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BIO201-Ch9-Muscles 1
BIO201 - Ch 9 - Muscles & Muscle Tissue - Marieb/Hoehn - RioSalado - AZ
| Question | Answer |
|---|---|
| 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. |
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