• Define the role of the epimysium, perimysium and endomysium in the organization of skeletal muscle
- The endomysium is the connective tissue that covers each single muscle fiber or myofiber or muscle cell.
- The perimysium is the connective tissue that surrounds each bundle of muscle fibers. -
- The epimysium is the dense connective tissue that surrounds the entire muscle tissue
Describe how blood is supplied to working muscles
- Blood vessels are closely intertwined with skeletal muscle tissues lying between the fascicles, or bundles of muscle fibers. Each muscle is supplied by many capillaries. This close association reduces the diffusion distances, allowing for the efficient exchange of oxygen
Outline skeletal muscle ultrastructure
- striated appearance of skeletal muscle fibres is due to the organisation of two contractile proteins: actin (thin filament) and myosin (thick filament).
Describe all the components of a sarcomere
- Z line – where the actin thin filaments are anchored.
- M line – where the myosin thick filaments are anchored.
- I band – contains only actin filaments.
- A band – the length of a myosin filament, may contain overlapping actin filaments.
- H zone – contains only myosin filaments.
What is the role of the Z line within the sarcomere
- The Z-line defines the lateral boundaries of the sarcomere and anchores thin, titin and nebulin filaments
- Responsible for force transmission
Explain the role of actin and myosin filaments in crossbridge cycling
- Myosin is a type of molecular motor and converts chemical energy released from ATP into mechanical energy.
- Myosin cross bridges cyclically attach, rotate and detach from the actin filaments with energy from ATP hydrolysis
What happens when sarcomeres contract
- the Z lines move closer together and the I band gets smaller. The A band stays the same width and, at full contraction,
Detail the role of calcium in the tubule system within a muscle fibre.
- Ca2+ ions create interactions between the proteins, myosin and actin. The Ca2+ ions bind to the C component of the actin filament, which exposes the binding site for the myosin head to bind to in order to stimulate a muscle contraction
What is the sliding filament theory?
- myosin (a motor protein) binds to actin. The myosin then alters its configuration, resulting in a “stroke” that pulls on the actin filament and causes it to slide across the myosin filament.
List the sequence of muscle action events (7)
- Action potential generated, which stimulates muscle
- Calcium released
- Calicum binds to troponin, shifting actin filaments which exposes binding sites
- Mysoin cross bridges attach and detach pulling actin filaments toward center
- Muscle contracts
- Calcium removed, which sifts actin filaments to original position
- Muscle contraction stops
• Relate differences in muscle fibre architecture with muscle fibre types and their relationships with different energy systems
- parallel, pennate and hydrostat
- Aerobic energy system – slow twitch
- Anaerobic – fast twitch
Muscle fibre types
- and the difference
- Type 1: Slow twitch oxidative
Type 2a: fast twitch oxidative - Type 2b: Fast twitch glycolytic, highest contraction speed
- Slow-twitch muscle fibers support long distance endurance activities like marathon running, while fast-twitch muscle fibers support quick, powerful movements such as sprinting or weightlifting.
- Type 1 has more mitochondria
What is the thick and thin filament
- Thick – myosin
- Thin - actin
• Differentiate the central nervous system and the peripheral nervous system
- CNS consists of the brain and spinal cord, while the PNS includes all other nervous system tissue. All sensory receptors, sensory neurons and motor neurons are part of the PNS. The bones of the skull and spinal vertebrae encase all CNS neurons.
- The cns receives data from the PNS
- PNS carrys out info
• What is the role of the peripheral nervous system completing physical activity?
- The sympathetic nervous system regulates arterial blood pressure and blood flow during exercise, and several important neural mechanisms are responsible for changes in sympathetic vasomotor outflow.
- Also relays information about the external environment back to the CNS
What is the reflex arc
- The reflex arc is a special type of neural circuit involved in a reflex action
5 components of a reflex arc
- sensory receptor.
- sensory neuron.
- Interneuron
- motor neuron.
- Motor effector
Describe a motor unit
a motor neuron together with the muscle fibers on which it acts
Outline the all-or-none principle
- The all-or-none law is a principle that states that the strength of a response of a nerve cell or muscle fiber is not dependent upon the strength of the stimulus.
How can you describe neuromuscular fatigue?
- any exercise-induced decrease in a muscle’s ability to develop force or power
What is voluntary activation
- The level of neural drive to muscle during exercise is termed
