18 Questions
What is the function of the presynaptic terminal?
Converts electrical signal into a chemical signal
Which neurotransmitter is known to be the most abundant in the nervous system?
Glutamate
What type of channels are controlled by a neurotransmitter?
Ligand-gated channels
In Sherrington's concept of the synapse, what does an input result in?
Excitation or inhibition
What happens when a neurotransmitter binds to an ionotropic receptor?
The receptor opens a central channel for ions to pass through
Which neurotransmitter opens chloride gates, letting negatively charged ions enter faster?
Glycine
What type of chemicals are released by postsynaptic neurons to inhibit further release of transmitter?
Nitric Oxide, anandamide, and 2-AG
What is the primary purpose of electrical synapses?
To allow for faster transmission of signals between neurons
Which of the following is an example of an electrical synapse?
The cells that control your rhythmic breathing
What is the purpose of the inhibitory chemicals released by postsynaptic neurons?
To suppress the release of transmitter from the presynaptic terminal
How do electrical synapses differ from chemical synapses?
Electrical synapses allow for faster transmission of signals, while chemical synapses are slower
What is the purpose of the illustration summarizing the effects of drugs on dopamine synapses?
To highlight the various ways in which drugs can affect the synthesis, release, action, reuptake, and breakdown of dopamine
What is the primary function of inhibitory messages at synapses?
To prevent excessive excitation of the postsynaptic neuron
Which statement accurately describes the concept of spontaneous firing rate?
It is the rate at which a neuron fires action potentials in the absence of any synaptic input
In the example provided, if a neuron's spontaneous firing rate is 10 action potentials per second, what would be the effect of a stream of EPSPs?
The firing rate would increase to 15 or more action potentials per second
Which statement accurately describes the process of chemical transmission at synapses?
It relies on the release of chemical neurotransmitters from the presynaptic neuron
In the example provided, if cell X has a threshold of +2, how many excitatory inputs from cells A and B are required for cell X to respond?
Inputs from both cell A and cell B are required
What was the significance of Loewi's experiment involving the stimulation of the vagus nerve in a frog?
It demonstrated the existence of chemical transmission at synapses
Study Notes
Synaptic Transmission
- Delay occurs in transmission through a synapse
- Excitatory messages can be regulated by inhibitory neurons
- EPSP (excitatory postsynaptic potential) is a burst of excitation in a neuron
- Inhibitory messages can regulate the timing of activity
Neuron Stimulation
- Axons from multiple cells can stimulate a single cell
- Threshold of stimulation determines response
- +1 unit stimulation can lead to response, while +2 units may be required for stimulation
Spontaneous Firing Rate
- Neurons have a spontaneous firing rate without synaptic input
- EPSPs increase firing rate, while IPSPs decrease it
Chemical Transmission
- Most synapses rely on chemical processes
- Chemical transmission involves release and reception of chemicals
- Nitric oxide and anandamide are examples of chemicals involved in transmission
Electrical Synapses
- Gap junctions allow direct contact between neuron membranes
- Electrical transmission is faster than chemical transmission
- Electrical synapses are used in cases requiring exact synchrony between cells
Hormones
- Hormones are chemicals secreted by cells to influence other cells
- Hormones are conveyed by the blood stream
Presynaptic and Postsynaptic Terminals
- Presynaptic terminal is where electrical signal is converted to chemical signal
- Postsynaptic terminal membrane contains specialized receptors
- Calcium entry into the terminal leads to exocytosis
Activating Receptors
- Ionotropic effects are brief on or off effects
- Ionotropic synapse has localized effects on one point on the membrane
- Transmitter-gated or ligand-gated channels are controlled by neurotransmitters
Neurotransmitters
- Glutamate is the most abundant excitatory neurotransmitter in the nervous system
- GABA is an inhibitory neurotransmitter that opens chloride gates
- Glycine is an inhibitory neurotransmitter found mostly in the spinal cord
Learn about the process of neurotransmitter release at the presynaptic terminal and its effects on the postsynaptic cell. Understand the conversion from electrical to chemical signals and the role of specialized receptors in synaptic transmission.
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