Bio 50.5-6 muscles (test2)

There is less myosin than in

-in striated muscle fibers, and the myosin is not associated with specific actin strands

Some smooth muscle cells contract only when stimulated by ___ while others ____

-neurons of the autonomic nervous system. -Others are electrically coupled to one another and can gener-ate action potentials without input from neurons. -Smooth muscles contract and relax more slowly than striated muscles.

exoskeleton example:

a hard covering deposited on an animal's surface. -The shells of clams and most other molluscs are made of calcium carbonate secreted by the mantle, a sheet-like extension of the body wall a.Clams and other bivalves close their hinged shell using muscles attached to the inside of this exoskeleton. As the animal grows, it enlarges its shell by adding to the outer edge.

what connects the nerves and muscles

a neuromuscular junction (the axon terminal of the neuron attaches to the muscle)

nerves cause

a twitch (action potential) that makes muscles move

Vertebrate (animals with backbones) cardiac muscle is found only in

in the heart and, like skeletal muscle, is striated

no oxygen in the muscles makes aneribic process

lactic acid causes use to be sore

the number of action potentials during a short period of time influences

the tension developed in a muscle fiber.

The nervous sys-tem produces graded contractions of whole muscles by vary-ing

(1) the number of muscle fibers that contract and (2) the rate at which muscle fibers are stimulated. Let's consider each mechanism in turn.

Endoskeletons

-Animals ranging from sponges to mammals have a hardened internal skeleton, or endoskeleton, buried within their soft tissues. -In sponges, the endoskeleton consists of hard needle-like structures of inorganic material or fibers made of protein.

Fiber is a surrounded by

-Each individual fiber is a single cell. Within are multiple nuclei, each derived from one of the embryonic cells that fused to form the fiber. -Surrounding these nuclei are longitudinal myofibrils,

Locomotion on Land

-On land, a walking, running, hopping, or crawling animal must be able to support itself and move against gravity, but air poses relatively little resistance, at least at moderate speeds. -its leg muscles expend energy both to propel it and to keep it from falling down. -the animal's leg muscles must over-come inertia by accelerating a leg from a standing start. For moving on land, powerful muscles and strong skeletal sup-port are therefore more important than a streamlined shape

action potential in skeletal muscle

-Somatic neuron goes to axon terminal -voltage gated calcium channels open a. calcium rushes in -calcium stiumulates neruotransmiter (ACH) -Binds to recepetors on skeletal muscles nicatinic (sodium channels) a. sodiums comes in to the cell depolirizin wave goes down T-tubles - triggers calcium in the sarcoplasmic reticulum (SR)

structure of a sarcomere called

-The borders of the sarcomere line up in adjacent myofibrils, forming a pattern of light and dark bands (striations) visible with a light microscope called striated muscle -basic contrac-tile units of skeletal muscle

Thin filaments attach at the___ of a sarcomere @ that ___ while thick filaments are____of the sarcomere ___

-Thin filaments attach at the Z lines at the sarcomere ends -while thick filaments are anchored in the middle of the sarcomere (M line)

Insects and other arthropods have a jointed exoskeleton called a Fibrils of chitin are embedded found in body parts that are?

-a cuticle, a coat secreted by the epidermis. About 30-50% of the arthropod cuticle consists of chitin, a poly-saccharide similar to cellulose -in a protein matrix, forming a com-posite material that combines strength and flexibility. -The cuticle may be hardened with organic compounds and, in some cases, calcium salts. -In body parts that must be flex-ible, such as leg joints, the cuticle remains unhardened. Muscles are attached to knobs and plates of the cuticle that extend into the interior of the body.

glycolytic fibers have a larger_____ less____ is what resp

-a larger diam-eter and less myoglobin -use glycolysis as their primary source of ATP and fatigue more readily than oxidative fibers.

myasthenia gravis controlled with drugs that inhibit

-autoimmune neuromuscular disorder characterized by weakness of voluntary muscles -As the disease progresses and the number of receptors decreases, transmission between motor neurons and muscle fibers declines. Myasthenia gravis can generally be controlled with drugs that inhibit acetylcholinesterase or suppress the immune system.

