A&P Chapter 10: Muscle Tissue

Skeletal Muscles can do 5 main functions being?

1. Moving the Body

2. Stabilizing joints, and maintaining body posture

3. Protecting and support of internal organs

4. Regulating the elmination of materials through sphincters and orifices

5. Producing Heat

What are the 5 main characteristics of all Muscle Tissue

1. Excitability: Respond to stimulus by changing electrical membrane potential

2. Conductivity: Sending electrical change down length of cell membrane

3. Contractility: Filaments sliding past each to cause movement

4. Extensibility: Ability to be stretched

5. Elasticity: Ability to return after lengthened or shortened

A skeletal Muscle is an organ why is that?

It has multiple types of tissues, skeletal muscle fibers, blood vessels, CT and nerves working together

Muscle fibers are the main muscle cell, which are within a?

Fascicle

What is the Epimysium, and what tissue is it?

Dense IR CT wrapping whole muscle

What is the Perimysium, and what tissue is it?

Dense IR CT wrapping fascicle

What does the Perimysium house?

Many blood vessels and nerves

What is the Endomysium, and what tissue is it?

Areolar CT and some Adipose wrapping indiviudal fiber

What are the functions of Endomysium?

Delicate layer for electrical insulation
Capillary support

Binding of neighboring cell

Image of Skeletal Muscle Organization

Attachment of muscle to bone, or to skin, or to another muscle can be?

• Tendons

• Aponeurosis

Tendons are cordlike structures of?

Dense Regular CT

Aponeurosis is thin, flattened sheets of?

Dense Irregular Tissue

Deep Fascia will separate? and bind what?

Individual muscles; and bind muscles with similar function
(Dense IR CT superficial to epimysium)

Superficial Fascia will separate?

Muscle from skin
(Areolar and Adipose CT superficial to deep fascia)

Are skeletal muscles vasuclarized?

Yes, with extensive blood vessels

Skeletal muscle will be innervated by?

Somatic Motor Neurons

Parts of a muscle cell (Muscle fiber)

Sarcoplasma (Cytoplasm) will have?

Typical organelles + contractile proteins and other specializations

The Sarcolemma or the Plasma Membrane will contain?

Voltage-gated ion channels for conduction
- T Tubules, that extend deep into cell

What does the T-Tubules contain?

Voltage-sensitive calcium channels

The Muscle Cell have multiple nuclei, cause the cell is formed in embryo when multiple myoblasts fuse, where some nearby myoblasts become undifferentiated satellite cells for support and repair of muscle fibers

Go back to slide 11-13 to ask about the images

Myofibrils are?

Bundles of myofilaments surrounded by sarcoplasmic reticulum

The Sarcoplasmic Reticulum is an internal membrane complex similar to Smooth ER

The Terminal Cisternae is a blind sac of the sarcoplasmic reticulum in which it serves as?

The reservoirs for calcium ions

Two Cisternae with T-tubule in between is the?

Triad

It contains calcium pumps that import calcium, where the calcium can bind to?

Calmodulin and calsequestrin

It also contains Calcium Release channels in which when triggered by what? will do what?

• Electrical signal traveling down T-tubule

• Calcium released in sarcoplasm

Myofilaments are?

contractile protein filaments within myofibrils
(Has two types listen below)

Thick Filaments which consists of?

Bundles of 200-500 myosin protein molecules

In the Thick, the Myosin heads (myosin ATPase) will?

Point towards ends of the filament

Thin Filaments are?

Twised strands of actin (each F-actin composed of G-actin monomers)

What does the G-actin have?

Myosin binding site where myosin heads attach

Which regulatory proteins are present in Thin Filaments?

Tropomyosin and Troponin

What is a Sacromeres?

Myofilaments that are arranged in repeating units
-Composed of overlapping thick and thin filaments

Each Sarcomere will be delineated or start and end where a?

Z disc is located

Which portion of the Sarcomere is anchored to the Z disc?

The Thin Filament

An I band is a light-appearing region that contains?

Only thin filaments

What will happen to the I band when muscle contracts?

Get smaller (can disappear with maximal contraction)

The A-band is the dark-appearing region that contains?

Thick filaments and overlapping thin filaments

The A band makes up the central region of sarcomere and contains?

H zone and M line

The H zone is the?, in which only what is present?

Central Portion of A band, where only thick filaments present

What will happen to the H zone during maximal msucle contraction?

It disappears

The M line is the middle of H zone, which is a _____ ______ _____ and is the attachment site for?

Protein meshwork structure
Attachment site for thick filaments

Sarcomere

Other structural and functional proteins

Connectin extends from?

Z disc to M line

What does Connectin do?

Stabilizes thick filaments and has “springlike” properties

Dystrophin will anchor?

