A&P Ch. 9

slow-twitch (high oxidative) fibers

"dark meat" -contract more slowly, smaller fibers, good blood supply, high number of mitochondria -more fatigue resistant -aerobic respiration predominant -contain higher myoglobin; myoglobin~ Hb, stores/reservoir for O2 -myglobin increases ability of muscle to do aerobic respiration

eccentric contraction

(type of isotonic contraction) muscle lengthens and does work

myofibril

- 80% of cellular volume - contain sarcomeres

Generation of end plate potential

- ACh binding to its receptors opens ligand gated ion channels allowing Na+ and K+ to pass - more Na+ diffuses in than K+ diffuses out - sarcolemma becomes less negative --> depolarization

Repolarization: Restoring sarcolemma to its initial polarized state

- Na+ channels close and voltage-gated K+ channels open - K+ diffuses rapidly out of muscle cell bc K+ concentration was higher inside the cell - restores negatively charged conditions inside the cell - restores ELECTRICAL CONDITIONS of resting state - need ATP because active transport through sodium-potassium pump

Endomysium

- connective tissue that surrounds each muscle cell/fiber - areolar

Perimysium

- connective tissue that surrounds fascicles - fibrous

Epimysium

- connective tissue that surrounds whole muscle - dense irregular

period of relaxation

- contractile force is declining - muscle tension decreases to 0 - any shortened muscles return to initial length

Excess postexercise oxygen consumption (EPOC)

- extra amount of oxygen body must take in for restorative processes - represents difference between amount of oxygen needed for aerobic muscle activity and amount actually used

fast glycolytic fibers

- fast contraction - fast myosin ATPase activity - anaerobic glycolysis - low myoglobin content - high glycogen stores - third recruitment order - fast rate of fatigue - best suited for short-term intense or powerful movements like hitting a baseball

T Tubules

- increase muscle fiber's muscle area

Muscle Functions (5)

- movement - maintaining posture - stabilizing joints - generating heat - protect internal organs

indirect attachments

- muscle's connective tissue wrappings extend as a tendon or as aponeurosis - more common because durability and small size

Direct/Fleshy attachments

- muscle's epimysium is fused to periosteum of bone or perichondrium of cartilage

somatic motor neurons

- nerve cells that activate skeletal muscle fibers - reside in brain or spinal cord - have axons that travel to muscle cells they serve

resistance exercise

- occur in anaerobic conditions - strength is important!! - promote significant increases in muscle strength and size - can convert fast oxidative fibers to fast glycolytic fibers -

Intracellular Tubules that help regulate muscle contraction

- sarcoplasmic reticulum - T tubules

DMD- Duchenne muscular dystrophy

- sex-linked recessive disease - normal appearing children become clumsy and fall frequently as skeletal muscles weaken - caused by defective gene for dystrophin - fragile sarcolemma tears during contraction and allows entry of excess calcium

Skeletal Muscle

- striated - voluntary - longest muscle cells - overall body mobility

maximal stimulus

- strongest stimulus that increases in contractile force - all motor units are recruited

contraction

- the activation of myosin's cross bridges - ends when cross bridges become inactive

Excitation-Contraction Coupling

- transmission of action potential along sarcolemma causes myofilaments to slide

rigor mortis

- when muscles stiffen 3 to 4 hours after death - occurs because ATP is no longer present in a dead body to detach cross bridges

muscle cells/muscle fibers are _______ cm long

1-40 (14 inches)

Steps for Contraction

1. Acetylcholine released and diffuses across gap at neuromuscular junction 2. Sarcolemma is stimulated, muscle impulse travels deep into fiber through t-tubules to sarcoplasmic reticulum 3. Ca ions from Saco ret are released into sarcoplasm and bind to troponin molecules 4. tropomyosin molecules move and expose binding (active) sites on actin 5. Linkages form between actin and myosin... actin filaments slide inward along myosin filaments...muscle fiber shortens-contraction

For muscle to return to its resting state these must occur (4)

1. Its oxygen reserves in myoglobin must be replenished 2. Accumulated lactic acid must be reconverted to pyruvic acid 3. Glycogen stores must be replaced 4. ATP and creatine phosphate must be resynthesized

Three distinct phases of every twitch myogram

1. Latent period 2. Period of contraction 3. Period of relaxation

Men's skeletal muscles make up approx.. __% of body mass

42%

Which of the following is not a role of ionic calcium in muscle contraction? A) triggers neurotransmitter secretion B) promotes breakdown of glycogen and ATP synthesis C) removes contraction inhibitor D) activates epinephrine released from adrenal gland

D) activates epinephrine released from adrenal gland

What is the most distinguishing characteristic of muscle tissue? A) the design of the fibers B) the sarcoplasmic reticulum C) the diversity of activity of muscle tissue D) the ability to transform chemical energy into mechanical energy

D) the ability to transform chemical energy into mechanical energy

organ

Each skeletal muscle is a discrete ___________________, made up of several kinds of tissues.

Terminal cisternae

Enlarged portions of the sarcoplasmic reticulum; where calcium ions are stored

1st Step Cross Bridge Cycle

FORMATION - energized myosin head attaches to actin myofilament --> cross bridge

Muscle contraction will always promote movement of body parts regardless of how they are attached. True / False

False

During isotonic contraction, the heavier the load, the faster the velocity of contraction. True / False

False Isotonic - muscle lengh changes and moves the load. iso = same ton = tension

__ movements precede __ ones

Gross, fine

Multiple motor unit summation

How a smooth increase in muscle force is produced

smallest fibers to largest fibers

How are different size muscle fibers used during graded response?

Many myosin ____ make up a myosin ______

Molecules, filament

Myosin (from notes)

Most abundant muscle protein (2/3's); one molecule is made of 2 twisted protein strands with globular corssbridges (heads) that project outward

Stimulation of what causes contraction?

Motor nerve fibers

Ca2+ signal and adequate ATP are present

Muscle contraction continues as long as the

False

Muscle contraction will always promote movement of body parts regardless of how they are attached.

isometric contraction

Muscle contracts but there is no movement, muscle stays the same length (lifting a building)

True

Single-unit smooth muscle is found in the intestines.

fibrosis

damages muscle tissue is replaced by CT

A bands

dark bands

Z disc

darker area of I band interrupting its midline

The sliding filament model of contraction involves ___. a) actin and myosin sliding past each other and partially overlapping b) the shortening of thick filaments so that thin filaments slide past c) actin and myosin shortening but not sliding past each other d) the Z discs sliding over the myofilaments

a) actin and myosin sliding past each other and partially overlapping

In an isotonic contraction, the muscle ___. a) changes in length and moves the "load" b) does not change in length but increases tension c) never converts pyruvate to lactate d) rapidly resynthesizes creatine phosphate and ATP

a) changes in length and moves the "load"

Elasticity

ability of muscle cell to recoil and resume its resting length after stretching

Extensibility

ability to extend or stretch

What are the two types of myofilaments?

actin myosin

Sliding Filament Theory

actin and myosin don't change length during contraction

M line muscle

bisects H zone made up of myomesin- line of protein that holds adjacent thick filaments together

How does the nervous system achieve greater muscular force?

by increasing firing rate of motor neurons

Which of the following is "not" a way muscle contractions can be graded? a) changing the frequency of stimulation b) changing the strength of the stimulas c) changing the type of muscle fibers involved in the contraction d) changing the type of neurotransmitter released by the motor neuron

c) changing the type of muscle fibers involved in the contraction

terminal cisterns

dilated end sacs of the sarcoplasmic reticulum

Each actin strands coil to form a ____________

double helix

aerobic respiration

duration of energy provided is hours

fast-twitch fibers display more ________ with training

edurance

ATP

energy source required by muscle cells

ATPase

enzyme in myosin that breaks the ATP into DP and P so energy is released

Muscles "can" or "cannot" have both?

can

This tissue makes up the bulk of the heart.

cardiac

elastic filament

composed of the giant protein titin

muscle tone

constant tension produced by muscles over long periods of time. -keeps back/legs straight, head upright, abdoment flat -depends on small number of motor units contracting out of phase with each other

actin

contain active sites for myosin heads

There must be a high concentration of Cs ions for ____

contraction

actin and myosin filaments

contraction Results from a movement within the myofibrils, in which______slide past one another, shortening the sarcomere.

More motor units responding increases _______ and ______

contraction force, tension

muscle twitch

contraction of muscle in response to a stimulus that causes an AP in one or more fibers

myofibers (muscle cells) and sarcomere

contractions of a muscle resuts from a contraction of ____

sarcomere

Smallest contractile unit of muscle fiber; region of a myofibrils between two Z disks

there are more thick filaments than thin filaments

Smooth muscle is characterized by all of the following except ________.

Smooth muscle contracts in a twisting way.

Smooth muscle is significantly different from striated muscle in several ways. Which of the following is true?

The myosin filaments are located in the ___. a) Z discs b) I band c) Myosin d) A band

d) A band Myosin filaments are bipolar and extend throughout the A-band. They are crosslinked at the centre by the M-band.