Fast twitch fibers enable ATP process used? what animals has these what part of the human body has fast twich

-brief, rapid, powerful contractions. -glycolytic or oxidative -Most human skeletal muscles contain -the muscles of the eye and hand are exclusively fast-twitch

contraction phase of the muscle cell muscle twich

-calcium is bond to actin alowing myosin to bind creating power strokes to the m- line a. atp binds to myosin it detaches the myosin head b. atp is hydrolysis to Adp and removes phoshate it attaches to myosin -muscle fiber shortening and creates tension

cardiac muscle cells are called in between them are

-cardiomyocytes -intercalated discs contains gap junctios that allow electrical stimulus to spread across the tissue -not voluntary a. autonomic system regulated by pace maker cells

Vertebrates have an endoskeleton consisting of

-cartilage, bone, or some combination of these materials. - The mammalian skeleton contains more than 200 bones, some fused together and others connected at joints by ligaments that allow freedom of movement

hydrostatic skeleton found in

-consists of fluid held under pres-sure in a closed body compartment -This is the main type of skeleton in most cnidarians, flatworms, nematodes, and annelids -These animals control their form and movement by using muscles to change the shape of fluid-filled compartments. -are well suited for life in aquatic environments. On land, they provide support for crawl-ing and burrowing and may cushion internal organs from shocks. However, a hydrostatic skeleton cannot support walking or running, in which an animal's body is held off the ground.

Fast-Twitch and Slow-Twitch Fibers: Fast-twitch fibers vs, slow The difference in contraction speed between slow-twitch and fast-twitch fibers mainly reflects the rate at which their

-develop tension two to three times faster than slow-twitch fibers. -depends on the speed of the myosin heads hydrolyze ATP. -there isn't a one-to-one relationship between contraction speed and ATP source.

a kangaroo

-each leap, ten-dons in its hind legs momentarily store energy. Much like the energy in a compressed spring, the energy stored in the tendons from one jump is released in the next jump, reducing the energy the animal must expend to travel.

a slow twitch fiber has less ATP process used?

-has less sarcoplas-mic reticulum and pumps Ca2+ more slowly. Because Ca2+ remains in the cytosol longer, a muscle twitch in a slow fiber lasts about five times as long as one in a fast fiber. -are oxidative

Invertebrates have muscle cells arthropod skeletal muscles are nearly identical -the wings of some insects can actually

-have muscle cells similar to vertebrate skel-etal and smooth muscle cells; -to those of vertebrates. However, because the flight muscles of insects contract in response to stretching, the wings of some insects can actually beat up and down faster than action potentials can arrive from the central nervous system. -Another interesting evolutionary adapta-tion has been discovered in the muscles that hold a clam's shell closed. Modification of certain proteins in these muscles allows them to remain contracted for as long as a month with only a low rate of energy consumption

Smooth muscle in vertebrates is found in the walls of it con-trols

-hollow organs, such as vessels and tracts of the circulatory, digestive, and reproductive systems. -it con-trols blood flow in the arteries, moves food through the diges-tive system, carries out uterine contractions during labor, in the eye (where its action controls focusing and pupil diameter) and assists in regulating the temperature of the testicles.

what are the three phases of a muscle cell, for contraction?

-latent phase -contraction phase -relaxtion phase

structure of a myosin molecule

-long "tail" region and globular "head" region. -The tail adheres to the tails of other myosin molecules, binding together the thick filament. -The head, jutting to the side, can bind ATP. Hydrolysis of bound ATP converts myosin to a high-energy form that binds to actin, forming a cross-bridge between the myosin and the thin filament. -The myosin head then returns to its low-energy form as it helps to pull the thin filament toward the center of the sarcomere.

what are the layers of the smooth muscle?

