Question | Answer |
What are the Muscular system functions? | movement
maintain posture
respiration
production of body heat
communication
heart beat
contraction of organs and vessels |
Types of muscles (3) | skeletal cardiac smooth |
Ablities of Skeletal Muscles (4) | Contractility (ablitily to shorten)
Excitablitiy (respond to stimulus)
Extensibility (ablilty to strench)
Elasticity (ablilty to recoil) |
Skeletal Muscle Characteristics | Makes up 40% of body weight
Many named after for bones attached to
many nuclei per cell
longest of muscles types
striated |
Skeletal Muscles Structures-Connective Tissues Coverings | Layers of dense connective tissues, called fascic, surround and seperate each muscle. This connective tissues extends beyond the ends of the muscle and give rise to tendos that are fused to the periostem of bones |
Epimysium or Fascia | Connective tissue that surrounds entire skeletal muscle(outside) |
Muscle fascicles | bundles of muscle fibers |
Perimysium | Connective tissue around each muscle fascicles |
Skeletal Muscle Structures-muscle Fiber Structure | A muscle(cell fiber is a single cylindrical fiber with many nuclei \the cell membrane is called the sarcolemma |
Sarcoplam | cytoplasm of muscle fiber(cell) |
T-tubules(transerve) | tube-like invaginations, at regular intervals, extend inward, connect sarcolemma to sarcoplasim reticulum |
Sarcoplasmic reticulum | highlu organized smooth ER, stores and releases Ca+2 ions |
Myofibril | thread-like structures that extend from one end of muscles fibers to other |
Myofibrils (two major kinds) | actin, myosin |
Actin & myosin are arragned by: | highly ordered, repeating units ca;;ed sacromeres (transverse straiations) |
Actin | thin myofilament,resemble 2 strands of perals |
Troponin | attachment site on actin for ca+2 |
tropomyosin | filament on grooves of actin, attachment site on actin for myosin |
myosin | thick myofilament,resemble golf club with myosin heads can bind to actin bend/staighten, use atp |
saromere | dmsllrdy portions of muscles able to contract, contains actin and myosin. each saromere extend from one Z disk to the next Z disk |
Z disk | attachment site fo actin
arragement of actin and myosin(overlaps) give myofibiril braided or straited aperaance |
H zone | center of sarcomere, contains only myosin |
I band | contains only actin |
A band | where atctin and myosin overlkap |
M line | where myosin are anchored |
Muscle fibers | hvae electrial propers
inside cell membrance s negatively chraged compared to outside
membrane is polarized
resting membrane potentila is the charge difference occurs due to an uneve distribution of ions across the cell membrane |
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