Whic of the following is not a role of ionic calcium in muscle contraction? a) triggers neurotransmitter secretion b) promotes contraction inhibitor c) removes contraction inhibitor d) activates epinephrine released from adrenal gland

d) activates epinephrine released from adrenal gland

The main effect of the warm-up period of athletes, as the muscle contractions increase in strenth, is to ___. a) increase the myoglobin content b) convert glycogen to glucose c) tone the muscles and stabilize the joints for the workout d) enhance the availability of calcium and the efficiency of enzyme systems

d) enhance the availability of calcium and the efficiency of enzyme systems

Which of the following would be crecuited later in muscle stimulation when contractile strength increases? a) motor units with the longest muscle fibers b) many small motor units with the ability to stimulate other motor units c) large motor units with small, highly excitable neurons d) motor units with larger, less excitable neurons

d) motor units with larger, less excitable neurons

The contractile units of skeletal muscles are ___. a) microtubules b) mitochondria c) T tubules d) myofibrils

d) myofibrils

Babies' movements are ____ and ____

Uncoordinated and reflexive

insertion

When a muscle contracts, the movable bone, the muscle's __________________________, moves toward the immovable or less movable bone (the muscle's origin)

Actin (Newville)

thin filaments, where myosin heads attach during contraction; two stands twisted together

general area

varicosities release neurotransmitters into the ________________ of multiple smooth muscle cells

wave/temporal summation

when second contraction is stronger than the first and occurs before the muscle is completely relaxed - contractions are basically added together

isotonic contraction

when the developed muscle tension overcomes load and muscle shortening occurs (amount of muscle shortening is measured)

threshold stimulus

minimal level of stimulation required to activate a motor unit

muscles which generate more powerful movements have motor units with ______ number of muscle fibers, which results in more power/strength

more

cross bridge

myosin head + active site of actin

What happens when a muscle fiber stretches so much that filaments don't overlap?

myosin heads have nothing to attach to and cannot generate tension

motor neurons

nerve cells that propagate action potentials (APs) to skeletal muscle

Muscles are sometimes analyze as a result of damage to the ____ that are associated with them.

nerves

axons of motor units combine to form _______

nerves

diffuse junctions

neurotransmitter signals diffuse to adjacent smooth muscle cells via ____________________________; creates ripples of stimulus

oxygen debt

oxygen required after intense activity to reestablish normal concentration of creatine phosphate, ATP and to convert lactic acid---> pyruvate (within liver) -pyruvate-->glucose-->glycogen conversion restores [glycogen] in liver and muscle

cramps

painful, spastic contractions; caused by increased [lactic acid] and fibrositis

synaptic cleft

physical gap between synaptic knob and sarcolemma

sarcoplasma

plasma in sarcolema

sarcolemma

plasma membrane of muscle fiber

anaerobic threshold

point at which muscle metabolism converts to anaerobic glycolysis

neuromuscular junction

point of contact between a motor neuron and a skeletal muscle cell

maintaining body position, stabilizing joints, heat generation

secondary functions of muscle tissue

_____ muscle tissue is found into the walls of hollow internal organs

smooth

hormones

smooth muscle doesn't have to have a nervous signal, it can be signaled by ____________________

muscle fatigue

state of physiological inability to contract even though the muscle still may be receiving stimuli

direct (or fleshy) attachments

the epimysium of the muscle is fused to the periosteum of a bone or perichondrium of a cartilage.

cross bridges (Newville)

thick and thin filaments link during contractions; act as motors to create the tension developed by a contracting muscle cell ->***link that forms between actin and myosin****

Muscular dystrophy

Inherited muscle-destroying diseases that appear in childhood; initially enlarge (due to fat) but then atrophy

______ ____ are found between the cells of cardiac muscle tissue.

Intercalated disks

What may cause muscle fatigue?

Ionic imbalances - accumulation of Pi that may interfere with calcium release from SR or release of Pi from myosin and hamper power strokes - lactic acid --> raises concentration of H+ and alters contractile proteins and also counteracts high K+ levels

What happens when CA ions bind to troponin?

It changes the position of the tropomyosin and they move so that the active sites of actin are exposed and then linkages can form between actin and myosin filaments

entire, isn't activated

It is important that all connective tissue in a muscle work as a single piece so that the ___________________ muscle an contract even if every muscle fiber ______________ isn't activated.

One of the important functions of skeletal muscle contraction is a production of heat. True / False

True Muscles perform at least four functions: movement, maintains posture, stabilize joints and generates heat.

Peristalsis is characteristic of smooth muscle. True / False

True Peristalsis - the wavelike muscular contraction of the intestine or other tubular structure that propel the contents onward by alternate contraction and relaxation.

Single-unit smooth muscle is found in the intestines. True / False

True Single-unit smooth muscle, commonly called visceral muscle because it is in the walls of all hollow organs except the heart.

Although there are "no" sacromeres, smooth muscle still possesses thick and thin filaments. True / False

True sacromere = muscle segment The smallest contractile unit of a muscle fiber.

Endomysium

Whisky fine areolar connective tissue sheath around each individual muscle fiery; sheaths are continuous with each other; when muscle fibers contract, pull on sheath, pull on bone to be moved

allows for refined movement and more control

Why do muscles associated with finer movements contain more motor units (fewer fibers per unit)?

signals need a place to die

Why is it necessary to avoid direct connection between neuron and muscle fiber?

diffusion rate of calcium from the sarcoplasmic reticulum to sarcomere

Why is muscle contraction not an immediate process?

muscle fibers degenerate and atrophy

With muscular dystrophy ________.

glucose, fats and/or proteins

You have enough _____________________ to power your muscles for 30 - 50 minutes, after that you start processing _____________________

Red

________ (color) fibers are slow (oxidative) fibers.

ionic calcium

____________________ signals the release of acetylcholine (neurotransmitter) into the synaptic cleft

Most skeletal muscle contain ___. a) muscle fibers of the same type b) a mixture of fiber types c) a predominance of slow oxidative fibers d) a prejdominance of fast oxidative fibers

b) a mixture of fiber types

During muscle contraction, myosin across bridges attach to which active sites? a) myosin filaments b) actin filaments c) Z discs d) thick filaments

b) actin filaments

What is the functional role fo theT tubules? a) stabilize the G and F actin b) enhance cellular communication during muscle contraction c) hold cross bridges in place in a resting muscle d) synthesize ATP to provide energy for muscle contraction

b) enhance cellular communication during muscle contraction

Cardiac muscle

branched fibers, striated ~mononucleate, intercalated disks, autorhythmic, depolarization involves Na+/Ca2+ movement

atrophy

break down muscle

fast glycolytic fibers

fast contraction, anaerobic glycolysis, low myoglobin, white, few mitochondria, best suited for short-term intense or powerful movements

fascia

fiberous connective tissue outside of epimysium

slow-twitch fibers generate more _______ with training

force

active tension

force applied to object to be lifted when muscle contrats -as length of muscle increases, its active tension also increases -provides optimal overlap of actin/myosin filamentsl; x-bridge formation causes maximal contraction

muscle tension

force exerted by contracting muscle on an object

terminal cisterns

form larger, perpendicular cross channels at the a band -i band junction and always occur in pairs- expanded ends

multiunit smooth muscle

found as sheets (blood vessel walls), in small bundles (arrector pili) or as single cells (spleen) -contractions only when stimulated, few gap junctions

visceral/unitary smooth muscle

found in GI, reproductive and urinary tracts -occurs in "sheets", equipped with gap junctions (functional synctium) -some is autorhythmic (GI tract), some must be stimulated (bladder)

smooth muscle tissue

found in the walls of hollow visceral organs, its role is to force fluids and other substances through internal body channels, consists of elongated cells, has no striations, involuntary

excitability, contractibility, extensibility, elasticity

four characteristics associated with all muscle tissue

sacromere

functional unit of muscle

sarcomere

functional unit of muscle contraction

Glucose is stored into the form of___

glycogen

whole muscles respond in a ______ rather than all-or-none fashion

graded

glycosome

granules of stored glycogen in the sarcoplasm that provide glucose during muscle cell activity

Fascicle

grouped muscle fibers

excitation contraction coupling

mechanism by which AP results in muscle contraction

poliomyelitis

motor unit destruction, causes loss of muscle function in fibers innervated by destroyed nerves

muscle twitch

motor unit's response to single action potential of its motor neuron

power stroke

movement of myosin head while x-bridge is in place

muscle tension

muscle contraction leads to the generation of force or

skeletal muscle tissue

muscle fibers that are the longest muscle cells, and have obvious striations, often activated by reflexes, but mostly subject to conscious control

cardiac

muscle tissue type with branched cells

ATP is stored within the ______ head

myosin

Each G-actin monomer has a binding site for _______

myosin

subthreshold stimulus

no action potential produced, no resultant contraction

cardiac muscle tissue

occurs only in the heart, striated, involuntary (contracts without being stimulated by the nervous system)

motor unit

one motor neuron + muscle fibers it innervates - motor neuron fires --> all associated muscle fibers contract

load

opposing force exerted on muscle by weight of the object to be moved

perimysium

surrounds a bundle (fascicle) of muscle fibers

unfused/ incomplete tetanus

sustained but quivering contraction after degree of wave summation becomes greater and greater

isometric muscle contraction

tension increases during contraction but length of muscles does not. -contractions exhibited by postural muscles

elasticity

the ability of a muscle cell to recoil and resume its resting length after stretching

____ is a byproduct of cellular respiration

heat

True

The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.

muscle relaxation

Ca2+ reabsorbed into sarcoplasm reticulum

Why are muscles not infected easily?

Rich blood supply

Gap junction is aka ____

Synaptic clefts

I band

The ________ contains only the actin filaments.

creatine phosphate

stores energy, used to replenish ATP supply

voltage increases

what triggers additional motor unit recruitment?

Step 4 causes generation of an action potential in the muscle cell

which leads to release of Ca2+ ions from SR into sarcoplasm and eventually muscle contraction.

