Ch.10 muscular tissue study guide

to is a wide and flat tendon

Aponeurosis

When a muscle fiber is relaxed the concentration of Ca in the sarcoplasm is very slow , but the concentration of Ca in the sarcoplasm reticulum ( SR ) is very high

As a result , to trigger muscle contraction , Ca must be released from SR .

is the delicate connective tissue that surrounds the individual muscle fiber and contains a large capillary network

Endomysium

_ is the dense irregular connective tissue that surrounds the entire muscle

Epimysium

lines the body wall and limbs that surround and support muscles

Fascia

Fast fibers is

Fast glycolytic fibers FG )

In skeletal muscles the combined amounts of creatine phosphate and ATP provide enough energy for the

Muscle to contract maximally for 15 seconds.

________Embryonic cell (stemcell)that forms musclefiber

Myoblast

The protein of M line is is

Myomesin

is a fibrous connective tissue that covers each fascicle of muscle and contains nerves and blood vessels that service the muscle fibers

Perimysium

_________is plasma membrane of a muscle fiber ( muscle cell )

Sarcolemma I

is the cytoplasm of a muscle fiber and myoglobin

Sarcoplasm

is the series of membraneous channels that surround each myofibril

Sarcoplasmic reticulum

The order of steps in generation an action potential a

a . Step 1 : The arrival of a nerve impulse at a motor neuron opens voltage - gated calcium Ca channel in the sarcolemma , allowing Ca enter to the synaptic terminal to trigger the releasing of acetylcholine . b . Step 2 : Ach diffuses across the synaptic cleft by exocytosis and binds to receptors in the motor - end plate . The binding opens voltage - gated sodium Na channel in the sarcolemma allowing Na enters to the sarcoplasm . c . Step 3 : The influx of Na produces a depolarization of the sarcolemma called " muscle action potential " d . Step 4 : The muscle action potential that propagates along the T. Tubules triggers the opening of voltage - gated Ca channel in the sarcoplasmic reticulum ( SR ) . SR releases Ca into sarcoplasm Step 5 : Termination of Ach by enzyme Acetylcholinesterase ( AChE ) f . Step 6 : Ca " binds to troponin on the thin filament exposing the active site or myosin - binding site of actin . 8. Step 7 : Crossbridges are formed and contraction cycle begins . h . Step 8 : When the generation of action ential ends , Ca is pumped back to the SR by an active transport

A Troponin molecule consists three globular subunits :

a . Unit 1 binds to tropomyosin b . Unit 2 binds to G - actin c . Unit 3 binds to calcium ions .

Cross bridges

a . are portions of thick filament ( myosin head ) b . act as ( an enzymes ) ATPase during the contraction cycle of muscle c . generate force

After prolonged strenuous exercise has stopped heavy breathing will often continue for several minutes in order toprovide the oxygen needed to

a . convert the lactic acid produced during exercise back into glycogen b . resynthesize creatine phosphate c . replace oxygen displaced from muscle myoglobin

Slow fibers Slow oxidative fiber ( SO )

a a . . Sme Small diameter b . MOST resistant to fatigue c . Oxidative fibers have many mitochondria . That is a reason why they use aerobic respiration . d . high concentration of myoglobin ( Red meat ) e . Produce slow contraction

Twitch is

a brief contraction of all muscle fibers in a motor unit in response to a single action potential moving down the somatic motor neuron

Nebulin is

a long non - elastic protein wrapped around the entire length of each thin filament

Complete tetanus fused tetanus ) :

a muscle producing peak tension with rapid cycles of contraction and relaxation

The refractory period is

a period that the muscle fiber loses its excitability and cannot response to a second stimulus

A myogram is of

a record of muscle contraction

Motor unit is

a somatic motor neuron and all the skeletal muscle fibers it stimulates

Tetanus is due to

a toxin that makes the muscle cell membrane more permeable to calcium ions ( Ca ) , causing powerful tetanic contraction

Myasthenia Gravis is

an autoimmune disorder that targets the ACh receptors at the NMJ and ultimately reduces the number of available receptors . Treat the patient with a drug that inhibits the activity of acetylcholinesterase will increase contraction

A muscle fiber develops its greatest tension when there is

an optimal zone of overlap sarcomere length is 2.0 2.4 μm ) between thick and thin filament . This dependency is the length - tension relationship .

