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BIO201-Ch9-Muscles 1

BIO201 - Ch 9 - Muscles & Muscle Tissue - Marieb/Hoehn - RioSalado - AZ

QuestionAnswer
Muscle tissue makes up nearly __ of body mass. Nearly half
What is the most distinguishing functional characteristic of muscles? Ability to change ATP into directed mechanical energy.
There are __ types of muscle tissue. Name them. 3 - Skeletal, cardiac, & smooth.
Origin End of a muscle attached to bone - doesn't move much.
Insertion Other side of muscle attached to bone that moves most.
Synergistically Working together.
Antagonistically Works in opposition.
Actin Globular protein that can contract.
Myosin Protein with two heads & a tail.
Skeletal & smooth muscle cells - not cardiac - are elongated & called __. Muscle Fibers.
Muscle contraction depends on two kinds of __. Myofilaments
Meaning of prvixes "myo" or "mys". "Muscle"
Meaning of prefix "sarco" "flesh" in relation to muscles.
Sarcolemma Plasma membrane of muscle fibers.
Sarcoplasm Muscle fiber cytoplasm
Organs that attach to & cover bony skeleton. Skeletal muscles.
Longest muscle cells. Skeletal muscle fibers.
3 keywords regarding skeletal muscle tissue? Skeletal, striated, & voluntary.
Which muscle can contract rapidly, but tires easily? Skeletal muscle - must relax.
Keywords to remember for cardiac muscle. Cardiac, striated, involuntary.
What usually sets the steady rate of heart beats? Heart's pacemaker.
What allows heart to "shift into high gear" briefly? Neural controls
What is the role of smooth muscle tissue? Force fluids & etc through body channels.
Keywords for smooth muscles? Visceral, nonstriated, & involuntary.
What muscle tissue have slow & sustained contractions? Smooth muscle tissue.
5 functional characteristics of muscle tissue. Excitability, responsiveness, contractility, extensibility & elasticity.
Excitability/responsiveness refers to? Ability to receive & respond to a stimulus.
Give an example of excitability. Contraction as a result of receiving an electrical impulse from a nerve cell.
Which function characteristic sets muscle apart from all other tissue types? Contractility - ability to shorten forcibly when adequately stimulated.
Define "extensibility". The ability to be stretched or extended.
4 important functions performed by muscles. Movement, maintains posture, stabilized joints, & generates heat.
When do muscles generate heat? As they contract.
How do smooth muscles protect organs? They form valves to regulate substance passage.
How do skeletal muscles protect organs? By enclosure.
List the 6 levels of organization of skeletal muscles. Myofilament=>sarcomere=>myofibril=>muscle fiber (cell)=>fascicle=>muscle
Each skeletal muscle is a descrete __. Organ
In general, each muscle is served by __. 1 nerve, 1 artery, 1 or more veins that enter/exit near center & branch out.
Each skeletal muscle fiber is supplied with a __. Nerve ending that controls its activity.
Individual muscle fibers are wrapped & held together by several different __. Connective tissue sheaths.
What prevents bulging muscles from bursting during exceptionally strong contractions? Strong connective tissue sheaths.
Endomysium surrounds what? Each muscle fiber.
What is endomysium comprised of? Areolar & reticular fibers.
Endomysium-wrapped muscle fibers are grouped into __. Fascicles.
What fibrous CT surrounds each fascicle? Perimysium.
Epimysium surrounds the __. Whole muscle.
Epimysium is? A dense "overcoat" of dense, irregular CT surrounding whole muscle.
Epimysium sometimes blends with what? Deep fascia between muscles or superficial fascia deep to the skin.
When muscle fibers contract, they pull on __ which transmits pulling force to the bone to be moved. Connective tissue sheaths of skeletal muscle.
What are the "series elastic components?" Connective tissue sheaths because they contribute to the natural elasticity of muscle tissue.
The thick myofilaments contain __. Bundled myosin molecules.
The thin filaments contain __. Actin molecules.
What maintains the organization of the A band & provides for elastic recoil? Elastic filaments.
