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Physiology
Chapter 12
| Question | Answer |
|---|---|
| Fasicle | Bundle of muscle cell |
| Muscle fiber (cells) | In fasicle |
| Myofirbil | Protein filaments *aids in muscle contraction |
| What are the components of muscle fiber? | Sarcolemma,multinucleated, sarcoplasm,myofibrils, sarcoplasmic reticulum, transverse tubules, mitochondria |
| Sarcolemma | Cytoplasm membrane of the muscle cells (outer layer of cell, phospholipid bilayer) |
| sarcoplasm | Equivalent to cytoplasm |
| sarcoplasmic reticulum | Equivalent to smooth ER, surrounds ea. myofibrils *releases Ca to form a crossbride |
| transverse tubules (T Tubules) | connected to sarcolemma. Helps transmit AP from sarcolemma deep inside muscle |
| Types of myofibril | Thin and Thick filaments |
| Thin and Thick filaments | *Run parallel to long axis of muscle cell *orderly arranged |
| What are thin filaments made of? | Protein called actin |
| What are thick filaments made of? | Protein called myosin |
| Sarcomere Function and location | Function unit of muscle contraction in muscle cells *located between 2 Z-lines (where thin filaments are attached) |
| Where does striation of sarcomere come from? | arrangement of thin and thick filaments |
| Crossbridge process | Myosin head binds with actin and pulls it causing contraction and sarcomere to shorten |
| Sliding filament mechanism | Explains how muscles shorten *thin filaments slides towards center of thick filaments cntracting sarcomeres |
| Excitation contraction coupling | sequence of events that link AP to contraction in muscle cell *requires Ca *depends on neural input |
| Steps to Excitation contraction coupling | 1. AP in sarcolemma 2. AP travels down tubule 3.AP triggers release of Ca from sarcoplasmic reticulum 4.Ca binds to troponin to expose myosin-binding sites 5. cross bridge cycling occurs |
| Troponin and tropomyosin | regulate contraction via calcium binding *tropomyosin long *troponin pearl strands |
| calcium in muscle contraction | triggers contraction by reaction with movement of troponin and tropomyosin on their thin filaments and this enables the myosin molecule heads |
| isotonic contraction | muscle maintains the same tension as it shortens. Ex)walking |
| isometric contraction | same length. muscle does not shorten but individual muscle fibers will shorten |
| Recruitment of motor unit | dependent on FORCE production (in exercise) needs of the muscle and proceeds from the ‘smallest‘ motor units in size to ‘largest’ |
| SMOOTH MUSCLE | contracts blood vessels, GI tract, bladder, uterus *smaller than skeletal *autorythmic, involuntary *controlled by ANS & Endocrime *non-striated |
| cardiac muscle | Autorythmic, involuntary *controlled by ANS & Endocrime |
| What happens when Ca is released from sarcoplasmic reticulum | *Ca bind to troponin *changes shape to move tropomyosin to allow myosin head to bind actin and form crossbridge *myson head is activated when atp binds to it and turns into ADP |
Created by:
izis
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