anatomy 101 Ch.10

how long does cardiac muscle remain contracted?

10 to 15 seconds longer than skeletal muscle tissue because of the prolonged delivery of calcium ions into the sarcoplasm

In skeletal muscles, the combined amounts of creatine phosphate and ATP provide enough energy for the muscle to contract maximally for approximately

15 seconds

fibromyalgia

A chronic, painful, nonarticular rheumatic disorder that affects the fibrous connective tissue components of muscles, tendons, and ligaments. A sign is when pain results from a gentle pressure at specific tender points.

Place the muscle tissue type in order from least to most mobility A. Skeletal, cardiac, smooth B. cardiac, smooth, skeletal C. smooth, skeletal, cardiac D. Skeletal, smooth, cardiac

A. Skeletal, cardiac, smooth

What three ways can muscle fibers produce ATP?

1. from creatine phosphate 2. by anaerobic glycolysis 3. aerobic respiration

Place muscle tissue type in order from least to most able to regenerate

1. skeletal 2. cardiac 3. smooth

Three ways to restore metabolic conditions to the resting level

1. to convert lactic acid back to glycogen stores in the liver 2. to resynthesize creatine phosphate in ATP in muscle fibers 3. replace the oxygen removed from myoglobin

when does the first pair of somites appear?

20th day of embryonic development, 42 to 44 pairs of somites are formed by the end of the fifth week

contraction cycle

4 steps where the repeating sequence of events that causes filaments to slide

I band

A lighter less dense area that contains the rest of the thin filaments but no thick filaments in the Z disc passes through the center of each of these bands

Triad

A transverse tubule and the two terminal cisterns on either side of the cisterns is called this

H zone

A zone in the center of each a band that contains thick but not thin filaments

What energizes the myosin head?

ATP hydrolysis reaction

The first step of the contraction cycle

ATP hydrolysis, myosin head hydrolyzes ATP and becomes energized and oriented, the myosin head is perpendicular relative to the thick and thin filaments and has the proper orientation to bind to an actin molecule.

actin and myosin

Actin are thin filaments while myosin are thick filaments, both Thin and Thick filaments are directly involved in the contractile process. There are two Thin filaments for every thick filament in the regions of a filament overlap

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

Actin filaments

Which of the following functions as a motor protein in all three types of muscle tissue? A. Actin B. Myosin C. Troponin D. Titin

B. Myosin

Which correctly lists the sequence of structures that action potentials must move through to excite skeletal muscle contraction? A. Sarcolemma, Axon of Neuron, T Tubules B. Axon of neurons, sarcolemma, t tubules C. T tubules, sarcolemma, axon of neuron

B. axon of neuron, sarcolemma, t tubules

Sarcomere

Compartment where filaments are arranged, basic functional units of a myofibril

The fourth step of contraction cycle

Detachment of myosin from actin, as myosin head binds ATP the crossbridge detaches from actin.

Terminal cisterns

Dilated end sacs of Dilated end sacs of the sarcoplasmic reticulum, Butts against a t tubule from both sides, Release of calcium ions from this of the sarcoplasmic reticulum triggers muscle contraction sarcoplasmic reticulum, Butts against a t tubule from both sides

World class shot-putters will have a higher percentage of ______in their arm muscles?

Fast glycolytic fibers

Epimysium

Outer layer that encircles the entire muscle and is comprised of irregular connective tissue.

Calmodulin

a regulatory protein that binds the calcium ions in the sarcoplasm, activates an enzyme called myosin light chain kinase

muscle tone

a small amount of tautness or tension in the muscle due to weak involuntary contractions of its motor units, established by neurons in the brain and spinal cord that excite the muscles motor neurons

the mnemonic of the bands

The letter i is thin which contains thin filaments while the letter H is thick and contains thick filaments

Which statement explains the sarcomere appearance change during a muscle contraction?