_______ muscles are composed of many motor units

whole

receive nervous system stimulation differently

why is smooth muscle incapable of strong contractions?

Excitability/Responsiveness

- ability to receive and respond to stimulus - stimulus=usually a chemical with muscles

refractory period

-during repolarization -cell cannot be stimulated again until repolarization is complete - repolarization restores ELECTRICAL CONDITIONS of resting state Na+-K+ pumps restores IONIC CONDITIONS of resting state

Which of the following is true about smooth muscle contraction? A) Certain smooth muscle cells can actually divide to increase their numbers. B) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements. C) Smooth muscle cannot stretch as much as skeletal muscle. D) Smooth muscle has well-developed T tubules at the site of invagination.

A) Certain smooth muscle cells can actually divide to increase their numbers.

Of the following muscle types, which has only one nucleus, no sarcomeres, and rare gap junctions? A) visceral smooth muscle B) multiunit smooth muscle C) cardiac muscle D) skeletal muscle

B) multiunit smooth muscle

The muscle cell membrane is called the ________. A) endomysium B) sarcolemma C) perimysium D) epimysium

B) sarcolemma

presence or absence of sarcomers

Banding is caused by ___________________

Which of the following statements is true? A) Cardiac muscle cells have many nuclei. B) Smooth muscle cells have T tubules. C) Striated muscle cells are long and cylindrical with many nuclei. D) Cardiac muscle cells are found in the heart and large blood vessels.

C) Striated muscle cells are long and cylindrical with many nuclei.

Which of the following describes the cells of single-unit visceral muscle? A) They contract all at once. B) They are chemically coupled to one another by gap junctions. C) They exhibit spontaneous action potentials. D) They consist of muscle fibers that are structurally independent of each other.

C) They exhibit spontaneous action potentials.

Muscle tone is ________. A) the ability of a muscle to efficiently cause skeletal movements B) the feeling of well-being following exercise C) a state of sustained partial contraction D) the condition of athletes after intensive training

C) a state of sustained partial contraction

The oxygen-binding protein found in muscle cells is ________. A) hemoglobin B) ATP C) myoglobin D) immunoglobin

C) myoglobin

cross bridges (from notes)

In the presence of Ca (calcium) ions react with actin filaments and shorten the myofibrils - contraction; contain ATP binding sites

What are the three types of muscle tissue?

Skeletal, cardiac, smooth

refractory period

When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods?

contraction

active process, ATP required

An enaerobic metabolic pathway that results in the productionof two net ATPs per glucose plus tow pyruvic acid molecules is ___. a) the citric acid cycle b) glycolysis c) hydrolysis d) the electron transport chain

b) glycolysis

The oxygen-binding protein found in muscle cells is ___. a) hemoglobin b) ATP c) myoglobin d) immunoglonin

c) myoglobin

triad

grouping of 2 terminal cisternae with T tubule in between

troponin

has 3 binding sites: 1 for actin, 1 for tropomyosin, 1 for Ca2+

I bands

light bands

H zone

lighter region in midsection of A band

dystrophin

links thin filaments to proteins of sarcolemma

endomysium

loose connective tissue surrounding muscle fibers (outside external lamina)

subthreshold stimuli

no observable contractions

myo, mys, sarco

prefixes that reference muscle

myogram

recording of contractile activity

energy economy

smooth muscle has improved ___________________ over skeletal muscles; they don't provide as strong of contractions, but they don't need as much energy

reduce energy need

smooth muscle myofilaments can connect to each other during prolonged contractions to ______________________

cardiac and smooth

uninucleate muscle tissue types

aerobic/endurance exercise (swimming, jogging, fast walking, biking)

- # of capillaries surrounding muscle fibers increases - number of mitochondria within muscle fibers increases - fibers synthesize more myoglobin - most dramatic in slow oxidative fibers - changes = greater endurance, strength, and resistance to fatigue

As muscle shortens:

- I bands shorten - distance between Z discs shortens - H zones disappear - contiguous A bands move closer (length doesn't change)

Depolarization: Generation and propagation of an action potential

- Na+ enters - action potential is generated if threshold is reached - action potential propagates and spreads to adjacent areas of sarcolemma - opens voltage-gated Na channels - Na+ diffuses into cell following electrochemical gradient (more Na+ going in than K+ going out)

elastic filament

- composed of titin - holds thick filaments in place = maintains organization of A band - helps muscle recoil

fused/complete tetanus

- contractions fuse into smooth, sustained contraction plateau after frequency continues to increase then muscle tension increases and reaches maximal tension - does not happen often like on the rare occasions someone shows superhuman strength

recruitment aka multiple motor unit summation

- controls force of contraction more precisely - achieves more smooth, continuous muscle contractions

period of contraction

- cross bridges are active - if tension becomes great enough to overcome resistance of load, muscle shortens

sliding filament model of contraction

- during stimulation: myosin heads latch onto actin and sliding begins - cross bridge attachments form and break several times to propel thin filaments towards center of sarcomere

fast oxidative fibers

- fast contraction - fast myosin ATPase activity - mostly aerobic pathway for ATP synthesis - high myoglobin content - intermediate glycogen stores - 2nd recruitment order - intermediate rate of fatigue - best suited for sprinting or walking

For a muscle cell to contract (4)

- fiber must be stimulated by nerve ending so that membrane potential changes - must generate an action potential in sarcolemma - action potential propagates along sarcolemma - intracellular Ca ions must rise briefly --> final trigger for contraction

muscular dystrophy

- group of inherited muscle-destroying diseases - affected muscles enlarge due to deposits of fat and connective tissue but muscle fibers atrophy and degenerate

creatine phosphate

- high energy molecule tapped to regenerate ATP - CP + ADP --> creatine + ATP

Smooth Muscle

- in walls of hollow organs (stomach, bladder, respiratory passages) - force substances through internal body channels - no striations - involuntary - slow and sustained contractions - only has endomysium

thick filaments

- mainly composed of myosin molecules - head has actin and ATP binding sites

How motor neuron stimulates a skeletal muscle fiber

- nerve impulse reaches end of axon - axon terminal releases ACh into synaptic cleft - ACh diffuses across cleft - ACh attaches to ACh receptors on sarcolemma of muscle fiber - ACh binding --> electrical events --> action potential

Cardiac Muscle

- only in the heart - striated - involuntary - can and usually contracts without nervous system stimulation

slow oxidative fibers

- slow contraction - slow myosin ATPase activity - aerobic pathway for ATP synthesis - high myoglobin content - low glycogen stores - first recruitment order - slow rate of fatigue (fatigue-resistant) - best suited for endurance type activities

sarcomeres

- smallest contractile elements of skeletal muscle cells - contain myofilaments - contains A band flanked by half an I band at each end - region of myofibril between 2 successive Z discs

Sarcoplasmic reticulum

- smooth ER of muscle fibers - regulates intracellular levels of ionic calcium - stores calcium and releases it on demand when muscle fiber is stimulated

graded muscle responses

- variations in healthy muscle contractions - grades muscle contraction by changing frequency of stimulation and changing strength of simulation

muscle tone

- when relaxed muscles are almost always slightly contracted - due to spinal reflexes that activate first one group of motor units then another in response to activated stretch receptors - does not produce active movements - keeps muscles firm, healthy, and ready to respond - skeletal tone helps stabilize joints and maintain posture

Things that happen in excitation contraction coupling

-AP reached T-tubules (carries depolarization to interior of muscle fibers) -Ca2+ diffuses into sarcoplasm surrounding myofibrils -Ca2+ binds to troponin -troponin-tropomyosin complex "moves" deeper into groove between 2 F-actin molecules -active site on actin is exposed -actin-myosin x-bridge form

Things that happen in muscle relaxation

-Ca2+ leaves troponin -troponin/tropomyosin move back into resting position -actin active site in covered up

Special Characteristics of Muscle Tissue (4)

-Excitability -Contractility -Extensibility -Elasticity

anaerobic pathway

3rd energy reserve course - about 1 minute; required no oxygen; useful for short, high-tensity load; wasteful; lasts about a minute max (text says 30 - 40 seconds)

FOURTH channel involved in initiating muscle contraction

4. AP transmission along T tubules --> changes conformation of voltage-sensitive proteins in them --> stimulates SR calcium release channels to release Ca 2+ into cytosol

aerobic pathway

4th energy reserve course; - responsible for all long-term muscle energy needs; requires oxygen, very productive, but slow to make.

Muscle strength has usually decreased by ___% at 80 y/o

50%

There are ___ actin molecules of every 1 myosin molecule.

6

Which of the following statements is most accurate? A) Muscle tension remains relatively constant during isotonic contraction. B) T tubules may be sliding during isotonic contraction. C) The I band lengthens during isotonic contraction. D) Myofilaments slide during isometric contractions.

A) Muscle tension remains relatively constant during isotonic contraction.

