Muscular System A & P Livestock

contract

all muscles have the ability to

stimulated

all muscles must be ____ to move

Skeletal

type of muscle that is striated and controls voluntary movement

Cardiac

type of muscle that is striated and controls involuntary movement

Smooth

type of muscle that is innervated by the autonomic nervous system and controls involuntary movement

allow locomotion and movement of limbs

primary role of skeletal muscle

circulation, digestion, respiration, reproduction, waste removal

some of the physiological processes that smooth muscle does predominantly

skeletal muscle

makes up the meat of livestock animals; voluntarily contracts to allow movement of bones; nearly all are connected to bones using tendons

Flexor

muscle on the side of the limb toward which a joint bends; decreases angle between the segements

Extensor

the muscle on the side of the limb opposite toward where it bends; increases the angle between segments

Adductors

muscles that pull a limb toward the median plane

Abductors

muscles that move the limb away from the median plane

Sphincters

muscles that surround an opening; can be striated or smooth

Cutaneous muscles

occur in superficial fascia between skin and deep fascia covering skeletal muscles; allows movement of skin

Epimysium

connective tissue covering entire muscle

Perimysium

connective tissue layer that covers bundles of muscle

hundreds of muscle bundles

each muscle is made up of _______

thousands of muscle fibers

each muscle bundle is made up of ________

Sarcolemma

Membrane surrounding the muscle fiber; excitable membrane with electrical potential

Sarcoplasm

the cytoplasm of muscle

Sarcoplasm reticulum

specialized form of endoplasmic reticulum that lies within each muscle fiber; just under the sarcolemma; composed of longitudinal tubules that parallel the muscle fiber that terminate in flattened channels called terminal cisternae

Sarcomere

repeating units within muscle fibers; each muscle fiber is made up of approximately 20,000 repeating units; basic contractile unit of skeletal muscle; made up of thick and thin filaments

Z lines, thin filament

sarcomeres are separated by ____, and _____ _____ attach to them

I bands

contain only thin filaments

A bands

contain both thick and thin filaments

H zone

contains only thick filaments

shorten, Z lines

during contractions, sarcomeres ____ and ___ ____ are pulled closer together

Myofilaments, I bands, H zone

_____ DO NOT change length, __ ____ shorten as myofilaments slide over each other, __ ____ disappears

actin

thin filaments are made up primarily of

two strands of actin proteins

each actin filament is composed of

tropomyosin

what is wrapped around the two actin strands in thin filaments

troponin complex

a third protein in the thin filament made up of T, C, and I types

myosin

thick filaments are composed of

thick helical rod with globular head

what a thick filament looks like

swivel at helical rod and globular head, hinge in helical rod

two flexible regions of thick filaments

ordered tail-to-tail interactions

myosin filament is formed by

high affinity for binding actin, ATP and catalyze its conversion to ADP + P

globular heads of myosin have __________ and also bind ________

Myosin heads activated by ATP, heads attach to actin and pull, ADP is released, thin filaments slide past thick filaments, ATP binds to myosin head and detaches it from actin

steps of contraction when ATP is available and Ca+ level near the troponin-tropomyosin complex is high

six

each thick filament is surrounded by ___ thin filaments

three

each thin filament is in contact with ____ thick filaments

actin and myosin are in close proximity but are not bound, myosin head is bound to ADP + P

at rest, thick and thin filaments

somatic nervous system

nerve fibers that stimulate skeletal muscle generally originate in

alpha motor neurons

large, myelinated fibers which branch several hundred times

single muscle cell

each nerve ending stimulates a

single alpha neuron, hundreds

a ____ _____ _____ can stimulate ______ of muscle cells

motor unit

the nerve fiber and muscle cells the nerve ending stimulates

motor end plate

where nerve fibers terminate

synaptic troughs

invaginations on sarcolemmas that increase the surface area

acetylcholine, synaptic cleft, receptors, muscle membranes

action potential travels down the alpha motor neuron and ends up at the motor end plate, resulting in the release of _____ into the _____ ____, then acetylcholine binds to _____ in the _____ _____ to start an action potential in the muscle cell

curare

skeletal muscle relaxant used for anesthesia, acetylcholin antagonist

botulinum toxin

causes paralysis, acetylcholin antagonist

nicotine

affects mood and other hormones, agonist

acetylcholinesterase, acetylcholine, laryngeal spasm

many drugs inactivate _______, which allows the buildup of _______, and smothers people due to ______ ______

sarcolemma, t-tubule, terminal cisternae, longitudinal tubule

where the action potential travels, in order

Ca+ channel

action potential causes the opening of _________ and allows them to rapidly flow into the cell

troponin complex binds up actin filament and uncovers the myosin binding sites on actin

what happens when Ca+ enters the cells from the SR

myosin head binds to actin, releases ADP + P, rotation of myosin

once Ca+ is bound to troponin complex, the __________, _________, and causes a free energy change that results in _____________

power stroke

rotation of the myosin head that pulls the actin towards the center of the sarcomere

4-5 nm

each rotation of the myosin head pulls the actin filaments about

loses affinity for actin, hydrolyzed to ADP + P, resting state

myosin head binds to ATP and _________, ATP is rapidly ________, myosin returns to 90 degree angle and results in __________

stop contraction, elongate the muscle

two steps to relaxation

myosin head binds almost irreversibly with actin

without ATP, this happens in myofilaments

Ca+ pump removes Ca+ from cell

what allows the myosin binding site on actin to be re-covered by troponin/tropomyosin complex

zero

the rate of contraction when the load equals the force of contraction

muscle tone

skeletal muscles always being in a slight state of tension is known as

number of motor units stimulated

the nervous system can adjust the

Isometric contraction

muscle contracts against a load but does not shorten, force of contraction equals force of the load on the muscle, used in posture or types of resistance to a load where movement doesn’t occur

Isotonic contraction

muscle shortens as it contracts, force of contraction is greater than the force of the load, type of muscle contraction involved in movement