The light A bands remain at a constant length

aerobic training

build endurance for prolonged activities

Contraction of myofibrils within a muscle fiber begins when

calcium is released from sarcoplasmic reticulum

What are the 2 contractile proteins?

myosin and actin

Why does Muscle contraction occur?

myosin heads attached to and walk along the thin filaments at both ends of a sarcomere, progressively pulling the thin filaments toward the M line. the thin filaments slide Inward and meet at the center of a sarcomere. has the thin filaments slide inward the I band and H Zone narrow and eventually disappear altogether when the muscle is maximally contracted.

Somatic motor neurons

neurons that stimulate skeletal muscle fibers to contract, has a thread-like axon that extends from the brain or spinal cord to a group of skeletal muscle fibers

somatic motor neurons

neurons that stimulate skeletal muscle to contract. Threadlike axon extends from brain or spinal cord to a group of skeletal muscle fibers. The axon of a SMN typically branches off many times each innervating a different skeletal muscle fiber.

How many neuromuscular Junctions can a skeletal muscle fiber have and where is it located?

only one near muscular Junction and it is located near the midpoint of the fiber

Sarcolemma

plasma membrane of a muscle fiber

Caveolae

pouch like invaginations of the plasma membrane that contain extracellular calcium ions used for muscle contraction

smooth muscle tone

prolonged presence of calcium ions in the cytosol, a state of continued partial contraction most smooth muscle fibers contract or relax in response to Action

calsequestrin

protein molecule within the SR that binds to Ca2+ allowing for more Ca2+ to be stored in the SR.

Epimysium Perimysium Endomysium

the 3 connective tissues that extend from fascia

Motor unit recruitment

the process in which the number of active motor units increases delays muscle fatigue

motor end plate

the region of the sarcolemma opposite the synaptic end bulbs, a muscular part of the neuromuscular Junction, has acetylcholine receptors which are integral transmembrane proteins to which acetylcholine specifically binds

cardiac muscle tissue contracts when stimulated by acetylcholine released by a nerve impulse in a motor neuron or when stimulated by its own autorhythmic muscle fibers?

when stimulated by its own autorhythmic muscle fibers

Which microscopic structure is found only in the cardiac muscle tissue?

Intercalated discs

Myoglobin

It is a red-colored protein that is found only in the muscle and allows oxygen that diffused into the muscle from the interstitial fluid to bind to it. Once oxygen is need by the mitochondria for ATP production the myoglobin release the oxygen molecule.

what happens when there are no transverse tubules and smooth muscle fibers?

It takes longer for calcium ions to reach the filaments in the center of the fiber and Trigger the contractile process

steps of twitch contraction

Latent period, contraction period, relaxation period

During muscle contractions, thin filaments are pulled towards the

M line

Rigor mortis occurs because ________?

No ATP is available to release attached actin and myosin molecules

The third step of the contraction cycle

Powerstroke, myosin head pivots pulling the thin filament past the thick filament toward the center of the sarcomere, myosin head changes position to a 45 degree angle. ADP is then released from myosin head

What is the primary function of wave summation?

Produce smooth, continuous muscle contraction

Functions of Muscular Tissue

Producing body movements, stabilizing body positions, storing and moving substances within the body, and generating heat.

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

Regulate intracellular calcium concentration

Ca2+-ATPase pumps

Reside within the SR and uses ATP constantly to transport Ca2+ from the sarcoplasm to SR

What portion of the neuromuscular junction initially contains the neurotransmitter acetylcholine?

Synaptic vesicles.

What happens when the thin filaments slide inward in muscle contraction?

The Z discs come closer together and the sarcomere shortens.

Myosin

The main component of the thick filaments and functions as a motor protein in all three types of muscle tissue

Actin

The main component of the thin filament is this. Individual molecules join to form a filament that is twisted into a helix, on each molecule is a myosin binding site where myosin head can attach.

concentric isotonic contraction

The muscle shortens and pulls on another structure such as attending to produce movement and to reduce the angle at a joint ex. picking up a book from a table

Perimysium

This layer is also comprised of irregular connective tissue, however, this layer encloses groups of 10-100+ of muscle fibers separating them into little bundles called fascicles.