What is the functional unit of a skeletal muscle called? A) a sarcomere B) a myofilament C) a myofibril D) the sarcoplasmic reticulum

A) a sarcomere

The sliding filament model of contraction involves ________. A) actin and myosin sliding past each other and partially overlapping B) the shortening of thick filaments so that thin filaments slide past C) actin and myosin shortening but not sliding past each other D) the Z discs sliding over the myofilaments

A) actin and myosin sliding past each other and partially overlapping

In an isotonic contraction, the muscle ________. A) changes in length and moves the "load" B) does not change in length but increases tension C) never converts pyruvate to lactate D) rapidly resynthesizes creatine phosphate and ATP

A) changes in length and moves the "load"

What part of the sarcolemma contains acetylcholine receptors? A) motor end plate B) end of the muscle fiber C) part adjacent to another muscle cell D) any part of the sarcolemma

A) motor end plate

Which of the following is the correct sequence of events for muscle contractions? A) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments B) neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke C) muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments D) neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke

A) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

What structure in skeletal muscle cells functions in calcium storage? A) sarcoplasmic reticulum B) mitochondria C) intermediate filament network D) myofibrillar network

A) sarcoplasmic reticulum

Muscle tissue has all of the following properties except ________. A) secretion B) contractility C) extensibility D) excitability

A) secretion

Equation for formation of ATP

ATP <=> ADP + P + energy

ATPase breaks down ______

ATP---> ADP+Pi

Elasticity

Ability of a muscle cell to recoil and resume resting length after being streched

Extensibility

Ability to be stretched or extended 1. Cell shorten when contracting 2. But can be stretched when relaxing

Excitability/Responsiveness/irritability

Ability to receive and respond to a stimulus (usually a chemical); the response is "conductivity"

Contractility

Ability to shorten forcibly when stimulated; sets muscles abort from others (muscles are only tissue with this ability)

flaccid paralysis

Ach can't bind to receptor at NM junction therefore muscle doesn't contract -e.g., curare, binds to Ach receptors at NM junction

spastic paralysis

Ach is not degraded and accumulates at synapse -muscle contracts/can't relax -e.g., organophosphate pesticides

What is the role of tropomyosin in skeletal muscles? A) Tropomyosin is the name of a contracting unit. B) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules. C) Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules. D) Tropomyosin is the receptor for the motor neuron neurotransmitter.

B) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.

The term aponeurosis refers to ________. A) the bands of myofibrils B) a sheetlike indirect attachment to a skeletal element C) the rough endoplasmic reticulum D) the tropomyosin-troponin complex

B) a sheetlike indirect attachment to a skeletal element

During muscle contraction, myosin cross bridges attach to which active sites? A) myosin filaments B) actin filaments C) Z discs D) thick filaments

B) actin filaments

Which of the following surrounds the individual muscle cell? A) perimysium B) endomysium C) epimysium D) fascicle

B) endomysium

What is the functional role of the T tubules? A) stabilize the G and F actin B) enhance cellular communication during muscle contraction C) hold cross bridges in place in a resting muscle D) synthesize ATP to provide energy for muscle contraction

B) enhance cellular communication during muscle contraction

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________. A) the citric acid cycle B) glycolysis C) hydrolysis D) the electron transport chain

B) glycolysis

What controls the force of muscle contraction? A) wave summation B) multimotor unit summation C) treppe D) concentric contractions

B) multimotor unit summation

Smooth muscles that act like skeletal muscles but are controlled by autonomic nerves and hormones are ________. A) single-unit muscles B) multiunit muscles C) red muscles D) white muscles

B) multiunit muscles

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, ________. A) cross bridge attachment would be optimum because of all the free binding sites on actin B) no muscle tension could be generated C) maximum force production would result because the muscle has a maximum range of travel D) ATP consumption would increase because the sarcomere is "trying" to contract

B) no muscle tension could be generated

When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods? A) relaxation period B) refractory period C) latent period D) fatigue period

B) refractory period

What produces the striations of a skeletal muscle cell? A) a difference in the thickness of the sarcolemma B) the arrangement of myofilaments C) the sarcoplasmic reticulum D) the T tubules

B) the arrangement of myofilaments

What does oxygen deficit represent? A) amount of energy needed for exertion B) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used C) the amount of oxygen taken into the body prior to the exertion D) the amount of oxygen taken into the body immediately after the exertion

B) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used

M lines

Bisect H zones vertically; myosin linked by accessory proteins

Which of the following statements is false or incorrect? A) Cardiac muscle contracts when stimulated by its own autorhythmic muscle cells. B) Under normal resting conditions, cardiac muscle tissue contracts and relaxes about 75 times per minute. C) Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP. D) Cardiac muscle fibers can use lactic acid to make ATP.

C) Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP.

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction? A) calcium ions returning to the terminal cisternae B) the tropomyosin blocking the myosin once full contraction is achieved C) acetylcholinesterase destroying the ACh D) the action potential stops going down the overloaded T tubules

C) acetylcholinesterase destroying the ACh

What is the role of calcium ions in muscle contraction? A) form hydroxyapatite crystals B) reestablish glycogen stores C) bind to regulatory sites on troponin to remove contraction inhibition D) increase levels of myoglobin

C) bind to regulatory sites on troponin to remove contraction inhibition

Which of the following is not a way muscle contractions can be graded? A) changing the frequency of stimulation B) changing the strength of the stimulus C) changing the type of muscle fibers involved in the contraction D) changing the type of neurotransmitter released by the motor neuron

C) changing the type of muscle fibers involved in the contraction

Which of the following is not a usual result of resistance exercise? A) increase in the efficiency of the respiratory system B) increase in the efficiency of the circulatory system C) increase in the number of muscle cells D) increase in the number of myofibrils within the muscle cells

C) increase in the number of muscle cells

Which of the choices below does not describe how recovery oxygen uptake (oxygen deficit) restores metabolic conditions? A) converts lactic acid back into glycogen stores in the liver B) resynthesizes creatine phosphate and ATP in muscle fibers C) increases the level of lactic acid in the muscle D) replaces the oxygen removed from myoglobin

C) increases the level of lactic acid in the muscle

The strongest muscle contractions are normally achieved by ________. A) increasing stimulus above the threshold B) increasing stimulus above the treppe stimulus C) increasing the stimulation up to the maximal stimulus D) recruiting small and medium muscle fibers

C) increasing the stimulation up to the maximal stimulus

Which of the following is a factor that affects the velocity and duration of muscle contraction? A) number of muscle fibers stimulated B) size of the muscle fibers stimulated C) load on the fiber D) muscle length

C) load on the fiber

Which muscle cells have the greatest ability to regenerate? A) skeletal B) cardiac C) smooth D) no muscle can regenerate

C) smooth

Myoglobin ________. A) breaks down glycogen B) is a protein involved in the direct phosphorylation of ADP C) stores oxygen in muscle cells D) produces the end plate potential

C) stores oxygen in muscle cells

The warm-up period required of athletes in order to bring their muscles to peak performance is called ________. A) twitch B) wave summation C) treppe D) incomplete tetanus

C) treppe

4th Step Cross Bridge Cycle

COCKING OF MYOSIN HEAD - ATP hydrolyzed --> ADP + Pi - myosin returns to cocked position (high energy)

troponin

Calcium ions bind to the ________ molecule in skeletal muscle cells.

The main effect of the warm-up period of athletes, as the muscle contractions increase in strength, is to ________. A) increase the myoglobin content B) convert glycogen to glucose C) tone the muscles and stabilize the joints for the workout D) enhance the availability of calcium and the efficiency of enzyme systems

D) enhance the availability of calcium and the efficiency of enzyme systems

During vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to ________. A) a strong base B) stearic acid C) hydrochloric acid D) lactic acid

D) lactic acid

Which of the following would be recruited later in muscle stimulation when contractile strength increases? A) motor units with the longest muscle fibers B) many small motor units with the ability to stimulate other motor units C) large motor units with small, highly excitable neurons D) motor units with larger, less excitable neurons

D) motor units with larger, less excitable neurons

The contractile units of skeletal muscles are ________. A) microtubules B) mitochondria C) T tubules D) myofibrils

D) myofibrils

The major function of the sarcoplasmic reticulum in muscle contraction is to ________. A) make and store phosphocreatine B) synthesize actin and myosin myofilaments C) provide a source of myosin for the contraction process D) regulate intracellular calcium concentration

D) regulate intracellular calcium concentration

Creatine phosphate functions in the muscle cell by ________. A) forming a temporary chemical compound with myosin B) forming a chemical compound with actin C) inducing a conformational change in the myofilaments D) storing energy that will be transferred to ADP to resynthesize ATP

D) storing energy that will be transferred to ADP to resynthesize ATP

Z line/disc

Darker midline bisecting in I bands; actin form one sarcomere connects to actin of next

atrophy

Decrease in size/muscle mass

Fatigue occurs when ATP production fails to keep pace with ATP use even though the muscle still receives stimuli.

Define physiologic muscle fatigue.

Acetylcholinesterase

Destroys ACh.

acetylcholinesterase

In the synaptic cleft of a neuromuscular junction, an enzyme called ________ is always present.

Smooth Muscle

In walls of visceral organs: hollow organs Involuntary No striations Slow, sustained rate of contraction (turtle)

As we age, our amount of connective tissue _____and number of muscle fibers ___

Increases, decreases

durability and small size

Indirect attachments are much more common because of their ________________________________________.

a state of sustained partial contraction

Muscle tone is ________.

The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily T/F

True

The force of muscle contraction is controlled by multiple motor unit summation or recruitment. True / False

True

The thin filaments (actin) contain a polypeptide subunit G actin that bears active sites for myosin attachment. True / False

True

When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands move closer together but do not diminish in length. True / False

True

Excitation-contraction coupling requires which of the following substances? a) Ca2+ and ATP b) Ca2+ only c) ATP only d) ATP and glucose

a) Ca2+ and ATP

Which of the following is true about smooth muscle contraction? a) Certain smooth muscle cells can actually divide to increase their numbers. b) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or secrete any connective tissue elements. c) Smooth muscle cannot stretch as much as skeletal muscle. d) Smooth muslce has well-developed T tubules a the site of invagination.

a) Certain smooth muscle cells can actually divide to increase their numbers.

