The Muscular System Flashcards
Muscle activity is a response to — from the nervous system
Input
The action of a muscle is always to —; Extension is —
- Contract
2. Passive
Muscle contration depends on the interation between what two types of filaments?
Thin & Thick filaments
What are thin filaments mostly composed of?
Actin
What are thick filaments mostly composed of?
Myosin
The vertebrate skeletal muscle helps to move what?
Moves limbs & other body parts
The vertabrate skeletal muscle is characterized by what?
A hierarchy of smaller & smaller units
A skeletal muscle consists of a bundle of ——, each a ——
- Long Fibers
2. Single Cell
What direction do the fibers of skeletal muscle’s run?
Parallel to the length of muscle
What does each muscle fiber consists of?
A bundle of smaller myofibrils
How are myofibrils arranged?
Longitudinally(parallel with the muscle fiber) that extend the entire length of the muscle fiber
What are the 2 kinds of myofilaments that myofibrils are compsoed of?
Thick & Thin Filaments
Staggered arrays of myosin molecules
Thick Filaments
Consist of 2 strands of actin & 2 strands of a regulatory protein
Thin Filaments
What is the functional unit of a muscle called?
Sarcomere
Location where actin filaments are anchored
Z Lines
Located where thick filaments are anchored
M Lines
A skeletal muscle is also called what? Because the regualar arrangement of myofilaments creates a pattern of light & dark bands.
Striated Muscle
Thin & thick filaments ratchet past each other —, this is powered by ——.
- Logitudinally
2. Myosin Molecules
The “head” of a myosin molecule binds to an ——
Actin filament
When a myosin molecule binds to an actin filament this forms a ——, & pulls the — filament toward the center of the —
- Cross-Bridge
- Thin
- Sarcomere
Muscle contraction requires repeated cycles of this — & —
- Binding
2. Release
When a muscle fiber is at rest — & the —— bind to actin strands on thin filaments
- Tropomyosin
2. Troponin Complex
When tropomyosin and troponin complex bind to actin strands on thin filaments, what does this prevent?
It prevents actin & myosin from interacting
For a muscle fiber to contract, the myosin-binding sites on the actin thin filaments must be —
Uncovered
When a myosin binding site is uncovered, this occurs when?
Ca2+ ions are high & bind to the troponin complex
When do muscle contractions stop?
Concentration of Ca2+ is low (Myosin-binding sites are covered)
A twitch results from a single —— in a ——
- Action Potential
2. Motor Neuron
- Varying the number of fibers that contract
- Varying the rate at which fibers are stimulates
What are the 2 mechanisms?
2 basic mechanism by which the nervous system produes graded contractions
The extent and strength of its contraction can be voluntarily altered
How the contraction of a whole muscle is graded
Each motor neuron may synapse with — muscle fibers, although each fiber is controlled by — motor neuron
- Multiple
2. One
What consists of a single motor neuron and all the muscle fibers it controls?
Motor Unit
The more motor units that are recruited, the — the contraction
Stronger
More rapidly delivered action potentials produce a graded contraction by —, this process is called —
- Summation
2. Recruitment
State of smooth, sustained contraction when the rate is so high the muscle fiber cannot relax between stimuli
Tetanus
Muscles are classified by what 2 sources of ATP powering the muscle activity
- Oxidative Respiration (oxidative)
2. Glycolyis (glycolytic)
What are the speed of muscle contraction?
Slow-twitch & Fast-twitch
What do oxidative fibers rely on to generate ATP?
Aerobic Respiration
Oxidative Fibers have many —, a rich — supply, & a large amount of —.
- Mitochondria
- Blood
- Myoglobin
Binds oxygen more tightly than hemoglobin does
Myoglobin
What do glycolytic fibers use as their primary source of ATP?
Glycolysis (Anaerobic Respiration)
Glycolytic fiber have — than oxidative fibers, & — more easily
- Less
2. Tire
In poultry and fish, — meat is composed of glycolytic fibers, while — meat is composed of oxidative fibers
- Light
2. Dark
Contract more slowly, but sustain longer contractions & all are oxidative
Slow-twitch
Contract more rapidly, but sustain shorter contractions & can be either glycolytic or oxidative
Fast- Twitch
Most skeletal muscles contain what slow & fast-twitch muscles in — ratios
Varying
Some vertebrates have muscles that twitch at rates —— than human muscles
Much Faster
