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Parallel Muscle

the fascicles are parallel to the long axis of the muscle

Most of the skeletal muscles in the body are

parallel muscles

flat bands with broad attachments at each end

aponeuroses

A skeletal muscle fiber can contract until it has shortened by roughly___%

30

convergent muscle

muscle fascicles extending over a broad area converge on a common attachment site

Ex. of convergent muscle

pectoralis muscle of the chest

Pennate muscle

fascicles form a common angle with the tendon

Unipennate

if all the muscle fibers are on the same side of the tendon

Bipennate

muscle fibers on both sides of the tendon ( more common)

multipennate

if the tendon branches within a pennate muscle

circular muscles or sphincter muscles

fascicles are concentrically arranged around an opening or a recess

guard entrances and exits of internal passageways such as the digestive and urinary tracts

circular muscles

lever

rigid structure that moves on a fixed point called a fulcrum

each bone is a

lever

each joint is a

fulcrum

levers can change

(1) the direction of an applied force (2) the distance and speed of movement produced by an applied force (3) the effective strength of an applied force

first class lever

fulcrum lies between the applied force and the resistance

second class lever

resistance lies between applied force and the fulcrum

Ex. first class lever

extension of the neck

Ex. second class lever

ankle extension by the calf muscles

Most common levers

third class

Third Class levers

applied force lies between resistance and the fulcrum

Ex. third class lever

biceps brachii muscle (flexes elbow)

origin

place where the fixed end attaches to a bone, cartilage, or connective tissue

insertion

site where the movable end attaches to another structure

flexion

when the joint angle is decreasing

extension

when the joint angle is increasing

adduction

motion that pulls part toward the midline of the body

abduction

motion that pulls part away from the midline of the body

agonist

a muscle whose contraction is chiefly responsible for producing a particular movement

antagonist

a muscle whose action opposes that of a particular agonist

synergist

provide additional pull near the insertion or may stabilize the point of origin

fixators

synergists that assist agonist by preventing movement at another joint and stabilizing the origin of the agonist

rectus

straight

rectus muscles are

parallel muscles

extrinsic

muscles whose position stabilize an organ

intrinsic

muscles located within an organ

axial muscles

position the head and spinal column and also move the rib cage

appendicular muscles

stabilize or move components of the appendicular skeleton

innervation

the distribution of nerves to a region or organ

action

movement produced when a muscle contracts

perineum

muscular sheet that closes the pelvic outlet

fibrosis

the formation of fibrous connective tissue; in muscles, the replacement of muscle tissue by fibrous connective tissue makes muscles weaker and less flexible

The strongest masticatory muscle is the

masseter

The muscle that rotates the eye medially is the

superior oblique muscle

The major extensor of the elbow is the

triceps brachii muscle

The powerful flexors of the hip are the

iliopsoas

all-or-none principle

states that a muscle fiber will contract to its fullest extent once stimulated

muscle tone increases when you are

anxious

muscle tone decreases when you are

asleep

deadweight

loss of all muscle tone

deadweight occurs when you are

unconscious

atrophy

decreasing in size and strength

hypertrophy

muscle enlargement

motor unit

a motor neuron plus all of the muscle fibers it innervates.

skeletal muscle (nuclei)

multi

skeletal muscle (filament organization)

In sacromeres along myofibrils

skeletal muscle (control mechanism)

neural, at single neuromuscular junction

skeletal muscle (function)

moves skeleton, creates heat, protects organs

cardiac muscle (nuclei)

one

cardiac muscle (filament organization)

In sarcomeres along myofibrils

cardiac muscle (control mechanism)

automaticity (SA node's pacemaker cells)

cardiac muscle (function)

circulate blood

smooth muscle (nuclei)

one

smooth muscle (filament organization)

scattered throughout sarcoplasm

smooth muscle (control mechanism)

automaticity (pacesetter cells), neural or hormonal

smooth muscle (function)

regulates blood vessels, moves urin, moves food

isometric exercises

contraction in which tension increases, but muscle length remains the same

isotonic exercises

tension in muscle builds until it exceeds resistance and the muscle shortens

diameter of slow fibers

small

diameter of intermediate fibers

intermediate

diameter of fast fibers

large

tension of slow fibers

low

tension of intermediate fibers

intermediate

tension of fast fibers

high

contraction speed of slow fibers

slow

contraction speed of intermediate fibers

fast

contraction speed of fast fibers

fast

fatigue resistance of slow fibers

high

fatigue resistance of intermediate fibers

intermediate

fatigue resistance of fast fibers

low

color of slow fibers

red

color of intermediate fibers

white

color of fast fibers

white

myoglobin content of slow fibers

high

myoglobin content of intermediate fibers

low

myoglobin content of fast fibers

low

capillary supply of slow fibers

dense

capillary supply of intermediate fibers

scarce

capillary supply of fast fibers

scarce

mitochondria of slow fibers

many

mitochondria of intermediate fibers

intermediate

mitochondria of fast fibers

few

sarcomere

functional unit of muscle

A band

contains both thick and thin filaments

I band

contains thin filaments only

H band

contains thick filaments only

M line

holds thick filaments together

Z line

thin filaments attach to this

striations (dark bands)

A bands

light bands

I bands

sarcolemma

cell membrane

sacroplasm

cytoplasm

sarcoplasmic reticulum

endoplasmic reticulum of muscle

multinucleated

several hundred nuclei

T-tubules

carry impulse into muscle cell interior

myofibrils

responsible for muscle fiber contraction

thin filaments

actin

thick filaments

myosin

satellite cells

assist in tissue repair

muscle fibers develop through the fusion of mesodermal cells called

myoblasts

What blocks the site of myosin cross bridge attachment?

tropomyosin

How many Ca++ ions bind to each troponin?

4

What happens after the Ca++ ions bind to troponin?

tropomyosin moves away from the binding site

Once energized, myosin binds to actin and

the head tilts and propels the thin filament

During relaxation, where are the calcium ions?

trapped within the SR

How does the action potential enter the cells interior?

T-tubules

3 proteins comprising the thin filaments

actin, tropomyosin, and troponin

In order for muscles to contract, the cross bridges must first do what?

attach to the actin filaments

Why do cross bridges not attach during relaxation?

because the sites for myosin attachment on the actin filaments are covered by tropomyosin attachment

What does troponin need to fulfill its purpose?

Ca++

What happens when Ca++ is absent?

The tropomyosin reverts back to its original position and blocks attachment

What controls relaxation and contraction?

movement of Ca++ from the SR to the cytoplasm and back

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