HBS 1.2.1-1.2.2 Muscle anatomy & contraction cycle

Skeletal muscle

A muscle that is attached to the bones of the skeleton and provides the force that moves the bones. Striated and voluntary.

Cardiac muscle

Involuntary muscle tissue found only in the heart. Striated.

Smooth muscle

Involuntary muscle found inside hollow internal organs of the body, blood vessels, and ureters. Not striated.

ATP

(adenosine triphosphate) main energy source that cells use for most of their work made of carbon, oxygen, nitrogen, and phosphorous. Energy is harnessed when the third phosphate is removed.

Muscle contraction requires

ATP and ions like sodium (salt) & calcium

Binding of Calcium ion to troponin

Causes Troponin to release Tropomyosin so it can reveal the myosin binding sites

Myosin head flexes (pulls)- the power stroke

Occurs when Myosin releases ADP +P

ATP bonds to the myosin head

Causes Myosin Head to detach from Actin

ATP is converted into ADP +P

Causes Myosin heads to return to a high energy (ready to bond) position

actin, tropomyosin, troponin

What are the three protein molecules that make up the thin filaments?

Actin

What is part A?

Length stays the same

Length of Thin Filaments during Muscle Contraction

Calcium ions being returned to Sarcoplasmic Reticulum

Causes troponin-tropomyosin to cover the actin binding sites

Length shortens

The length of a sacromere during muscle cell contraction

Tropomyosin

What is part B?

Troponin

Structure at Pink Arrow

Thick filament

Composed primarily of myosin

epimysium

a sheath of fibrous elastic tissue surrounding a muscle

perimysium

Connective tissue surrounding a fascicle

endomysium

Connective tissue surrounding individual muscle fibers

Muscle cramps and spasms

painful involuntary contraction due to fatigue/ATP loss, ion loss (sodium, magnesium), or dehydration.

antagonistic muscles

muscle pairs arranged to work against each other to move a joint in both directions - flexion and extension ex: biceps & triceps brachii

origin

attachment of a muscle that remains relatively fixed during muscular contraction

insertion

The attachment of a muscle tendon to a moveable bone or the end opposite the origin

flexion

Decreases the angle of a joint, often ventral

extension

increases the angle of a joint

striations

alternate dark and light bands found on skeletal and cardiac muscle that run in the direction of/parallel to the direction of the action of the muscle from origin to insertion

biceps brachii

2 headed muscle on arm that flexes elbow

Percent Change Formula (the real one)

((final-initial)/initial) x 100

A leg in a cast for two months will

have decreases in size and function due to disuse of the muscle, which results in a loss of muscle fibers over time. "use it or lose it."

Prue diagnosis

Degenerative disc disease in back and neck

Ren diagnosis

Grade 2 Strain of distal leg muscles

Jackson diagnosis

Radius and Ulna fractures & Grade 1 Strain of distal arm muscles

Hazel diagnosis

Cerebral Palsy

Dillon diagnosis

Juvenile idiopathic arthritis of mainly the hands, knees, and elbows

Muscle rule 1

Must have 2+ attachments and cross at at least 1 joint

Muscle rule 2

Muscles only can "pull" and get shorter when they contract

Muscle rule 3

The attachment that moves is known as the insertion and the attachment that remains stationary is known as the origin, muscles need at least one of each type.

Muscle rule 4

Muscles that decrease the angle between bones at a joint are known as flexors. Muscles that increase the angle between bones at a joint are known as extensors

Muscle rule 5

Muscles usually work in opposing "antagonistic" pairs- at least one flexor and one extensor for each joint.

Muscle rule 6

Muscle striations point to the attachments and show the direction of pull/contraction

Muscle nomenclature

Muscles get their names for either their shape, size, location, orientation, action, attachments, or # of origins

Pectoralis major action

flexion, adduction, and medial rotation at shoulder

Intercostals origin and insertion

O: inferior border of rib above

I: superior border of rib below

brachialis action

flexes elbow (under & more distal to biceps brachii)

Brachialis origin and insertion

origin: distal portion of anterior humerus both medial and lateral

insertion: proximal posterior ulna