Chapter 10B - Muscular System

Front 1

Three kinds of proteins Myofibrils are made up of:

Back 1

Contractile, Regulatory, Structural

Front 2

Contractile proteins (define - 2 types)

Back 2

the pushes and pulls of these proteins acheive movement by converting the chemical energy of ATP to the mechanical energy of motion.

- Myosin, Actin

Front 3

Myosin (3 points)

Back 3

-motor protein

-main component of thick filaments

- shaped like two golf clubs twisted together

Front 4

Actin (3 pont)

Back 4

-main component of thin filaments

-twisted into a helix

- has myosin binding sites (a spot where myosin head can attach)

Front 5

Regulatory Proteins (2 kinds)

Back 5

help switch the contraction process on and off

(tropomyosin, troponin) - complex

Front 6

Tropomyosin

Back 6

blocks the myosin-binding sites on actin

Front 7

Troponin

Back 7

-holds the tropomyosin in place on actin

-Ca2+ binds to it

Front 8

The troponin/tropomyosin complex moves _____ from _____ when ______ ions bind to complex.

-without ______ ions, the myosin-binding sites are covered by the ______ proteins and myosin cannot bind to _____ (no contraction).

Back 8

away, actin, calcium

calcium, regulatory, actin

Front 9

Myosin head

Back 9

attaches to specific spot on actin to allow sliding

Front 10

Hypocalcemia

Back 10

Low blood Ca2+ lever = muscle weakness

Front 11

Break down of Muscles

Back 11

Skeletal Muscle->Fascicles->Muscle Fibers->Myofibrils->Sarcomeres->Thick & Thin Filaments -> Motion

(fig 10.6)

Front 12

Structural Proteins (2 types)

Back 12

contribute to the alignment, stability and elasticity of myofibrils

Actinin & Titin

Front 13

Actinin

Back 13

connects thick myofilaments to adjacent sarcomeres

Front 14

Titin

Back 14

Attaches thick myofilaments to Z Line

Front 15

Normal Contraction is under ___ control. A ____ activates a muscle fibber through stimulation of its ______.

Back 15

voluntary, neuron, sarcolemma

Front 16

Stimulation of the sarcolemma causes the release of ____ ions from the ______.

Back 16

calcium, sarcoplasmic reticulum

Front 17

Calcium Ions trigger interaction between ____ and _____ ______, resulting in

Back 17

thick and thin filaments, muscle fiber contraction and the consumption of energy in the form of ATP. The filament interactions produce muscle tension.

Front 18

Neuromuscular Junction

Back 18

specialized intercellular connection where communication between the nervous system and a skeletal fiber occurs.

Front 19

Motor End Plate

Back 19

the point where a neuron meets another cell

Front 20

The NMJ is a type of synapse representing a region of communication between the ____ and a _____. In a synapse there is usually a small gap between the neuron and the other cell, called the ____

Back 20

motor neuron, skeletal muscle fiber, synaptic cleft

Front 21

Neurons pass on messages to the next cell by using a ______

Back 21

electrical message

Front 22

Neurotransmitters

Back 22

chemical molecules that are stored in synaptic vesicles in the synaptic terminal (axon terminal) of the motor neuron.

Front 23

At NMJ, the neurotransmitter that the neurons release is:

Back 23

acetylcholine (ACh)

Front 24

Motor = __

Back 24

Movement

Front 25

Synapse

Back 25

a 'meeting' point

Front 26

Events at the NMJ occur through a series of steps (6):

Back 26

1. Action Potential (electrical stimulus) arrives at end of motor neuron

2. Exocytosis of ACh

3. ACh diffuses across synaptic cleft -> binds to motor end plate

4. Leads to sodium channel opening: sodium goes into cell (goes down gradient) -> generates action potential along sarcolemma, T-tubule -> arrives at triad

5. While this occurs, ACh is quickly removed from the synaptic cleft by an enzyme called acetylcholinesterase which frees the receptors on the motor plate so that they can respond when a subsequent action potential reaches the motor neuron

6. Return to the initial state

Front 27

Acetylcholinesterase

Back 27

enzyme that breaks down ACh

Front 28

Hyponatremia

Back 28

Low blood sodium

Front 29

Excitation-Contraction Coupling

Back 29

the link between the generation of an action potential in the sarcolemma and the start of a muscle contraction

Front 30

Excitation-Contraction Coupling occurs at the:

Back 30

Triad

Front 31

A large amount of ___ is stored in the ____. Calcium ____ pumps, which are energized by _____, continuously move Ca2+ into the _____.

