functional anatomy Flashcards
fusiform
fibers run longitudinally from a tendon. Can shorten over large range but not very strong
penniform
fibers that run at an angle from the tendon (unipennate, bipennate, multipennate. Produce more force but not as quick.
Epimysium
muscles are in a thin layer of connective tissue call epimysium
fasciculi
inside the epimysium are bundles of muscle fibers caller fasciculi
sarcolemma
each muscles fiber is encased by a thin membrane called sarcolemma
myofibrils
each muscles is made up of a bundle of 100s of myofibrils
sarcoplasm
is a gel like structure between the myofibrils which contains mitochondria, fat, gylcogen, ATP ect…
sarcomere
each myofibril is the length of a muscle fiber and contains many sarcomeres, which is the basic contractile unit of the muscle.
sliding filament (explanation)
- when there is a neuromuscluar stimulation, calcium is released into the sacroplasmic reticulm
- this prompts binding sites on the actin to be exposed, so that myosin heads can attach (cross bridges)
- with the use of ATP the myosin heads contract and pull/slide the actin filaments across the myosin filaments
- the actin filaments are pulled towards each other (when totally contracted actin and myosin filaments will overlap causing the I bands and H zones to disapear)
what impacts the amount of force being produced?
the amount of force generated by the muscle depends on the number of myosin cross-bridges attaching to actin.
characteristics of type I
slow twitch slow to fatigue contract slowly best for aerobic work red in colour
type IIa
can sustain for long period Or;
can burst with force then fatigue
white in colour
intermediate fast twitch
type IIb
contract quickly and powerfully tire quickly best for speed and strength (anaerobic) fast twitch white in colour restiance to fatigue low cp levels high motor unit size large capaliery density low mitacondrah density low
force-velocity (concentric)
maximum force is achieved when a muscle contracts at a low velocity
As velocity of contraction increases, the force generated decreases
force-velocity (eccentric)
max force is achieved at max velocity
as velocity of contraction increases force generated increases
force-length relationship
the amount of force that can be produced by a muscle is also related to the length at which the muscle is held.
max force (length)
80% and 120% of resting length
shorten/lengthen
shorten are max overlapped and lengthen to much space in between creating a slippage in cross bridge
structure a neuron (dentrites)
receives impulse/stimulus from the spinal cord and sends it to the cell body
structure a neuron (cell body)
processes and directs the impulse to the axon and along the axons length
structure a neuron (axon)
delivers the impulse along its length to the end of the axon (axon terminal) to the end motor plates where they stimulate the muscle fibres
central nervous system (brain)
- analyses the info recieved from the sensory neuron
- determines the most suitable response
- sends impulses to the targeted muscles via the spinal cord and peripheral nerves
central nervous system (spinal cord)
- delivers sensory messages from the brain to the body
2. delivers motor messages (movement) from the brain to the body (muscles)
the peripheral nervous system
is made up of sensory and motor neurons which transmit messages to and from the central nervous system
sensory/motor division
sensory: carries singals from the receptors to the CNS
motor: carries signals from the CNS to the muscles
components of a motor unit
comprises of a motor neuron and the muscle fibres
a whole muscle has many many motor units which allow the muscle to generate different types of force
neuromusular junction
the area between the axon terminal and neurons and muscle fibres
recognition of a stimulus
- when we recognize a stimulus using our senses, a sensory neuron sends an impulse to the central nervous system
- the brain will acknowledge the stimulus and decides what movement is necessary for that situation
- our brain then sends an impulse down the spinal cord to the relevant motor neurons
- the motor neuron will send a message to their associated muscle fibre to contract
innervating a muscle fibre (action potential)
the electrical impulse that travels from the cell body to the neuromuscular junction is called the action potential
innervating muscle fibres (what happens when action potential reaches the required threshold)
a neurotransmitter is released from the neuron and passes across the neuromusclar junction
innervating muscle fibres (The neurotransmitter for muscle contraction is?)
acetylcholine
innervating muscle fibres (Acetylcholine binds to?)
the acetycholine receptors on the muscle fibres. this allows sodium into the muscles and potassium out creating a positive charge
innervating muscle fibres (what happens to the positive charge?)
spreads across muscle fibres, which triggers a release of calcium from the sacroplasmic reticulm. then contracts
innervating muscle fibres (if not stimulated again?)
calcium ions are drawn back into the sacroplasmic reticulm and the muscle returns back to OG.
preferential motor unit recruitment
motor units are recruited in a given order depending on exercise intensity
