Autacoid Factors Quiz and Flashcards for Function Study

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Questions and Answers

What is the characteristic of autacoids in terms of their production and action?

Produced systemically and act locally

Produced locally, act locally and metabolized locally (correct)

Produced locally and act on distant tissues

Produced locally and act systemically

What is the effect of histamine on the heart?

Increases IC Ca2+ influx into cardiac cells (correct)

Has no effect on the heart

Decreases cardiac contraction

Decreases IC Ca2+ influx into cardiac cells

What is the effect of histamine on vascular smooth muscle?

Increased blood pressure

Vasoconstriction

No effect

Vasodilation (correct)

What is the process by which L-histidine is converted to histamine?

Decarboxylation Signup and view all the answers

What is the effect of histamine on the smooth muscles of the bronchi?

Contraction Signup and view all the answers

What is the effect of histamine on gastric acid secretion?

Increased gastric acid secretion Signup and view all the answers

What is the receptor subtype involved in the brain and peripheral nerves?

H3 Signup and view all the answers

What is the enzyme responsible for the degradation of histamine in the liver?

Diamine oxidase Signup and view all the answers

What is the function of histamine in the CNS?

Neurotransmitter Signup and view all the answers

What is the clinical manifestation of histamine action on lungs?

Asthma-like symptoms Signup and view all the answers

What is the effect of histamine on CNS?

Wakefulness Signup and view all the answers

What is the effect of histamine on the GIT?

Regulation of acid secretion Signup and view all the answers

What is the mechanism of histamine-induced edema?

All of the above Signup and view all the answers

What is the effect of histamine on the arterioles and post-capillary venule bed?

Dilation Signup and view all the answers

What is the effect of histamine on the uterus?

Contraction Signup and view all the answers

What is the receptor subtype involved in allergic responses?

H4 Signup and view all the answers

What is the mechanism of anaphylaxis?

IgE-mediated mast cell degranulation Signup and view all the answers

What is the effect of histamine on heart?

Increased inotropism and chronotropism Signup and view all the answers

What is the result of the activation of the immune system?

Sensitization of mast cells Signup and view all the answers

What is the effect of receptor crosslinking on mast cells?

Degranulation Signup and view all the answers

What is the result of systemic vasodilation?

Decrease in blood pressure Signup and view all the answers

What is the effect of histamine on airways?

Severe bronchoconstriction Signup and view all the answers

What is the mechanism of action of H1 antagonists?

Competitive antagonists of H1 receptors Signup and view all the answers

What is the effect of administering antihistamines?

Inhibition of histamine action Signup and view all the answers

What is the mechanism of action of Cromolyn and Nedocromil?

Prevention of mast cell degranulation Signup and view all the answers

What is the effect of functional antagonists of histamine?

Inhibition of histamine action Signup and view all the answers

What is the most frequently used approach to inhibit histamine action?

Administering antihistamines Signup and view all the answers

What is the effect of ACE inhibition on bradykinin levels?

Increased levels Signup and view all the answers

What is the role of the B1 receptor?

Chronic pain and inflammation Signup and view all the answers

What is the primary ligand for the B2 and B1 receptors?

Bradykinin Signup and view all the answers

What is the effect of bradykinin on bronchoconstriction receptors?

Stimulation Signup and view all the answers

Which receptor is constitutively expressed?

B2 receptor Signup and view all the answers

What is the effect of Gi on adenylate cyclase?

Inhibition Signup and view all the answers

What is the effect of Gq on phospholipase C?

Stimulation Signup and view all the answers

What is the receptor family to which B1 and B2 receptors belong?

G protein-coupled receptor (GPCR) family Signup and view all the answers

What is the recent discovery about the kinin B1 receptor?

Recruits neutrophil Signup and view all the answers

What is the function of platelet-activating factor acetylhydrolase in the body?

To degrade PAF Signup and view all the answers

Which cells are primarily involved in producing PAF?

Platelets, endothelial cells, neutrophils, monocytes, and macrophages Signup and view all the answers

What is the effect of PAF on vascular permeability?

It increases vascular permeability Signup and view all the answers

What is the role of PAF in inflammation?

It is a potent mediator of inflammation Signup and view all the answers

What is the effect of PAF on platelets?

It induces platelet aggregation and degranulation Signup and view all the answers

What is the function of CV-3988?

It is a PAF antagonist Signup and view all the answers

Which enzyme is involved in the metabolism of SM-12502?

