Muscles Flashcards
What are important structures in skeletal muscles?
Blood vessels; nerves
What do blood vessels do?
- Deliver nutrients and oxygen (glucose, aa, fats)
- Remove waste (lactic acid, CO2)
- Regulate temperature (help keep at correct temp, remove heat*)
What do nerves do?
-Stimulate contraction; handle voluntary control
What are muscle fascicles?
- Many in a body
- In each one, there is a bundle of muscle fibers (cell)
Muscle fibers
- Contain mitochondria
- Contain energy substrate (fat and glycogen)
- Contain myofibrils
Glycogen
- polysaccharide
- multiple glucose units
- storage form of carbs in body
Myofibrils
- Divided into regions called sarcomeres
- many sarcomeres within a myofibril
- contraction occurs within a sarcomere
What is a sarcomere?
Basic unit of muscle tissue
What is involved in the contraction in sarcomeres?
- Interaction of 2 types of filament (thick and thin)
- The filaments “slide” across each other “shortening = contracting”, requires Ca+ and ATP
Summary of Muscle Contractions
- Neural impulse occurs signaling a need to contract
- Ca+ is released
- Ca+ causes a change that allows the thick and thin filaments to interact
- The sarcomere shortens (contraction) (slide)
* 5. ATP is used in this process*
Thin filaments
Actin
Thick filaments
Myosin
ATP
Adenosine triphosphate
4 sources of ATP?
- Stored ATP (very little)
- Creatine phosphate (little more still not much)
- Anaerobic glycolysis (limited amounts)
- Aerobic metabolism of carbs and fats
Anaerobic metabolism
- does not need oxygen
- uses carbs, not fats
- results in some ATP and lactic acid
Aerobic metabolism
Fats and carbs > O2 > ATP+CO2+H2O
Advantages of aerobic metabolism
- much more efficient
- more ATP/more energy produced
- can use fat
- produce water as well
Type I muscle fibers
- slow twitch
- most endurance
- slow rate of cross bridge formation
- very aerobic (lots of mitochondria, good capillary supply, small cross sectional diameter)
- high in lipids low in glycogen
Type IIA muscle fibers
- fast twitch
- faster rate of cross bridge formation
- moderately aerobic (good blood supply, many mitochondria, moderate cross section)
- Moderate amount of lipid and glycogen
Type IIX muscle fibers
- fastest rate of cross bridge formation
- speed, strength, not endurance
- low aerobic capacity
- high glycolytic capacity (few mitochondria, lower blood supply)
- Highest in glycogen, lowest in fat
- largest cross-sectional area
What fiber type is for postural muscles?
Type 1, deep muscles, ex: neck
What fiber type is for driving muscles?
Type II, duperficial muscles
What type of fibers do Arabians mostly carry
Type 1 and IIA
What type of fibers do quarter horses have?
Type IIA and IIX
