Neurones+Pacinian Corpuscle Flashcards
Stimuli
-Changes to the body’s internal or external environments
Response to Stimuli
-In response to a stimulus, the sensory receptor generates an electrical impulse
-this impulse is transmitted to the CNS (brain and spinal cord) by a sensory neurone
-a relay neurone in the CNS carry the signal and transmits it to a motor neurone
-The impulse passes down the motor neurone to an effector (muscle or gland)
-the effector then carries out a response
Cell Body
All neurones contain a cell body
-Cell bodies contain a nucleus, motochondria and an endoplasmic reticulum
-Cell bodies are involved in the production of neurotransmitters
Dendrons in a sensory neurone
Dendrons carry impulses from the sensory receptors to the cell body
Axons
Axons carry impulses away from the cell body
Differences between motor neurones and sensory neurones (structure)
-Sensory neurone cell body is outside of the CNS whereas the motor neurone cell body is at the end of the neurone and within the CNS
-Sensory neurone has a short axon carrying the impulse from the cell body to the CNS whereas motor neurones have a long axon carrying impulses from cell body to effectors
Similarities between motor neurones and sensory neurones (structure)
-Both have a nucleus, mitochondria and an endoplasmic reticulum in the cell body
-Both have axons that carry the impulse away from the cell body
-Both can be myelinated to speed up impulse conduction
Both have nodes of ranvier between sections of myelin
Differences and similarities between motor neurones and sensory neurones (function)
-Sensory neurones carry impulses from the sensory receptors to the CNS whereas motor neurones carry impulses from the CNS to effectors
-Sensory neurones pick up the impulse from sensory receptors whereas motor neurones collect the impulse from relay neurones (CNS)
Myelin Sheath
-Made up of many layers of schwann cells wrapped around a neurone, forming multiple layers of plasma membrane
-Together with the nodes of ranvier speeds up the transmission of electrical impulses
Nodes of Ranvier
-Small gaps between the sections of the myelin sheath
-works with the myelin sheath to speed up electrical impulses
Motor Neurone
-Motor neurone cell body contains a number of short dendrites
-These short dendrites transmit electrical impulses from the sensory neurone or relay neurone towards the cell body of the motor neurone
-Motor neurone has one long axon
-This axon passes the impulse away from the motor neurone cell body, towards an effector (muscle or a gland)
-Cell body of a motor neurone is located inside of the CNS
Sensory neurone
Sensory neurone contains a dendron (transmits signal from sensory receptors the the sensory neurone cell body)
and it contains an axon (transmits impulse away from the cell body and towards the axon terminal/CNS)
Transmits impulse to the CNS/relay neurones in the CNS
-contains a myelin sheath+ node of ranviers
-Cell body of a sensory neurone is outside of the CNS
Relay Neurone
-Relay neurone transmits impulses from the sensory neurones towards the motor neurones
-Can contain multiple short dendrons and axons
-Relay neurone is unmyelinated (does not contain a myelin sheath)
-The cell body is within the CNS
Pacinian Corpuscle (function+location)
-Pacinian corpuscle detects pressure
-is found in deep layers of skin (soles of feet/ fingertips) or joints
-In response to pressure the Pacinian corpuscle produces a nervous impulse
-It converts mechanical energy (pressure) into energy for a nervous impulse (which is why it is considered a transducer)
Pacinian Corpuscle (structure)
The end of the sensory neurone is located in the center of the Pacinian corpuscle and is surrounded by connective tissue
-In the membrane of the neurone, there are stretch-mediated sodium ion channels
-These are usually too narrow to allow diffusion of sodium ions to the inside of the membrane
When pressure is applied to the Pacinian Corpuscle…
The shape of the Pacinian Corpuscle changes
-This causes the membrane of the neurone to stretch
-The stretch-mediated sodium channels in the membrane widen, allowing sodium ions to diffuse through the channels and into the neurone
-This causes the interior of the neurone to become positively charged
-This depolarises the membrane (generator potential)
-This generator potential causes a wave of depolarisation to pass down the neurone to the CNS (action potential)
