Summation in muscle fibers means that ___________ of the fiber increases with repeated action potentials.

Action potentials are propagated from the surface to the interior of a muscle fiber by way of: A. the sarcomeres. B. the sarcoplasmic reticulum. C. the endomysium. D. the myofibrils. E. the T tubules.

A cell membrane is referred to as a fluid-mosaic because: A. it is made up of mostly water B. it contains many different molecules that are weakly bonded to one another C. it contains proteins that keep the phospholipids locked rigidly together D. it permits no molecules to pass into or out of the cell E. its structure is still a mystery to biologists

After the oxidation of glucose is complete, the carbon that was formerly part of glucose is now a part of _______. A. the electron transport chain. B. NADH C. H2O D. CO2 E. ATP

At the END of the electron transport chain, the electrons: A. are transferred back to NAD+ to make NADH. B. are transferred back to FAD to make FADFH2 C. combine with H+ and oxygen to make water. D. combine with carbon and oxygen to make CO2. E. Both A and B are correct.

Which of the following is not found in the thin filaments of striated muscle? A. actin B. myosin C. troponin D. tropomyosin E. Ca+ receptors

Design of Muscle Cellular/Tissue Level Organ Level Gettin’ Buff

Myofibril

Trade-offs in Muscle Design You Can’t Always Get What You Want

Trade-offs in Muscle Design You cannot build a muscle cell that does it all! Sarcoplasmic Reticulum Determines speed of contraction

Trade-offs in Muscle Design You cannot build a muscle cell that does it all! Myofibrils Determines force of contraction

Trade-offs in Muscle Design You cannot build a muscle cell that does it all! Mitochondria Determines muscle stamina

Constraints on Muscle Action Anaerobic High Force Aerobic Low Force High Freq Low Freq

Types of Muscle Fibers Mitochondria high low Capillaries high low Structural Density Slow Oxidative Fast Gylcolytic Mitochondria high low Capillaries high low Glycolytic enzymes low high Myoglobin high low Glycogen stores low high Function Twitch slow fast Time to Fatigue long short

Types of Muscle Fibers Oxidative Fiber Glycolytic Fiber Red color Small diameter “Slow Twitch” Glycolytic Fiber Pale color Large diameter “Fast Twitch”

What Determines Your Fiber Type? Sprinter Marathon

What Determines Your Fiber Type? Weight training influences muscle development Sprinter Marathon

What Determines Your Fiber Type? Weight training influences muscle development Heavy Weight/Low Rep Low Weight/High Rep Sprinter Marathon

What Determines Your Fiber Type? Weight training influences muscle fiber development Heavy Weight/Low Rep Low Weight/High Rep Genes Sprinter Marathon

Fast Twitch Muscle Fibers Rapid ATPase in myosin Fatigue easily as glycogen storage is temporary Short-term, intense movement 50 % of a weighlifter’s muscle fibers are fast-twitch

Slow Twitch Muscle Fibers Slow ATPase in myosin Energy from oxidative phosphorylation High endurance 80% of a marathon runners fibers are slow-twitch Used for standing, walking

Keith Richards and Prof. Storm We share 1 trait in common

Keith Richards and Prof. Storm We share 1 trait in common Jon and I are keeping our options open

Design of Muscle Cellular/Tissue Level Organ Level System Level

Motor Units Neuron and the muscle fibers that it innervates. Fine Control: Motor unit with few (~20) muscles Strength: Motor unit with many

Design of Muscle Cellular/Tissue Level Organ Level Getting Buff’

Exercise Influences Muscle Mass Change in muscle fiber size No change in number of fibers More myofibrils in fibers Muscle overload and trauma

Anabolic Androgenic Steroids Synthetic testosterone Increase muscle mass Activate myogenesis genes Decrease muscle breakdown

Muscular Dystrophy Muscle-destroying diseases Onset during childhood Fat deposition in muscle Muscle fibers atrophy Respiratory failure