Endomysium

This layer penetrates the interior of each fascicle separating the individual fibers. It is mostly comprised of reticular fibers.

subcutaneous layer (hypodermis)

This separates the muscle from the skin. It is comprised of areolar connective and adipose tissue. in addition, it provides a pathway for nerves, blood/lymphatic vessels to enter and exit the muscle. Also stores most of the bodies triglycerides. It also insulates to reduce heat loss and protects the muscles from physical trauma.

intermediate filaments

Threadlike proteins in the cell's cytoskeleton that are roughly twice as thick as microfilaments

The third most plentiful protein in skeletal muscle

Titin

Several key structural proteins

Titin, actinin, myomesin, nebulin, dystrophin

Why would cardiac muscles have longer refractory periods than skeletal muscles?

To preserve the normal rhythm of the heart and prevent fatigue

muscular atrophy

a decrease in size of individual muscle fibers from progressive loss of myofibrils.

Synapse

a region where communication occurs between two neurons or between a neuron and a Target cell

synaptic cleft

a small Gap separating two cells

neuromuscular disease

abnormalities of skeletal muscle function may be damage of any of the components of a motor unit of the somatic motor neurons neuromuscular Junctions or muscle fibers

the opening of ligand gates on the sarcolemma is directly caused by

acetylcholine attachment. calcium influx into the motor neuron . sodium influx into the muscle fiber. acetylcholinesterase activity. all choices are correct.

Step 2 of a nerve impulse eliciting a muscle action potential

activation of acetylcholine receptors- binding of two molecules of the acetylcholine to the receptor on the motor end plate opening an ion channel into the acetylcholine receptor, when open small cations can flow across the membrane

anaerobic training

activities stimulate synthesis of muscle proteins and result overtime and increase muscle size

Oxygen depth

added oxygen over and above the resting oxygen consumption that is taken into the body after exercise, used to restore my tablet conditions to the resting level in three ways

A runner nearing the end of a marathon race would produce most ATP by:

aerobic

Mesoderm

all muscles are derived from this except for the iris of the eyes and the arrector pili muscles attached to hairs

What does the myosin head have

an ATP binding site that functions as an ATPase and a phosphate group

Hyperplasia

an increase in the number of fibers

What atp production would be sufficient to run in place for one minute?

anaerobic cellular respiration

The second step of the contraction cycle

attachment of myosin to actin, myosin head binds to actin forming a cross Bridge, releases previously hydrolyzed phosphate group. only one head binds to actin at a time

potentials from the autonomic or somatic nervous system

autonomic nervous system

where do calcium ions flow in a smooth muscle?

both the interstitial fluid and sarcoplasmic reticulum

twitch contraction

brief contraction of all muscle fibers in a motor unit in response to a single action potential

Smooth muscle tone is maintained by the prolonged presence of [_____] in the muscle cell's cytosol?

calcium ions

What does the sarcoplasmic reticulum release at the onset of contraction?

calcium ions

Relaxation period

calcium ions actively transported back into sarcoplasmic reticulum, myosin binding sites are covered by tropomyosin, myosin heads detach from actin intention in the muscle fiber decrease

What happens after calcium ions are released at the onset of contraction?

calcium ions bind to troponin and move tropomyosin away from the myosin binding sites on actin. once the sites are free the contraction cycle begins.

________ released from the sarcoplasmic reticulum bind to troponin to trigger exposure of binding sites on actin and begin the contraction cycle. ______ supplies energy to detach the myosin head from actin

calcium ions, ATP

What are the similarities between smooth muscle fiber and a striated muscle?

can increase in concentration of calcium ions in the sarcoplasm of the smooth muscle fiber initiates contraction

Which type of muscle tissue contracts when excited by their own autorhythmic muscle fibers?