Which of the following statements is most accurate? a) Muscle tension remains relatively constant during isotonic contraction. b) T tubules may be sliding during isotonic contraction. c) The I band lengthens during isotonic contraction. d) Myofilaments slide during isometric contractions.

a) Muscle tension remains relatively constant during isotonic contraction.

Which of the following is the correct sequence of events for muscle contractions? a) motor neuron action potential, meurotransmitter release, muscle cell action potential, release of calcium ions from SR, AtP-driven power stroke, sliding of myofilaments b) neurotransmitter release, muscle cell action potential, motor reuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke c) muslce cell action potential, neurotransmitter release, atp-driven power stroke, calcium ion release from SR, sliding of myofilaments d) neurotransmitter rlease, motor neuron cation potential, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke

a) motor neuron action potential, meurotransmitter release, muscle cell action potential, release of calcium ions from SR, AtP-driven power stroke, sliding of myofilaments

What structure in skeletal muscle cells functions in calcium storage? a) sacroplasmic reticulum b) mitochondria c) intermediate filament network d) myofibrillar network

a) sacroplasmic reticulum SR is an elaborate smooth endoplasmic reticulum. Its interconnecting tubules surrounds each myofibril the way a sleeve surrounds your arm.

Muscle tissue has all of the following properties except ___. a) secretion b) contractility c) extensibility d) excitability

a) secretion

Which of the following are composed of myosin? a) thick filaments b) thin filaments c) all myofilaments d) Z discs

a) thick filaments Thick filaments containing myosin (red). Thin filaments containing actin (blue).

above-threshold stimulus

action potential is produces, muscle contraction of the same magnitude as that produced by threshold stimulus results

striations

alternate dark and light bands found on skeletal and cardiac muscle; made of dark A bands and light I bands

passive tension

applied to the load when a muscle is stretched but not stimulated -due to the elasticity of muscle and its connective tissue

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers? a) a sprint by an Olympic runner b) a long, relaxing swim c) plaoying baseball or basketball d) mountain climbing

b) a long, relaxing swim

Which of the following surrounds the individual muscle cells? a) perimysium b) endomysium c) epimysium d) fascicle

b) endomysium Endomysium = within the muscle. Is a whispy sheath of connective tissue that surrounds each individual muscle fiber.

Fatigued muscle cells that recover rapidly are the products of ___. a) intense exercise of long duration b) intense exercise of short duration c) slow exercise of long duration d) slow exercise of short duration

b) intense exercise of short duration

Of the following muscle types, which has only one nucleus, no sacromeres, and rare gap junctions? a) visceral smooth muscle b) multiunit smooth muscle c) cardiac muscle d) skeletal muscle

b) multiunit smooth muscle

When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods? a) relaxation period b) refractory period c) latent period d) fatigue period

b) refractory period During repolarization, a muscle fiber is in the refractory period, because the cell cannot be stimulated again until repolarization is complete. Repolarization - the sarcolemma is restored to its initial polarized state. sarcolemma = plasma membrane

What does oxygen deficit reporesent? a) amount of energy needed for exertion b) the differnce between the amount of oxygen needed for totally aerobic muscle activity and the amound actually used. c) the amount of oxygen taken into the body prior to exertion d) the amount of oxygen taken into the body immediatly after the exertion

b) the differnce between the amount of oxygen needed for totally aerobic muscle activity and the amound actually used.

Smooth muscle is charaterized by all of the following except ___. a) it appears to lack troponin b) there are more thick filaments than thin filaments c) there are no sarcomeres d) there are noncontractile intermediate filaments taht attach to dense bodies within the cell

b) there are more thick filaments than thin filaments

tropomyosin

block myosin binding sites of actin

Which of the following statements is false or incorrect? a) Cardiac muscle contracts when stimulated by its own autorhythmic muscle cells. b) Under normal resting conditions, cardiac muscle tissue contracts and relaxes about 75 times per minute. c) Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP. d) Cardiac muscle fibers can use lactic acid to make ATP

c) Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP.

Which of the following statements is true? a) Cardiac muscle cells have many nuclei. b) Smooth muscle cells have T tubules. c) Striated muscle cells are long and cylindrical with many nuclei. d) Cardiac muscle cells are found in the heart and large blood vessels.

c) Striated muscle cells are long and cylindrical with many nuclei.

Muslce tone is ___. a) the ability of a muscle to efficiently cause skeletal movements b) the feeling of well-being following exercise c) a state of susteained partial contraction d) the condition of athletes after intensive training

c) a state of susteained partial contraction

Which of the following is "not" a result of resistance exercise? a) increase in the efficiency of the respiratory system b) increase in the efficiency of the circulatory system c) increase in the number of muscle cells d) increase in thenumber of myofibrils within the muscle cells

c) increase in the number of muscle cells

Which of the choices below does "not" describe how recovery oxygen uptake (oxygen deficit) restores metabolic conditions? a) converts lactic acid back into glycogen stores in the liver b) resynthesizes creatine phosphate and ATP in muscle fibers c) increases the level of lactic acid in the muscle d) replaces the oxygen removed from myoglobin

c) increases the level of lactic acid in the muscle

The strongest muscle contractions are normally achieved by ___. a) increasing stimulus above the threshold b) increasing stimulus above the treppe stimulus c) increasing the stimulation up to the maximal stimulus d) recruiting small and medium muscle fibers

c) increasing the stimulation up to the maximal stimulus

Immediately following the arival of the stimulus at a skeletal muscle cell there is a short period called the ___ period during which the events of excitation-contraction coupling occur. a) contraction b) relaxation c) latent d) refractory

c) latent Latent period - the first few millaseconds following stimulation when excitation-contraction coupling is occuring.

Which of the following is a factor that affects the velocity and duration of muscle contraction? a) number of muscle fibers stimulated b) size of the muscle fibers stimulated c) load on the fiber d) muscle length

c) load on the fiber

Rigor mortis occurs because ___. a) the cells are dead b) sodium oions leak out of the muscle c) no ATP is available to release attached actin and myosin molecules d) proteins are beginning to break down, thus preventing a flow of calcium ions

c) no ATP is available to release attached actin and myosin molecules

Myoglobin ___. a) breaks down glycogen b) is a protein involved in the direct phosphorylation of ADP c) stores oxygen in muscle cells d) produces the end plate protential

c) stores oxygen in muscle cells

The mechanism of contraction in smooth muscle is different from skeletal muscle in that ___. a) actin and myosin interact by the sliding filament mechanism b) the trigger for contraction is a rise in intracellular calcium c) the site of calcium regulation differs d) ATP energizes the sliding process

c) the site of calcium regulation differs

Which of the following describes the cells of single-unit visceral muscle? a) they contract all at once. b) They are chemically coupled to one another by gap junctions. c) they exhibit spontaneous action potentials. d) They consist of muscle fibers that are structurally independent of each other.

c) they exhibit spontaneous action potentials.

motor unit

combination of each axon and all associated muscle fibers; contract in unison

thin filaments

composed of actin, extend across the I band and partway into the A band

thin filaments

composed of actin, tropomyosin, and troponin

thick filaments

composed of myosin; extend the entire length of the A band

latent period

cross bridges begin to cycle but muscle tension is not yet measurable

Ach

crosses synaptic cleft and binds to Ach receptors on the motor end plate

sarcoplasm

cytoplasm of a muscle cell; contains unusually large amounts of glycosomes and myoglobin

sarcoplasm

cytoplasm of muscle cell

Creatine phosphate functions in themuscle cell by ___. a) forming a temporary chemical compound with myosin b) forming a chemical compound with actin c) inducing a conformational change in the myofilaments d) storing energy that will be transferred to ADP to resynthesize ATP

d) storing energy that will be transferred to ADP to resynthesize ATP

fatigue

decreased capacity to do work -muscle experiences reduced efficiency -usually follows period of activity

atrophy

decreases size of muscle with disuse

synaptic fatigue

depletion of synaptic vesicles & neurotransmitters Ach (rare)

muscular dystrophy

destroyed skeletal muscle replaced with CT -Duchenne: sex-linked inheritance, primarily affects males -Facioscapulohumoral: less sever form, both males/females affected equally

action potential

electrical signals from motor neurons

AP is a ___________ event

electrochemical

"Cocking" of the myosin head—

energy from hydrolysis (breakdown) of ATP cocks the myosin head into the high-energy state

Cholinesterase

enzyme that decomposes acetylcholine, located at neuromuscular junction in the membranes of the motor end plate

Anything that ends in ase =

enzymes

Direct/fleshy attachments

epimysium of muscle fuses to periosteum of bone/pericardium of cartilage

physiological contracture

extreme muscle fatigue, incapable of contracting/relaxing, due to low ATP

fast oxidative fibers

fast contraction, aerobic (some anaerobic glycolysis), high myoglobin, red to pink, many mitochondria; best suited for combination activities like alternating sprinting and walking

elasticity

has both stretch and recoil capabilities

troponin

has polypeptides - TnI binds to actin - TnT binds to tropomyosin that helps position it on actin - TnC binds calcium ions

intense exercise (anaerobic)

increase muscle strength/mass; has greater effect on fast-twitch fibers

hypertrophy

increase size/muscle mass; working out, exercising

anabolic steroids

increase size/strength of muscles; side-effects include: sterility, cardiovascular problems, liver dysfunction, irritability

multiple-wave summation

increased tension caused by increase in stimulus frequency

hypertrophy

increases cell size not cell number

aerobic exercise

increases number of mitochondria, increases blood supply, increases endurance of both slow/fast twitch fibers -primarily increases the size of slow-twitch fibers

