what is an epimysium ?
connective tissue sheath surrounding each muscle
what is the fascicle?
bundle of skeletal muscle fibres surrounded by the perimysium
what is the perimysium?
connective tissue which surrounds each bundle of muscle fibre
what is muscle fibre?
long lengths of muscle cells that make up skeletal muscles
what is the endomysium ?
connective tissue that surrounds each muscle fibre
what are myofibrils?
small thread like strands that rum through each muscle fibre
what are the steps to the sliding filament theory?
- there is a neurochemical stimulation, calcium ions are released from the sarcoplasmic reticulum into the sarcomere prompting a reaction in each muscle fibre between the myosin and the actin filaments
2.Breakdown of ATP releases energy to stimulate cross bridges - Myosin filaments attach to the actin via the myosin heads which creates crossbridges. These cross bridges attach and reattach at different times along the actin pulling on them to create movement and maintain tension
4.This causes the actin to move into the centre of the sarcomere, shortening the myofibril and causing the actin and myosin filaments to be almost fully overlapped when in a fully contracted position causing the H Zone and I band disappear. - As each sarcomere shortens, so does the total length of each muscle fibre
- When the contraction finishes, the myosin and actin filaments return to a relaxed position (ATP releases energy causing myosin to detach from the actin and crossbridge is broken)
what is the function of a dendrite?
passes information from the sensory receptor to the cell body of the sensory neuron
what is the function of a axon?
transmit electrical information away from cell body to the muscle fibre
what is the function of the spinal cord?
transmit electrical messages from the brain to parts of the body
what is the function of the motor unit ?
causes contraction of the associated muscle fibre
what is the function of a neuron?
a cell within the nervous system that transmits impulses to other nerve cell
how is a message transmitted?
- Brain receives a signal from the sensory nerve
- Message travels via motor neurons- Structure Slide
- Arrives at the neuromuscular junction and has to cross the synapses (RIVER/GAP)
4.Arrival of Action Potential which opens calcium channels Ca+ ions. - Influx of calcium triggers a biochemical cascade
- This causes the release of Acetylocholine which is a neurotransmitter into the syapse.
- Signal on the end plate then transmit nerve signals to the muscle fibre.
- This signal releases the calcium from the sarcoplasmic reticulum causing Sliding Filament Theory
- Nerves cells extend across the length of the Myofibril BUT only stimulate portions of the muscle belly
what is the all or nothing principle ?
if the electrical threshold of the motor neuron is reached than all the muscle fibres which are connected to the motor unit will contract at the same time and force
how can you produce more force?
- greater number of motor units
-type of fibre
-size of motor unit
what is the relationship between force and velocity?
- concentric contraction - the more force required the slower the movement
-eccentric contraction - more force is required the faster the movement
what is the relationship between force and length?
relates to the amount of muscle force that can be produced at varying lengths maximal force is produced at mid range
what are the characteristics of type 2 a?
- fast contraction speed
- moderate force contraction
- medium fatigue resistance
- moderate levels of myoglobin, mitochondria, blood capillaries
-stimulated with large motor with moderate frequency
what are the characteristics of type 2 b?
-rapid contraction speed
-high force contraction
- fast fatigue
-high capacity for anaerobic ATP production
-high levels of glycogen
-low levels of myoglobin, mitochondria, blood capillaries
-stimulated with large motor with high frequency
what are the characteristics of type 1?
-slow contraction speed
-low force contraction
-contracts repeatedly
-high force contraction
-fatigue resistance
-high levels of myoglobin, mitochondria, blood capillaries
-stimulated with small motor with low frequency
