Chapter 10

Oxygen Debt

Refers to the added oxygen, over and above the resting oxygen consumption, that is taken into the body after exercise

Compare the structure and function of the three types of skeletal muscle fibers

Slow oxidative fibers (SO) fast oxidative-glycolytic (FOG) fibers fast glycolytic fibers

Outline the steps involved in the sliding filament mechanism of muscle contraction

1.ATP hydrolysis- myosin heads hydrolyze ATP and become reoriented and energized 2.Attachment of myosin to actin to form cross-bridges - myosin heads bind to actin, forming cross-bridges 3.Power stroke- Myosin cross-bridges rotate toward center of sarcomere (power stroke) 4.Detachment of myosin from actin -As myosin head bind ATP, the cross-bridges detach from actin

In what order are the various types of skeletal muscle fibers recruited when you sprint to make it to the bus stop?

Slow oxidative, fast oxidative-glycolytic, fast glycolytic

Which type of muscular tissue has the highest capacity for regeneration?

Smooth muscle

Which structures develop from myotomes, dermatomes, and sclerotomes?

Somite

On a cellular level, what causes muscle hypertrophy?

The increase in size of thick and thin filaments

How are the structures of think and thick filaments different?

Thin filament-molecules strung together like beads to form two fibrous strands that twist around each other. Thick filament- shaped like golf clubs, with their long shafts bundled together to form a thick filament and their "heads" sticking out from the bundle.

Distinguish thick filaments from thin filaments

Thin filaments = action Thick filaments = myosin

What are differences between visceral and multiunit smooth muscle?

Visceral smooth muscle is found in the skin and in tubular arrangements that form part of the walls of small arteries and veins and of hollow organs such as the stomach Multiunit smooth muscle consists of individual fibers, each with its own motor neuron terminals and with few gap junctions between neighboring fibers

Why are some skeletal muscle fibers classified as "slow" and others are said to be "fast"?

a fiber is categorized as either slow or fast depending on how rapidly the ATPase in its myosin heads hydrolyze ATP

Contractility

ability of muscular tissue to contrast forcefully when stimulated by an action potential (holding a book in a outstretched hand)

Extensibility

ability of muscular tissue to stretch, within limits, without being damaged ex. each time you fill your stomach with food, the smooth muscle in the wall is stretched.

Electrical excitability

ability to respond to certain stimuli by producing electrical signals

nerve action potentials

action potential in nerves

muscle action potentials

action potentials in muscles

Which sources provide ATP during a marathon race?

aerobic cellular respiration ( pyruvic acid, fatty acids and amino acids)

Which ATP- producing reactions are aerobic and which are anaerobic ?

aerobic- carbon dioxide, water, ATP, and heat anaerobic- glycolysis

Describe how frequency of stimulation affects muscle tension

affected by the amount of stretch before contraction

Distinguish between anaerobic and a aerobic cellular reaction

anaerobic cellular respiration -a series of ATP-producing reactions that don't require oxygen. provides enough energy for about 30 to 40 seconds of maximal muscle activity aerobic cellular respiration-series of ATP producing reactions that require oxygen. aerobic supplies enough ATP for prolonged activity provided sufficient oxygen and nutrients are available

How are the sizes of motor units related to the degree of muscular control they allow?

because all of the muscle fibers of a motor unit contract and relax together, the total strength of a contraction depends, in part, on the size of the motor units and the number that are activated at a given time

Before muscle fatigue, the feelings of tiredness and the desire to cease muscle activity; caused by changes in the nervous system

central fatigue

Define each of the following terms:

concentric isotonic contraction eccentric isotonic contraction isometric concentration

Explain the importance of connective tissue components, blood vessels, and nerves to skeletal muscles

connective tissue components -

Describe the functions of skeletal muscle proteins

contractile proteins proteins that generate force during muscle contractions. Regulatory proteins proteins that help switch muscle contraction process on/off Structural proteins proteins that keep thick and thin filaments of myofibrils in proper alignment, give myofibrils elasticity and extensibility, and link myofibrils to sarcolemma and extracellular matrix