What does prolonged tetanus lead to?

inevitable muscle fatigue

fibrositis

inflammation of fibrous CT --> stiffness, pain, soreness

At rest tropomyosin and troponin _____ active sites on actin so linkages between actin and myosin ____ be formed

inhibit; CANNOT

psychological fatigue

involves CNS, "perceive" additional work is not possible so you consciously shutdown activity (muscle can still function) -additional burst of activity in athletes due to "crowd" ----> psychological fatigue can be overcome

hypertrophy

involves increase in muscle fiber size (more protein) rather than in number

ach receptor

ion channel that opens and allows for influx/entry of Na+ ions into the muscle cell

What kind of motor units do large, weight-bearing muscles, whose movements are less precise have?

large motor units

perimysium

layer of fibrous connective tissue that surrounds each fascicle

Ca2+ ions enter the axon terminal

leading to the release of Ach into synaptic cleft

aerobic endurance

length of time a muscle can continue to contract using aerobic pathways

muscles with delicate/precise movement have motor units with ______ number of muscle fibers, which results in more control.

less

What happens if sarcomeres are so compressed and cramped that Z discs abut the thick myofilaments and thin filaments touch and interfere with one another?

little or no further shortening can occur

H band

made of only thick filaments

epimysium

many fasicles grouped together

regular endurance exercise

may convert fast glycolytic fibers into fast oxidative fibers

contraction is a __________ event

mechanical

hypertrophy

muscle growth together with an increase in the size of muscle cells from strength or resistance training

skeletal and smooth

muscle tissue types that have tightly packed cells

myofilaments

myofibrils arises from orderly arrangement of even smaller structures within sarcomeres

relaxation

passive process, x-bridge release, no ATP required, but uses ATP pump

movement

primary function of muscle

agonist

prime mover; performs a specific movement

myasthenia gravis

produce Ab to Ach receptors therefore reduces number of functional receptors -causes flaccid paralysis -treated by neostigmine, blocks Achase activity allowing Ach to accumulate in the NM junction and bind to remaining receptors

myoblasts

produce muscle fibers

anaerobic respiration

produces 2 ATP per glucose

aerobic respiration

produces 32 ATP for every glucose

exercise

produces hypertrophy of existent muscle fibers

anaerobic respiration

produces lactic acid that has to be recycled by the liver

4 important functions of muscle tissues in the body

producing movement, maintaining posture and body position, stabilizing joints, and generating heat

as stimulus strength is increased from subthreshold to threshold to submaximal to maximal strengths, additional motor units are __________

recruited; recruitment

triads

regions where the SR terminal cisterns border a T tubule on each side

troponin

regulatory protein that binds to actin, tropomyosin, and calcium

tropomyosin

regulatory protein that covers myosin-binding sites to prevent actin from binding to myosin

tropomyosin

regulatory protein, "covers" 7 G-actin binding sites

aerobic respiration

requires mitochondria

excitability

responds to stimulus by nerves/hormones

myofilaments

responsible for muscle contraction Bundles of parallel protein microfilaments that make up a myofibril.

muscular fatigue

results form ATP depletion

external lamina

reticular fiber layer surrounding muscle fibers

recovery stroke

return of myosin head to its origonal position after x-bridge is broken

myosin

rod-shaped molecule with 2 heads (contain ATPase)

specific movements

roles of antagonist and agonists are really better applied to a _______________ than to the muscle itself because they play alternative roles

fasicle

root or bundle

synaptic vesicles

sac like structure in a synaptic know that contains Ach

stretch

smooth muscles can _______________ and still maintain contractility

The cross marking on skeletal muscles are called _____.

striations

maximal stimulus

strongest stimulus that increases contractile force; all motor units of a muscle are activated

Anything that ends in ose =

sugar

varicosities

swellings in nerve fibers, like axon terminals of motor neurons; release NT into wide synaptic cleft

isotonic muscle contraction

tension is constant during contraction and length of muscle changes. -contraction associated with joint movements

extensibility

the ability to extend or stretch

excitability or responsiveness

the ability to receive and respond to a stimulus

contractility

the ability to shorten forcibly when adequately stimulated (this ability sets muscle apart from all other tissue types)

contraction

the activation of myosin's cross bridges, which are the force-generating sites.

sarcolemma

the plasma membrane of a muscle fiber

sliding filament model of contraction

the thick and thin filaments past each other, shortening the sarcomere.

myosin

thick filaments

T-tubules

tubelike invaginations of sarcolema

T tubules

tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side

1. number of motor units recruited, 2. size of muscle fibers, 3. frequency of stimulation, 4. degree of stretching

what are the factors that influence how much force a muscle produces

length-tension relationship

when muscle is slightly stretched and thin and thick filaments overlap optimally, permitting sliding along nearly entire length of thin filaments

isometric contraction

when muscle tension develops but load is not moved (increasing muscle tension is measured) muscle is not shortening nor lengthening

all-or-none-law

with an appropriate stimulus received, muscle fibers produce contractions of equal force

aerobic respiration

with oxygen present, glucose broken down to CO2+H2O with the production of large quantities of ATP -supports edurance activites

fascicles

within each skeletal muscle the muscle fibers are grouped into bundles called ___________________; these resemble bundles of sticks

anaerobic respiration

without oxygen present, lactic acid accumulates -can be used for short bursts of energy but not for endurance activity

synergist muscles

work in conjunction with agonist and antagonist to provide extra strength, prevent damaging movement, or immobilize larger muscles.

antagonist

work in direct opposition to agonist; usually limit agonist range of motion to avoid overextension

secretion

Muscle tissue has all of the following properties except ________.

Indirect attachments

Muscle's connective tissue extents as tendon (or aponeurosis) anchors to the bone/cartilage/other-muscle-fascia; more common; smaller, durable

work best

Muscles _______________ when not completely extended or contracted

Muscle tone is the small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units. True / False

True

Steps for Relaxation

1. cholinesterase decomposes acetylcholine so sarcolemma is o longer stimulated 2. CA ions are actively transported back into the Saco ret 3. Linkages between actin and myosin are broken 4. Troponin and tropomysocin molecules inhibit the binding (active) sites of actin 5. Actin and myosin filaments slide apart...muscle fiber lengthens-relaxation

how is ATP regenerated after being hydrolyzed to ADP and Pi

1. direct phosphorylation of ADP by creatine phosphate 2. anaerobic respiration (glycolysis and lactic acid formation) which converts glucose to lactic acid 3. aerobic respiration

recruitment process

1. motor units with smallest muscle fibers activated first 2. motor units with larger and large muscle fibers get excited --> contractile strength increases 3. largest motor units with large muscle fibers controlled by largest neurons are activated when most powerful contraction is necessary

4 Factors that affect force of muscle contraction

1. number of muscle fibers stimulated 2. relative size of fibers 3. frequency of stimulation 4. degree of muscle stretch

Smooth muscles relax when intercellular Ca2+ (calcium ion) levels drop but may not cease contractions. True / False

True

If stimulus strength is held constant and muscle is stimulated at increasingly faster rate

1. relaxation time between twitches get shorter and shorter 2. concentration of calcium in cytosol rises higher and higher 3. degree of wave summation becomes greater and greater

Actin (from notes)

1/4 total protein in skeletal muscle; globular structure with myosin binding sites attached to surface

ATP reserves in muscle

1st energy reserve source - only 4 - 6 seconds worth of energy

Citric Acid Cycle

2 ATP; waste: carbon dioxide

Each actin myofilament contains _______________

2 fiberous actin (F-actin) + tropomyosin + troponin

smooth muscle facts:

-spindle-shaped fibers, mononucleate, involuntary -NOT organized into sacromeres, not striated -slower contraction speed but sustain tension longer -decreased number of actin/myosin filaments present -contain intermediate filaments and dense bodies -actin attaches to intermediate filaments (~equivalent to Z lines) -Ca2+ binds to calmodulin and activates myosin kinase -myosin kinase adds Pi from ATP to myosin -myosin phosphatase removes Pi from myosin (release of x-bridge)

neromuscular junction

-synaptic vesicles contain NT (neurotransmitter) acetyelcholine (Ach) -acton potentials at prsynaptic terminal causes Ca2+ channel to open which causes vesicles to migrate -NT released into synapse -Ach binds to protein receptor on postsynaptic side -ligand-sensitve Na+ channels open -AP is propagated along sarcolema

_____ molecule of ATP is required for x-bridge formation/movement/release cycle

1

motor units

1 motor neuron and all the muscle fibers it innervates

3 steps involved in generating action potential

1. Generation of end plate potential 2. Depolarization 3. Repolarization

Two steps of cellular respiration

1. Glycolysis (2 ATP) 2. Aerobic respiration (34 ATP) - Citric Acid Cycle (Krebs's) (2 ATP) - Electron Transport Chain (32 ATP)

FIRST Channel Involved in Initiating Muscle Contraction

1. Nerve impulse reaches axon terminal and opens voltage-gated Ca channels in axonal membrane --> influx of Ca triggers release of ACh into synaptic cleft

Slow twitch/red muscle

"dark meat" lots of myoglobin and lots of mitochondria so does lots of cellular respiration to get ATP; does NOT fatigue easily; ex: back muscles (for posture) and thigh muscles

sarcoplasmic reticulum

"endoplasmic reticulum" of a muscle fiber; membranous channels that run parallel to and surround each myofibril