Back 31

calcium, Sarcoplasmic Reticulum, transport, ATP, Sarcoplasmic Reticulum

Front 32

The concentration Ca2+ inside the SR is about _____x higher than in th cytosol of a relaxed muscle fiber

Back 32

10,000

Front 33

Steps of Excitation-Contraction Coupling (6)

Back 33

1. Neural Control

2. Excitation->ACh release->binds to receptors on motor end plate->ATP along sarcolemma

3. Ca+ release from SR (by diffusion)

4. Contraction cycle begins (new shape no longer covers the myosin-binding sites on actin)(Ca2+ makes myosin binding site on actin available by inducing the troponin/tropomyosin complex to move away from the myosin binding sites

5. Sarcomeres Shorten (interaction of thick and thin filaments)

6. Muscle Tension Generated

Front 34

Contraction Cycle and Cross-Bridge Formation

Back 34

1. Contraction cycle begins

2. Active-site exposure

3. Cross Bridge Formation

4. Pivoting of Myosin Head

5. Myosin head detaches

6. Myosin reactivation

Front 35

Contraction cycle begins

Back 35

- arrival of Ca+ ions in the zone of overlap in a sarcomere

Front 36

Active Site Exposure

Back 36

Ca+ binds to troponin and causes tropomyosin to move to the side and expose the myosin-binding site on the actin filaments and allow interaction with the energized myosin heads

Front 37

Cross Bridge Formation

Back 37

the energized myosin head attaches to the myosin-binding site

Front 38

Pivoting of Myosin Head

Back 38

(power stroke) the myosin head rotates and releases the ADP and phosphate group

- this rotation moves the thin filament past the thick filament

Front 39

Myosin Head Detaches

Back 39

Atp needed - at the end of the power stroke, the myosin head is still stuck to actin. It will come off when another ATP molecule attaches to the myosin head

Front 40

Myosin Reactivation

Back 40

reactivation occurs when the free myosin head splits the ATP molecule into ADP and a phosphate group, but remains attached to the myosin. This release of energy recooks or energizes the myosin head and the entire cycle can now repeat.

Front 41

The cycle repeats over and over again, as long as there is ___ and __ near the thin filaments is high enough to keep the complex from blocking their binding sites. Also needs a _____ at the beginning,

Back 41

ATP, Ca+, Neural input

Front 42

Rigor Mortis (causes... effect... length)

Back 42

After death, ATP production ceases and cell membranes (including SR) become leaky (i.e. the active transport pumps don't work anymore).

Therefore, calcium leaks out and sets the whole muscle contraction cycle in motion. Myosin binds to actin, but since ATP synthesis has ceased, the myosin heads cannot detach from actin. The resulting state of muscle rigidy is called Rigor Mortis. (body is 'stiff as a board')

Lasts from 3-24 hours after death. Sets in 2-3hrs after death. Muscles eventually relax when enzymes from lysosomes digest the crossbridges.

Front 43

Botulism

Back 43

A toxin produced by the bacteria Clostridium botulinum, found in improperly canned foods, blocks the release of ACh at the neuromusclar junction. Without release, muscles cannot contract. The diaphragm is one of the muscles that is paralyzed, which causes breathing to stop.

Front 44

Botox treatments

Back 44

Clostridium botulinum (botulism bacteria) is used where injection of varients of this toxin are used to relax specific muscles that cause facial wrinkles or alleviate chronic back pain due to muscle spasms. Doesn't last forever.

Front 45

Curare

Back 45

Curare is a plant derivative that also works at the neuromuscular junction. It causes every muscle in the body to become paralyzed by binding to ACh receptors so that ACh itself is not able to bind.

