bio 112 - chapter 8 - extra

what are muscles?

organs that generate for to cause movement

what are the 3 types of muscle tissue?

skeletal, smooth, and cardiac

what is the dense connective tissue that surrounds and separate each muscle called?

fascia

what is the connective tissue that connects muscle together?

aponeuroses

what does the fascia blend with?

epimysium

what is epimysium?

a layer of connective tissue around each skeletal muscle

what is a fascicle?

a bundle of muscle fibers

what is the perimysium?

the connective tissue layer that surrounds each fascicle

where is the perimysium located?

it extends inward from the epimysium

what is endomysium?

connective tissue ayer that surrounds each individual muscle fiber

what are three connective tissue layers of skeletal muscle, from outermost to innermost?

epimysium→perimysium→endomysium

(TIP) remember these!! the answer will be labeled (KEY)

(KEY) EPI= entire muscle; PERI= pack/bundle (fascicle); ENDO= each individual fiber

how do you describe each muscle fiber?

single, long, cylindrical muscle cell

what is the cell membrane of a muscle fiber?

sarcolemma

what is the cytoplasm muscle cell called?

sarcoplasm; contains mitochondria and nuclei

sarcoplasm contains ______ and is active in muscle contraction?

myofibrils

thick filament in myofibrils consists of what protein?

myosin

thin filaments in myofibrils are mainly composed of what proteins?

actin, troponin, tropomyosin

the organization of these filaments produces bands called ____?

striations

myofibrils are made up of what?

sacromeres; joined end-to-end

What is made up of actin filaments and are anchored to the Z lines?

I bands (light bands)

what is made up of overlapping thick and thin filaments?

A bands (dark bands)

the H zone consists of what?

myosin filaments

where and what consists of proteins that hold myosin filaments in place?

M line

what is the term? a network of membranous channels which is the endoplasmic reticulum of a muscle cell

sarcoplasmic reticulum (SR)

the SR is associated with what?

transverse (T) tubules; invaginations of the sarcolemma

each T tubules lye between what?

2 cisternae

skeletal muscle fibers contract only when stimulated by?

motor neuron

what creates a synapse?

every skeletal muscle fiber is functionally connected to the axon of a motor neuron

how does the neuron communicate with the muscle fibers?

neurotransmitters

what is neuromuscular junction?

a synapse between a motor neuron and a muscle fiber that it regulates

what is the motor end plate?

it’s where the sarcolemma is tightly folded; contains specific receptors for the neurotransmitter

what is the gap between the membranes of the neurons and muscle fiber?

synaptic cleft

what is released into the synaptic cleft at the end of an electric pulse?

synaptic vesicles release neurotransmitters

what happens to sarcomeres during muscle contraction?

they shorten

what creates the pulling force during muscle contraction?

myosin binds to actin and pulls on it

what happens to actin and myosin during contraction?

they slide past each other, increasing their overlap

what do actin and myosin filaments do?

they slide past each other

what causes a muscle fiber to shorten?

the increased overlap between actin and myosin filaments

what happens when individual muscle fibers shorten?

the entire muscles shortens

what do filaments do?

they slide

what do myosin molecules consist of?

two twisted strands with globular heads projected outward along the strands

what do actin molecules consist of?

globular proteins arranged in twisted filaments

what are 2 proteins associated with actin molecules?

troponin and tropomyosin

what is acetylcholine?

a neurotransmitter for skeletal muscle fiber contraction

where is acetylcholine produced and released at?

its produced in the motor neuron; released into the synaptic cleft

what does sarcoplasmic reticulum release?

stored calcium

what does the motor neuron release?

Acetylcholine (ACh)

what does (ACh) bind to?

ACh receptors on the muscle fiber membrane (saecolemma)

where does the muscle impulse travel to?

across the sarcolemma and down the transverse tubules

what does the impulse cause the sarcoplasmic reticulum to release?

calcium (Ca2+)

what does calcium bind to?

troponin

what happens when calcium binds to troponin?

it moves

what happens when the binding sites are exposed?

myosin binds to actin, forming cross-bridges

what do cross-bridges do?

pull thin filaments towards the center of the sarcomere

what is the first phase of cellular respiration and occurs in the cytoplasm?

glycolysis; yields 2 ATP

what is aerobic respiration?

a complete breakdown of glucose and requires oxygen; yields 28 ATP

what is hemoglobin?

red blood cells carries oxygen to muscle tissue

what is oxygen debt?

the amount of oxygen that liver cells require to concert the accumulated lactate back into glucose

what is the leftover cellular respiration become?

heat

what is the heat used for?

to help maintain body temperature

what happens when a muscle loses its ability to contract during strenuous exercise?

fatigue

what classifies as fast fibers?

make up majority of muscle fibers; rapid movements; fatigue quickly; larger diameter; few mitochondria; powerful contractions

what classifies slow fibers?

small diameter; takes longer to reach peak; used in endurance activities; many mitochondria

what is hypertrophy?

enlargement of a muscle due to repeated exercise

what is atophy?

decrease in muscle size and strength

what is a threshold stimulus?

the minimum strength of a stimulus required to generate a impulse through the muscle fiber

what is a twitch?

response of a single muscle fiber to a single impulse

what is myogram?

a recording of an electrically stimulated muscle contraction

what is the latent period?

a brief delay between the stimulation and beginning of the contraction

summation slide 37