Exam 2 Chapter 10 Flashcards
What structural similarities are shared by all muscle tissue?
All muscle tissue contains the myofilaments actin and myosin, generating contractile forces.
- plasma membrane = sarcolemma
- cytoplasm = sarcoplasm
What are the unique functional properties of this tissue?
- contractility
- excitability
- extensibility
- elasticity
Which types of muscle tissue are striated?
Cardiac muscle and skeletal muscle
Which types are called visceral muscle?
cardiac muscle and smooth muscle
- in visceral organs not voluntarily controlled by
In which types are the muscle cells called fibers?
skeletal muscle and smooth muscle
Name the connective tissue that surrounds a fascicle.
Perimysium
What are the functional definitions of the origin and insertion of a muscle?
attachment site of the muscle that doesn’t move when the muscle contracts
In the limbs, what are the conventional definitions of a muscle’s origin and insertion?
Origin = proximal attachment
Insertion = located distally
Place the following structures in order from smallest to largest and define myofibril, muscle fiber, myofilament, sarcomere.
1) Myofilament - contractile proteins actin and myosin
2) Sarcomere - made of myofilaments in striated muscle
3) Myofibril - organelle within a muscle cell made up of repeating sarcomeres
4) Muscle fiber - muscle cell
Which myofilaments are found only in the A band?
thick myofilaments (myosin)
What are the functions of the terminal cistern and the T tubules?
- Terminal cistern stores Ca++
- T tubules carry the stimulus to contract from the surface sarcolemma to the deeper regions of the muscle fiber, initiating the release of Ca++ from the terminal cistern
Why is overlap of the thin and thick filaments essential for muscle contraction?
The myosin heads must attach to the overlapping thin filament to generate a contractile force
- no overlap = nothing to attach to
Which region of the myofibril changes in length during contraction: the A band, the I band, or the Z disc?
The length of I band shortens during muscle contraction
Differentiate a neuromuscular junction from a motor unit.
The neuromuscular junction is the connection between a single terminal bouton and a muscle fiber
- motor unit = single motor neuron and all the muscle fibers it innervates
What connective tissue lies just outside the sarcolemma of an individual muscle cell?
endomysium
What is true about fibromyalgia?
It is a chronic pain syndrome.
Its cause is unknown.
It mostly affects women.
Which filament contains myosin heads?
thick filament
Which filament contains actin?
thin filament
Which filament does not lie in the H zone?
thin filament
Which filament contains myosin?
thick filament
Which filament attaches to a Z disc?
thin filament
Which filament does not lie in the I band?
thick filament
Does the H band narrow when a skeletal muscle fiber contracts?
Yes
Does the A band narrow when a skeletal muscle fiber contracts?
no
Does the I band narrow when a skeletal muscle fiber contracts?
yes
Does the M line narrow when a skeletal muscle fiber contracts?
no
What skeletal muscle organization is rod-shaped organelle and made of sarcomeres?
myofibril
What skeletal muscle organization is an organ?
muscle
What skeletal muscle organization is a bundle of cells?
fascicle
What skeletal muscle organization is a group of large molecules?
myofilament
What skeletal muscle organization is a cell?
fiber
What’s false about fast glycolytic fibers?
They use aerobic pathways to produce ATP.
They don’t generate much power.
They don’t tire quickly..
Which fiber type would be the most useful in the leg muscles of a long-distance runner?
fast oxidative
What’s false about titin, a myofibril protein?
It’s a very small molecule.
It’s responsible for the M line.
It’s found in the H zone.
What muscle is striated and involuntary?
cardiac muscle
What muscle is striated and voluntary?
skeletal muscle
What muscle is not striated and involuntary?
smooth muscle
What muscle is present in wall of bladder?
smooth muscle
What muscle is located only in the heart?
cardiac muscle
What muscle is located only in the heart?
skeletal muscle
What muscle has giant, multinucleate cells as fibers?
skeletal and smooth muscle
What muscle has individual muscle cells called muscle fibers?
smooth muscle
What muscle has no A or I bands?
smooth muscle
What muscle is located in the walls of hollow body organs/
smooth muscle
What muscle has extranuclear materials called sarcoplasm instead of cytoplasm and plasma membrane called sarcolemma?
skeletal, cardiac, smooth muscle
Name and explain the four special functional properties of muscle tissue.
1) Contractility: muscle tissue contracts forcefully
2) Excitability: nerve signals or other stimuli excited muscle cells, causing electrical impulses and contraction in muscle cells
3) Extensibility: muscle cells can be stretched; contraction of one = stretch in opposition
4) Elasticity: muscle tissue recoils passively and resumes its resting length
Describe the arrangement of the epimysium, perimysium, and endomysium in a skeletal muscle.
Epimysium = outer layer of dense, irregular connective tissue surrounding the whole skeletal muscle
Perimysium = a layer of fibrous connective tissue surrounding each fascicle
Endomysium = a fine sheath of loose connective tissue consisting mostly of reticular fibers surrounding each muscle fiber in a fascicle
Name the structure that these three sheaths help to form.
a tendon
Explain the sliding filament theory of contraction.
The sliding filament theory of muscle contraction describes how muscles generate force and movement. Within each muscle fiber, myofibrils contain sarcomeres composed of actin (thin) and myosin (thick) filaments. During contraction, myosin heads bind to actin, forming cross-bridges that pull the actin filaments toward the center of the sarcomere, known as the power stroke. This action shortens the sarcomere, causing the muscle fiber to contract. ATP provides the energy for cross-bridge cycling, and when neural stimulation stops, calcium ions return to the sarcoplasmic reticulum, allowing the muscle to relax. Overall, the sliding filament theory elucidates the molecular processes underlying muscle contraction, fundamental to understanding muscle function and movement.
Define motor unit.
motor neuron and all the muscle fibers it innervates
List the structural differences between the three distinct types of skeletal muscle fibers.
1) Slow oxidative fibers: large number of mitochondria and a rich supply of capillaries
2) Fast glycolytic fibers: pale (little myoglobin and twice the diameter of slow oxidative fibers, contain more myofilaments, and generate much more power
3) Fast oxidative fibers: large number of mitochondria and rich supply of capillaries
Differentiate between myofilaments, myofibrils, fibers, and fascicles.
1) Myofilaments: smallest units within muscle fibers responsible for muscle contraction
2) Myofibrils: cylindrical organelles within muscle fibers, composed of bundles of myofilaments (actin and myosin)
3) Fibers: single, elongated cells containing multiple myofibrils
4) Fascicles: bundles of muscle fibers surrounded by connective tissue, forming the visible structure of a muscle
Which components of the sarcoplasm separate the myofibrils in a fiber from one another?
Sarcoplasm = cytoplasm of muscle fiber, surrounding and supporting the myofibrils
Sarcoplasmic reticulum: specialized type of smooth endoplasmic reticulum found in muscle cells
Define sarcolemma and sarcoplasm.
Sarcolemma: plasma membrane of muscle fiber
Sarcoplasm: cytoplasm of muscle fiber
When does titin function?
- molecular spring or elastic element within the sarcomere
- helps stabilize the sarcomere structure during relaxation phases of the muscle
- signaling pathways related to muscle development and adaptation to mechanical stress.
