Chapter 9 (Exam 1) Flashcards
___ is a term used to describe when a muscle is stimulated repeatedly at a high rate, the amount of tension gradually increases to a steady maximum tension, and a higher stimulation frequency eliminates the relaxation phase.
Complete Tetanus
The muscle fiber cannot produce any active tension when the ____ is reduced to zero?
Zone of Overlap
The type of muscle fiber that is most resistant to fatigue is the ________ fiber.
Slow
A ___ consists of a transverse tubule and 2 terminal cisternae.
Triad
____ is the smooth but steady increase in muscular tension that is produced by increasing the number of active motor units.
Recruitment
The ___ is the region of the sarcomere that always contains thin filaments.
I band
During which phase of the contraction cycle do the calcium ions bind to troponin?
Active Site Exposure
The ____ acts as an ATPase during the contraction cycle of muscle.
Myosin head
____ is the delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent muscle fibers together.
Endomysium
Interactions between actin and myosin filaments of the sarcomere are responsible for ____.
Muscle Contraction
The approach that occurs during a sustained contraction, when motor units are activated on a rotating basis, so some of them are resting and recovering while others are actively contracting is known as ____.
Asynchronous motor unit summation
Muscular force can be adjusted to match different loads by what 3 things?
- Recruiting more motor units
- Varying the frequency of action potentials in motor neurons
- Recruiting larger motor units
Most of muscles energy is produced where during activities that require aerobic endurance?
Mitochondria
____ is the type of contraction in which the muscle fibers do not shorten.
Isometric
When a muscle fiber ____ the zones of overlap get larger, the H bands and I bands get smaller, the Z lines get closer together, and the width of the A band remains constant.
Contracts
What region of the sarcomere contains the thick filaments?
A band
The end plate membrane becomes more permeable to sodium ions when ___ binds to receptors at the motor end plate.
ACh (Acetylcholine)
Synaptic vesicles containing neurotransmitters are released by ________ when the action potential arrives.
Exocytosis
4 function of skeletal muscle?
- Maintain Body Temperature
- Maintain Posture
- Produce Movement
- Guard Body Entrances and Exits
A single motor neuron together with all the muscle fibers it innervates is called ____.
A Motor Unit
The plasma membrane of skeletal muscle is called the ____.
Sarcolemma
Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber ____.
Shortens
After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as ____.
Rigor Mortis
The Sarcoplasmic Reticulum (SR) releases ____ in response to action potentials arriving along the Transverse Tubules (T Tubules).
Calcium Ions
Calcium ions arriving within the zone of overlap initiates the ____.
Contraction Cycle
What thin filaments structure consists of three globular subunits one of which has a receptor that binds 2 calcium ions.
Troponin
____ occurs when a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs.
Wave summation
The ___ surrounds individual muscle cells.
Endomysium
From microscopic to gross levels determine the correct structural order of skeletal muscles. (Fiber, Fascicle, Myofibril, Muscle)
Myofibril, Fiber, Fascicle, Muscle
____ is the dense layer of connective tissue that surrounds the entire skeletal muscle.
Epimysium
At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a____.
Tendon
Glucose is produced from lactate in the liver during what cycle?
Cori Cycle
___ acts as an energy reserve in the muscle tissue.
Creatine Phosphate (CP)
At rest, active sites on the actin are blocked by ____.
Tropomyosin
Muscle tissue consists chiefly of cells that are specialized for ____.
Contraction
ACh receptors are located on the ____.
Motor End Plate
During the ___ phase of a muscle twitch active sites on thin filaments are exposed and cross-bridge interactions occur.
Contraction Phase
____ fibers have a large diameter, have densely packe myofibrils, have large glycogen reserves, and have a few mitochondria.
Fast
____ and ____ become connected by myosin cross-bridges during muscle contraction.
Thin and thick filaments
____ motor units have small fiber diameters, take about 3 times as long to reach peak tension, are rich in the red protein myoglobin, and generate much less tension
Slow Motor Units
During excitation contraction coupling calcium ions are released from the ____.
Sarcoplasmic Reticulum (SR)
___ is a repeating unit of striated myofibrils.
Sarcomere
The ____ is the storage and the release site for calcium ions.
Sarcoplasmic Reticulum
A muscle produces its highest tension when in complete ________.
Tetanus
The complex of a transverse tubule and two adjacent terminal cisternae is known as a ________.
Triad
The most important factor in decreasing the intracellular concentration of calcium ion after contraction is
Active Transport of Calcium into the SR
The skeletal muscle relies primarily on the aerobic metabolism of pyruvate to generate ATP at what level of activity?
Moderate
Thin filaments are anchored where?
Z line
An oxygen debt, a shift to anaerobic glycolysis, muscle fatigue, and an increase in intracellular lactate are all signs of what to a muscle?
Decreased blood flow
Calcium levels fall during what phase of a muscle twitch?
Relaxation
What begins when stored calcium ions are released into the sarcoplasm through gated calcium channels?
Muscle Contraction
After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs.
An Oxygen Debt
Muscle tension exceeds the load and the muscle lifts the load in what type of contraction?
Isotonic Contraction
What are the 3 types of muscle tissue and their locations?
- Skeletal - attached to bones of skeleton
- Cardiac - located in the heart
- Smooth - located in the digestive tract
A/an ____ provides attachment over a broad are that may involve more than one bone.
Aponeurosis
____ is an enlargement of the stimulated muscle.
Hypertrophy
____ is the loss of muscle tone and mass due to lack of muscle stimulation.
Atrophy
____ produces paralysis of skeletal muscles by preventing ACh release at neuromuscular junctions.
Botulism
____ is a fibrous layer that divides the skeletal muscle into a series of compartments.
Perimysium
