muscle

thin filaments that consist of twisted chain of actin molecules

• thick filament are bundles of many myosin molecules
• each molecule consists of two long polypeptide chains coiled together, each ending in a large globular head
• the heads have sites that bind to actin, forming bridges between the actin and myosin
• heads also contain ATPse activity

functional unit of a myofibrils, bounded by the Z lines

• protein that binds the bundles of myosin filaments together
• titin molecules are very elastic, accounting for the resistance to stretch in relaxed skeletal muscle

• tropomyosin blocks the place where the globular head would beind
• troponin holds tropomyosin in place and can be activated (move tropomyosin) in the pressence of Ca++

when in the absence of ATP, actin-myosin bonds can't be broken

muscles fibers connected to a single motor neuron

plasma membrane that allows nerve synapses to activate the entire muscle fiber simultaneously

smallest unit of contractoin, measured in tension

the maximum amount of tension generated by a muscle fiber

• Increase the APF in each motor neuron
• Recruitment of motor units

• have many mitochondria
• lots of myoglobin
• prolonged aerobic ATP production
• well supplied with blood vessels and fuel reserves

• develop maximum tension more rapidly
• fatigue rapidly
• myosin have high ATPase activity but cannot replenish ATP fast enough

• pre-formed ATP and creatine phosphate is used as energy supply muscles with energy
• only lasts a couple of seconds

• metabolizes carbohydrates to lactate and pyruvate producing ATP
• anaerobic - can only be done for about one minute before lactic acid build up slows the reaction

• metabolixes of carbohydrates or fats to water and CO2 producing ATP through the electron transprot system and ATP synthase in mitochondria
• can be done for extended periods of times but takes about a minute to start functioning and is only limitted by blood flow