Transverse tubules

"t-tubules"; membranous channels that go from the sarcolemma all the way through the muscle fiber; open to the outside of the muscle fiber; invaginations of the sarcolemma; contain extracellular fluid

fast-twitch (low-oxidative) fibers

"white meat" -respond quickly, less-developed blood supply, low number of mitochondria -fatigue quickly -high deposits of glycogen -adapted for anaerobic respiration

concentric contraction

(type of isotonic contraction) muscle shortens and does work

Rich blood supply because (2)

1. Uses huge mounts of energy 2. Removes numerous amounts of metabolic wastes

What is the role of calcium ions in muslce contraction? a) form hydoxyapatite cyrstals b) reestablish glycogen stores c) bind to regulatory sites on troponin to remove contraction inhibition d) increase levels of myoglobin

) bind to regulatory sites on troponin to remove contraction inhibition

Contractility

-ability to shorten forcibly when adequately stimulated

What happens during contraction:

-actin and myosin slide past eachother -x-bridges form between actin/myosin----> x-bridges form, move, release, reform -action results in inward movement of actin filaments towards H zone -Z lines are brought closer together

acetylcholinesterase

-breaks down unused Ach within synaptic cleft -prevents constant stimulation of the junction; 1 presynaptic AP--> 1 postsynaptic AP

smooth muscle RMP

-doesn't respond in an all-or-none fashion -slow wave of depolarization due to Na+ and Ca2+ movement -epinephrine stimulates muscle contraction by activating G-proteins -oxytocin stimulates muscle of uterus -smooth muscle contracts when stretched and exhibits constant tension -innervated by ANS (involuntary)

SECOND Channel Involved in Initiating Muscle Contraction

2. ACh binds to receptors on sarcolemma and opens ligand-gated Na+-K+ channels --> influx of Na+ causes voltage change (depolarization)

__-__% of energy available from cellular respiration and ___% is lost as heat

20-25%; 75%

Each F-actin polymer is about equal to _________ globular actin (G-actin) monomers

200

direct phosphorylation of ADP by creatine phosphate

2nd energy reserve source - required NO oxygen, 1 to 1 production rate; about 20 - 30 seconds (text says 15)

THIRD channel involved in initiating muscle contraction

3. Depolarization opens voltage-gated sodium channels in neighboring region of sarcolemma allowing more Na+ to enter --> more depolarization in sarcolemma --> generates and propagates an action potential

Electron Transport Chain

32 ATP; waste: water

Glucose molecule gives enough energy for __ ATP

36

Women's skeletal muscles make up approx. __% of body mass

36%

myoblasts

A cell that builds muscles

True

A contraction in which the muscle does not shorten but its tension increases is called isometric.

Aerobic respiration

A metabolic pathway that provides for a large amount of ATP per glucose because oxygen is used. Products are water and carbon dioxide and ATP.

False

A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.

Motor unit

A motor neuron and the muscle fiber it controls; page 286-7

isotonic contraction

A muscle contraction that pulls on the bones and produces movement of body parts. (picking up a box)

Acetylcholine

A neurotransmitter released at motor end plates by the axon terminals.

Slow (oxidative), fatigue-resistant fibers

A relatively high percentage are found in successful marathon runners.

True

A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.

the area between two Z discs

A sarcomere is ________.

Z discs

A sarcomere is the distance between two ________.

local depolarization (end plate Potential)

ACh binding opens chemically (ligand) gated ion channels Simultaneous diffusion of Na+ (inward) and K+ (outward) More Na+ diffuses, so the interior of the sarcolemma becomes less negative Local depolarization - end plate potential

Energy for contractions comes from what?

ATP

______ is energy source for muscle contraction

ATP

Aerobic respiration

Aerobic; sequence of chemical reactions in which the bonds of fuel molecules are broken and the energy releases is used to make ATP (34 ATP); includes Citric Acid Cycle and Electron Transport Chain

level in the cytoplasm drops

After nervous stimulation of the muscle cell has ceased, the calcium ________.

True

Although there are no sarcomeres, smooth muscle still possesses thick and thin filaments.

glycolysis

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is ________.

no contraction at all by nervous mechanisms, but contraction if stimulated by an external electrode

An individual has just ingested a chemical that binds irreversibly to the ACh receptors in the sarcolemma. By itself it does not alter membrane potential, yet prevents normal neurotransmitter binding. Ignoring the effects on any other system, the consequence to skeletal muscle would be ________.

myoglobin

An oxygen-storing, red pigmented protein in muscle cells.

Glycolysis

Anaerobic; first phase of cellular respiration that breaks glucose down into tow pyruvic acid molecules and tow ATP; occurs in cytoplasm (2 ATP)

Perimysium

Around each fascicles, is a layer of fibrous connective tissue

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers? A) a sprint by an Olympic runner B) a long, relaxing swim C) playing baseball or basketball D) mountain climbing

B) a long, relaxing swim

limping

Claudication might more simply be called ________.

Red muscles tend to have a slow (oxidative) rate and fatigue resistance, whereas white muscle cells have a fast (oxidative) rate and fatigue easily.

Compare red and white muscles relative to their speed of action and endurance.

biochemistry

Constant temperature is necessary because our _______________________ has adapted to that temperature and will only function correctly there.

Tetanus

Continued sustained smooth contraction due to rapid stimulation.

True

Contractures are a result of a total lack of ATP.

Equation for creating phosphate

Creatine phosphate + ADP => creatine + ATP

storing energy that will be transferred to ADP to resynthesize ATP

Creatine phosphate functions in the muscle cell by ________.

sarcoplasm

Cytoplasm of muscle cell; has large amounts of glycosomes

Actin molecules arranged in a ____ ___ to form an actin filament

Double helix

False

During isometric contraction, the energy used appears as movement

False

During isotonic contraction, the heavier the load, the faster the velocity of contraction

actin filaments

During muscle contraction, myosin cross bridges attach to which active sites?

Generation and propagation of an action potential:

End plate potential spreads to adjacent membrane areas Voltage-gated Na+ channels open Na+ influx decreases the membrane voltage toward a critical threshold If threshold is reached, an action potential is generated

4 Characteristics of muscle tissue

Excitability/Responsiveness/Irritability Contractility Extensibility Elasticity

During isometric contraction, the energy used appears as movement. True / False

False Muscles act to hold joints in stationary positions while movement occurs at other joints.

A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate. True / False

False; Motor unit not motor end plate.

Once a motor neuron has fired, all the muscle fibers in a muscle contract T/F

False; all the muscle fibers in innervates contract

Fast twitch/white muscles

Few mitochondria and less myoglobin; gets most of its ATP through creating phosphate and Glycolysis and; DOES fatigue easily; found in muscles used in rapid movement

The ____ muscle fibers in a motor unit, the ___ movements of the muscle (example:__)

Fewer; finer; eye muscles

Cellular respiration formula

Glucose + oxygen => carbon dioxide + water + ATP C6H12O6 + 6O2 => 6CO2 + 6H2O + Energy/ATP

conserves energy

Graded response of muscle fibers; not activating more muscle fibers than we need ___________________

sarcopenia

Gradual loss of muscle mass

Fast (oxidative or glycolytic), fatigable fibers

Have very fast-acting myosin ATPases and depend upon anaerobic metabolism during contraction.

Creatine phosphate

High energy molecule stored in muscles; tapped to regulate ATP while metabolic pathways are adjusting to higher demands for ATP; short-lived

1 ATP

How much energy is necessary for each myosin head to bind with actin?

changes in length and moves the "load"

In an isotonic contraction, the muscle ________.

one nerve, one artery, and one or more veins

In general, _________________________________________ serve each muscle. These structures all enter or exit near the central part of the muscle and branch profusely through its connective tissue sheaths.

remove the blocking action of tropomyosin

In skeletal muscle contraction, calcium apparently acts to ________.

Cardiac Muscle

In the heart Involuntary Striated Steady and constant rate of contraction

proximal

In the muscles of the limbs, the origin typically lies ___________________________ to the insertion.

I bands

Lighter bands between each A band; contains actin

H zones

Lighter region in middle of A band; myosin

How can old people get muscle strength back/maintain it?

Lightly working out

Intermittent claudication

Limping condition that restricts blood delivery to the legs and has excruciating pains in the leg muscles while walking

fascicle

Muscle fibers grouped together; wrapped in perimysium

What is a myofilament?

Long strands of muscle

myofibrils

Microscopic protein filaments that make up muscle cells.

When is the natural peak of motor control?

Mid adolescence

Another name for muscle cells

Muscle fibers

ATP, mechanical energy

Muscles transform chemical energy of _____________ into _______________________ for movement.

run the length

Myofibrils ______________________ of the cells (their orientation).

stores oxygen in muscle cells

Myoglobin ________.

Repolarization:

Na+ channels close and voltage-gated K+ channels open K+ efflux rapidly restores the resting polarity Fiber cannot be stimulated and is in a refractory period until repolarization is complete Ionic conditions of the resting state are restored by the Na+-K+ pump

Each muscle is served by one ___, ____, and more than one ____

Nerve, artery...vein

Calcium ions

Normally stored in the terminal cisternae of the sarcoplasmic reticulum

Lactic Acid formation

Occurs when not enough oxygen is available to send pyruvic acid into aerobic respiration; due to extreme exercise; ex: muscles working hard due to running so can't get enough oxygen into body (lung capacity) so blood can't get to lungs to pick up more oxygen so causes oxygen deficit/debt

multiunit smooth muscle

Of the following muscle types, which has only one nucleus, no sarcomeres, and rare gap junctions?

