lecture 2 Flashcards
simplest transmission pathways
reflex arcs - chain of neurons that link sensory receptors to motor neurons
muscles and neurons
transmit action potentials
sensory neuron
somatosensory neuron
a neurone which the sensory terminals are in bodily issues
trisynaptic arc
2 interneurons but 3 interconnections
disynaptic arc
1 interneuron but 2 interconnections
polysynaptic arc
more than 3 interneurons
the simplest reflex arc is
monosynaptic - the sensory neutron connects directly to the motor neurone
the only monosynaptic reflex arc is
phasic muscle stretch reflex
phasic muscle stretch reflex is said to be
spinal - all the neural cell bodies lie within the spinal cord - brain plays no role
spinal reflex
a reflex with neural circuitry confined to the spinal cord and body
no brain
the sensory neurone cell bodies are in the
dorsal root ganglia
motor neurones are located in the
ventral part
muscles are made up of
long muscle fibres - responsible for contraction
two types of sensory endings
primary- 1a afferent endings
secondary- type 2 afferent endings
primary sensory endings
responsive to the SPEED at which a muscle is getting longer
Secondary sensory endings
responsive to the AMOUNT the muscle has been stretched
slow adapting properties
response strength is measured by the
rate of AP’S - firing rate AP’S per second
small stretch
weak stimulus
large stretch
strong stimulus
quick stretch
strong stimulus - more AP’S fire
slow stretch
weak stimulus
when the length is not changing
there is little response - fast adapting receptors
monosynaptic stretch reflex arc is responsible for
limb jerk reaction/ phasic muscle stretch reflex in response to tendon taps
tapping the tendon produces
little change in the length of the quadricep muscles
tapping elicits a knee jerk response
if the muscle is not stretched enough to stimulate receptors how can there be a stretch reflex response
because 1a afferent endings respond to the SPEED od the stretch
