neurons and synaptic transmission Flashcards
(12 cards)
neurons
nerve cells that process and transmit messages through electric and chemical signals.
sensory neurons
-carry messages from the PNS to the CNS (carry nerve impulses from sensory receptors e.g vision,taste,touch to spinal cord and brain.
-covert info from sensory receptors into neural impulses. when these reach brain are converted into sensations so an organism can respons appropriately
-not all sensory info travels as far as the brain so neurons terminate in the spinal cord which allows reflex actions to occur quickly without delay of sending impulses to brain
-have long dendrites and short axon
sensory neurons have ________ dendrites and ___________ axons.
sensory neurons have long dendrites and short axons.
relay neurons
-connect the sensory neurons to the motor neurons or other relay neurons.
-allow sensory and motor neurons to communicate with each other
-lie wholly within brain and spinal cord
-they have short dendrites and short axons.
motor neuron
-connect the CNS to effectors such as muscles and glands
-located in CNS and project their axons outside SNS to directly or indirectly control muscles
-form synapses with muscles and control their contractions
-when stimulated motors neurons release neurotransmitters that bind to receptors on the muscle and trigger a response which leads to muscle movement. when the axon of a motor neuron fires the muscles with which it formed synapses contracts.muscle relaxation caused by inhibitions of motor neuron.
-short dendrites and long axons
-when _____________ motors neurons release ______________ that bind to receptors on the muscle and trigger a response which leads to muscle movement. when the axon of a motor neuron fires the muscles with which it formed synapses _________.muscle relaxation caused by ______ of motor neuron.
-when stimulated motors neurons release neurotransmitters that bind to receptors on the muscle and trigger a response which leads to muscle movement. when the axon of a motor neuron fires the muscles with which it formed synapses contracts.muscle relaxation caused by inhibitions of motor neuron.
relay neurons have ____ dendrites and _________ axons.
relay neurons have short dendrites and short axons.
motor neurons have _____ dendrites and ________ axons.
motor neurons have short dendrites and long axons.
Neurons typically consist of a cell body,
dendrites and an ______.________one end of the neuron receive signals from other neurons or from sensory receptors. Dendrites are connected to the cell body, the control centre of the neuron. From the cell body, the impulse is carried along the axon where it terminates at
the axon ____. In many nerves, including
those in the brain and spinal cord, there is an insulating layer that forms around the axon the _______ sheath. This allows nerve impulses to transmit more_________along the axon. If the ________
sheath is damaged, impulses slow down.
Neurons typically consist of a cell body,
dendrites and an axon. Dendrites at one end of
the neuron receive signals from other neurons
or from sensory receptors. Dendrites are
connected to the cell body, the control centre
of the neuron. From the cell body, the impulse
is carried along the axon where it terminates at
the axon terminal. In many nerves, including
those in the brain and spinal cord, there is an
insulating layer that forms around the axon
the myelin sheath. This allows nerve impulses to transmit more rapidly along the axon. If the myelin
sheath is damaged, impulses slow down.
Electric Transmission- When a neuron is in its resting state, the inside of the cell is ________ charged compared to the
outside. When a neuron is activated by a stimulus, the inside becomes _______ charged for a split
second causing an ________ potential to occur. This creates an electrical impulse that travels down the
axon towards the end of the neuron.
Electric Transmission
When a neuron is in its resting state, the inside of the cell is negatively charged compared to the
outside. When a neuron is activated by a stimulus, the inside becomes positively charged for a split
second causing an action potential to occur. This creates an electrical impulse that travels down the
axon towards the end of the neuron.
synaptic transmission
1) when the action potential has arrive at the terminal button at the end of the axon , it needs to be transferred to another neuron or tissue. to achive this it must cross the synapse between the presynaptic neurpn and post synaptic neuron.
2) the end of the axon there are a number of sacs called synaptic vesicles, which contain neurotransmitters
3)when the action potential reaches the synaptic vesicles it cause them to release their neurotransmitters, which diffuses across the synapse to the post synaptic neuron, where it binds to the specialised receptors.
4) once the neurotransmitter crosses the gap and has been taken up by the post-synaptic receptor site the chemical message in converted back into an electical impulse
Neurons can only transmit information in one direction at a synapse. This is because the vesicles
containing the neurotransmitter are only present and released from the presynaptic membrane.
Likewise the receptors for the neurotransmitter to bind to (fit into like a key into a lock) are only
present on the post synaptic membrane. Finally, as the neurotransmitters travel across the synaptic
gap by the process of diffusion they therefore go from high concentration to low, so can only travel
from pre to post synaptic membranes.
Neurons can only transmit information in one direction at a synapse. This is because the vesicles
containing the neurotransmitter are only present and released from the presynaptic membrane.
Likewise the receptors for the neurotransmitter to bind to (fit into like a key into a lock) are only
present on the post synaptic membrane. Finally, as the neurotransmitters travel across the synaptic
gap by the process of diffusion they therefore go from high concentration to low, so can only travel
from pre to post synaptic membranes.
