Muscle Tissue Flashcards
what is the function of muscle?
give movement, produce heat, gives shape, maintain posture, support other structures, regulate s organ volume
what is the name of muscle cells>
muscle fibers
what is epimysium?
surrounds entire muscle?
what are muscles a bundle of? surrounded by?
fascles, perimysium
within a fascle there are bundles of?
muscle fibers/muscle cells
what surrounds muscle fibers?
endomysium
what is the membrane of the muscle cell called?
sarcolemma
invagination of sarcolemma are called?
T tubules
sarcolemma is largely filled with?
myofibrils
what are glycogen?
energy storer of glucose
what are myoglobin?
oxygen
what stores Ca++?
sarcoplasmic reticulum
what are myofibrils?
sacs of sarcomers; used for contraction
what are sarcomers?
regions between z discs, filled with thick and thin myofilaments
which myofilament are thin?
I bands - light
which myofilament are thick?
A bands - dark
what types of muscle proteins are there?
contracting protein, regulatory protein and structural proten
what is contracting protein?
myosin, actin
what is regulatory protein?
troponin, ropomyosin
what is structural protein?
titin
what is thick filament?
myosin, held by m-line - doesnt move
what is thin filament?
actin, troponin, tropomyosin held by z disc
when muscle is relaxed what happens?
myosin binding sites on actin is covered by tropomyosin supported by troponin
what does titin protein do?
hold thick filament to z disc and m line
what is a neuromuscular junction?
where the nervous and muscle tissue meet
mechanism of contraction
Ap travels down axon of motor nerve, Ach leased, binds to receptors along sarcolemma, which causes Na+ channels to open and creating AP along sarcolemma through T tubules, which causes Ca++ to be leased from Sarcoplasmic Reticulum, which binds to troponin, which causes tropomyosin binding site to be exposed
contraction cycle
- ATP attach to myosin - cock position - ADP + P 2. myosin head attached to actin - P released making bind stronger 3. ADP releases causing myosin to move back to original position, pulling thin filament towards m-line 4. ATP attached to myosin head, weakens bond, myosin detaches
relaxation of muscle
AChE breaks down ACh, CA++ channel closes, Ca++ pumped back into Sarcoplasmic Reticulum, no more action potential, no more exposed binding site
what are the 3 sources of ATP?
- creatine phosphate 2. anaerobic cellular respiration 3. aerobic cellular respiration
what occurs in creatine phosphate?
ATP-ADP, phosphate to creatine=Creatine phosphate
how long does creatine phosphate source last?
15 seconds
what occurs in anaerobic cellular respiration?
glycolysis-> glucose splits into 2 pyruvic acid and 2 ATP, if no oxygen pyruvic acid turns into lactic acid, which diffuse into blood and burns
how long does anaerobic cellular respiration source last?
30-40 seconds
what occurs in the aerobic cellular respiration
2 pyruvic acid from anaerobic cellular respiration and make 36 ATP in mitochondria if oxygen is available
how long does the aerobic source last?
+30seconds, after 10 mins this is muscles 90% source of ATP
what is muscle fatigue?
inability to contract forcefully after prolonged activity
what is central fatigue
general feeling of tiredness
what is muscle fatigue due to?
lack of creatine, too little Ca++ in sarcoplasm, lack of oxygen, increase of lactic acid and ADP, not enough ACh from motor neuron
what is a motor unit?
10-15 to 3,000 muscle cells with one motor neuron
unified contraction amongst muscle cells from one motor unit is calleD?
unison
what is the average amount of cells to motor unit?
150
what is a twitch contraction
1 motor unit, with a brief contraction due to a single action potential
what is a myogram?
a graph of muscle contraction
how long does an action potential lasts?
1-2 msec
how long does a twitch contraction lasts?
20-200 msec
what are the periods of twitch contraction?
- latent period 2. contraction period 3. relaxation period
what occurs during latent period?
lasts 2msec, tension in filaments but no shortening, Ca++ released from SR
what occurs in the contraction period?
lasts 10-100 msec, filaments slide closer to M-line
what occurs in relaxation period?
lasts 10-100 msec, Ca++ actively back to SR
what is wave summation?
after refractory period, before muscle can relax, muscle hit with stimulation again, second stimuli stronger
what is unfused tetanus?
continuous stimulation with little relaxation between each stimuli, lasts about 20-30 times per second
what is fused tetanus?
sustained stimuli with no relaxation between stimuli, lasts about 80-100 times per second
what is the graded response of muscles?
- muscles fibers will contract maximally no matter if weak or strong signal 2.depends on how many muscle fibers stimulated or frequency of stimulation
what is significant about muscle tone?
most muscles are partially contracted all of the time, not enough to move but ready to contract important for maintaining posture and blood pressure
what types of whole muscle contraction are there?
isotonic and isometric
what is isotonic whole muscle contraction?
actually causing movement in your body, shortening muscle
what is isometric whole muscle contraction?
increasing muscle tension and force but no shortening on muscles
what is significant about cardiac muscles?
striated banches which allows interactions between fibers, less SR, more sarcoplasm and mitochondria, contraction lasts 10-15 times longer
what are the types of smooth muscle?
viscera and multiunit
what is significant about viscera?
1 motor neuron to one cell, gap junction allows for interaction with other muscle cells
what is significant about multiunit?
1 motor neuron with one cell, found in larger arteries, airways, arrector pili, iris, capillary body