Which molecule of the myofilament has "heads"? Myosin molecule.
What is a segment of a myofibril called? A sarcomere - section between 2 Z-lines - functional unit.
What is the contractile unit of a muscle? The sarcomere - made of myofilaments of contractile proteins.
A myofibril or "fibril" is composed of ? Myofibrils that are composed of sarcomeres arranged end-to-end.
Complex organelle composed of myofilament bundles. Myofibril or fibril.
A muscle cell is also called a __. Muscle fiber.
A muscle cell is surrounded by __. Endomysium.
A discrete bundle of muscle cells surrounded by perimysium. A fascile.
Consists of hundreds to thousands of muscle cells. A muscle.
In limb muscle, the origin typically lies __ to the insertion. Proximal
Muscle attachments may be __ or __. Direct or indirect.
In direct or flashy attachments __. The muscle epimysium is fused to the periosteum of bone or perichondrium of cartilage.
In indirect attachments __. CT of msucle tissue wrappings extends as tendons or sheet-like aponeurosis.
Tendons or aponeurosis anchor muscle to __. CT covering bone or cartilage or fascia of other muscles.
Which type of muscle attachment is more common & why? Indirect attachments - because of their durability & small size.
Tendons conserve __. Space
Compared to other cells, the diameter of a muscle cell is __ larger. 10 times
Each muscle cell is produced by the fusion of __. Hundreds of embryonic cells.
The sarcoplasm of muscle fiber contains unusual amounts of __. Glycosomes (stored glycogen) & myoglobin.
Myoglobin Red pigment that stores oxygen.
Each muscle fiber contains 100-1000's of rod-like __. Myofibrils
Myofibrils account for about __% of cellular volume. 80%
Striations are a repeating series of __. Dark A bands & light I bands.
H Zone Helle - "bright" zone - lighter stripe in middle of A band.
M Line "Middle" line - a dark line that bisects H zone.
Z line or Z disc Midline interruption of I band.
The functional units of skeletal muscles. Sarcomeres.
__ filaments extend whole length of A band. Thick
__ filaments extend across the I band & part of A band. Thin
The banding pattern of myofibril arises from __. Orderly arrangement of myofilaments.
The Z disc is composed largely of __. The protein alpha actinin.
__ filaments connect each myofibril to the next. Intermediate (desmin) filaments at Z disc.
The H zone of A band appear less dense why? Because the thin filaments do not extend in to this region.
The M line in center of H zone is darker why? Presence of fine protein strands that hold thick filaments together.
Myofilaments are connected to sarcolemma at __ & the __. Z discs & M lines.
Each thick filament is surrounded by __. 6 thin filaments.
Each thin filament is enclosed by __. Three thick filaments.
Each mysoin molecule has __. Rod-like tail & 2 globular heads.
Each myosin tail consists of __. Two interwoven helical polypeptide chains.
The globular heads of myosin link __. Thick & thin filaments together - crossbridges.
During contraction, globular heads __ around their point of attachment. Swivel.
Cross bridges act as __ to generate tension. Motors
Each thick filament contains about __ myosin molecules. About 300
What coils around the helix actin strands & reinforces them? Tropmyosin Molecules
The heads of myosin contain __ enzymes. ATPase - they split ATP to generate energy.
In the string of pearls design of actin, __ are the pearls and __ is the string. Globular (G) actin, Fibrous (F) actin.
What protien in actin core blocks myosin binding sites? Tropomyosin
__ is a 3-polypeptide complex involved in myosin-actin contraction interactions. Troponin
The elastic filament is made of the protein __. Titin
Which filament holds the thick filament in place & assists muscle cell to spring back into shape? Elastic filament.
Sliding filament model Thin slides past thick & overlap - myosin filaments slide & pull actin towards the center of sacromere.
3 Metabolic pathways for muscles. (1) Dephosphorylation of creatine phosphate,(2) glycolysis, (3) aerobic respiration.
Sarcoplasmic Reticulum (SR) Surrounds muscle cell's myofibrils - takes up & releases calcium ions - smooth ER.
