Muscle Physiology Set 2

Front 1

actin

Back 1

thin strand is made of many repeating units called g-actin. Each strand of actin has tropomyosin a long filamentous protein associated with it

Front 2

troponin

Back 2

a protein found at interval along the actin and is directly associated with the filamentous tropomyosin

Front 3

tropomyosin

Back 3

a long filamnetous protein.tropomyosin is like a thin string that is wrapped alongside each actin filament

Front 4

power stroke

Back 4

where the release of a the phosphate initiates "power stroke" which is where the myosin head goes from its high energy state to its low energy state, pulling the actin filament relative to the myosin

Front 5

rigor

Back 5

rigid state that the myosin and actin are in after the release of the power stroke

Front 6

tetanus

Back 6

In tetanus, the muscle has a steady sustained contraction that does not show any twitch nature. the skeletal muscle fiber is being stimulated so reapidly that the twiches are crowded together and it is impossible to observe them individually

Front 7

latent period

Back 7

The latent phase occurs because it takes a brief period for the muscle fiber to repond to the action potential. During the latent phase, the action potential travels alond the muscle fiber and into the t-tubles, causing Ca++ channels to open in the SR and Ca++ goes into the cytosol of the cell

Front 8

summation of the twitches

Back 8

Normal muscle contraction is due to the motor neuron firing many times in quick succession which causes a summation of twitches. The twitches will begin to sum if a neuronal action potential is followed quickly by a second neuronal action potental. If the second occurs before the twitch that caused the first has ended then the twitches sum

Front 9

motor unit recruitment

Back 9

predicts the order in which motor units of different sizes are recruited. The size preinciple state that when motor units are recruited smaler units are recruited first then larger ones.. Motor units with the smalles cell bodies will reach their threshold member potential -55 mC first because they have the smallest cell volume

Front 10

motor unit rotation

Back 10

at sub-maximal tensions, motor units alternate activity (take turns contracting) allowing rest periods and prolonging the time in which the muscle can stay tonically contracted

Front 11

aerobic system

Back 11

Aerobic exercise, on the other hand, includes lower intensity activities performed for longer periods of time. Such activities like walking, running (including the training known as an interval workout), swimming, and cycling require a great deal of oxygen to generate the energy needed for prolonged exercise (i.e., aerobic energy expenditure).

Front 12

fast-twitch glycolytic

Back 12

type of muscle fibre that can reach peak tension quickly. It has a low oxidative capacity (low ability to use oxygen for aerobic metabolism), a high glycolytic capacity (high ability to respire without oxygen during anaerobic metabolism), and it fatigues quickly. Each fast-twitch motor unit consists of a single neurone and 300-800 muscle fibres (compared with only 100-180 muscle fibres in each slow-twitch motor unit). Fast-twitch motor units are therefore much stronger than slow-twitch motor units. Muscles consisting mainly of fast-twitch fibres appear white because of their low levels of myoglobin and low density of mitochondria.

Front 13

fast-twitch oxidative

Back 13

fast twitch or fast oxidative fibres, contain very large amounts of myoglobin, very many mitochondria and very many blood capillaries. Type II A fibres are red, have a very high capacity for generating ATP by oxidative metabolic processes, split ATP at a very rapid rate, have a fast contraction velocity and are resistant to fatigue. Such fibres are infrequently found in humans.

Front 14

slow twitch oxidative

Back 14

low twitch or slow oxidative fibres, contain large amounts of myoglobin, many mitochondria and many blood capillaries. Type I fibres are red, split ATP at a slow rate, have a slow contraction velocity, very resistant to fatigue and have a high capacity to generate ATP by oxidative metabolic processes. Such fibres are found in large numbers in the postural muscles of the neck.

Front 15

myoglobin

Back 15

Myoglobin is a single-chain globular protein of 153 amino acids, containing a heme center around the remaining apoprotein folds. It has hydrophobic core, it is the primary oxygen-carrying pigment of muscle tissues.
The binding of oxygen by myoglobin is unaffected by the oxygen pressure in the surrounding tissue. Myoglobin is often cited as having an "instant binding tenacity" to oxygen given its hyperbolic oxygen dissociation curve.
High concentrations of myoglobin in muscle cells allow organisms to hold their breaths longer.

Front 16

muscle fatigue

Back 16

muscle fatigue experienced by athletes after long and intense exercise may be caused by a problem with calcium flow inside muscle cells. According to Dr. Andrew Marks, who lead the study, fatigue occurs due to tiny leaks of calcium inside the muscles. One of the functions of calcium is to help control muscle contractions. This research found that after extended high-intensity exercise, small channels in the muscle cells begin to leak calcium, which leads to weakened muscle contractions. This leaked calcium also stimulates an enzyme that attacks muscle fibers and also leads to fatigue.

Front 17

dense bodies

Back 17

electron-dense portions of smooth muscle which thin filaments(actin and tropomyosin namely) bind.

Front 18

MLCK

Back 18

Myosin, light chain kinase
This kinase phosphorylates myosin regulatory light chains to facilitate myosin interaction with actin filaments to produce contractile activity

Front 19

smooth muscle

Back 19

Smooth muscle is an involuntary non-striated muscle
Smooth muscle fibers are spindle-shaped, and, like striated muscle, can tense and relax.
Smooth muscle does not contain the protein troponin; instead calmodulin is a significant protein expressed within smooth muscle.