cardiac muscle

physiological enlarged heart

cardiac muscle fibers can undergo hypertrophy in response to an increased workload, can also use lactic acid produced by skeletal muscle fibers to make ATP

enzyme creatine kinase

catalyzes the transfer of one of the high-energy phosphate groups from ATP to creatine forming creatine phosphate and ADP

two types of isotonic contractions

concentric and eccentric

multi-unit smooth muscle tissue

consist of individual fibers each with its own motor neuron terminals and with few Gap Junctions between neighboring fibers, simulation A1 multi-unit fiber causes contraction of that fiber only, found in the walls of large arteries, and airways to lungs, in the arrector pili muscles attached to the hair follicles, in the muscles of the iris to adjust pupil diameter and in the ciliary body

A band

dark area; extends length of the thick filaments, there is a zone of overlap where thick and thin filaments lie side by side

Slow oxidative fibers

dark red because they contain large amounts of myoglobin and many blood capillaries, Many mitochondria, high capacity for generating ATP with aerobic respiration, resistant to fatigue and capable of prolonged sustained contractions for many hours because of slow fibers, contributes to running a marathon

fast oxidative glycolytic fibers

dark red, largest fiber with high amounts of myoglobin, generates considerable ATP by aerobic respiration giving them high resistance to fatigue, High intracellular glycogen level causes them to generate ATP by anaerobic glycolysis, fast fibers because ATPase, contributes to walking and sprinting

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

dystrophin

Properties of Muscular Tissue

electrical excitability, contractility, extensibility, elasticity

Recovery oxygen uptake

elevated body temperature increases the rate of chemical reactions which use ATP more rapidly causing oxygen to produce more ATP, the heart in the muscles used in breathing are still working harder than the rest consuming more ATP, tissue repair processes are occurring at an increased pace

myosin light chain kinase

enzyme that uses ATP to have phosphate group to a portion of the myosin head, allows myosin head to bind to actin and contraction occurs, Works slowly

Cardiac muscle tissue has an endomysium, perimysium but lacks an epimysium, Sarcoplasmic reticulum or desmosomes

epimysium

The outermost layer of connective tissue surrounding a skeletal muscle is the

epimysium

People with high proportion of fast glycolytic fibers often

excel in activities that require periods of intense activity such as weight lifting or sprinting

creatine phosphate

excess ATP is used to synthesize this energy-rich molecule that is found in muscle fibers, more plentiful than ATP in the sarcoplasm of a relaxed muscle fiber

Which property of muscle gives it the ability to stretch without damage?

extensibility

true or false cardiac muscle fibers do not have the same arrangement of actin and myosin and the same bands of zones and Z discs as skeletal muscle fibers

false

true or false, glycolysis needs oxygen

false

Leg muscles are predominantly composed of which type of muscle fiber?

fast oxidative-glycolytic

sarcoplasmic reticulum (SR)

fluid-filled system of membranous sacs that encircle each myofibril. stores and releases calcium ions.

Visceral smooth muscle tissue

found in the skin and tubular Arrangements that form part of the walls of the small arteries and veins end of hollow organs, autorhythmic, connected by gap junctions, single unit

Which of the regions of a sarcomere contain titin?

from M line to Z disc

what occurs in the cytosol and produces a net gain of two molecules of ATP

glycolysis

After the fusion of myoblasts, the muscle fiber loses its ability to

go through mitosis

Strength training would result in

hypertrophy of fast oxidative-glycolytic fibers

muscle fatigue

inability of a muscle to maintain force of contraction after prolonged activity, inadequate release of calcium ions from SR

Motor unit recruitment occurs when there is a(n) ___ in the number of active motor units within a skeletal muscle.

increase

Acetylcholine

inside the synaptic vesicles are thousands of molecules that the neurotransmitter is released at the neuromuscular Junction

Which microscopic structure is found only in the cardiac muscle tissue?

intercalated discs

Glycogen

large molecule composed of glucose and can be used for the synthesis of ATP.

