Skeletal Muscle & Nerves Overview Flashcards
structure of a nerve
whole nerve -> fascicles -> cells (neurone) -> axons
neurons & communication
neurone are the communication wires within our body
they transmit signals between different parts of our body
neurons use signals in the form of bio electricity and neurotransmitters to communicate
structure of a neuron
dendrites
cell body
axon
synaptic terminals
name of bioelectrical signals
action potentials
action potentials travel along the axon from ___ to ___
the cell body to synaptic terminals
input zone function
dendrites, take in information
cell body function
process information
axon function
transport signals to where they need to be
synaptic terminals function
sends out signals
bio electricity function
the bioelectricity generated in a neuron passes its bio electricity onto other neurons or muscles to communicate
waves of bio electricity sent down axons
what is an action potential/what does it do?
the propagation of a change in voltage (movement of ions) across the cell membrane down an axon
depolarisation = cell becomes more positive
depolarisation = cell returns to resting voltage
3 main subtypes of muscle
cardiac
smooth
skeletal
where, what, control of cardiac muscle
where = heart what = rhythmic & coordinated contractions for pumping blood around body control = autonomic nervous system (involuntary)
where, what, control of smooth muscle
where = gastrointestinal what = rhythmic & coordinated contractions for pumping blood around body control = autonomic nervous system (involuntary)
where, what, control of skeletal muscle
where = core & limb muscles what = movement of skeleton posture (thermoregulation) control = somatic nervous system (voluntary)
layers of skeletal muscle
- whole muscle (bundle of fascicles)
- fascicles (bundle of fibres)
- cells (myofibers)
- myofibrils
- myofilaments (actin & myosin)
muscle cell name
myofiber
muscle cell: structure of a sarcolemma
surrounds each myofiber (cell membrane)
muscle cell: structure of a sarcomere
functional unit, does the work
comprised of filaments thick and thin (contractile units)
muscle cell: structure of a mitochondria
energy unit
creates ATP for muscle contraction
structure of a muscle cell
sarcolemma
sarcomere
mitochondria
transverse tubules (t-tubules)
muscle cell: structure of t-tubules
extensions of the sarcolemma that dive deep into the muscle
structure & function of a sarcomere
the contractile unit of a muscle cell located very close to t-tubules and sarcoplasmic reticulum made up of 2 myofilaments: 1. actin (thin filament) 2. myosin (thick filament) have a striated appearance (stripes)
definition of a motor unit
comprised of a motor neuron and all the muscle fibres that it innervates
function of motor neurons
motor neuron cell bodies (somas) are in the ventral (front) part of the spinal cord
function of axons
project out of the spinal cord to the target muscle
function of nerve axons
close to the muscle
branch so that each axon innervates one or more myofibers
how many axons can innervate a myofiber?
only one myofiber is innervated by one axon
BUT one axon can innervate multiple myofibers
motor units in a whole muscle function
a whole muscle contains a collection of different motor units
the number of motor units activated at any one time can be varied to change the amount of force produced, this is called recruitment
why do we need the skeletal muscle system?
movement
posture
thermoregulation