-longitudinal layers a. run parallel to the axis of the organ contraction will diulate -circular layer a. makes contraction constrict/lengthen the organ -alternate contractions that move materials in called peristalsis

the first in skeletal actional potential (membrane potential) of the cell

-neuron sends stimules down axon to terminal (neuromuscular junction) -relases ACH at the synapsis and at the ACH binding to receptors on the membrane of muscle (sarcolemna) a. this will open the ion channels other sodium ion channels to open that cause potassium to enter and soidum (depolorization) , to exit. Generating a actional potential b. action potential goes down the t-tubles to the SR c. action potential causes a rise of calcium leaves to the muscle fiber

what is the latent phase of muscle cell contraction? muscle twich

-neuron stimules that activate sodium channels -actional potential occurs in the sarcoplasmic reticulum relaseing calcium -binds to protein on actin tryponin

what makes smooth muscle different from cardia / skeletal muscle

-one nucleus -cells are spindle shaped -they are not striated (no sacromeres) -myfilaments are scatteres

In a resting (relaxed) myofibril, thick and thin filaments helps do what Near the edge of the sarcomere there are the zone in the center contains

-partially overlap. This partially overlapping arrangement is the key to how the sarcomere, and hence the whole muscle, contracts -Near the edge of the sarcomere there are only thin filaments, whereas the zone in the center contains only thick filaments.

osteoblasts

-secrete bone matrix and thereby build and repair bone (see Figure 40.5). Osteoclasts have an opposite function, resorbing bone components in remodeling of the skeleton.

skeletal system Converting muscle contraction to movement requires a -Often muscles are anchored to -moving a body part back and forth typically requires

-skeleton—a rigid structure to which muscles can attach. An animal changes its shape or location by contracting muscles connecting two parts of its skeleton. -Often muscles are anchored to bone indirectly via connective tissue formed into a tendon. a. Because muscles exert force only during contraction, moving a body part back and forth typically requires two muscles attached to the same section of the skeleton. We can see such an arrangement in the upper portion of a human arm or grasshopper leg

locomotion keep an animal stationary To move, an animal must expend

-the ability to move from place to place -Friction and gravity tend to keep an animal stationary and therefore oppose locomotion. -To move, an animal must expend energy to overcome these two forces. As we will see next, the amount of energy required to oppose friction or gravity is often reduced by an animal body plan adapted for movement in a particular environment -The legs of an insect, dog, or human also retain some energy during walking or running, although a considerably smaller share than those of a kangaroo.

what doe the thick / thin filaments look like in smooth muscles

-thick filaments are scattered through-out the cytoplasm -thin filaments are attached to structures called dense bodies, some of which are tethered to the plasma membrane.

graded response (potential) of a skeletal muscle is depended on?

-to get a muscle from resting membrane potential of a muscle cell and bring to threshold depend on the frequency of neural stimulus to strength of neural stimulus

myofibrils are made of

-which consist of bundles of thin and thick filaments. -made up of repeating sections called sarcomeres, which are the basic contrac-tile units of skeletal muscle.

Vertebrate skeletal muscle made of

-which moves bones and body, has a hierarchy of smaller and smaller units -is a bundle of long fibers running along the length of the muscle. Each individual fiber is a single cell.

smooth muscle contracts where?

-will contract in blood vessel walls to regulate pressure and distributes blood -present in airways contract to controls passage of air -present in digestive tract wall contracts to push food along -in bladder to push urine -in reproductive system to push a baby

what is the structure of a muscle

1. sarcolemma (sarcoplasmic reticulum) 2.micro fiber 3.faceles (bundles of muscle cells) a. Myofibril myofilaments 4.myofibril a. sacromere

Motor neurons cause muscle contraction steps

1.Acetylcholine (ACh) is released at the synaptic terminal. It diffuses across the synaptic cleft and binds to receptor proteins on the muscle fiber's plasma membrane, triggering an action potential in the muscle fiber. 2.The action potential is propagated along the plasma membrane and down T tubules. 3.The action potential triggers Ca2+ release from the SR 4.Calcium ions bind to troponin in the thin filament; myosin-binding sites are exposed. 5.Cycles of myosin cross-bridge formation and breakdown, coupled with ATP hydrolysis, slide the thin filament toward the center of the sarcomere. 6.After the action potential ends, cytosolic Ca2+ is removed by active transport into the SR 7.Once cytosolic Ca2+ is removed, tropomyosin again blocks the myosin-binding sites. Contraction ends, and the muscle fiber relaxes.

myosin and actin interaction underlying muscle fiber contractions

1.the myosin head is bound to ATP and is in its low-energy configuration on a thick filament 2.The myosin head hydrolyzes ATP to ADP and phosphate) and is in its high-energy configuration. 3.The myosin head binds to actin, forming a cross-bridge with the thin filament. 4.The cross-bridge couples the release of ADP and to a power stroke that slides the thin filament along the myosin and returns the myosin head to a low-energy state. 5.Binding of a new molecule of ATP releases the myosin head from actin, and a new cycle begins.

