Muscle Tissue Flashcards
List the characteristics and overall functions of muscle tissue
Muscle is
a) excitable
b) contactable
c) Extends and relaxes
d) high blood and nerve supply
Function:
- motion
- posture and support
- heat (maintain body tempature shivering)
- guards exits and entraCnces to body
Compare location, microscopic appearance, nervous control, and function of 3 kinds of muscle
- Smooth muscle- nonstriated, involuntary causes mixing & movement called peristalsis (walls of viscera)
- Cardiac muscle-striated with intercalated discs, involuntary
- Skeletal muscle- striated, voluntary
Fascia
- Connective tissue grouping of whole muscle (spiderweb like)
- provides origin of muscles
- space filling
Epimysium
-Connective tissue around entire (singular) muscle
Facicles
-Cell bundles (gives stringy texture to brisket)
Perimysium
-Connective tissue around fascicles (the bundles of cells)
Endomysium
(not gross anatomy)
-Connective tissue around single muscle cell
Tendon
Cord like
-attaches muscle to bone (epinysium to periosteum)
Aponeurosis
Broad sheet like tendon
Explain the relationship of blood vessels and nerves to the skeletal system
Skeletal muscle must have nerve supply to function and has an excellent blood supply.
-Anaerobic metabolism
Sarcolemma
Unique Muscle Cell Membrane
Myofiber
Muscle cell
- Multlinucleatice- making lots of atp
- no Mitosis (muscle cannot repair itself, scar tissue is formed)
- Sarcolemma-the membrane of the muscle
Myofibril
Striated Cylinder inside of cell
- responsible for contraction
- Attaches to sarcolemma
- I bands (isotropic)
- A Bands (anisotropic)
- z lines
Myofilament
Actual Contractile proteins (allows bulk up of muscle)
- Thick (myosin)
- Thin (Actin, Tropomyosin, Troponin)
A-band
Dark band
anisotropic
I-Band
Light band
isotropic
Z- line
1 cell ends another begins
-actin and the thick myosin myofilaments
Sarcomere
The distance between the z line to the next z line
-the function unit of muscle contraction because it squeezes together during contraction from myosin pulling on the actin.
Myosin
(two gulf clubs intertwined)
- In the a band
- Grabs actin for movement
Actin
(two strands of pearls)
-Anchored to the Z line.
Sarcoplasmic reticulum
The sarcoplasmic reticulum with its expanded regions called terminal cisternae are the muscle cell’s version of an endoplasmic reticulum. It functions to store calcium ions.
Tropomyosin
(Protein string wrapped around (actin) pearl string)
- Regulation
- Acts as a block to myosin to prevent contraction by blocking myosin from attaching head with actin
Troponin
(keeps ribbon in place)
- Has binding sites with calcium
- releases when calcium binds to it
- Anchors tropomyosin to actin
Transverse tubules
Transverse tubules are inward extensions of the sarcolemma into the interior of the cell.
-Brings excitement into where calcium is stored
Terminal Cisternae
Sarcoplasmic Reticulum
- the special er of muscle
- calcium stored in cisternae
Describe the principal events associated with the sliding-filament theory
Excitation/Contraction coupling
- T tubules excitement from nerve releases calcium (from the sarcoplamic reticulum) which is the main regulator of contraction
- The calcium binds to troponin causing it to relase the tropomyosin which can move out of the way
- The myosin head can form a cross bridge binding to actin
- the myosin head is energized with the binding of ATP and swivels towards the center of the sarcomere causing a power stroke (Sarcomere squeezes together)
- ATP needed for actin and myosin to release from each other for relaxation and it is needed to put calcium back into the sarcoplasmic reticulum (active transport)
Describe the structure and importance of a neuromuscular junction (motor end plate)
- motor neuron tells muscle to contract
- motor unit- nerve+muscle
- There is a gap between the distal end of the neuron and the muscle cell call the neruomusclar junction.
- Neurotransmitter- Acetylcholine nerve to muscle communication
- Motor unit: 1 to many= back muscle less control, 1 to 1= higher control-eye lid
What is acetylcholine
nerve to muscle communication
Describe why calcium regulates contraction.
Calcium is the glue that controls the on and off switch
-binds to troponin causing a physical block, the tropomyosin to move out of the way.
Describe ATP sources for skeletal muscle contraction
–A little bit of ATP is present in this state in the muscle cell. More can be quickly manufactured by converting creatine phosphate to ATP. Rapidly, but inefficiently, you can make ATP from anaerobic metabolism.
As long as oxygen supply is sufficient, you can very efficiently make a lot of ATP from aerobic metabolism, a slow process.
Describe restorative processes following strenuous exercise
Oxygen debt causes one to breath hard after oxygen depletion causes by the aerobic metabolism process of making ATP for muscle stimulation.
