TEST 3 Muscle Fibers Flashcards
Properties and Char of Muscle Tissue(4)
1) Contractility 2) Excitability 3) Extensibility 4) Elasticity
Different Types of Muscle
1)Skeleton 2) Cardiac 3) Smooth
Functions of Muscle(3)
Movement 2) Posture 3) Temperature regulation
What is a muscle cell called
Muscle fiber
Covering Layers Outside to in
1) Deep Fascia 2) Epimysium 3) Perimysium 4) Endomysium
Aponeurosis
narrow tendon
Origin
Less movable
Insertion
More Movable
Anatomy of A skeletal Muscle fiber
1) Covered by endomysium 2) Sarcolemma (plasma membrane) 3) Sarcoplasm(cytoplasm) 4) Bundles of Myofibrils 5) Covered with Sarcoplasmic Reticulum joining together with 6) Transverse (t) Tubules which are open to sarcolemma
Sarcolemma Plasma
membrane of a muscle fiber Surrounds muscle fiber and regulates entry and exit of materials
Myofibrils
Organized bundles of myofilaments; cylindrical structures as long as the muscle fiber itself. Contain myofilaments that are responsible for muscle contraction Myosin(thick); Actin(thin) and Titin
Sarcoplasm
Cytoplasm of a muscle fiber
Sarcoplasmic reticulum
Smooth endoplasmic reticulum in a muscle fiber Function: Stores calcium ions needed for muscle contraction.
Thick filament
Fine protein myofilament composed of bundles of myosin
Thin filament
Fine protein myofilament composed of actin; troponin; and tropomyosin
Transverse tubule (T-tubule) Define and Function
Narrow; tubular extensions of the sarcolemma into the sarcoplasm; contacting the terminal cisternae; wrapped around myofibrils. Function: Quickly transports a muscle impulse from the sarcolemma throughout the entire muscle fiber
Actin
Double-stranded contractile protein Binding site for myosin to shorten a sarcomere. Has two associated proteins Troponin and Tropomyosin
Tropomyosin
Double-stranded regulatory protein. COVERS the myosin active sites on ACTIN preventing myosin from binding to actin when muscle fiber is at rest
Troponin Function
Regulatory protein that holds tropomyosin in place and anchors to actin. When CALCIUM ION BINDS to one of its subunits; troponin changes shape; causing the tropomyosin to move off the actin active site; and this permits myosin binding to actin
Myosin
Thick Filament made from myosin molecules has two Heads (crossbidges) and Tails. Head has a site for ATP(looks like 2 twisted golf clubs)
Sarcomere
1) Functional unit of skeletal muscle(function contractile unit) It is defined as the distance from one Z disc to the next adjacent Z disk. Each myofibril contains many Sarcomeres. Sarcomeres Give skeletal muscle it STRIPED appearance
A band
Composes of an entire Thick filament(Myosin)
H zone
The distance between thin filaments that shortens when muscle contracts(does not contain thin filaments)
I Band
contains only thin filaments and titin proteins goes across 2 sarcomeres
M line
Midline of the (A) band
Titin
Provides structural support and elasticity to the sarcomere
Neuromuscular Junction(NMJ)
Site where a motor neuron meets a muscle fiber(LAB TEST). Acetylcholine(ach) is release from a electrical signal
sarco-
muscle
Skeleton Muscle Char
1) Multinuciated 2) Highly ORGANIZED 3) Lots of Many mitochondria
action potential
electrical signal
Motor Unit(MU)
A motor neuron and all the muscle fibers it innervates(all fibers within a MU are the Same Type
Small vs Large Motor Unit
Gross movement (hips) vs (eyes; fingers) small group of muscles
Muscle contraction theory
1) Sliding filament theory: myofilaments slide past each other this is accomplished by the cross-bridge cycle.
Cross- bridge cycle
Cross-bridges on myosin bind actin and pull actin across myosin with a supply of ATP
When a muscle contracts do sarcomere length and myofilaments shorten?
Sarcomeres Shorten; myofiliaments stay the same length
What causes Striations(dark vs light)
The overlap of Thin and Thick filaments
Acetylcholine(ach) Cause what
Causes an action potential on the sarcolemma and when it reaches the T-tubules it goes down into the muscle fibers CAUSing the Sarcoplasmic Reticulum(SR) to release CALCIUM
Excitation-Contraction Coupling
Action potential release Calcium in SR which then can bind to Tropin . This cause the troponin to move tropomyosin out of the way so actin and myosin can interact. If ATP is available cross-bridge cycle occurs
When do contraction stop?
when the stimulus from the nervous system is removed and calcium is pumped back into the SR
Types of Muscle contraction
Dynamic(concentric and eccentric)(shortening/lengthening) and Static(ISOmetric) (holding object not moving (not isotonic)
3 types of Muscle Fibers
Type 1(SLOW; oxidative; slow-twitch) 2) Type 2a (fast oxidative; glycolytic fast twitch fatigue-resistant) 3) Type 2b (fast glycolytic fast twitch fatigable.
Type 1 Fiber type Char(6)
1 )ATP mainly made aerobically 2)High # of mitochondria 3)High # of capillaries4) Contract slowly 5)Moderate force production 6)Fatigue resistant
Type 2b Fiber type Char(6)
1) ATP mainly made anaerobically 2) Low # of mitochondria 3)Low # of capillaries 4)Contract fast 5) High force production 6)Fatigue easily
Atrophy(muscle)
Muscles get smaller
Hypertrophy(muscle)
Muscles get bigger
Hyperplasia(muscle)
Increase # of fibers (not in humans)
Roles of muscles (4) and char
1) agonist(prime mover) 2) Antagonist (opposite movement) 3) Synergist(helps out but not main muscle) 4) Fixator/stabilizer(hold in place)(shoulder)
Cardiac Muscle Char
1) striated 2) 1-2 nuclei 3) branched 4) intercalated discs 5) auto rhythmic(own electrical wiring)
Smooth Muscle Char
1)fusiform shape 2) 1 nuclei 3) involuntary 4) slow 5) fatigue resistant 6) nonstriated 7) DENSE BODIES 8) form vessels and viscera(internal organs) 9) twisting contraction
Anabolic steroids
Family of hormones that are similar to testosterone in the body Increase protein synthesis and give male secondary sex characteristics There is conclusive evidence that they increase muscle strength and mass However; several dangerous side effects make their use unhealthy and illegal!