Thin and thick filaments do not extend the entire length of muscle fiber Instead they are

arranged in compartment called sarcomere

Cardiac muscle cells usually have only one sometimes two

centrally located nuclei and are branched

Rigor mortis is

condition in which muscles are in a state of rigidity 3-4 hour after death and last about 24 hours

Myofibrils are

contractile organelles of muscle cell

Actin and myosin are

contractile proteins of the muscle fiber

Cori cycle is a

cycle in the liver in which the lactic acid is converted to pyruvic acid and glucose .

The zone of overlap is

dark region where thin and thick filaments lie side by side

cardiac Skeletal muscle is

Voluntarily controlled

Hypotonia refers to

decreased or lost muscle tone

Terminal cisterns are

dilated end sac of the SR

The mechanisms of rigor mortis is due to

due to calcium ions leak out of the SR ( allowing myosin heads to bind to actin ) and muscle fibers run out of ATP ( causing the cross - bridges cannot detach from actin ) .

The part of the titin that extends from the Z disc is very elastic . Thus , titin accounts for much of the

elasticity and extensibility of myofibrils

ATP hydrolysis reaction

energizes the myosin head

Creatine phosphate acts as an

energy reserves in muscle tissue

The overlapping of thick and thin filaments and the prominent striations of the myofibrils make the

entire skeletal muscle fiber appear striated

Muscle fibers have many nuclei in order to produce large amounts of the

enzymes and structural proteins needed for contraction

The sequence of events that links excitation generation an action potential ) to the contraction is called

excitation - contraction coupling

Cardiac muscle cells also are connected to each other via

gap junctions

Like cardiac muscle cells some smooth muscle cells communicate via

gap junctions

Sarcoplasm stores

glycogen and myoglobin a red colored protein that binds O₂ .

The ratio of motor neurons to muscle fiber is the

greatest in muscles that control the eye and the tongue

Mitochondrial activity in skeletal muscle cells are usually efficient but can

have limited ATP production if there is limited O , availability

At rest the tropomyosin molecule is

held in place by troponin .

When a skeletal muscle fiber contracts in the sliding filament mechanism

in a . Z line ( Z disk ) moves closer together b . The H zones and I bands get smaller c . The width of the A band remains constant d . The zone of overlap gets larger ( more zone of overlaps between thin & thick filament )

Recruitment is the

increase in muscle tension that is produced by increasing the number of active motor units .

Hypertonia refers to

increased muscle tone

Spasticity is an

increased muscle tone associated with an increase in tendon reflexes .

Rigidity is an

increased muscle tone which tendon reflexes are not affected ( tetanus

Both cardiac and smooth muscle tissue are

involuntary and auto rhythmic

An action potential or a ( depolarization ) or a ( nerve impulse )

is required for the SR releases Ca into

After the fusion of myoblasts the muscle fiber

loses its ability to go through mitosis .

During the refractory period additional oxygen is required to

metabolize the lactic acid produced during exercise

The cytoplasm of the synaptic terminal at NMJ contains

mitochondria and vesicles filled with neurotransmitter acetylcholine

Skeletal muscle cells have _________________ nucleus are large and run parallel to each other

more than 1

There are approximately 40 million receptors for Ach that are found in the

motor - end - plate

Receptors for acetylcholine are located on the

motor - end plate ( the region of the sarcolemma opposite the synaptic end )

In multi - unit smooth muscle tissue

muscle cells have few gap junctions with neighboring cells and thus must be excited by their own motor neuron terminal .

In multi - unit smooth muscle tissue ,

muscle cells have few gap junctions with neighboring cells and thus must be excited by their own motor neuron terminal .

