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PHYS2
Muscle III
| Question | Answer |
|---|---|
| How many muscle fiber types is an entire muscle composed of? | Most muscles are made of all three |
| CONTROL OF MUSCLE TENSION | CONTROL OF MUSCLE TENSION |
| What does the tension of WHOLE muscle contraction depend on? | 1. Amt of tension in each fiber 2. Active fibers in muscle |
| What does the number of active fibers depend on? | Number of fibers in unit and number of active motor units |
| Which motor unit would produce the biggest tension: One with a small diameter or large diameter? | Large diameter; remember those glycogenic fibers |
| NUMBERS OF FIBERS | NUMBER OF FIBERS |
| Muscles that produce delicate movements have how much fibers per motor unit? | Few fibers |
| Postural muscles like the back and leg have how much fibers per motor unit? | More fibers per motor unit |
| T or F. If you have a greater number of fibers in a motor unit, that gives you a greater motor unit. | Yes. |
| How much fibers per m.u. do fast glycolytic fibers have? | Large numbers of fibers per m.u. |
| Define: Recruitment: | Increasing number of ACTIVE motor units |
| How is this done? | Increase synaptic input |
| What is the relationship between the recruited unit number and the tension? | Direct. As recruitment goes up, tension goes up |
| RECRUITMENT HIERARCHY | RECRUITMENT HIERARCHY |
| What is the order of recruitment in regards to muscle fibers from first to last and in what contraction strenght? | Slow Ox in weak contractions to fast ox to fast gly in strong contractions |
| SHORTENING VELOCITY | SHORTENING VELOCITY |
| What does shortening velocity depend on? | 1. Load, types of motor units, and recruitment |
| What is the relationship between recruitment and shortening velocity? | Inreasing recruitment will increase velocity at which a muscle moves a load |
| What does muscle mass measure? | Size of the muscle NOT the number of muscle fibers |
| Atrophy vs. hypertrophy: | Decrease vs. increase muscle mass |
| What results from low-intesity excercise? | Increased endurance and NO hypertrophy |
| What causes this? | More mitochorndria and blood vessels come in muscle |
| What results from short duration, high intesity muscles? | Increased fiber diameter (hypertrophy) and increased strenght |
| What causes this? | Inreased synthesis of actin and myosin |
| What happens to force generated by a muscle with each? | It decreases by almost half |
| Why? | Decrease in muscle fiber diameter |
| What happens to the muscle's ability to adapt to excercise with age? | It decreases |
| What does movement around a joint require? | Two antagonistic groups of muscles; one flexes and another extends at the joint |
| SMOOTH MUSCLE | SMOOTH MUSCLE |
| What are the characteristics of smooth muscles that differentiate them from our skelatal muscles? | No striations, single nucleus, and capable of cell division |
| So if they don't have striations, do they have myosin and actin? | YES. YES, they do!!! |
| How are they controled? | Autonomic control mostly |
| CROSS BRIDGE ACTIVATION OF SMOOTH MUSCLES | CROSS-BRIDGE ACTIVATION OF SMOOTH MUSCLES |
| What is the first step in activating smooth muscles? | Inrease calcium leads to calcium binding with CALMODULIN |
| Step 2: | Calcium-calmodulin complex binds to and activates myosin kinase |
| What does this enzyme do? | Uses ATP to phosphorylate smooth muscle myosin |
| Step 3: | phosphorylated myosin binds to actin to get cross-bridge cycling |
| What is the rate of ATP splitting in smooth muscle myosin? | SLOW, so not as fast cross bridge cycling |
| Why is this mainly? | Because there are no straitions in smooth muscles |
| What are the two sources of calcium for the smooth muscles? | SR and extracellular calcium via calcium channels |
| What can cause depolarization in smooth muscles? | 1. RAndom electrical activity in fiber's PM, neurotransmitters released by ANS, and some sort of stimuli |
| Give an example of such a stimuli | HOrmones, stretch, and changes in chemical compositions |
| What are the two types of smooth muscles? | Single unit and multiunit |
| Single Unit: | AP from cell to cell via gap junctions |
| Multiunit: | Not much gap junction AP passing, contractile activity coupled w/ neural activity |
Created by:
talkglitter2486