The four properties of muscular tissue

electrical excitability contractility extendibility elasticity

Muscle cell stimuli

electrical signals (autorhythmic) chemical signals (neurotransmitter)

Action potentials (impulses)

electrical signals produced during electrical excitability

How is muscle tone produced

established by neurons in the brain and spinal cord that excite the muscle's motor neurons

Thermogenesis

heat produced during muscle contraction

Concentric isotonic contraction

if the tension generated is great enough to overcome the resistance of the object to be moved, the muscle shortens and pulls on another structure, such as a tendon, to produce movement and to reduce the angle at a single joint

Describe the factors that contribute to muscle fatigue

inadequate release of calcium ions from the SR, resulting in a decline of CA2+ concentration depletion of creatine phosphate insufficient oxygen depletion of glycogen and other nutrient buildup of lactic acid and ADP failure of action potential in the motor neuron to release acetylcholine

Which factors contribute to muscle fatigue?

inadequate release of calcium ions from the SR, resulting in a decline of CA2+ concentration depletion of creatine phosphate insufficient oxygen depletion of glycogen and other nutrient buildup of lactic acid and ADP failure of action potential in the motor neuron to release acetylcholine

Hyperplasia

increase in the number of fibers

Shivering

increases the rate of heat production

Fast oxidative-glycolytic (FOG) fibers

intermediate in diameter between the other two types of fibers. FOG fibers generate considerable ATP by aerobic cellular respiration, which gives them a moderately high resistance to fatigue

Distinguish between isotonic and isometric contractions

isotonic contractions the tension remains constant while the muscle changes length; used for body movements and for moving objects (concentric and eccentric) isometric contractions the tension generated is not enough to exceed the resistance of the object to be moved, and the muscle does not change in length

Why is muscle tone important?

keeps skeletal muscles firm also in smooth muscle tissues, such as those found in the gastrointestinal tract

Explain the phases of a twitch contraction

latent period (delay 2msec) the muscle action potential sweeps over the sarcolemma and the calcium ions are released from the SR contraction period( 10-100msec) Ca2+ binds to troponin, myosin-binding sites on actin are exposed, and cross-bridges form relaxation period(10-100msec) CA2+ is actively transported back into the SR, myosin-binding sites are covered by tropomyosin, myosin heads detach from actin, and tension in the muscle fiber decreases

Smooth Muscle

located in G.I. tract, uterus, eye, blood vessels; involuntary

Cardiac Muscle

located in the heart; involuntary

Skeletal Muscle

located in the skeleton; voluntary

What features distinguish the three types of muscular tissue?

location, function, appearance and control

Describe the structure and function of a motor unit

made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals;motor units often work together to coordinate the contractions of a single muscle

Producing body movements

movements of the entire body rely on the functions of the skeletal muscles, bones and joints

Describe the development of muscles

muscles derive from mesoderm

Generating heat

muscular tissue contracts and heat is produced (thermogenesis)

Sphincters

prevent outflow of the contents of a hollow organ

Define motor unit recruitment

process in which the number of active motor units increases

List the general functions of muscular tissue

producing body movements stabilizing body positions storing and moving substances within the body generating heat

Explain the structural differences between the three types of muscular tissue

skeletal - striated; parallel fibers cardiac- striated; branched fibers smooth- non striated

Stabilizing body positions

skeletal muscle contractions stabilize joints and help maintain body positions, such as standing or sitting

Compare the special properties of the three muscular tissue

skeletal- maintain your posture or stabilize your body positions cardiac-autorhythmicity smooth-

Compare the functions of the three muscular tissue

skeletal- movement, heat, posture cardiac-pump blood continuously smooth - peristalsis, blood pressure, pupil size and erects hairs

Slow oxidative fibers (SO)

smallest in diameter and are the least powerful; SO fibers generate ATP mainly by aerobic cellular respiration, which is why they are called oxidative fibers