1 molecule of glucose yields aerobic respiration

38 ATP -glycolysis a.sugar broken down 2 pyruvac acid/NADH by 2 ATP -kreb cyle -electron chain

Myoglobin function

A brownish red pigment, myo-globin binds oxygen more tightly than does hemoglobin, enabling oxidative fibers to extract oxygen from the blood efficiently -found on Oxidative and Glycolytic Fibers

glycolysis

A metabolic process that breaks down carbohydrates and sugars through a series of reactions to either pyruvic acid or lactic acid and release energy for the body in the form of ATP

What is a motor unit?

A motor neuron and all of the muscle fibers it innervates

myosin

A protein present in muscle fibers that aids in contraction and makes up the majority of muscle fiber

skeletal shapes for swimming animals

A sleek, fusiform (torpedo-like) shape is a common adaptation of fast swimmers

ATP hydrolysis reaction

ATP + H20 ---> Energy + ADP + Pi {ATPase} -the breakdown of ATP into ADP and Pi resulting in the release of energy

We typically clas-sify these varied fiber types both by the source of

ATP used to power their activity and by the speed of their contraction

creatine phosphate

An energy storage molecule used by muscle tissue. The phosphate from creatine phosphate can be removed and attached to an ADP to generate ATP quickly. -In this way, the resting supply of creatine phosphate can sustain contractions for about 15 seconds.

why can fast glycolytic fibers develop into fast oxidative fibers.

Because fast oxidative fibers fatigue more slowly than fast glycolytic fibers, the result will be a muscle that is more resis-tant to fatigue.

what regulates smooth muscle contraction how? they dont have ? and their sarcoplasmic reticulum is?

Ca2+ a. Calcium ions cause contrac-tion by binding to the protein calmodulin, which activates an enzyme that phosphorylates the myosin head, enabling cross-bridge activity. -is not well developed.

Worms carry out locomotion in a variety of ways. -nematodes (roundworms) -In earthworms and many other annelids

In planarians and other flatworms, body movement results mainly from muscles in the body wall exerting local-ized forces against the interstitial fluid. -longitudinal muscles contracting around the fluid-filled body cavity move the animal forward by wavelike motions called undulations -circular and longitudinal muscles act together to change the shape of individual fluid-filled segments, which are divided by septa. a.These shape changes bring about peristalsis, a movement produced by rhyth-mic waves of muscle contractions passing from front to back

sarcoplasmic reticulum

Organelle of the muscle fiber that stores calcium.

aerobic respiration

Respiration that requires oxygen

Glycogen

Storage form of glucose metabolized by aeriobic respiration started by pyr

how ATP is made

The transfer of a phosphate group from creatine phos-phate to ADP in an enzyme-catalyzed reaction synthesizes additional ATP.

intercalated disks

These structures branch and connect cardiac cells. They contain specialized gap junctions and coordinate muscle contractions.

antagonistic pair -when you extend your arm 1 motor does what the other does what

Two muscles which carry out opposite effects -when you extend your arm, motor neurons trigger your tri-ceps muscle to contract while the absence of neuronal input allows your biceps to relax.

Depending on the number of motor neurons your brain recruits and the size of their motor units, you can lift a

a fork or something much heavier, like your biology textbook.

cells in one part of the heart act as a______ that signals occur by___

a pacemaker to initiate contraction -Signals from the pacemaker spread throughout the heart because special-ized regions called intercalated disks electrically couple each cardiac muscle cell to the adjacent cells. -It is this coupling that enables action potentials generated in one part of the heart to trigger contraction throughout the organ. Although these action potentials last up to 20 times longer than those of skeletal muscle fibers, a long refractory period prevents summation and tetanus.

what is a muscle twitch?

a rapid contraction response to a single action potential of neuron (stimulus)

. A single action potential produces a twitch

a twitch lasting about 100 milliseconds or less

The synaptic terminal of a motor neuron releases

acetylcholine, which depolarizes the plasma membrane of the muscle fiber

Oxidative use what resp. Fibers have what organelles oxygen-storing protein called apparent in what animal

aerobic respiration are called oxidative fibers -They have many mitochondria, a rich blood supply, and a large amount of an oxygen-storing protein called myoglobin -are readily apparent in the muscle of poultry and fish a.The dark meat (red muscle) is made up of oxidative fibers rich in myo-globin, and the light meat (white muscle) is composed of glycolytic fibers.