Contraction period

last 10 to 100 milliseconds, calcium ions binds to troponin, myosin binding sites on actin are exposed and crossbridges form, peak tensions develop

Voltage gated Ca2+ channels

located within the t-tubules membrane; they are arranged in clusters of four known tetrads. Their main role in the coupling is to serve as voltage sensors that trigger the opening of the Ca2+ release channels

why are concentric, eccentric and isometric contractions important?

maintains posture pain support for objects in fixed positions

intercalated discs

microscopic structures that are irregular transverse thickenings of the sarcolemma that connect the ends of the cardiac muscle fibers to another, contains desmosomes which hold the fibers together in gap Junctions which allowed the muscle action potentials to spread from one cardiac muscle fiber to another

Which term describes a somatic motor neuron and all the skeletal muscle fibers it stimulates?

motor unit

Which function do all three muscles perform?

moving and storing material throughout the body

muscular hypertrophy

muscular growth which is denoted by the enlargement of existing muscle fibers. Due to an increased production of myofibrils, mitochondria, sarcoplasmic reticulum, and other organelles. This is caused by forceful repetitive muscular activity like weight training.

The contractile organelles of a skeletal muscle fiber are _______ which are composed of repeating units called ____

myofibrils and sarcomeres

Muscle damage can be indicated by...

myoglobin found in blood

Cross bridges are formed during muscle contraction when _____ binds to _____.

myosin, actin

Z discs

narrow, plate-shaped regions of dense material that separate one sarcomere from the next

frequency of stimulation

number of impulses per second

a muscle fiber contracts in response to

one or more action potentials propagating along its sarcolemma and through the system of T tubules

Myalgia

pain associated with muscles

myomalacia

pathological softening of muscle tissue

volkmann's contracture

permanent shortening of a muscle due to replacement of a destroyed muscle fiber by a fibrous connective tissue

Ca2+ release channels

present in the terminal cisternae membrane of the SR. when the skeletal muscles fiber is at rest, part of the Ca2+ release channels that extends into the sarcoplasm is blocked by a given cluster of voltage-gated Ca2+ channels, preventing Ca2+ from leaving the SR

Step 3 of a nerve impulse eliciting a muscle action potential

production of muscle action potential, The inflow of the sodium ions makes the inside of the muscle fiber more positively charged triggering muscle action potential, propagates along the sarcolemma into the system of T tubules releasing stored calcium ions into the sarcoplasm and the fiber contracts

Myogram

record of muscle contraction

Step 1 of a nerve impulse eliciting a muscle action potential

release of acetylcholine arrival of the nerve impulse at the synaptic end bulbs stimulate voltage-gated channels to open, calcium ions enters stimulating the synaptic vesicles to undergo exocytosis, the acetylcholine diffuses across the synaptic cleft between the motor neuron and the motor end plate

excitation-contraction coupling

sequence of events that links excitation (muscle action potential) to a contraction (sliding of the filaments)

what is between the layers of the cardiac muscle fibers?

sheets of connective tissue that contains blood vessels and nerves and a conduction system of the heart

what types of skeletal muscle fibers are there?

slow oxidative, fast oxidative glycolytic, fast glycolytic

Creatine

small amino acid like molecule that is synthesized in the liver kidneys and pancreas and then transported to muscle fibers

Myofibrils

small thread like structures that are stuffed within the sarcoplasm. they are the contractile organelles of the skeletal muscles. about 2 micrometers in diameter and extend the entire length of muscle fiber. They make the entire skeletal muscles appear striated.

motor unit

somatic motor neurons plus all of the skeletal muscle fibers it stimulates, can make contact with an average of 150 skeletal muscle fibers

Columns of mesoderm undergo segmentation into a series of cube like structures called this

somites

how is hypertonia expressed

spasticity or rigidity, increase muscle tone

anabolic steroids

steroid hormones similar to testosterone taken to increase muscle size by increasing the synthesis of proteins and muscles and thus increasing strength

wave summation

stimuli arriving at different times cause large contraction

many smooth muscle fibers contract or relax in response to

stretching, hormones or local factors such as changes in PH, oxygen and carbon dioxide levels, temperature, and ion concentrations

myology

study of muscles

M line

supporting proteins that hold the thick filaments together in the center of H zone

synaptic vesicles

suspended in the cytosol within each synaptic end bulb are hundreds of membrane enclosed sacs