- To remove lactic acid, the end product of aerobic metabolism from the muscle cell.
- glycogen debt is to restore glucose stores and the best way to restore these is to eat carbohydrates.
Describe muscle fetigue
a muscle cannot move until ATP is regained, caused by lack of ATP after strenuous activity.
Describe the phases of contraction in a typical myogram of a twitch contraction.
- This is the mechanical response of a single muscle cell to a single action potential.
- Latent period (10ms)- excitation contraction coupling
- Contraction period (40ms)- tension/ shortening of the sarcomear.
- Relaxation period (50ms)- Returns to unstimulated tension/length.
Describe the all-or-none principle of muscular contraction.
All stimuli strong enough to cause a muscle twitch will cause identical muscle twitches. However, the all-or-none principle applies to the muscle CELL only, not the entire muscle.
Explain how whole muscle response are grade contractions to meat the demands of the task at hand
1) all or nothing response- refers to myofiber
2) multiple motor unit stimulation-Nerve + Muscle
3) Muscle tone- firmness with out movement
- For a small contraction of your biceps muscle, 10% of the muscle cells will do their “all.” For a bigger contraction of your biceps muscle 60% more muscle cells contract maximally.
- For a maximal contraction of the whole biceps muscle, all of the muscle cells will be contracting maximally
multiple motor unit summation
more then one nerve+muscle addition aka spatial
-individual motor units combine their activities to increase the contraction of the entire muscle
spatial summation
Multiple motor unit- summation and occurs when many muscle cells or motor units contract at the same time making a bigger whole muscle contraction
temporal summation
wave summation and is when muscle cells contract repeatedly and rapidly, so that the next contraction is occurring before the previous one has totally relaxed.
Examples incomplete tetanus and complete tetanus
wave summation
temporal- time
- summation in time, before complete relaxation
- incomplete tetanus
- complete tetanus
incomplete Tetanus
example of wave summation
-contraction strength increases in amplitude with partial relaxation.
complete tetanus
(holding books with out dropping)
-sustained contraction with out relaxation, can only do this for so long that atp is avalible
treppe
(staircase)
- stronger contractions after muscle has contracted several times
- different then incomplete tetanus because relaxes all the way
- warming up for a race
asynchronous motor unit summation
head/neck muscle taking turns
-different motor units are activated at different times.
Motor tone
firmness with out movement
-at any given time some fibers are contracted which tightens muscle but no enough to produce movement
Contrast isometric and isotonic contractions
isotonic contractions- tension develops and it shortens
isometric- tension develops and doesn’t shorten
-Isometric contractions occur when you pick up something that is too heavy. While your muscle is working and creating tension, it is not shortening. Isotonic contractions result in shortening, as in bending your elbow.
compare the structure and function of the three types of skeletal fibers (slow intermediate and fast)
- Slow fibers are fatigue resistant and are red. They have excellent blood supply and myoglobin for oxygen storage (think of dark meat of chicken). Therefore they are geared toward aerobic metabolism and while this is not fast these fibers do not run out of ATP and do not fatigue (think of the chicken walking around all day long).
- Fast fibers are fatiguable and are white. They do not have great blood supply and do not have myoglobin. They are geared toward anaerobic metabolism. They can make the ATP very quickly (think of the breast meat of chicken and the chicken flying quickly to a tree when being chased) but will run out of it soon and cannot endure (the chicken cannot fly long distances, but the goose has dark meat for the breast, why?).
- Intermediate are more fatigue-resistant fast fibers. You can get these through endurance training, but the fast and slow fibers are genetically determined.
Describe the relationship between bones and skeletal muscles in producing movements
The arrangement is as a lever system which gives you a mechanical advantage making the work less
define origin
- Proximal connection to skeletal system
- less movable
define belly
-red portion of muscle
define insertion
- Distal connection to skeletal system
- More movement
define lever and falcrum
- falcrum- pivot point
- lever- mechanical advantage
Compare the three classes of levers on the basis of placements of the falcrum effort and resistance
- Class 1 lever- sea saw (R to L or L to R)
- effort, falcrum(center), resistance
- Class 2 lever- wheel barrow
- Falcrum(wheel), resistance, effort
- Class 3 lever- shovle
- Falcrum(handle), effort, resistance
discuss most movement as activities of groups of muscles by explaining the roles of the prime mover (agonist), antagonist, synergist and fixator
- Antagonist- the prime mover, causes a desired action. ex elbow flex-bicept
- antagonist- opposite effect of the agonist ex elbow flex- triceps
- synergist- helps the agonist in the desired action- ex elbow flex- breckials
- Fixator- stabilizing muscle- ex: rotator cuff muscle of the scapula
define the criteria employed in naming skeletal muscles
- action
- origin and insertion
- direction of muscle fibers
- location
- number of origins
- size
- shape