False

Once a motor neuron has fired, all the muscle fibers in a muscle contract

a sarcomere

One functional unit of a skeletal muscle is ________.

True

One of the important functions of skeletal muscle contraction is production of heat.

___ motor nerve fiber is connected to ____ muscle fibers so ___ muscle fibers connected to the same nerve fiber contract ______

One; many; all; simultaneously

skeletal

Only ________ muscle cells are always multinucleated.

cardiac

Only ________ muscle cells commonly branch.

Skeletal muscle

Organs that attach to/cover bony skeleton Rapid contraction, but tires easily (bunny) Striations voluntary

False

Oxygen debt refers to the oxygen required to make creatine phosphate.

2nd Step Cross Bridge Cycle

POWER STROKE - ADP and Pi are released - myosin head pivots & bends --> low-energy state - pulls actin filament toward M line

True

Peristalsis is characteristic of smooth muscle

sarcolemma

Plasma membrane around muscle fiber

Cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen; eating and breathing to get energy

Muscle functions

Producing body movement (locomotion, manipulation) Maintaining postures and body positions Stabilizing joints Generating heat (40% of body mass; most responsible for heat)

False

Recruitment is an option in a single-unit smooth muscle cell

myoglobin

Red pigment that stores oxygen, transports it

Conductivity

Response; generation of electrical impulse that passes along plasma membrane of muscle cell and causes cell to contract

A contraction in which the muscle does not shorten but its tension increases is called isometric. True / False

True Isometric - tension may build to the muscle's peak, tension producing capacity, but the muscle neither shortens or lengthens. iso = same metric = measure

triad

Sarcoplasmic reticulum Transverse tubules Terminal cisternae

Calcium ions

Serves as the actual "trigger" for muscle contraction by removing the inhibition of the troponin molecules.

Duchesne muscular dystrophy

Sex-linked recessive disease; females carry and transmit; almost always males have it; 2-7 years old; healthy people become clumsy and fall as skeletal muscles fail; usually die in 20s

Neuromuscular junction

Site where motor nerve fibers and muscle fires meet; also called myoneural junction

The fibers of ____ and ____ are striated.

Skeletal and cardiac

muscle fibers

Skeletal and smooth muscle cells are elongated, and for this reason, they are called ________________________.

40%

Skeletal muscle accounts for at least ______________________ of body mass.

*Other functions of muscle*

Skeletal muscles protect inner organs Smooth muscle forms valves for passage (sphincters) Dilate pupils of eyes

Motor end plate

Specialized part of sarcolemma/muscle at the neuromuscular junction; sarcolemma is extensible folded; area has many nuclei and mitochondria

Development in a kid begins in ___ and radiates ___

Starts in head, radiates outward

contractures

State of continuous contractions; ex: writer's cramp

Muscle fatigue

State of physiological inability to contract even though the muscle still may be receiving stimuli; results from a relative deficit of ATP; not its total absence

steroids

Synthetic male hormones

exhibit spontaneous action potentials

The cells of single-unit visceral muscle ________.

myofibrils

The contractile units of skeletal muscles are ________.

Eccentric contractions are more forceful than concentric contractions. True / False

True Eccentric contractions - muscle generates force as it lengthens in your calf muscles as you walk up a hill. Concentric contractions - muscle shortens and does work, such as picking up a book or kicking a ball.

insertion

The end of the muscle that typically moves when a muscle contracts is called the ________.

True

The force of muscle contraction is controlled by multiple motor unit summation or recruitment.

enhance cellular communication during muscle contraction

The functional role of the T tubules is to ________.

enhance the availability of calcium and the efficiency of enzyme systems

The main effect of the warm-up period of athletes, as the muscle contractions increase in strength, is to ________.

regulate intracellular calcium concentration

The major function of the sarcoplasmic reticulum in muscle contraction is to ________.

the site of calcium regulation differs

The mechanism of contraction in smooth muscle is different from skeletal muscle in that ________.

False

The more slowly a skeletal muscle is stimulated, the greater its exerted force becomes

the ability to transform chemical energy into mechanical energy

The most distinguishing characteristic of muscle tissue is ________.

voltage (electrical)-gated Na+ and K+ channels

The muscle AP propagates over the surface of the muscle cell membrane (sarcolemma) via

sarcolemma

The muscle cell membrane is called the ________.

A band

The myosin filaments are located in the ________.

myoglobin

The oxygen-binding protein found in muscle cells is ________.

Treppe

The phenomenon in which the contraction strength of a muscle increases, due to increased Ca2+ availability and enzyme efficiency during the warm-up.

bind to regulatory sites on troponin, changing the configuration

The role of calcium ions in muscle contraction is to ________.

calmodulin

The site of calcium regulation in the smooth muscle cell is ________.

Wave summation

The situation in which contractions become stronger due to stimulation before complete relaxation occurs

actin and myosin sliding past each other and partially overlap

The sliding filament model of contraction involves ________.

Maximal stimulus

The stimulus above which no stronger contraction can be elicited, because all motor units are firing in the muscle

the arrangement of myofilaments

The striations of a skeletal muscle cell are produced, for the most part, by ________.

increasing the stimulation up to the maximal stimulus

The strongest muscle contractions are normally achieved by ________.

Myosin

The thicker filaments are the ________ filaments.

contraction

The time in which cross bridges are active is called the period of ________.

An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops. True / False

True

Contractures are a result of a total "lack" of ATP. True / False

True

Muscle fibers don't have to completely relax before being stimulated by a second action potential. True/False?

True

treppe

The warm-up period required of athletes in order to bring their muscles to peak performance is called ________.

Smooth and cardiac do not do what?

They don't fuse

Myosin (Newville)

Thick filaments; solid with projections coming off; rod-like tail with two heads; 6 strands

a long, relaxing swim

Three discrete types of muscle fibers are identified on the basis of their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers?

both the sarcoplasmic reticulum and transverse tumbles function to___________________________

To activate the muscle contraction mechanism

tendons

Tough collagen fibers that withstand touch bony protections; small size-conserve space

Creatine phosphate

Used to convert ADP to ATP by transfer of a high-energy phosphate group. A reserve high-energy compound.

Heart is pumping blood by what week?

Week 3

Skeletal muscle fibers are contracting by what week?

Week 7

Oxygen Deficit/Debt

When have less than amount of oxygen a body must take in for restorative process; causes arctic acid buildup; occurs when you don have enough oxygen in you body to send all the pyruvic acid into the aerobic part of cell respiration

Muscle's origin

When muscle contracts: immovable

Muscle's insertion

When muscle contracts: moveable

False

Whereas skeletal muscle cells are electrically coupled, smooth muscle cells appear to be chemically coupled by gap junctions.

thick filaments

Which of the following are composed of myosin?

a change of temperature

Which of the following does not act as a stimulus to initiate a muscle contraction?

Muscle tension remains relatively constant during isotonic contraction.

Which of the following is most accurate?

increase in the number of muscle cells

Which of the following is not a usual result of resistance exercise?

Certain smooth muscle cells can actually divide to increase their numbers.

Which of the following is true about smooth muscle contraction?

There is no biological basis for the difference in strength between women and men.

Which of the following statements is not true concerning developmental aspects of muscle?

Striated muscle cells are long and cylindrical with many nuclei.

Which of the following statements is true?

motor units with larger, less excitable neurons

Which of the following would be recruited later in muscle stimulation when contractile strength increases?

treppe

a "staircase"-like graded response -a "warming-up" phenomenon in rested muscle -first few action potentials result in contraction of increasing strength/tension -all further contractions show same tension

synaptic cleft

a gap into which neurotransmitters are released from the axon terminal

The giant protein titin maintains the orgainzation of the ___ assisting in muscle stretching. a) A band b) I band c) Z disc d) M line

a) A band

threshold stimulus

action potential produced, muscle contraction results

total tension

active+passive tension

Nerve endings controls ____

activity

maximal stimulus

all motor units of a muscle are activated

Why is the size principle important?

allows increases in force during weak contractions to occur in small steps

epimysium

an "overcoat" of dense irregular connective tissue that surrounds the whole muscle

troponin

calcium binds with ________________ which pulls the tropomyosin out of the way of the actin binding sites and allow myosin to bind with actin

extensibility

can be stretched beyond their resting length to some degree

sarcolemma

cellular membrane of muscle fiber (plasma membrane)

involuntary

chemical control of smooth muscle is identical to skeletal muscle, but they are completely __________________

fibromyalgia

chronic muscle pain syndrome

additive

sequential stimulations are ______________ if they are close together

head production

shivering -muscle contractions generate heat, increase body temperature

cross bridges

shortening of fiber occurs when tension generated by _____ on the thin filaments exceeds forces opposing shortening

contractility

shortens when stimulated

Cells of ____ muscle tissue have many nuclei.

skeletal

What kind of motor units do muscles that exert fine control have?

small motor units

threshold stimulus

stimulus when first observable contraction occurs

skeletal & cardiac

striated muscle types

myfibrils

threadlike structures composed of 2 myofilaments

lag phase

time between stimulus at motor neuron & beginning of contraction

contraction phase

time of contraction (muscle shortening)

relaxation phase

time of relaxation (recovery)

directly proportional

trength of muscle contraction is _______________ to the number of motor units activated (allows for a smooth and continuous variation of tension)

Actin filament has two other proteins associated with it

tropomyosin; troponin