Triads of skeletal muscular fibers

t-tubules that lie between the two terminal cisternae of the sarcoplasmic reticulum

isotonic contraction

tension developed in the muscle remains almost constant while muscle changes in length used for body movements and moving objects

Skeletal muscle contraction is triggered to begin when calcium is released from

terminal cisterns of sarcoplasmic reticulum

Step 4 of a nerve impulse soliciting a muscle action potential

termination of acetylcholine activity, acetylcholinesterase only allows the acetylcholine binding to last briefly, breaks down acetylcholine into acetyl and choline which both cannot activate acetylcholine receptor

sarcoplasm

the cytoplasm of the muscle and resides within the sarcolemma. Includes substantial amount of glycogen. Furthermore, the sarcoplasm contains red colored proteins called myoglobin.

axon terminal

the end of the motor neuron where it divides into a cluster of synaptic end bulbs

hypertrophy

the enlargement of existing cells, when mature skeletal muscle fibers lose the ability to undergo cell division

Anaerobic glycolysis

the entire process by which the breakdown of glucose gives rise to lactic acid when oxygen is absent or at low concentration, quickly breaks down each glucose molecule into two molecules of pyruvic acid

Length tension relationship

the forcefulness of muscle contraction depending on the length of the sarcomeres within a muscle before contraction begins

What happens during relaxation in excitation-contraction coupling?

the level of calcium ions in the sarcoplasm is low only 0.1 because calcium ions are pumped into the sarcoplasmic reticulum by calcium ions ATPase pumps

synaptic end bulbs

the neural part of the neuromuscular Junction

cardiac muscle tissue

the principal tissue in the heart wall

unfused tetanus

the result I was sustained wavering contraction after a skeletal muscle fiber is stimulated at a rate of 2230 times per second where it can only partially relax between stimuli

What is the result of acetylcholine attaching to the ligand gates of the motor end plate?

the sarcolemma increases permeability to sodium

Sliding filament mechanism

the skeletal muscle shortens during contraction because the thick and thin filaments slide past one another.

neuromuscular junction

the synapse between a somatic motor neuron and a skeletal muscle fiber

Exocytosis

the synaptic vesicles fuse with the motor neurons plasma membrane liberating acetylcholine into the synaptic cleft

isometric contraction

the tension generated is not enough to exceed the resistance of an object to be moved in the muscle does not change in its length ex. holding a book study using an outstretched arm

As the sarcomeres of a muscle fiber are stretched to a longer length(contracts)

the zone of overlap shortens and fever myosin heads can make contact with thin filaments, the tension the fiber can produce decreases, the thin and thick filaments on each side begin to overlap each other more to a point where thin filaments on each side will touch and no more contraction can occur. there will be less myosin heads on the thick filaments to make contact with the thin filaments

muscle fibers

they are cells within skeletal muscles called myocytes. Muscle cell and muscle fiber are two terms for the same structure.

Myosin heads cannot bind to

thin filaments

dense bodies

thin filaments attached to these structures which are functionally similar to Z discs in striated muscle fibers, attached to sarcolemma or dispersed throughout the sarcoplasm

What does shortening of the sarcomeres cause?

this leads to shortening of the entire muscle.

transverse tubules (t-tubules)

thousand of invaginations on sarcolemma. They are filled with interstitial fluid and they allow for action potentials to travel down sarcolemma and enter through the invaginations to muscle fibers allow excitation of fibers

Connective tissue

tissue that surrounds and protects the muscular tissue

What do smooth muscle fibers lack?

transverse tubules and only has a small amount of sarcoplasmic reticulum for storage of calcium ions