When energy reserves in a muscle are exhausted and lactic acid levels increase

muscle fatigue occurs

When acetylcholine binds to receptors at the motor - end plate , the

muscle membrane becomes more permeable to sodium ions Voltage - gated Na channel opens to allow Na ions entering inside the sarcolemma )

Synaptic cleft is the

narrow space between the neuron and the muscle fiber

Somatic motor neurons ( voluntary control ) provide

nerve impulses that stimulate skeletal muscle to contract

Each skeletal muscle fiber is controlled by a

neuron at a single neuromuscular junction

Aerobic respiration supplies enough ATP for muscles during periods

of rest or moderate exercises running jogging swimming walking

In sarcomere thick and thin filaments are linked laterally by

of the M line

At peaklamels of exercion mitochondria can provide only

one - third 33 % ) of the ATP needed . The remainder comes from glycolysis

Each thin filament consists of a

pair of protein actin strands wound together into a helix

Dystrophin is

protein used to reinforce the sarcolemma and help transmit the tension generated by the sarcomeres to the tendons

Rigor mortis disappears as

proteolytic enzymes from lysosomes digest the cross - bridges

Tropomyosin and troponin are

regulatory proteins of the muscle fibers

To generate an action potential acetylcholine Ach a neurotransmitter must be

released at the neuromuscular junction NMJ

There are two types of smooth muscle

single - unit visceral smooth muscle and multi - unit smooth muscle

Individual who lifts weights build larger muscles because

skeletal muscles increase number of myofibrils but not number of cells

Muscle tone is a

small amount of tension in the muscle at rest due to weak , involuntary contractions of its motor units .

Single unit smooth muscle is is found found in the skin and in tubular arrangements that form part of the walls of —

small arteries and veins and of hollow organs such as the stomach intestines , uterus , and urinary bladder .

Microfilaments are

smaller proteins within myofibrils

Muscle tissues have no striation is

smooth muscle

Flaccid is a-

state of limpness in which muscle tone is lost .

Titin myomesin nebulin Actinin and dystrophin are

structural proteins of the muscle fibers

NMJ is the

synapse between the terminal end of a somatic motor ( axon terminal ) neuron and a portion sarcolemma ( called Motor - End - Plate of a skeletal muscle fiber .

The epimysium perimysium and endomysium are all continuous with the connective tissue to form a rope like _______________that attaches a muscle to the periosteum of the bone

tendon

Titin is the largest size protein in the muscle fiber that extends from

the Z disk to M line

A band :

the darker middle area of sarcomere that contains thick & thin filament

Treppe is

the increased strength of a contraction that occurs when a second stimulus arrives after the muscle fiber has relaxed completely following the previous stimulus

fiber Wave summation is

the increased strength of a contraction that occurs when a second stimulus arrives before the muscle fiber has relaxed completely

A myogram of twitch contraction includes

the latent period , the contraction period , and the relaxation period

I band :

the light area of the sarcomere that contains thin filament only

Myosin is

the main component of the thick filament and functions as motor protein of muscle tissue

Actin is i

the main protein of the thin filament

Eccentric isotonic contractionis

the muscle fiber lengthens object is dropped

Concentric isotonic contraction is

the muscle fiber shortens . ( object is lifted )

When cross - bridges bind to the active site of actin thin filaments myosin binding site ) ,

the thick filaments pivot toward the M line .

Isotonic contraction is

the type of contraction in which the muscle fibers produce tension while muscle length is changed .-

Multi unit smooth muscle is found in

the walls of large arteries , in airways to the lungs , in the arrector pili muscles that attach to hair follicles , in the muscles of the iris that adjust pupil diameter , and in the ciliary body that adjusts focus of the lens in the eye

