BIOL 216 TOPIC 8

Functions of the muscular system include ___________ of the body, maintenance of _________, ___________, production of body _________, ____________, constriction of organs and __________, and contraction of the _______.

Movement, posture, respiration, heat, communication, vessels, heart

The 4 properties of muscle are ___________ (ability of a muscle to shorten with force), ______________ (capacity of a muscle to respond to a stimulus from a nerve), ___________ (muscle can stretch beyond its resting length to a degree), and ____________ (ability of a muscle to recoil to its resting length after being stretched).

Contractability, excitability, extensibility, elasticity

Skeletal muscles are attached to bones via _________, which are comprised of _________ tissue. Skeletal muscle itself is composed of muscle ________ (which are long, cylindrical, and multi nucleated cells), _________ tissue, ________ vessels, and nerves.

Tendons, connective, fibers, connective, blood

In the connective tissue of skeletal muscle, muscle fibers are clumped together in round _____________ and are surrounded by blood vessels. Many fasciculThe plasma membrane of a muscle fiber is called a ___________ and the cytoplasm is called a ___________. The basic unit of contraction is a ____________ and many sarcomeres form a _________. They are composed of actin _____ filaments and myosin _____ filaments and are located between 2 _ lines.

Fasciculi, sarcolemma, sarcoplasm, sarcomere, myofibril, thin, thick, Z

The Z disk of a sarcomere is a filamentous network of _______ which serves as an attachment for ______ filaments. The I band runs between two _____ filaments and the A band runs along the _______ of a thick filament. The H zone is a region in the _____ band where actin and myosin do not ________. The M line is in the middle of the ____ zone and is composed of delicate filaments holding myosin in place.

Proteins, actin, thick, length, A, overlap, H

Associated with the thin actin filament of a sarcomere is _____________, an elongated protein that winds along the groove of the actin double _____. Also associated is ________, which is found between the ends of the tropomyosin molecules. It is composed of three subunits: one which binds to ______, one which binds to tropomyosin, and one which binds to ________. Together, these two proteins regulate the interactions between active sites on actin and myosin.

Tropomyosin, helix, troponin, actin, calcium

The thick filaments are composed of _______ and corresponding _______ proteins. ______________ is a motor protein found in skeletal muscle which generates force for muscular __________. It is formed from two heavy chains and two copies each of two light chains. The head of the protein ______ and ________ ATP, generating force, while the tail is formed from ____________ interactions between two alpha helices of heavy chains.

Myosin, motor, Myosin II, contraction, binds, hydrolyzes, coiled-coil

The myosin thick filament is a large, __________ filament formed from tail-tail interactions between myosin molecules. Thick filaments can _______ oppositely oriented pairs of actin filaments past each other. To initiate this movement, a myosin head switches from its _____ energy conformation to its ____ energy conformation by converting ___ to ___. It binds to an active site on actin and releases the phosphate group and ADP, re-entering its _____ energy conformation and solidifying the bond. This allows actin to move to the _______ of the sarcomere. The myosin head can be activated by ATP and the process repeats.

Bipolar, slide, low, high, ATP, ADP, low, center

Through myosin head muscle shortening, the _____ band and _____ zone decrease in length. In the process of muscle shortening, thin filaments slide over thick filaments simultaneously on both sides of the sarcomere while the thick filament _________ move, causing the fiber and sarcomere to both _________ which results in a buildup of force and muscle ____________.

I, H, doesn’t, shorten, contraction

Motor _______ stimulate muscle fibers to contract. The ________________________ is the contact point between axon and muscle. Signals are transmitted from the ______’s presynaptic terminal to the ________, and the _______________ is located between them. The ________ is the specific location where the two touch. The neurotransmitter used in skeletal muscle is ___________ and it _________ action potentials. It is transported into the synaptic cleft in vesicles and binds to nonspecific cation channels on the sarcolemma which induce depolarization, then unbinds, is degraded into choline by __________, is up took by the presynaptic cell, and is used again.

Neurons, neuromuscular junction, axon, sarcolemma, synaptic cleft, synapse, acetylcholine, induces, acetylcholinesterase

A ____________, also called a transverse tubule, is a deep invagination of the sarcolemma found only in skeletal and cardiac muscle cells which allows depolarization to quickly spread from membrane to cell interior.

T-Tubule

The ____________ is in the middle of the myosin thick filament and it contains no myosin heads.

Bare zone

In a skeletal muscle AP, depolarization spreads through the __________ to the ______________________, stimulating it to release _________ into the sarcoplasm. Calcium then combines with _______ to induce a conformational change that moves ____________ away from myosin binding sites on actin filaments. Exposing these active sites allows ________ to form, and cyclic reactions powered by ____________ pull on the thin filaments and _________ the muscle fiber. Once APs stop, calcium is removed from troponin and is transported back into the sarcoplasmic reticulum through calcium pumps. Everything returns to its resting position.

T-Tubules, sarcoplasmic reticulum, calcium, troponin, tropomyosin, cross bridges, ATP hydrolysis, shorten

____________________ describes how, a few hours after death, calcium leaks into the sarcoplasm and causes muscle contractions. There is no ATP so the muscle never releases from the contraction, and these contractions can last for 48-60 hours but generally peak at around 12 hours.

Rigor Mortis

Skeletal muscle cells appear ________ due to thin and thick filaments. Skeletal muscle is primarily used during _______ movement but also during some forms of involuntary movement including ______ expressions, ________, and respiratory movements.

