Chapter 9 part 2

Thin filament

Also known as actin and is blue

Thick filament

Also known as myosin and is orange

Elastic filaments

Also known as titin and is yellow

Fun fact

Alternating striations of muscle tissue is produced by alternating dark A band and the light I band

Latent period

Brief period of time between the application of an impulse and the beginning of a muscle contraction. Very brief period of time

Tetanus

Calcium is not removed from sarcoplasm of muscle fiber during this. Can be dangerous and deadly

I band

Contains only thin filaments Z disc passed through the I band

Atp

Contractions require large supplies of atp. Muscle fibers have ability to produce atp. Produced by muscle fibers via 3 major systems: phosphagen system, glycogen lactic acid system, and aerobic cellular respiration

Tropomyosin

Covers myosin binding sites. When molecules are relaxed. This blocks attachment of myosin heads to actin. The train track

Adenosine triphosphate (ATP)

Energy source of living cells. In relaxed muscles, ago is attached to sites on myosin molecules.

Acetylcholinesterase

Enzyme, breaks down ach in synaptic cleft

Myosin cross bridges or myosin heads

Extend towards the thin filament. Has an actin binding site on the tip

T-Tubules

Extensions of the sarcolemma that protrudes deep into the muscle fiber. These allow impulses and nutrients to travel deep into muscle fibers

Actin

Forms the bulk of the thin filaments

Myosin

Forms thick filaments. Shaped like two golf clubs twisted together

Myosin tails

Golf club handles. Point towards m line in the center of sarcomere

Elastic filaments

Help hold thick filaments in place

Troponin

Hold the Tropomyosin in place over the myosin binding sites of actin molecules. Rail spike

Mitochondria

Involved in cellular respiration

What are the phases in typical myogram

Latent Contraction Relaxation Refractory

Sarcoplasm

Liquid in muscle fiber

H zone

Located in center of a band. Only has thick filamnets

Sarcolemma

Membrane around the muscle fiber

What are the two contractile proteins in myofibrils

Myosin and actin

Wave summation

Occurs when 2 stimuli are applied and the second one is delayed until refractory period is over

Isometric contraction

Occurs when a muscle does not or cannot shorten during a contraction but the tension on muscles increase

Isotonic contraction

Occurs when a muscle shortens to pull on a bone to produce a movement

Staircase effect (treppe)

Occurs when a muscles as been relaxed for a long time and then is stimulated to contract. First few contractions is stronger then the previous. Calcium closely accumulated in sarcoplasm until a maximum contraction can occur

Myosin binding sites

On each actin molecule. Myosin cross bridges can attach to these binding sites

Refractory period

Period during which a second contraction can't occur. Very short in skeletal muscle fibers but longer in cardiac muscle tissue( allows heart to fill with blood)

Z disc

Played that separate one sarcomere from another

Phosphagen system

Prodvides energy for about 15 seconds. Provides enough energy for short bursts of activity. When the creatinephosphate is depleted muscles turn to glycogen lactic acid system

Myogram

Record of muscle contraction

S.R.

Release of calcium from the sarcoplasmic reticulum into the sarcoplasm around thick and thin filaments trigger muscle contractions to begin

What are the parts of a muscle fiber

Sarcolemma Sarcoplasm Myofibrils Numerous mitochondria

The sliding filament mechanism of muscle contraction

Skeletal muscle shortens as thick and thin filaments slide past one another. During contraction myosin heads pull on thin filaments, causing them to slide towards H zone.

Tetanus

Sustained contraction in which a muscle can only partly relax between impulse stimulation

What are the three types of filaments in myofibrils

Thick thin elastic

Reason filaments overlap

To produce the striations in skeletal and cardiac muscles

What are the types of muscle contractions

Twitch contraction Wave summation Tetanus Staircase effect (treppe) Isotonic Isometric

What calcium does in muscle contraction

When calcium levels increase, contractions occur Changes shape of Troponin- Tropomyosin complex that covers myosin binding sites on actin molecules.

Sarcomeres

Where filaments that make up myofibrils are found. Basic functional units of striated muscle fibers

A band

Within each sarcomere. Contains thick and thin filaments

What is the organization and structure of a sarcomere

Z disc A band The I band H zone M line

Creatine phosphate

muscle fiber. This compound can transfer phosphate group to adp to produce atp. This and atp together make up the phosphagen system.

Twitch contraction

Brief contraction of all muscle fibers in motor unit of a muscle. In response to single impulse

M line

Divided H zone in half

Myofibrils

Small thread like structures in sarcoplasm of muscle fiber

Sarcoplasmic reticulum(S.R.)

Storage. Fluid filled bags the encircle each myofibrils. Stores calcium ion.

What are the 2 regulatory proteins in thin filaments

Tropomyosin Troponin