reflexes and pacinian corpuscle Flashcards
what is the PNS divided into
sensory and motor neurones
what are the motor neurones divided into
somatic nervous system and autonomic nervous system
what is a reflex
a rapid, automatic response to a stimulus
what happens from a stimulus being detected to how the organism responds
receptors - sensory neurone - CNS - relay neurone - motor neurone - effectors
different types of receptors (5)
thermoreceptors, chemoreceptors, photoreceptors, mechanoreceptors, baroreceptors
why is a neurotransmitter localised and short-lived
localised - neurotransmitters are secreted directly onto target cells
short-lived - removed quickly
somatic system
- under conscious control
- includes sensory neurones and motor neurones
autonomic system
- without conscious control
- has 2 pathways : parasympathetic and sympathetic
importance of reflex arcs
- fast
- involuntary
- protect from injury
differences between nervous and hormonal system
- HS act slower
- HS transported all over body., NS bind to specific complementary receptors within the target cells’s membrane
- HS broken down slowly
role of sensory neurones
convert a particular form of energy into electrical impulses
what does the pacinian corpuscle respond to
mechanical pressure
how a pacinian corpuscle functions - model answer
- stimulated by pressure, lamellae are deformed
- membrane of sensory neurone becomes stretched
- this stretches channel proteins called stretch-mediated sodium ion channels, causing them to open
- this allows sodium ions to diffuse into the neurone
- this produces a generator potential, which triggers an action potential if it reaches the threshold
- action potential travels along rest of sensory neurone to reach the CNS
