger calcium release from the sarcoplasmic reticulum.
What do ryanodine receptors (RUBI) do?
They release calcium from lateral sacs of the sarcoplasmic reticulum.
What is the first step in muscle contraction involving calcium?
Calcium binds to troponin.
What happens to tropomyosin when calcium binds to troponin?
Tropomyosin gets removed, exposing actin binding sites.
What is the term for the muscle contraction that occurs due to a single stimulation?
Twitch.
What is the difference between summation and tetanus in muscle contractions?
Summation is the increase in force with repeated stimulation, while tetanus is sustained contraction due to high-frequency stimulation.
What is the optimal length for generating maximal force in muscle contraction?
Optimal length = optimal force.
What is the role of ATP in muscle contraction?
ATP is necessary for forming cross-bridges and releasing myosin from actin.
What are the two types of isotonic contractions?
- Concentric - towards the center of the body
- Eccentric - away from the center of the body.
What type of contraction occurs during a plank, pilates, or yoga?
Isometric contraction.
What happens during muscle relaxation?
Calcium is pumped back into the sarcoplasmic reticulum.
What is rigor mortis?
A condition where no ATP is available, causing calcium to be bound and resulting in stiffness.
What is the process of glycolysis?
It occurs in the cytoplasm and does not require oxygen.
What type of respiration occurs in the mitochondria?
Oxidative respiration.
Fill in the blank: The sliding filament model involves the interaction of _______ and myosin.
actin.
True or False: Isometric contractions result in movement.
False.
What are the characteristics of smooth muscle?
Unstriated, dense bodies, poorly developed sarcoplasmic reticulum, does not have troponin
Smooth muscle is different from skeletal muscle in structure and function.
What is the role of tropomyosin in smooth muscle?
Tropomyosin is present but functions differently than in skeletal muscle
In smooth muscle, tropomyosin does not block myosin binding sites as it does in skeletal muscle.
What are the two types of smooth muscle?
Multi-unit smooth muscle and single-unit smooth muscle
Each type has distinct structural and functional characteristics.
How is multi-unit smooth muscle stimulated?
Each cell is independently stimulated
Examples include the iris and ciliary muscle.
How is single-unit smooth muscle characterized?
Electrically linked cells, functioning as a unit
This type is commonly found in organ systems.
What is a key advantage of smooth muscle?
Uses much less energy than skeletal muscle
This efficiency is beneficial for long-term contractions.
What is the function of gap junctions in smooth muscle?
Allow electrical coupling between cells
This enables coordinated contractions in single-unit smooth muscle.
Fill in the blank: Smooth muscle has _______ bodies instead of Z lines.
dense
Dense bodies serve as anchorage points for the contractile apparatus.
True or False: Smooth muscle has a well-developed sarcoplasmic reticulum.
False
Smooth muscle has a poorly developed sarcoplasmic reticulum compared to skeletal muscle.
What activates crossbridge formation in smooth muscle?
Calcium ions
Calcium binds to calmodulin, which activates myosin light chain kinase.
What is the significance of pacemaker activity in smooth muscle?
It helps regulate rhythmic contractions
Pacemaker cells can initiate spontaneous contractions in some smooth muscle tissues.
What are the two main types of muscle fibers?
Fast and Slow
Fast fibers are used for quick bursts of activity, while slow fibers are used for endurance activities.
What type of activities predominantly use slow muscle fibers?
Walking, posture
Slow fibers are utilized frequently for activities that require endurance.
What type of activities predominantly use fast muscle fibers?
Sprinting, piano playing
Fast fibers are used occasionally for activities requiring quick bursts of energy.
What is the primary role of mitochondria in muscle fibers?
Energy production
Mitochondria are responsible for ATP production, crucial for muscle function.
What is myoglobin?
A protein that stores oxygen in muscle cells
Myoglobin is particularly abundant in red muscle fibers.
What are the two types of muscle fatigue?
Central Fatigue and Peripheral Fatigue
Central fatigue involves the brain’s influence, while peripheral fatigue relates to muscle function.
What is central fatigue?
Mind over matter phenomenon
Central fatigue can affect performance due to psychological factors.
What disease is associated with muscular dystrophy?
Duchenne Muscular Dystrophy
This is a genetic disorder characterized by progressive muscle degeneration.
What is dystrophin?
A protein that holds muscle fibers together
Dystrophin attaches muscle fibers to the sarcolemma.
What role does lactic acid play in muscle fatigue?
It accumulates during intense exercise
Lactic acid buildup can contribute to muscle fatigue and soreness.
What is the primary function of the Golgi Tendon Organ?
Governs tension in muscles
The Golgi tendon organ helps prevent muscle damage by sensing tension.
What is the role of muscle spindle receptors?
Governs stretch in muscles
Muscle spindles are sensory receptors that detect changes in muscle length.
Which levels of the nervous system control motor movement?
Spinal Cord, Brain Stem, Motor Cortex
Each level plays a distinct role in the coordination of movement.
True or False: Cardiac and respiratory failure can affect muscle function.
True
These conditions can lead to reduced oxygen supply and muscle performance.
Fill in the blank: The _______ is responsible for the stretch reflex in muscles.
muscle spindle
Muscle spindles detect stretch and initiate reflex actions.