Curare was used by native peoples in tropical South America as a poison on blow darts or srrows used for hunting. Drugs related to curare are used during surgery to relax muscles. Antidotes are available to stop their effect.

Front 46

Tension Production (depends on 3 things)

Back 46

Frequency muscle stimulation, Starting sarcomere length, number of muscle fibers being stimulated.

Front 47

Twitch

Back 47

a single contraction produced by a single stimulation. Only occur during shivering (repeated twitches) and as a result of certain nervous system problems.

Front 48

Treppe

Back 48

fusion of successive twitches with some evidence of relaxation remaining (doesn't happen often)

Front 49

Wave Summation

Back 49

continuous contraction with no relaxation due to extremely rapid stimulation. Produces maximum tension.

Front 50

Incomplete Tetanus

Back 50

Not all muscle fibers are activated

Front 51

___ # of muscle fibers (/MU) = ____ contraction/ _____ controlled

Back 51

greater number

stronger

less

Front 52

Complete Tetanus

Back 52

No Relaxation -> Max Tension

Front 53

Motor Units

Back 53

Fibers within a muscle at arranged into motor units. All muscle fibers in a motor unit are controlled by a single motor neuron.

Front 54

Strength of contraction depends on (2)

Back 54

number of motor units (MUs) that stimulated simultaneously

number of muscle fibers innervated by any one motor unit

Front 55

Starting Sarcomere Length of the muscle implacts _____.

Back 55

the ability of the muscle to produce tension.

Front 56

Two types of muscle contractions:

Back 56

Isotonic contraction

Isometric contraciton

Front 57

Isotonic Contraction

Back 57

tension remains constant while the muscle changes in length there is movement. Two sub-types: Concentric, Ecentric

Front 58

Concentric Contraction

Back 58

muscle tension exceeds the load and the muscle shortens

Front 59

Eccentric Contraction

Back 59

peak tension developed in less than the load and the muscle elongates due to contraction of another muscle or the pull of gravity.

Front 60

Isometric Contraction

Back 60

the muscle develops tension but does not change in length and there is no movement. The tension produced never exceeds the load.

Front 61

Three ways ATP is produced

Back 61

Creatine Phosphate, Anerobic Cellular Respiration, Aerobic Respiration

Front 62

Creatine Phosphate

Back 62

while they are relaxed, muscle fibers produce excess ATP and transfer a high-energy phosphate group from excess ATP molecules to creatine to synthesize creatine phosphate, an energy-rich molecule found only in muscle fibers. Process yields enough energy to provide maximal contraction for about 10 seconds.

Front 63

Anerobic Cellular Respiration

Back 63

a series of ATP-producing reactions that do not require oxygen. When muscle activity continues and the supply of creatine phosphate is depleted, glucose is catabolized in the cytosol to generate ATP in process called glycolosis.

Front 64

Aerobic Respiration

Back 64

muscle activity that last longer than a minute depends on oxygen in series of reactions that use pyruvic acid to produce ATP in mitochondria.

-process yields an additional 34 ATP for each glucose catabolized. Byproducts are H2O and CO2.

-aerobic cellular respiration provides enough ATP for prolonged activity as long as sufficient oxygen and nutrients are available.

Front 65

Muscle Fatigue

Back 65

the inability of a muscle to contract forcefully after prolonged activity. This fatigue results mainly from changes within m uscle fibers and/or neurons responsible from stimulating the fibers - includes both central and peripheral nervous system components.

Front 66

Muscle fatigue has been correlated with... (4)

Back 66

1. Decrease PH (acidosis)

2. Damage to Sarcolemma & SR

3. Depletion of Metabolic Reserves

4. Tiredness -> from brain

Front 67

Oxygen Debt

Back 67

The extra oxygen demand above resting level after activity. (heavy breathing)

Front 68

DOMS

Back 68

Delayed Onset Muscle Soreness (DOMS)

pain that results after a bout of excercise that was more strenuous than usual. The pain occurs usually 1-2 days later after the event.

