Introduction And Overview Neurohumoral Flashcards
What experiment did Otto Loewi perform to demonstrate chemical neurotransmission?
A: He stimulated the Vagus nerve of a perfused frog heart and allowed the perfusion fluid to come in contact with a second frog heart, which then exhibited the same effect as the first heart.
What were the substances called that Otto Loewi discovered through his experiments?
Vagusstuff (Acetylcholine) and Acceleranstuff
What did Langley postulate about effector cells in 1905?
He postulated that effector cells have excitatory and inhibitory receptive substances, and the response to Adrenaline depends on which type of receptive substance was present.
What did Dixon show in 1907 regarding Vagal stimulation?
He showed that there are close similarities between the effects of muscarine and Vagal nerve stimulation, suggesting that Vagus nerve stimulation releases a muscarine-like substance.
Who introduced the term “Parasympathomimetic” and what does it describe?
Dale introduced the term in 1914 to describe the effect of Acetylcholine (ACh) that mimics parasympathetic nerve stimulation
What did Reid Hunt describe about Acetylcholine (ACh)?
He described the action of ACh and Choline esters.
What did Dale demonstrate about Acetylcholine in 1914?
He demonstrated a similarity between the action of Acetylcholine and responses to parasympathetic nerve stimulation
What did Von Euler identify in 1946
Von Euler identified “Sympathin” as Noradrenaline.
What did Uvidile establish in 1921 regarding Adrenaline?
He established the similarity between the action of Adrenaline and sympathetic stimulation.
What are the effects of drugs on chemical neurotransmission?
Drugs can produce effects by inhibiting or potentiating various steps of neurotransmission.
What is the role of pre-ganglionic synapses in Neurohumoral Transmission?
They are the sites where neurotransmitters are released to transmit signals between neurons in both sympathetic and parasympathetic ganglia.
How did Langley and others contribute to the understanding of neurotransmission
They provided early evidence and theories suggesting that chemical substances released from nerves could produce effects similar to direct nerve stimulation.
What process occurs when a neurotransmitter binds to a receptor on the effector cell?
It results in either the opening of an ion channel or the release of a second messenger, leading to signal transduction.
What is the role of enzymes in terminating neurotransmitter action?
Enzymes break down neurotransmitters to terminate their action, ensuring the signal does not persist indefinitely.
What was the significance of the Accelerator nerve stimulation in Otto Loewi’s experiment
demonstrated that the substance released caused an increased rate in both the donor and recipient hearts.
What is the importance of recovering a neurotransmitter compound from an innervated structure during stimulation?
It provides evidence that the compound is actively involved in neurotransmission during nerve stimulation.
How are responses to nerve stimulation and neurotransmitter administration modified
They are modified in the same way by various drugs, which is a criterion for identifying a substance as a neurotransmitter
What is the latent period in neurotransmission?
It is the time between nerve stimulation and the response of the effector, which should not be reducible.
What evidence did Otto Loewi and Navratil provide in 1926?
They presented evidence that the “Vagusstuff” was actually Acetylcholine (ACh).
What is the significance of demonstrating the presence of a neurotransmitter in the perfusate during stimulation?
It confirms the release of the neurotransmitter during active neurotransmission.
What did the first experimental evidence of chemical transmission of nerve impulses show?
It showed that nerve impulses are transmitted by the release of certain chemicals, rather than purely electrical impulses.
What happens during the storage step in chemical neurotransmission?
The transmitter substance is stored in vesicles within the neuron until it is released by a nerve action potential.
How is the recovery of the effector cell membrane achieved after neurotransmission
It involves the removal of the neurotransmitter and restoration of the membrane to its resting st
What is Neurohumoral Transmission?
Neurohumoral Transmission is a chemical process involved in the transmission of nerve impulses at synapses between neurons and at effector organs, carried out by the release of neurotransmitters.