Whereas contraction of a single skeletal muscle fiber is a brief

all-or-none twitch, contraction of a whole muscle, such as the biceps in your upper arm, is graded; you can voluntarily alter the extent and strength of its contraction.

Active flying animal

an animal's wings must develop enough lift to overcome gravity's downward force. The key to meeting this challenge is wing shape. All wings act as airfoils—structures whose shape alters air currents in a way that helps animals or airplanes stay aloft.

when our muscles use up alot of oxygen kicks into

anerobic respiration

vertebrates

animals with backbones

Ball-and-socket joints

are found where the humerus contacts the shoulder girdle and where the femur contacts the pelvic girdle. These joints enable the arms and legs to rotate and move in several planes.

why do smooth muscles lack striation?

because their actin and myosin filaments are not regularly arrayed along the length of the cell. -Instead, the thick filaments are scattered through-out the cytoplasm, and the thin filaments are attached to

During light or moderate muscle activity, this glucose is metabolized

by aerobic respiration. This highly efficient metabolic process yields enough power to sustain contractions for nearly an hour.

Several diseases cause paralysis caused by

by interfering with the excitation of skeletal muscle fibers by motor neurons.

The action potentials trigger the release of Calcium initiates

calcium (green dots) from the sarcoplasmic reticulum into the cytosol. Calcium initiates the sliding of filaments by allowing myosin to bind to actin.

Motor neurons enable actin and myosin to interact by triggering a release of binds to? causing?

calcium ions (Ca2+) into the cytosol. Once in the cytosol, Ca2+ binds to the troponin complex, causing the myosin-binding sites on actin to be exposed

A motor unit

con-sists of a single motor neuron and all the muscle fibers it controls -there may be hundreds of motor units In the whole muscle, (for twitch)

Each end of a thick filament contains

contains approximately 300 heads, each of which forms and re-forms about five cross-bridges per second, driving the thick and thin filaments past each other

When a motor neuron produces an action potential, all the muscle fibers in its motor unit recruitment

contract as a group. The strength of the resulting con-traction depends on how many muscle fibers the motor neuron controls. -As more and more of the corresponding motor neu-rons are activated, a process called recruitment a.the force (tension) developed by a muscle progressively increases.

Tropomyosin

covers the myosin-binding sites along the thin filament, preventing actin and myosin from interacting

Powering repetitive contractions requires two other storage compounds:

creatine phosphate and gly-cogen.

In amyotrophic lateral sclerosis (ALS)

degenerative disorder of motor neurons in the spinal cord and brainstem

Binding of acetylcholine to receptors on the muscle fiber leads to a

depolarization that initiates an action potential.

a fast twitch fiber example

enable brief, rapid, powerful contractions. -the muscles of the eye and hand are exclusively

Pivot joints enable

enable rotating the forearm at the elbow and turning the head from side to side.

skeletal muscle fiber is surrounds by what tissue

epimysium

Most human skeletal muscles contain what twitch

fast-twitch and slow-twitch fibers

cnidarians hydrostatic skeleton

for example, a hydra elongates by closing its mouth and con-stricting its central gastrovascular cavity using contractile cells in its body wall. Because water maintains its volume under pressure, the cavity must elongate when its diameter is decreased.

summation

increased force of contraction by a skeletal muscle fiber when a twitch occurs before the previous twitch relaxes

Within the muscle fiber, the action potential spreads deep into the

into the interior, following infoldings of the plasma mem-brane called transverse (T) tubules

Note that the effect of Ca2+ Binding to Ca2+ causes the troponin complex to

is indirect: Binding to Ca2+ causes the troponin complex to change shape, dislodging tropomyosin from the myosin-binding sites

The nervous system regulates

muscle contraction not only by controlling which motor units are activated but also by varying the rate of muscle fiber stimulation.

