Skeletal Muscle System

What are the 3 types of skeletal muscle?

skeletal muscles

Cardiac muscles

Smooth Muscle

Skeletal Muscle is:

Striated

Voluntary movement

Multiple nuclei

Long cells

Cardiac Muscle is:

Striated

Involuntary Movement

1 or 2 nuclei

short and branched cell that is inter connected

Smooth muscle is:

Non-striated

Involuntary movement

1 nucleus

Typically long and spindle-shaped

What are the functions of skeletal muscle?

Produce movement

Maintain posture and body position

stability ad support

Heat generation (thermogenesis)

Swallowing and speach

Metabolism

Where is glycogen (a form of glucose) stored?

Skeletal muscle

In regards to metabolism Skeletal muscle also…

regulates blood glucose levels

Releases molecules during exersize that regular the inflammation and metabolism.

Functional characteristics of

Excitability

Extensibility

Elasticity

Contractility

Each cuddle cell is supplied by

A nerve and an artery

Muscle fibre =

= Muscle cell

Sarcolemma

Plasma Membrane

Myofibril

Is a bundle of protein filaments

What is the joy fibril responsible for?

Contraction

Scarcomere

I band to I band on protein filament

thick filament

Myosin

thin Filament

Actin

Describe myosin

Each thick filament consists of many myosin molecules whose heads protrudes at opposite ends of the filament

Describe the thin filament

a thin filament consists of 2 strands of actin subunits twisted into a helix plus 2 types of regulatory proteins (troponin and tropomyosin)

Sarcoplasmic reticulum location

found throughout muscle cell, wrapped around each myofibril

Sarcoplasmic reticulum function

Stores and releases calcium to control muscle contraction

what do T (transverse) tubules do?

allow action potentials to reach all parts of the muscle cell simultaneously

Where do T (transverse) tubules go?

Tubes of sarcolemma that protrude deep into muscle fibres

What do T (transverse) tubules ensure?

This ensures that all myofibrils within a muscle fibre contract at the same time.

What does myoglobin contain?

Stored oxygen

What do glycosomes contain?

Granules of stored glycogen

Sarcoplasmic is..

The cytoplasm of a muscle cell

What happens during the power stroke?

Myosin pull sat in inward

What happens during reset?

Myosin detaches from actin

What happens during the Crossbridge stage?

Myosin binds with actin

Action potential travels….

Down the T-tubules

When action potential reaches the t-Tubule…

The Calcium ion channels on the Sarcoplasmic reticulum to open

After the calcium ions channels do the Sarcoplasmic reticulum open…

Calcium ions rush out of the sarcoplasmic reticulum and into the Sarcoplasm.

Calcium ions will bind to

Troponin

After calcium binds to troponin….

Tropomyosin moves off of the myosin binding sites on actin

Once the tropomyosin is removed off of actin…

Myosin will bind to the actin

What is myosin binding to actin called?

Cross bridge

The cross bridge results in…

Muscle contraction

contraction is also known as :

sliding filament theory/ Cross bridge cycle

Basic contraction description (idk how to word this i’m so sorry)

This filaments slide past thick ones so that actin and myosin filaments over lap

What is the term used for many muscle fibres bundles together called?

fascicle

When Myosin heads bind to actin forming a:

Crossbridge

Myosin heads move actin in words to the:

M-line

When actin moves towards M-line via Myosin, this is called:

The Powerstroke

What is Muscle tension

Force exerted by a contracting muscle on an object

What is a load?

the opposing force exerted on a muscle by the weight of something

What is isometric contraction?

Muscle tension developed, but the load is not moved

What is isotonic contraction?

Muscle tension overcomes the loss and teh muscle shortens

What is a motor unit?

A single motor neuron and all of the muscle fibre cells it supplies

Do all muscle fibres within the muscle contract with every contraction?

No

Small motor units are activated for

Fine motor movements

Large motor units activate for

Gross motor movements

What is baseline muscle tone?

Some muscles are always activated even when no movement is taking place

What is motor Unit recruitment

Activation os more motor units to increase tension in the muscles as the load increases

How does the body prevent muscle fatigue?

Buy not having all motor units be simultaneously active

What is the muscle twitch?

It is a motor units response to a single action potential sent from supplying motor neuron

What are the 3 periods of a muscle twitch?

1. Latent period

2. Period of contraction

3. Period of relaxation

What is a myogram?

Tracing of electrical activity of a muscle contraction

when is the latent period of a muscle twitch?

First few Milliseconds after stimulation

what happens during the latent period of a muscle twitch?

E-C coupling (excitation contraction )

what happens at the end of the latent period during a muscle twitch

Cross bridges begin to form, tension is not seen on myogram

How long does the period of contraction during a muscle twitch last?

10-100 milliseconds

What happens during the period of contraction during a muscle twitch?

The cross bridges are active

When does the period of contraction start?

From onset of the measurable contraction to peak of muscle tension

How long does the period of relaxation last?

10-100 miliseconds

What happens during the period of relaxation?

Tension decreases to 0

What is the period of relaxation defined by?

The pumping of calcium ions back to the Sarcoplasmic reticulum

what is a graded muscle response?

they are longer muscle contractions of varying strength

What 2 ways are muscle contractions graded?

Changing frequency of waves (wave summation)

Changing stimulus strength (which affects recruitment)

What is wave summation?

When a motor neuron fires before the is has completely relaxed. (Piggy backing)

Why is a 2nd muscle twitch stronger than teh first one?

Second action potential triggers the release of more calcium (more calcium=more everything)

What is infused to incomplete tetanus?

the “sustained but quivering” muscle contraction from wave summation.

What is fused or complete tetanus?

When stimulation frequency is so high that it causes a a sustained contraction is maximal tension. No relaxation period between twitches

What causes complete or fused tetanus?

Clostridium (bacteria)

What is treppe

the stair case effect on a myogram that happens after prolonged rest. Mostly seen in labs and not in real life

What is requirement is regards to a graded response?

The number of muscle units that are stimulated during a contraction

What is the size principle?

Smaller muscles are activated first, larger one are only activates when needed

What is the muscle tone?

The slight tension / contraction the muscle always as that does not produce movement.

What are the 3 types of muscle fibres ?

1. type 1= “slow twitch”/ slow oxidative

2. type 2a fast oxidative

3. Type 2b fast glycolytic

Which muscle fibres are slow to fatigue?

Type 1

which muscle fibres fatigue quickly?

Type 2a and 2b

Which muscle fibres are used for resistance training or walking?

Type 2a

which muscle fibres are used for sprinting, speed +power activities

Type 2b

Which muscle fibre makes ATP the fastest?

Type 2a

which muscle fibre makes APT the slowest?

Type 2b

What colours are type 2b muscle fibres?

White