Anatomy Chapter 10

Muscle Tissue: Structure of a skeletal muscle, Connective tissue coverings, Myofibril and sarcomere structure, Skeletal muscle fiber typesMuscle proteins,

What connects muscle belly to skeleton?

Tendons

What type of muscle in the belly?

Body of muscle

How many muscle fibers does muslce belly have?

Hundreds to thousands

How is muscle belly arranged?

Variety of shapes depending on function

Is belly muscle vascular?

Highly vascular (has blood flow / blood supply)

What are tendons made up of?

Dense regular CT

Are tendons vascular?

Minimally vascular

What shape does tendon take?

Many shapes depending on function

What type of bundles tendons made up of?

Parallel bundles of collagen fibers with few fibroblasts

What makes up structure of skeletal muslce?

Muscle belly and tendon

What does endomysium cover?

Each muscle fiber

What does endomysium bind to?

Muscle fibers while allowing them to move freely

What shape is endomysium?

Reticular (weblike)

What do capillaries do?

carries small blood supply

What does perimysium cover?

each fascicle

What are fascicles?

Bundle of muscle fibers

What does fasicle allow?

Allows some freedom of movement

What is fasicle made of?

Dense irregular CT

What does fasicle carry?

Blood vessels

What does epimysium cover?

muscle belly

What are the connective tissue coverings?

1. Epimysium

2. Perimysium

3. Endomysium

What is epimysium made up of?

Dense irregular CT

What type of elements are myofibrils?

contractile elements

Myofibirls are bundles of?

contractile protein filaments

What do myofibrils look like?

Striated

Types of filaments

1. thin

2. thick

Thin filaments

8 nm diameter, made primarily of actin

Thick filaments

16 nm diameter, made primarily of myosin

Sarcomere

basic functional unit of a myofibril

Z-discs

narrow regions of dense protein, separate one sarcomere from the next

I band

thin filaments only, lighter region

A band

length of thick filament, darker region

What are A band regions

1. Zone of overlap

2. H zone

3. M line

Zone of overlap

edges of A band, where thin and thick filaments overlap

What is the H zone center of and contain?

center of A band, thick filaments only

What is M line center of and what is it composed of?

center of H zone, line of proteins holding thick filaments in

What do contractile proteins generate?

force

What are myosin main components of?

thick filaments

What do motor protein convert.

chemical energy from ATP to mechanical energy

How many molecules of myosin form 1 thick filament?

300

Myosin Tails

point towards M line, lie parallel to each other

Myosin Heads

Extend towards thin filament

Actin is main component of what filament?

thin filaments

What does each actin have?

a myosin-binding site where myosin heads can attach

Regulatory Proteins turn what on and off?

Turn contraction on and off

Type of Regulatory Proteins?

• Troponin

• Tropomyosin

Troponin

complex of proteins, holds tropomyosin in place

Tropomyosin

Covers myosin-binding sites on actin

What will Troponin do when bound to calcium?

Will move tropomyosin away from myosin-binding sites

Structural proteins contribute to 4 thing of myofibrils. Name them.

alignment, stability, elasticity, and extensibility of myofibrils

How many Structural Proteins identified?

Around a dozen

Is titin abundant?

3rd most plentiful protein in skeletal muscle

Where does titin extend from and to?

Extends from Z disc to M line

Largest known Structural Proteins

titin

titin functions

1. Anchors thick filament to both Z discs and M line - stabilizes position of the filament

2. Accounts for elasticity and extensibility of myofibrils

What does myomesin form and what does it bind to?

forms M line, binds to titin

What does nebulin anchor and to what does it anchor it to?

anchors thin filaments to Z discs

Types of structural protein?

1. Titin

2. Nebulin

3. Dystrophin

4. Myomesin

What does dystrophin link and to what?

links thin filaments to integral membrane proteins of sarcolemma

Where does dystrophin transmit tension to?

tendons

label thick filament, myosin head, myosin tail

label Actin, Troponin, and Tropomyosin

Red fibers

Fibers with high myoglobin

White fibers

Fibers with low myoglobin

SO or Type I

Slow oxidative fibers

Why are Slow oxidative fibers Dark red?

lots of myoglobin

How do Slow oxidative fibers generate ATP

aerobically

How do Slow oxidative fibers contract?

Slow contraction - use ATP slowly

What are Slow oxidative fibers resitant to ______ so capable of _______?

Fatigue, sustained contraction (endurance)

FOG or Type lla

Fast oxidative-glycolytic fibers

Why are Fast oxidative-glycolytic fibers red?

Contains some myoglobin

How do Fast oxidative-glycolytic fibers generate ATP?

aerobically and anaerobically (glycolysis)

How do Fast oxidative-glycolytic fibers contract?

Faster contraction with some fatigue-resistance

FG or Type lIb

Fast glycolytic fibers

Why are Fast glycolytic fibers white?

low myoglobin

What do Fast glycolytic fibers stores lots of?

glycogen

How do fast glycolytic fibers generate ATP?

glycolysis

How does fast glycolytic fibers contract?

Strong and fast but fatigues quickly

How do fast glycolytic fibers move?

Intense anaerobic movements of short duration

What do Exercise and Muscle Fibers affect?

characteristics of existing fibers

Endurance exercises

gradual transformation of some FG fibers to FOG

High intensity exercises

increase size and strength of FG fibers

Skeletal muscle fiber types

• Slow oxidative

• Fast oxidative

• Fast glycolytic