Some myofibrils to sarcolemma proteins
(Abnormalities of this can cause muscular dystrophy)

Nebulin is anchored to? and extends the length of?

Z disc, and extends the length of thin filaments
(Functions in sarcomere assembly; role in cross-bridge cycling)

The Motor Unit, is a?

Motor neuron and all the muscle fibers it controls

Axons of the motor neuron from spinal cord will innervate numerous muscle fibers, in which different motor units innervate different amounts, for example?, and which those amount of muscle fibers it allows for?

• Small motor units have less than five muscle fibers, which allow for precise control of force output

• Larger motor units have thousands, allowing for large amounts of force, but not precise

The Neuromuscular Junction is the location where?

Motor Neuron innervates muscle
(Usually mid region of muscle fiber, has synaptic knob, synaptic cleft, and motor end plate)

The Synaptic Knob is an?

Expanded tip of motor neuron axon

The Synaptic Knob will house?, which are filled with?

House Synaptic Vesicles with NT acetylcholine (ACh)

The Synaptic Knob has pumps in the plasma membrane which establishes a?

Calcium gradient, with more outside the neuron

The Synaptic Knob also has voltage-gated channels

The Motor End plate is a specialized region of the sarcolemma with numerous folds, in which it has? (Hint: Has two things to talk about)

ACh receptors, and Plasma membrane protein channels opened by binding of ACh, which allow entry and exit

The Synaptic Cleft is a Narrow fluid-filled space which does what?

Separates synaptic knob from motor end plate

What resides in the synaptic cleft, and what does it do?

Acetylcholinesterase, an enzyme that breaks down ACh

Close up of Neuromuscular Junction

What do Muscle Fibers exhibit?

A Resting Membrane Potential at about -90 mV, established by leak channels and pumps

End-Plate Potential will follow the same Calcium to NT path, since it’s a graded potential, but which NT will it use?

ACh

AP and EPP

Events of AP at the Sarcolemma

Use slides 42-62 to help with the understanding of cross-bridge cycling

What are Skeletal Muscle Fibers classified on?

1. Type of contraction generated

2. Means for supplying ATP

Contractions generated will differentiate in?

Power, Speed, and Duration

Power is related to the?

Diameter of muscle fiber

Speed and duration will be related to the? (hint: Their are 3 things to note)

1. Type of myosin ATPase

2. Quickness of AP propagation

3. Quickness of release and reuptake by sarcoplasmic reticulum

Fast-Twitch fibers will have what kind of contractions?

More powerful, quicker and briefer

For the Means for Supplying ATP, you will see the difference of Oxidative versus Glycolytic Fibers

Oxidative fibers will use?, and what is their idea of fatigue?

Aerobic Cellular Respiration

Fatigue-resistant

What will Oxidative have/differ from Glycolytic

Extensive capillaries, many mitochondria, large supply of myoglobin

What color fiber is Oxidative

Red

Glycolytic fibers will use?, and what is their idea of fatigue?

Anaerobic Cellular Respiration

Fatigable

What will Glycolytic have/differ from Oxidative

Fewer capillaries, fewer mitochondria, small supply of myoglobin, large glycogen reserves

What color is Glycolytic?

White fibers

What contractions do Slow Oxidative (SO) fibers (type I) have?

Slower and less powerful

Does SO have high or low endurance, and why?

High, since ATP is supplied aerobically

SO is about half the diamter of other fibers, and red due to myoglobin

What contractions do Fast Oxidative (FO) fibers (type LLa, intermediate) have?

Fast and powerful

Is FO Aerobic or Anaerobic?

Aerobic, but will delivery of oxygen lower

FO is intermediate in size, and light red in color

What contractions do Fast Glycolytic (FG) fibers (Type llx)

Fast and powerful, but brief

Why is FG contractions brief?

ATP production is primarily anaerobic

FG is largest in size, white in color due to lack of myoglobin

Distribution of Skeletal Muscle Fiber Types

Muscle Tension is the force generated when?

A muscle is stimulated to contract

What does the generation of force show you?

The number of cross-bridges we are able to form

A muscle twitch is the?

Breif contraction to a single stimulus

How can we increase the contraction?/ More Tension?

Increase the frequency

What is happening at each period of the Muscle Twich

Latent: No Change in Tension (time after stimulus, but before contraction beings)
Contraction: Begins as power strokes pull thin filaments
Relaxation: Begins with release of cross-bridges

If stimulating voltage increases as a muscle is stimulated repeatedly, what will occur?

More units are recruited, called Recruitment, or Multiple Motor Unit Summation

What does recruitment explain?

How muscles exhibit varying degress of force

Wave Summation, and ideas

In a myogram, what if the frequency is increased further?

Incomplete Tetany is exhibited

What if it is increased further still past Incomplete Tetany