Motor units in a vertebrate skeletal muscle: In vertebrates, each branched motor neuron may form synapses with

one motor neuron, but each motor neuron typically synapses with many muscle fibers. -A motor neuron and all the muscle fibers it controls constitute a motor unit.

Echinoderms' bodies are reinforced by

ossicles, hard plates composed of magnesium carbonate and calcium carbonate crystals. Whereas the ossicles of sea urchins are tightly bound, the ossicles of sea stars are more loosely linked, allowing a sea star to change the shape of its arms

fast twitch can be either rate of fatigue

oxidative -intermediate glycolytic -fast

During intense muscle activ-ity what is limited

oxygen becomes limiting and ATP is instead generated by lactic acid fermentation

fascicle is surrounds by what tissue

perimysium

the nervous system may alternate activation among the motor units,

reducing the length of time any one set of fibers is contracted.

the cross-bridge is disrupted by

releasing the myosin head from the actin filament

Atp to ADp

removal of a phosphate from Atp replaced by water

some cardiac muscle cells can initiate____ without nervous system input

rhythmic depolarization and contraction without nervous system input

T tubules is in between the

sarcoplasmic reticulum

A contracting muscle does what

shortens, but the filaments that bring about contraction stay the same length

skeletal muscle help with

simple movements running position swallowivg body temp

cardia muscle has the same structure as

skeletal but shorter branced cells than it with onle 1 or two nucleus

troponin complex

small, calcium-binding protein on each tropomyosin molecule

if such a muscle is used repeatedly for activities requiring high endurance, what ATP process is used?

some fast glycolytic fibers can develop into fast oxidative fibers. Because fast oxidative fibers fatigue more slowly than fast glycolytic fibers, the result will be a muscle that is more resis-tant to fatigue.

Oxidative (slow twitch) fibers are: speed ATP source rate of fatigue mygoglobin

speed is slow aeroibic rate of fatigue is slow mygolgin is hight

Hinge joints

such as between the humerus and the head of the ulna, restrict movement to a single plane.

skeletons also function in

support and protection. -formless without a framework to maintain its shape. In many animals, a hard skeleton also protects soft tissues. For example, the ver-tebrate skull protects the brain, and the ribs of terrestrial vertebrates form a cage around the heart, lungs, and other internal organs.

the cycles of change in the myosin molecule

that convert the chemical energy of ATP into the longitudinal sliding of thick and thin filaments.

When the Ca2+ concentration falls

the binding sites are covered, and contraction stops.

lactic acid fermentation

the chemical breakdown of carbohydrates that produces lactic acid as the main end product -This anaerobic pathway, although very rapid, generates much less ATP per glucose molecule and can sustain contraction for only about 1 minute.

When the Ca2+ concentration rises in the cytosol,

the cycle of cross-bridge formation begins, the thin and thick filaments slide past each, and the muscle fiber contracts.

When motor neuron input stops,

the filaments slide back to their starting position as the muscle relaxes.

sliding-filament model

the thin and thick filaments ratchet past each other, much like the segments of a telescoping support pole powered by myosin molecules.

If a second action potential arrives before the muscle fiber has completely relaxed When the rate is so high that the muscle fiber

the two twitches add together, resulting in greater tension -Further summa-tion occurs as the rate of stimulation increases. -When the rate is so high that the muscle fiber cannot relax at all between stimuli, the twitches fuse into one smooth, sustained con-traction called tetanus. -(Note that tetanus is also the name of a disease of uncontrolled muscle contraction caused by a bacterial toxin.)

thick filaaments pull the

thin filaments towards the center

Proteins bound to ____in controlling muscle contraction

to actin

In a muscle fiber at rest what proteins, are bound to the actin strands of thin filaments

tropomyosin/a regulatory protein, and the troponin complex,

who has a faster muscle fibers that twitch Some vertebrates (animals with backbones) or human muscle

vertebrates have skeletal muscle fibers that twitch at rates far faster than any human muscle. For example, super-fast muscles produce a rattlesnake's rattle and a dove's coo. Even faster are the muscles surrounding the gas-filled swim bladder of the male oyster toadfish

skeletal musle is

voluntary

ATP stores are also replenished when

when glycogen is broken down to glucose

relation phase muscle twich

when potassium, leaves the cell calcium goes back to SR cross bridge becomes inactive