C2.2 Neural Signalling Flashcards
What is the function of the sodium-potassium pump?
Restores the resting membrane potential by exchanging three Na+ ions out for two K+ ions in
* transmembrane protein
* requires energy
* goes through conformational change (ATP donates phosphate)
The sodium-potassium pump uses energy to maintain ion concentration gradients.
What ensures that action potentials can only go in one direction?
- The refractory period, during which sodium channels are closed => neuron is unresponsive
- receoptors ONLY on postsynaptic neuron
This prevents backflow of action potentials.
WHat triggers release of neurotransmitter?
- Voltage-gated calcium channels open
- allowing calcium ions to flow into the cell
- cause synaptic vesicle formation (NT isnide)
- fuses with membrane => exocyosis of NT
(later is dgeraded or reabsorbed!)
This triggers the release of neurotransmitters.
Define saltatory conduction.
impulse jumps from node to node of ranvier in myelinated cells
This is facilitated by the myelin sheath.
What is the resting membrane potential of a neuron?
-70mV
* cause of K+ leakage & Na/K pump
It indicates the polarized state of the neuron when not conducting an impulse.
Fill in the blank: Action potentials are ______.
all or nothing
This means that once the threshold is reached, the action potential will occur with the same magnitude.
What is the role of excitatory postsynaptic potentials (EPSPs)?
They make an action potential more likely by causing depolarization
EPSPs result from the opening of ion channels allowing Na+ influx.
What are the two types of fibers involved in transmitting impulses related to pain?
Afferent nerve fibers and efferent fibers
Afferent fibers transmit impulses toward the brain, while efferent fibers transmit impulses from the brain.
What affcets speed of nerve impulse transmission
- myelination = faster in myelinated
- diameter of neuron => faster in large diameter
- temperature = faster in high temp
Myelination increases the speed of impulses by saltatory conduction.
What occurs during repolarization of a neuron?
K+ ions rush out of the cell, => becomes more negative inside
This happens after the peak potential is reached.
What is the function of neurotransmitters at synapses?
They transmit signals across the synapse to the postsynaptic neuron
This occurs via exocytosis into the synaptic cleft.
ACtion potential graph numbers
peak = +40mV
treshold = -50/55 mV
failed intiiations = -70-(-50)
resting potential = -70 mv
hyperpolarization = below -70
This is the maximum membrane potential reached during depolarization.
What are the types of receptors found in the skin for pain perception?
Thermoreceptors
Meissner’s corpuscles= light vibrations & touch
nociceptors = pain
Pacinian corpuscles= skin stretch and pressure
Ruffini endings & free nerve endings
Each receptor type is responsible for different sensory information.
What is the difference between presynaptic and postsynaptic neurons?
Presynaptic neuron carries impulse towards a synapse
postsynaptic neuron carries impulse away from a synapse
Presynaptic neurons are the ‘sender’ and postsynaptic neurons are the ‘receiver’.
What is the role of calcium ions in synaptic transmission?
They cause exocytosis, releasing neurotransmitters
This process is essential for communication between neurons.
neonicotinoid ?
- blcoks synaptic transmission by binding to acetylcholine receptor in CNS of insects = die
- Reduction in honeybee and bird populations
does not work on mammals as it bind strong in insects onlx
This is due to the loss of insects as a food source and has led to restrictions in some countries.
What is the function of Schwann cells?
They form the myelin sheath around axons, providing insulation
This insulation is crucial for increasing the speed of nerve impulses.
What is a neuromuscular junction?
A specialized synapse between a motor neuron and a muscle fibre.
What initiates muscle contraction at the neuromuscular junction?
Binding of acetylcholine to receptors on the plasma membrane of the muscle fibre, leading to depolarization.
What are the two types of postsynaptic potentials?
- EPSP (excitatory postsynaptic potentials)
- IPSP (inhibitory postsynaptic potentials)
What is summation?
Additive effect of inhibitory and exciutatory stimuli received from multiple postsynaptic neurons
Where is conscious awareness primarily associated?
The cerebral cortex of the brain. = cerebrum
What is the resting potential?
The voltage across the membrane when a neuron is not firing.
What are the three types of neurons?
- Sensory neurons
- Motor neurons
- Relay neurons