Myoma

tumor consisting of muscle tissue

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

twitch contraction

Two types of smooth muscle tissue

visceral smooth muscle tissue and multi-unit smooth muscle tissue

A muscle action potential propagating along a transverse tubule causes

voltage-gated calcium ions channels to undergo a conformational change that opens calcium ions release channels in the sarcoplasmic reticulum, calcium ions flow into the sarcoplasmic contraction begins

locations of smooth muscle tissue

walls of hollow viscera, Airways, blood vessels, Iris and ciliary body of eye

fused tetanus

when a skeletal muscle fiber is stimulated at a high rate of 80 to 100 times per second it does not relax which causes a sustained contraction which individual twitches

Aerobic respiration

when sufficient oxygen is present the pyruvic acid formed by glycolysis enters the mitochondria where undergoes this, a series of oxygen requiring reactions that produce ATP carbon dioxide water and Heat, glycolysis, the Krebs cycle and the electron transport chain occur

Aponeurosis

when the connective tissue elements extend as a broad, flat sheet. Example would be the epicranial aponeurosis on the top of the skull between the front and occipital bellies of the occipitofrontalis muscle

eccentric isotonic contraction

when the length of a muscle increases during a contraction, the tension exerted by the myosin cross-bridges resist movement of a load and slows the lengthening process ex. lowering the book to place it back on the table

fast glycolytic fibers

white in color, small amount of myoglobin, few blood capillaries and few mitochondria, large amounts of glycogen and generate ATP by glycolysis, contract strongly and quickly, contributes to weightlifting with throwing a ball but fatigues quickly

Fascia

Broad band of irregular connective tissue that lines the bodies wall and limbs. Provides support and surrounds the muscles and other organs. Also, allows free movement of the muscles; carries nerves, blood/lymphatic vessels; fills spaces between muscles.

how many times has cardiac muscle tissue contract and relax? A. 50 times a minute B. 60 times a minute C. 75 times a minute

C 75 times a minute

At the neuromuscular junction, _______must enter the synaptic end bulb to stimulate the release of ____________, which binds to ligand gates so ________can enter the muscle fiber? A. ACh, Sodium Ions, Calcium Ions B. Sodium Ions, Calcium Ions, ACh C. Calcium ions, ACh, Sodium Ions

C. Calcium ions, ACh, Sodium ions.

True or False, In motor unit recruitment, the number of active motor units increases.

True

tendon

When all 3 of the connective tissue come together to form a rope which attaches muscle to a periosteum of a bone. example: calcaneal (achilles) tendon of gastrocnemius attaches to the calcaneus (heel bone)

Filaments

Within myofibrils are smaller protein structures called this, these inside a myofibril do not extend the entire length of a muscle fiber, instead they are arranged in compartments

Sarcomeres run from _________________?

Z line to Z line

Two binding sites of myosin

1. actin binding site 2. an ATP binding site

what are the 3 proteins that build myofibrils?

1. Contractile proteins which generate force during contraction 2. Regulatory proteins which helps which the contraction process on and off 3. Structural proteins which keep the thick and thin filaments in the proper alignment give them myofibril elasticity and extensibility and Link the myofibrils to the sarcolemma and extracellular Matrix

Levels of organization within skeletal muscle

1. Skeletal Muscle 2. Fascicle 3. Muscle Fiber (cell) 4. Myofibril 5. Filaments (myofilaments)

Which region of a sarcomere contain thin filaments? Th Z band and the Z band or the I band and the A band

Both I band and A band.

Capillaries

Microscopic blood vessels. They bring in oxygen, nutrients, and remove heat/waste products of metabolism

Describe Myosin

Myosin is thick (15nm). It is a protein with a globular head and tail. One myosin microfilament is made of over 200 myosin molecules. One myosin molecule has two myosin proteins twisted around each other.

tropomyosin and troponin

Smaller amounts of two regulatory proteins, they are also part of the thin filament. In relaxed muscle myosin is blocked from binding to actin because strands of this cover the myosin binding sites on actin

Which characteristics describe both skeletal and cardiac muscle?

Striations

What is the role of tropomyosin in skeletal muscles?

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

What happens when Ca2+ bind to troponin?

Troponin undergoes a conformational change, this change moves tropomyosin away from myosin binding sites on actin and muscle contraction subsequently begins as myosin binds to actin.