Anatomy Chapter 11 (Muscular System)

What are the five functions of the muscular system?

produce movement, maintain posture, support soft tissues, guard entrances and exits, and maintain body temperature

What are the three types of tissue that muscle is composed of?

skeletal, connective, nerve

What are properties of muscles?

contractility, excitability, extensibility, and elasticity

What is connective tissue also known as?

fascia

What are the two types of fascia and where are they located?

superficial fascia: beneath the skin

deep fascia: organs and muscles

What are the three layers that connective tissue appears in when associated with muscle?

epimysium, perimysium, endomysium

Where is the epimysium located?

surrounds whole muscle and is deep fascia

Where is the perimysium located?

divides muscles into bundles of fascicles

What does the endomysium do?

envelops individual muscle cells

What extends the muscle from this connective tissue?

tendons

What is the fibrous wrapping of muscle as a broad flat sheet called?

aponeurosis

Is muscle highly specialized to contract?

yes

What is a sarcolemma?

plasma membrane

What is sarcoplasm?

cytoplasm?

What is the sarcoplasmic reticulum?

sac like organ with calcium ions

What are transverse tubules?

tube that intersect SR for calcium transport

What is a myofibril?

cyndrical cord of protein in the sarcoplasm

What are the two types of filaments?

thick: myosin

thin: actin, troponin, and tropomyosin

What are the two types of thin filaments besides actin?

troponin and tropomyosin

What is a sarcomere?

segment of myofibril (cyndrical cord) whose thick and thin filaments are divided into regions

What's an A Band, I Band, and H Zone?

A band: thin/thick overlap (dark)

I band: thin only (light)

H zone: thick only in center (light)

What provides stimulus to the muscle fiber?

motor neuron

What is one motor neuron with the muscle fiber innervating called?

motor unit

What is the reigion between the motor neuron and the sarcolemma?

neuromuscular junction

What is a synaptic cleft and where is it found?

recessed pocket of the sarcolemma that receives motor neuron in neuromuscular junction

What is the motor end plate and where is it found?

region of the sarcolemma at the synaptic cleft

What are synaptic vesicles and where are they found?

small sacs within terminal end of motor neuron w/ acetylcholine

Where is acetylcholine found?

synaptic vesicles

What is acetylcholine?

a neurotransmitter

What happens with the acetylcholine?

released as AP reaches terminal end of neuron then it diffuses across synaptic cleft until contact w/ motor end plate

When does a muscle contract?

thin slide across thick toward center of sarcomere

What happens when the fiber is at rest?

calcium ions in SR, ATP bound to myosin, thin are intact

What is the role of the stimulus?

to release Ca

What does the acetylcholine bind to?

receptor molecules in motor end plate of muscle fiber

Where is the AP stimulated?

sarcolemma

What does the AP cause the SR to do?

release Ca ions

Where does calcium diffuse to during muscle contraction?

sarcoplasm

When calcium diffuses, where do the Ca bind to?

thin filaments

What does the binding to thin filaments do?

frees binding sites on actin

What does the heads of thick attaching to binding sites on thin form?

cross bridge connections

What does muscle contraction require and where is it found?

ATP, myosin

What happens when shifting is complete?

ATP breaks bond between thick cross bridge and thin

What provides energy for enzymes to return Ca to the SR?

ATP

What does the lack of Ca cause?

thin to return to original shape

What are some other sources of energy?

glucose, creatine, phosphate, glycogen

What is required to synthesize ATP during muscle contraction?

oxygen

What produces during strenuous exercise?

lactic acid

What restores oxygen?

rapid breathing

What does oxygen debt lead to?

muscle fatigue

Where is cardiac muscle found?

heart

Does cardiac muscle contain striations and is it voluntary or involuntary

striations, involuntary

What does the heart contracting rhythmically and continuously provide?

constant blood flow

What are the specialized features cardiac muscles have to continuously pump blood?

parallel myofibrils, intercalated disks, and branching

What happens when cardiac impulses cannot come rapidly enough?

do not produce tetanus

Can cardiac muscles run low on ATP / experience muscle fatigue?

no

What do smooth cells look like?

small tapered cells with single nuclei

What are not present in smooth muscles?

no t tubules

What does Ca bind to in smooth muscle for contraction?

calmodulin

How are myofilaments organized?

NOT organized into sarcomeres

What are the two types of smooth muscle?

visceral and multiunit

What does a visceral muscle look like?

gap junctions join smooth muscle fibers into large continuous sheets

What kind of smooth muscle forms in walls of hollow structures?

visceral

Give an example of what a smooth muscle would form

digestive urinary

What does visceral muscle exhibit?

autorhythmicity

What is the multiunit smooth muscle like?

many independent cell units

What does autorhythmicity produce?

peristaisis

What is the weakest stimulus that can initiate contraction called?

threshold stimulus

What happens when the threshold stimulus is reached?

contracts completely

What is a twitch?

rapid response to a single stimulus

What are the three periods when a twitch is measured?

latent period, period of contraction, period of relaxation

What is the basic unit of muscle contraction?

twitch

What is a treppe?

muscle receives successive stimuli, strength of contraction increases slightly with each stimulus

What do we call a treppe?

staircase effect

What is a wave summation?

muscle receives second stimuli before the first is complete and the contraction will be stronger

What is tetanus?

successive stimuli are received. contractions are completed. the muscle reaches maximum contraction strength

What is incomplete tetanus?

relaxation occurs between contraction

What needs to happen for complete tetanus to occur?

no relaxation

What kind of contractions are used to produce most body movement?

tetanus

What is tension?

force exerted by muscle contraction

What is an isotonic contraction?

produces body movement with tension

What is an isometric contraction?

does not produce body movement with tension

What is muscle tone?

resting tension of skeletal muscle

What does it mean for muscle tone to be limp/flaccid?

little muscle tone

What does it mean for muscle tone to be moderate?

firm and solid

What does resting muscle tone do?

stabilizes position of bones and joints

How is heat produced for homeostasis?

muscle contraction to maintain constant body temperature

What do all three types of muscle provide?

movement necessary for survival