T tubules Tube-like extensions of muscle cell's plasma membrane where neural signals are received.
T tubules occur where? At each A band-I band junction.
What giant protein stiffens as it uncoils & helps the muscle to resist excessive stretching? Titin
What keeps the sarcomeres from being pulled apart? The giant protein titin.
What protein links the thin filaments to the integral proteins of the sarcolemma? Dystrophin
Skeletal muscle cells contain which 2 sets of intracellular tubules? The sarcoplasmic reticulum & T tubules.
The perpendicular cross channels of the SR are __. Terminal cisternae ("End sacs").
The major role of the SR is to __. Regulate intracellular levels of ionic calcium.
What are the triads? Structure formed by a T tubule w/a SR cisterna on either side. They form the excitation-contraction coupling.
Name the triads Terminal cisterna, T tubule, Terminal cisterna
Muscle contraction is ultimately controlled by? Nerve-initiated electrical impulses that travel along the sarcolemma.
T tubules are continuations of the __. Sarcolemma
T tubules conduct impulses to the __ & to every __. Deepest regions of muscle cells/ every sarcomere.
T tubules ensure that every myofibril __ at the same time. Contracts
What is known as the "double zipper" of integral proteins that protrude into the intermembrane spaces of T tubule? DHP receptors
DHP receptors act as __. Voltage sensors.
The "foot proteins" of the SR do what? Form channels so Ca 2+ can be released from SR cisternae.
Contraction refers to __. Activation of myosin's cross bridges.
Shortening occurs when __ generated by cross bridges exceeds the __. Tension/forces opposing shortening.
In relaxed muscle fiber, thin-thick overlap is minimal & occurs __. Only at ends of A band.
When muscle fibers are stimulated, __ latch on to __ & the sliding begins. Myosin heads/myosin binding sites on actin.
During contraction, Z discs are pulled __ thick filaments. Toward
Which zone disappears during contraction? H zone
Which bands do not change their length during contraction? A bands - only move closer together.
Which structure contains highest Ca 2+ in resting muscle cell? SR - it is a Ca storage depot.
To contract, an action potential must propagate along a muscle cell's __. Sarcolemma - causes rise in Ca ion levels.
Somatic motor neurons activate __. Skeletal muscle cells.
Ending of motor neuron axon forms curling branches w/muscle fiber & is called __ Neuromuscular junction
As a rule, each muscle has only one __ located midway along the fiber's length. Neuromuscular junction - only one.
The __ is teh space separating the axon terminal & muscle fiber. Synaptic cleft.
__ are small sacs at axon terminals that contain acetylcholine. Synaptic vesicles.
The __ or junctional folds in the sarcolemma help form neuromuscular junctions & provide large surface area for ACh receptors. Motor end plate
ACh receptors are located where? At themotor end plate/junctional folds.
What happens when impulse reaches end of axon? Voltage-gated calcium channels open.
What does the presence of CA inside axon terminal cause? Release of ACh into synaptic cleft by exocytosis.
ACh diffuse across synaptic cleft & attaches to ACh receptors on the __. Sarcolemma, where the receptors are.
What prevents continued muscle contraction in absence of nervous sys. stimulation? Destruction of ACh by acetylocholinesterase enzyme.
What is destroyed by the autoimmune disease, myasthenia gravis? ACh receptors - muscle weakness.
T tubules are inward __ of the sarcolemma. Invaginations
Binding of ACh molecules to ACh receptors at motor end plate opens __ & allows __ & __ to pass. Chemically (ligand) gated ion channes. - Both Na+ & K+
Depolarization When interior of sarcolemma becomes slightly less negative as Na+ & K+ diffuse out.
End plate potential Local depolarization
3 Steps of action potential across sarcolemma (1) Depolarization & gates open, Na+ enters (AP gen.), (2) Propagation of AP along sarcolemma, (3) repolarization as Na+ channels close & K+ open.
Cells cannt be stimulated again until __ is complete. Repolarization
During repolarization, muscle fiber is said to be in __. Refractory period.
Created by: Ladystorm on 2007-05-14



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