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Introduction And Overview Neurohumoral Flashcards

1
Q

What experiment did Otto Loewi perform to demonstrate chemical neurotransmission?

A

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.

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2
Q

What were the substances called that Otto Loewi discovered through his experiments?

A

Vagusstuff (Acetylcholine) and Acceleranstuff

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3
Q

What did Langley postulate about effector cells in 1905?

A

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.

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4
Q

What did Dixon show in 1907 regarding Vagal stimulation?

A

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.

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5
Q

Who introduced the term “Parasympathomimetic” and what does it describe?

A

Dale introduced the term in 1914 to describe the effect of Acetylcholine (ACh) that mimics parasympathetic nerve stimulation

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6
Q

What did Reid Hunt describe about Acetylcholine (ACh)?

A

He described the action of ACh and Choline esters.

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7
Q

What did Dale demonstrate about Acetylcholine in 1914?

A

He demonstrated a similarity between the action of Acetylcholine and responses to parasympathetic nerve stimulation

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8
Q

What did Von Euler identify in 1946

A

Von Euler identified “Sympathin” as Noradrenaline.

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9
Q

What did Uvidile establish in 1921 regarding Adrenaline?

A

He established the similarity between the action of Adrenaline and sympathetic stimulation.

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10
Q

What are the effects of drugs on chemical neurotransmission?

A

Drugs can produce effects by inhibiting or potentiating various steps of neurotransmission.

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11
Q

What is the role of pre-ganglionic synapses in Neurohumoral Transmission?

A

They are the sites where neurotransmitters are released to transmit signals between neurons in both sympathetic and parasympathetic ganglia.

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12
Q

How did Langley and others contribute to the understanding of neurotransmission

A

They provided early evidence and theories suggesting that chemical substances released from nerves could produce effects similar to direct nerve stimulation.

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13
Q

What process occurs when a neurotransmitter binds to a receptor on the effector cell?

A

It results in either the opening of an ion channel or the release of a second messenger, leading to signal transduction.

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14
Q

What is the role of enzymes in terminating neurotransmitter action?

A

Enzymes break down neurotransmitters to terminate their action, ensuring the signal does not persist indefinitely.

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15
Q

What was the significance of the Accelerator nerve stimulation in Otto Loewi’s experiment

A

demonstrated that the substance released caused an increased rate in both the donor and recipient hearts.

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16
Q

What is the importance of recovering a neurotransmitter compound from an innervated structure during stimulation?

A

It provides evidence that the compound is actively involved in neurotransmission during nerve stimulation.

17
Q

How are responses to nerve stimulation and neurotransmitter administration modified

A

They are modified in the same way by various drugs, which is a criterion for identifying a substance as a neurotransmitter

18
Q

What is the latent period in neurotransmission?

A

It is the time between nerve stimulation and the response of the effector, which should not be reducible.

19
Q

What evidence did Otto Loewi and Navratil provide in 1926?

A

They presented evidence that the “Vagusstuff” was actually Acetylcholine (ACh).

20
Q

What is the significance of demonstrating the presence of a neurotransmitter in the perfusate during stimulation?

A

It confirms the release of the neurotransmitter during active neurotransmission.

21
Q

What did the first experimental evidence of chemical transmission of nerve impulses show?

A

It showed that nerve impulses are transmitted by the release of certain chemicals, rather than purely electrical impulses.

22
Q

What happens during the storage step in chemical neurotransmission?

A

The transmitter substance is stored in vesicles within the neuron until it is released by a nerve action potential.

23
Q

How is the recovery of the effector cell membrane achieved after neurotransmission

A

It involves the removal of the neurotransmitter and restoration of the membrane to its resting st

24
Q

What is Neurohumoral Transmission?

A

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.

25
Q

Name the neurotransmitter used at parasympathetic post-ganglionic neuro-effector

A

Acetylcholine (ACh).

26
Q

What neurotransmitter is released by sympathetic post-ganglionic neurons at neuro-effector junctions?

A

Noradrenaline (NA).

27
Q

Who obtained the first evidence for Neurohumoral Transmission and when

A

Lewandosky in 1898 and Langley in 1901.

28
Q

What term did Dale introduce in 1914 to describe the effect of Acetylcholine (ACh)?

A

Parasympathomimetic

29
Q

What are the five major sites where Neurohumoral Transmission occurs in the Peripheral Nervous System (PNS

A
  1. Pre-ganglionic synapses at both sympathetic and parasympathetic ganglia.
  2. Parasympathetic post-ganglionic neuro-effector junction with Acetylcholine (ACh) as the neurotransmitter.
  3. All somatic motor-end plates on skeletal muscles with Acetylcholine (ACh) as the neurotransmitter.
  4. Sympathetic post-ganglionic neuro-effector junction with Noradrenaline (NA) as the neurotransmitter.
  5. Sympathetic cholinergic neurons innervating the sweat glands and some blood vessels with ACh as the neurotransmitter.
30
Q

What is the neurotransmitter used by sympathetic neurons that supply the Chromaffin cells of the adrenal medulla

A

Acetylcholine (ACh).

31
Q

Who suggested that sympathetic nerve impulses release small amounts of Adrenaline-like substances, and in what year

A

Elliot, 1905

32
Q

What did Otto Loewi’s classical experiment in 1921 demonstrate?

A

A: It demonstrated the chemical transmission of nerve impulses by showing that stimulating the Vagus nerve of a perfused frog heart caused a similar effect in a second frog heart without direct nerve stimulation

33
Q

Which researchers identified “Sympathin” as Noradrenaline?

A

Berger & Dale, Beck et al., and Von Euler

34
Q

What is “Parasympathin” as referred to in Otto Loewi’s experiment?

A

It is the term Loewi used to describe the substance released from the Vagus nerve, which was later identified as Acetylcholine (ACh).

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