Storing and moving substances within the body

storage is accomplished by sustained contractions of ring like bands of smooth muscles (sphincters)

Elasticity

the ability of muscular tissue to return to its original length and shape after contraction or extension

Fast glycolytic fibers

the largest in diameter and contain the most myofibrils. FG can generate the most powerful contractions

Describe the main structural and functional characteristics of cardiac muscle tissue

the principal tissue in the heart wall; the contractile cells of the heart, are sheets of connective tissue that contain blood vessels, nerves, and the conduction system of the heart

How is the motor end plate different from other parts of the sarcolemma?

the region of the sarcolemma opposite of the synaptic end bulbs. the muscle fiber part at the end of the NMJ

Describe how muscle action potentials arise at the neuromuscular junction

the synapse between a somatic motor neuron and a skeletal muscle fiber

Describe the main structural and functional characteristics of smooth muscle tissue

usually activated involuntarily; found in the skin and in tubular arrangements that form part of the walls of small arteries and veins

Eccentric isotonic contraction

when the length of a muscle increases during contraction

Isometric concentration

when the tension generated is not enough to exceed the resistance of the object to be moved, and the muscle does not change its legnth

Describe the reactions by which muscle fibers produce ATP

Creatine phosphate- When creatin phosphate transfers its high energy phosphate group to ADP, ATP is produced anaerobic cellular respiration -a series of ATP-producing reactions that don't require oxygen aerobic cellular respiration-series of ATP producing reactions that require oxygen

What types of fascia cover skeletal muscles?

Deep fascia

Why is the term recovery oxygen uptake more accurate than oxygen debt?

First: the elevated body temperatures after strenuous exercise increases the rate of chemical reactions throughout the body Second: the heart and muscles used in breathing are still working harder than they were at rest, they consume more ATP Third: tissue repair processes are occurring at an increased pace

Why is a rich blood supply important for muscle contraction?

For muscles to contract there needs to be an adequate supply of ATP within the cell. ATP is generated in part by a supply of glucose and oxidative phosphorylation. An inadequate supply of blood will not provide enough oxygen to keep up with the energy demands of contraction.

Demonstrate an isotonic contraction. How does it feel?

In an isotonic contraction, tension remains constant as muscle length decreases and increases;

During muscle contraction by the sliding filament mechanism, thin filaments are pulled towards the ?

M Line

Describe the microscopic anatomy of a skeletal muscle fiber

M-y S-on S-aw S-omeThing M-ean and S-trange M-oving and G-oing M-oo Mitrochondria - produces ATP for muscle Sacroplasm - cytoplasm of muscle fiber Sarcolemma - plasma membrane of muscle fiber Sarcoplamic reticulum - SER of muscle fiber full of Ca+ ions Transverse Tubules - extension of SER that signal when SR should release Ca+ Myofibrils - long bundles of myofilament that allow for muscle contraction Myofilaments - protein microfilaments composes of actin or myosin that help with muscle contraction Sarcomere - contractile mechanism of muscle fiber Glycogen - inclusion that provides energy during exercise Myoglobin - inclusion that stores oxygen

How does sarcomere length influence the maximum tension that is possible during muscle contraction?

Maximum tension during contraction occurs when the resting sarcomere length is 2.0-2.4 a muscle fiber develops its greatest tension when there is an optional zone of overlap between thick and thin filaments

The inability of a muscle to maintain force of contraction after prolonged activity

Muscle Fatigue

Describe the effects of exercise on different types skeletal muscle fibers

Total number of muscle fibers do not increase with exercise, changes can be induced Swimming, running: gradual change from fast glycolytic into fast oxidative glycolytic fibers, increases in diameter, number of mitochondria, blood supply, strength; endurance exercises cause cardiovascular and respiratory changes to receive better supplies of oxygen and nutrients but do not increase in muscle mass Great strength for short periods: increase in size from synthesis of thick and thin filaments and strength of fast glycolytic fibers, muscle enlargement from hypertrophy