Striated, voluntary, facial, posture

Cardiac muscle tissue is located around the heart and assists with ______ movement and _________. Cardiac muscle is _______, which means it generates its own rhythm, and is controlled by ________ and autonomic nervous systems. Composed of __________ cells due to _____ junctions which have a nucleus and intercalated disks which ____ cells and give a striated appearance.

Blood, heart rate, autorhythmic, endocrine, branched, gap, join

Smooth muscle tissue composes the walls of _______, blood ______, eyes, ______, and glands. It propels _______, mixes food in the digestive ______, __________ and constricts pupils, and regulates blood _______. Mostly involved in ___________ movement. In some locations, this tissue is __________. It is controlled by the endocrine and _______ nervous systems.

Organs, vessels, skin, urine, tract, dilates, flow, involuntary, autorhythmic, autonomic

Visceral smooth muscle is one specific kind of smooth muscle. It is located around the _______ and contains _____ junctions so that sheets of smooth muscle can function as a unit. The contraction of one sheet may induce the contraction of another. Contains slanted myosin and actin filaments, allowing the muscle to be ________ and form unique shapes such as _______ to line tubes. This muscle contains ____________, which are protein structures rich in ________ and their movement causes skeletal muscle to shorten and twist and which attach to thin filaments. Smooth muscle contracts more powerfully than skeletal.

Organs, gap, flexible, cylinders, dense bodies, actin

A _______________ is a muscle contraction in response to a stimulus that causes action potentials in one or more muscle fibers. Includes three phases: _________, __________, and _________. If multiple stimuli occur at the same time, they sum to yield an even greater contraction.

Muscle twitch, lag/latent, contraction, relaxation

_________ is a sustained muscle contraction evoked when the motor nerve that innervates a skeletal muscle emits action potentials at a very high rate.

Tetanus

There are 3 different kinds of muscle fibers. Slow (oxidative) muscle fibers have the _______ diameter but best ________ fatigue. They contract _____ and _________ due to a slow speed of ATP hydrolysis but they can remain contracted for long periods of time. They have high concentrations of ____________, an oxygen-supplying protein, and are used to maintain ___________.

Smallest, resist, slowly, weakly, myoglobin, posture

There are 3 different kinds of muscle fibers. Fast aerobic (fast oxidative glycolytic) fibers have _________ diameters, fatigue, and contractions. They contract relatively quickly and powerfully. They are used in _______ activities.

Intermediate, endurance

There are 3 different kinds of muscle fibers. Fast anaerobic (fast glycolytic) fibers have the ________ diameters and very ______ contractions, but they fatigue very _______. They have few mitochondria and myoglobin so they depend upon _______________ to produce ATP. They are used during ________ movements of short duration, for example, lifting weights/

Largest, strong, quickly, anaerobic glycolysis, rapid

There are 3 ways to synthesize ATP necessary for muscle contractions. Creatine phosphate accumulates in _________ and is used up very quickly. It stores _________ during resting conditions which can be used to synthesize ATP by reacting ADP with creatine phosphate with the help of a kinase. This reaction produces _________ and ATP.

Muscle tissue, energy, creatine

There are 3 ways to synthesize ATP necessary for muscle contractions. Anaerobic respiration occurs in environments without oxygen and results in the breakdown of __________ which yields ATP and __________. Used during short periods of high intensity activity, for example, _____________. ATP formed lasts for about 3 minutes.

Glucose, lactic acid, sprinting

There are 3 ways to synthesize ATP necessary for muscle contractions. Aerobic respiration occurs in the presence of oxygen and involves the breakdown of glucose into ________, _____________, and ATP. More ___________ than anaerobic.

Water, carbon dioxide, efficient

Creatine phosphate is used during the first ______ seconds of muscle activity, then __________________ for the next 3 minutes, and then _______________ for any further activity.

10, anaerobic respiration, aerobic respiration

Muscles can be converted. During endurance training, ___________ are converted from anaerobic to __________, allowing them to fatigue less quickly. During weight lifting, ______________ are converted from aerobic to __________, allowing for more powerful contractions.

Fast fibers, aerobic, fast fibers, anaerobic

Skeletal muscles are divided into motor units, which are groups of _________ activated by a single motor _________. The total force produced by a muscle is determined by the number of motor units activated. Large muscles have motor units with many muscle fibers, and small muscles have motor units with few muscle fibers for more _________ movements. _________ is the process of exciting more motor neurons because contractions are stronger when _________ motor units contribute.

Muscle fibers, neuron, delicate, recruitment, multiple

Muscles have an _________ which _______ cross bridge formation and yields the __________ contraction. Too long: little overlap between thick and thin filaments. Too short: thin filaments overlap and block active sites. In the body, muscles are attached to ______ and are stuck at their optimal length.

Optimal length, optimizes, strongest, bones

_________ muscle contractions occur when the muscle is at its __________ and, while the muscle is capable of exerting __________, it doesn’t shorten. Muscular force precisely matches load.

Isomeric, optimal length, force

___________ muscle contractions occur when the muscle length _________. Two kinds exist. __________ muscle contractions occur when the muscle shortens, generating force. _________ muscle contractions occur when the muscle elongates in response to a greater force, for ex, bicep curls.

Isotonic, changes, concentric, eccentric

Both skeletal and cardiac muscle contract _________ and don’t ________ quickly, however, they both involve _______ contractions.

Powerfully, fatigue, slow