Front 69

Factors involved in DOMS (4)

Back 69

1. Muscle Damage

2. Inflammation

3. Muscle Spasms

4. Tears in muscle tissue & tendons

Front 70

Sarcopenia

Back 70

Loss of skeletal muscle mass

Front 71

Duchenne Muscular Dystrophy

Back 71

most common form of muscular dystrophy. Men are more effected. Mutated form of dystrophin -> diagragm is affected.

Front 72

Spasm

Back 72

involuntary contraction of a single muscle in group

Front 73

Cramp (causes 4)

Back 73

a painful spasmodic contraction

Caused by: temp change, low electrolytes, hypoxia, dehydration

Front 74

Rhabdomyolysis

Back 74

breakdown of muscle tissue & release of myoglobin

- can cause a variety of serious effects i.e. kidney failure

Front 75

Tic

Back 75

Spasmodic twitching (involuntary) by normally voluntary muscles

Front 76

Tremor

Back 76

Rhythmic involuntary contraction -> shake or quiver

Front 77

Charley Horse

Back 77

term for painful contusion (bruise) of the quadriceps muscle that can cause several weeks of pain and disability.

- can occurs in sports from being struck

-sometimes used to decribe painful leg cramps in the thigh... unlike leg cramps a charley horse can occur when the muscle in question is not in use (i.e. in bed)

Front 78

Types of Muscle Fibers

Back 78

Slow Twitch

Fast Twitch - Fast Oxidative, Fast Glycolytic

Front 79

Slow Twitch (2 alt. names?)(colour)

Back 79

Slow Oxidative, Type I

Red

muscle fibers that contract relatively slowly (110ms) due to myosin isoforms that couple with actin more slowly. They function using aerobic cellular respiration and are also called slow oxidative fibers.

- Require continous supply of oxygen and thus have a high degree of blood suply and contain lots of myoglobin

Front 80

Myoglobin

Back 80

O2 binding muscle protein that is functionally similar to hemoglobin

Front 81

Fast Twitch (2 alt names)(colour)

Back 81

Type II, intermediate

Pale Red

muscle fibers that contract more quickly (50ms) due to myosin isoforms that couple with actin more quickly. Constitute the majority of fibers found in 'white meat'. There are two sub-types of fast twitch fibers:

Front 82

Type IIa (alt name)(colour)

Back 82

Fast Oxidative

-fibers that function using aerobic cellular respiration and are used for more rapid muscle contractions but still require oxygen to function

-they have a moderate aerobic endurance and are used for shorter, higher intensity events such as a 2km run or 400m swim

-Pale in colour and contain minimal amounts of myoglobin, like Type IIb fibers, but have more extensive capillary network, like type I fibers.

Front 83

Type IIb (alt name)(colour)

Back 83

Fast Glycolytic,

White Fiber

-fibers that function using glycolysis and are used inj the muscles that are required to generate maximal forces for a short duration and thus do not depend on oxygen for metabolism

-have a low aerobic endurance and are used for short very high intensity events, such as 100m dash and 50m swim sprint.

Front 84

Most skeletal muscle contains about ___% ST fibers, % FT fibers

Back 84

50/50

Front 85

General order of muscle recrution

Back 85

ST>FTa>FTb

Front 86

Cardiac Muscle Characteristics

Back 86

Striated

Under involuntary control

Intercalated discs (desosomes & gap junctions) result in very high tissue integrity and strength

Contain Sarcomeres

Contraction occurs without external stimulation and thus these cells exhibit auto___ , which is controlled by pacemaker cells located in the4 tissue and transmitted bia gap junctions

Front 87

Smooth Muscle is found in (6)

Back 87

Integumentary - regulates blood vessels, blood flow to dermis

Cardiovascular - encircles blood vessels to control flow

Respiratory - alters diameters of lung passages

Digestive - control motility and secretion

Urinary - control ___ in kidneys, transport urine

Reproductive - move sperm, assist with ejaculation, move oocytes, and ultimately the fetus at delivery

Front 88

Characteristics of Smooth Muscle Tissue

Back 88

Non-striated

Involuntary control

Spindle-shaped and have single nucleus

Does not contain sarcomeres, tendons, t-tubules or myofibrils

Filaments are scattered and connected to dense bodies which are connected in a network of filament composed of desmin