H: Muscle Tissue Flashcards
What is the name for the cytoplasm in a muscle cell?
Sarcoplasm
Smooth ER in a muscle cell?
Sarcoplasmic Reticulum
Plasma membrane in a muscle cell?
Sarcolemma
What are two alternate names for a muscle cell?
Muscle fiber or Myofiber
What are the three hierarchies of muscles?
Muscle cell -> muscle tissue -> muscle organ
What are the four special characteristics of muscle tissue?
- Excitability
- Contractility
- Extensibility
- Elasticity
What are the four major functions of muscle tissue?
- Producing movement
- Maintaining Posture
- Stabilizing joints
- Generating heat
Which type of muscle tissue is under voluntary control?
Skeletal muscle
Skeletal Muscle cells produce _____ and ______ contractions.
Strong; quick
What is a major defining characteristic of skeletal muscle?
Long multinucleate fibers. One cell can span the entire length of the muscle.
Cardiac muscles produce _____ and _____ contractions.
Strong; quick
What is a defining characteristic of cardiac muscle?
Intercalated discs that joint the branched uninucleate cells.
________ muscle fibers are striated but are very uniform, while _______ muscle fibers are striated but do not follow a uniform shape.
Skeletal; cardiac
_______ muscle fibers produce weak, slow contractions.
Smooth
Which muscle fiber does not have striations?
Smooth muscle
Which muscle fibers have central nuclei and arrange closely to form sheets?
Smooth muscle
Where is smooth muscle found?
In the walls of hallow organs.
Type I muscle fibers are ____, while type II muscle fibers are ____.
Slow; fast
Type I muscle fibers derive energy from what process?
Aerobic oxidative phosphorylation of fatty acids
Type I muscle fibers have many _______ and lots of _______ (give it its dark red color).
Mitochondria; myoglobin
T/F: Type IIb muscle fibers have more mitochondria and myoglobin, but less glycogen.
False!
Type IIa: many mitochondria, lots of myoglobin and glycogen
Type IIb: fewer mitochondria and myoglobin, but LOTS of glycogen (gives it pale color)
Which types of skeletal muscle fibers are adapted for rapid contractions, but fatigue quickly?
Type IIb
As fibers go from red (type I) to white (type IIb) what are the major physiological changes that occur?
Go from primarily aerobic oxidation (red, type I) –> oxidative metabolism and anaerobic glycolysis (intermediate, type IIa) –> primarily anaerobic glycolysis (white, type IIb)
A __________ __________ is a chemical synapse between a motor neuron and a skeletal muscle fiber.
Neuromuscular junction (aka motor end plate)
What does a motor unit consist of?
The motor neuron and all the muscle fibers it innervates.
What are the lateral boundaries of a sarcomere?
Z lines
What is the center line of a sarcomere?
M line
What are the thin filaments?
Actin
What are the the thick filaments?
Myosin
What is found in the A band?
Combination of myosin and actin
What is found in the I bands?
Only actin. No myosin.
The lengths of what do not change during muscle contraction?
Thin and thick filaments.
The ______ ______ and ______ _______ shrink and eventually disappear during muscle contraction.
H zone; I band
Describe the “excitation” steps in excitation-contraction coupling?
- Action potential moves along sarcolemma and down the T tubules
- Ca2+ release from terminal cisternae of SR
- Ca2+ binds to troponin, troponin changes shape removing binding sites of tropomyosin, exposing actin active sites
Describe the “contraction” steps in excitation-contraction coupling.
- Myosin cross bridges alternately attach and detach to actin, pulling the actin toward the m line. ATP powers the process.
- Removal of Ca2+ by active transport into SR once action potential ends.
- Tropomyosin blockage restored and muscle fiber relaxes ending contraction
What chemicals are released during the working stroke of myosin?
ADP and phosphate
What does a skeletal muscle organ consist of?
- Skeletal muscle tissue
- Vessels
- Nerve fibers
- Connective tissue
Where is endomysium found in skeletal muscle?
Between the fibers
Where is the perimysium found in skeletal muscle?
Around fascicles (bundles of muscle fibers).
Where is the epimysium found in skeletal muscle?
Surrounding the entire organ
T/F: Cardiac muscle cells contain larger mitochondria than skeletal muscle cells.
True
T/F: Terminal cisternae forms triads with t tubules in skeletal muscles, but form diads in cardiac muscles.
True