Active sites on the actin thin filament become available ( exposed ) for binding when calcium ion binds to troponin subunit Once Once calcium ion binds to troponin , troponin

then moves tropomyosin away from the myosin binding sites of thin filament

Smooth muscle cells are small but form

thick layers of hollow organs

There are two types of microfilaments :

thin and thick filaments

Action potentials are conducted into a skeletal muscle fiber by

transverse tubules T - tubules

A T - tubule and two terminal cisterns on either side form a

triad

At rest , active sites of actin ( myosin binding site ) thin filament are blocked ( covered ) by

tropomyosin molecules

Transverse tubules or T tubules are

tunnels in from the surface toward the center of each muscle fiber

Isometric contraction is the

type of contraction in which the muscle fibers produce tension but do not shorten nor lengthen . ( Object cannot be moved )

Thin filaments at either end of sarcomere are attached to the

Z line ( Z disc

In summary , in order to form crossbridges ,

a . ATP must be broken down by enzyme ATPase b . Calcium ions must be present in the sarcoplasm c . Myosin binding sites ( actin active site ) must be exposed

Major functions of smooth muscle :

a . Altering the diameter of the respiratory passageways b . Moving food materials along the digestive tract c . Moving sperms in the male reproductive tract and oocytes in the uterine tract d . Expelling fetus by contraction of the wall of the uterus e . Acting as a a sphincter

Four properties of muscle tissues are

a . Electrical excitability b . Contractility c . Extensibility [ property of muscle gives it the ability to stretch without damage ] d . Elasticity [ property of muscle gives it the ability to recoil ]

The factors that lead to muscle fatigue include

a . Inadequate release of calcium ions from the SR b . Depletion of creatine phosphate c . Insufficient oxygen d . Depletion of glycogen and other nutrients e . Buildup lactic acid f . Failure of a faction potentials in the motor neurons to release enough Ach

Activities during anaerobic endurance :

a . Most of the muscle's energy is produced in cytoplasm by glycolysis b . Glycolysis is a main source of ATP ( 2ATPs ) c . Oxygen debts are common d . Dependent on fast glycolytic fibers e . Oxygen is NOT required f Muscle fatigue quickly ( not able to have sustained contraction for hours )

Activities during aerobic endurance :

a . Most of the muscle's energy is produced in mitochondria b . Krebs cycle is a main source of ATP ( 36 ATPs ) c . No oxygen gen debt d . Oxygen is required e . Dependent on slow oxidative fibers f . Fatigue resistant ( sustained contraction for hours )

Muscle has three ways to produce ATP :

a . Producing ATP from creatine phosphate by direct phosphorylation b . Producing ATP from anaerobic glycolysis c . Producing aerobic respiration

Major functions of skeletal muscle include :

a . Producing body movement and storing nutrients as glycogen , proteins b . Maintaining posture ( upright position ) c . Generating heat d . Controlling entrance and exit

Major characteristics of smooth muscle cells :

a . Smooth muscle cells are uninucleate b . Smooth muscles lack sarcomeres c . Thin filaments are attached to dense bodies d . Transmitting the contractile forces from cell to cells throughout the muscle tissue . e . Involuntary control pacesetter cells

The contraction cycle includes

a . Step 1 : Myosin head hydrolyses ATP and become energized and oriented b . Step 2 : Myosin head binds to actin , forming the cross bridge c . Step 3 : Myosin head pivots , pulling the thin filament past the thick filament the sarcomere power stroke ) d . Step 4 : Another ATP binds attches to the cross bridge , myosin head detaches from actin . Then the cycle repeats

Plasticity is

an ability of the smooth muscle to function over a wide range of lengths

Anaerobic glycosi5 supplies enough atp for musclesfor :

: 2 minutes of maximal activity

H zone :

A band that contains thick filament only

In single unit smooth muscle tissue action potentials are initiated in response to neurotransmitters hormones or an auto - rhythmic signal

The action potential spreads throughout the tissue by moving through gap junctions that connect all the muscle cells together within the tissue

The SR sarcoplasmic reticulum releases

calcium in response to an arrival of action potential .

Smooth muscle contracts when—

calcium ions Ca interact with calmodulin which activate the enzyme myosin light chain kinase enabling myosin heads to attach to actin .

SR stores

calcium ions Ca² + )

Contraction of myofibrils within a muscle fiber begins when

calciumion is released from the terminal cistern of sarcoplasmic reticulum .