CYP2A6 Signup and view all the answers

What is the clinical significance of high PAF levels?

They are associated with a variety of medical conditions Signup and view all the answers

What is rupatadine?

An antihistamine and PAF antagonist Signup and view all the answers

Study Notes

Autacoids: Production and Action

Autacoids are biologically active substances produced by local tissues in response to various stimuli.
They have diverse actions, typically local rather than systemic, affecting nearby cells.

Effects of Histamine on the Heart

Histamine increases heart rate (positive chronotropic effect).
It can also enhance myocardial contractility (positive inotropic effect).

Histamine and Vascular Smooth Muscle

Histamine causes vasodilation of vascular smooth muscle, leading to decreased blood pressure.
It effects are more pronounced in the arterioles than in larger vessels.

Conversion of L-Histidine to Histamine

L-Histidine is decarboxylated by histidine decarboxylase to form histamine.

Effects of Histamine on Bronchial Smooth Muscles

Histamine induces bronchoconstriction, narrowing the airways and making breathing difficult.

Histamine and Gastric Acid Secretion

Histamine stimulates gastric acid secretion through H2 receptors on gastric parietal cells.

Receptor Subtypes

H1 receptors are involved in allergic responses and are located in various tissues, including the CNS.
H2 receptors are predominant in the stomach for gastric acid regulation.

Histamine Degradation in the Liver

Histamine is metabolized by the enzyme histamine N-methyltransferase in the liver.

Functions of Histamine in the CNS

Histamine acts as a neurotransmitter modulating wakefulness, appetite, and learning.

Clinical Manifestations of Histamine Action on Lungs

Histamine leads to symptoms of asthma, such as wheezing and shortness of breath due to bronchoconstriction.

Central Nervous System Effects of Histamine

It plays roles in arousal and cognitive functions, influencing sleep-wake cycles and emotional responses.

Histamine's Effects on the Gastrointestinal Tract

Stimulates gastric acid secretion and increases gastrointestinal motility.

Mechanism of Histamine-Induced Edema

Histamine increases vascular permeability, allowing fluids and proteins to leak into tissues, causing swelling.

Effects on Arterioles and Post-Capillary Venules

Histamine dilates arterioles and increases permeability of post-capillary venules, contributing to inflammation and edema.

Impact of Histamine on the Uterus

Histamine can stimulate uterine contractions, influencing reproductive processes.

Receptor Subtype Involved in Allergic Responses

H1 receptor is primarily responsible for mediating allergic reactions and symptoms.

Mechanism of Anaphylaxis

Anaphylaxis involves rapid histamine release from mast cells and basophils, resulting in severe allergic reactions.

Systemic Vasodilation

Activation of histamine receptors leads to systemic vasodilation, lowering blood pressure.

Effects of Histamine on Airways

Causes narrowing and obstruction of airways due to bronchial smooth muscle contraction.

Mechanism of Action of H1 Antagonists

H1 antagonists block the action of histamine on H1 receptors, reducing allergy symptoms.

Antihistamines Administration Effects

Administering antihistamines alleviates allergy symptoms by blocking H1 receptor activation.

Mechanism of Cromolyn and Nedocromil

These agents stabilize mast cells and prevent the release of histamine, reducing allergic responses.

Functional Antagonists of Histamine

These substances inhibit the effects of histamine indirectly, rather than blocking its receptors.

Most Common Approach to Inhibit Histamine Action

H1 receptor antagonists are frequently used to treat allergic reactions and insomnia.

ACE Inhibition and Bradykinin

ACE inhibitors increase bradykinin levels, which can result in vasodilation and improved blood flow.

Role of B1 Receptor

The B1 receptor is involved in pain, inflammation, and vasodilation processes, especially during tissue injury.

Primary Ligand for B2 and B1 Receptors

Bradykinin serves as the primary ligand for both B2 and B1 receptors in the kinin system.

Effects of Bradykinin on Bronchoconstriction Receptors

It induces bronchoconstriction by acting on specific receptors in the airways.

Constitutively Expressed Receptor

B2 receptors are continuously expressed and mediate most of bradykinin’s effects.

Effect of Gi on Adenylate Cyclase

Gi inhibits adenylate cyclase activity, leading to decreased levels of cyclic AMP (cAMP).

Effect of Gq on Phospholipase C

Gq activates phospholipase C, resulting in increased intracellular calcium and protein kinase C activation.

Receptor Family of B1 and B2 Receptors

B1 and B2 receptors belong to the G protein-coupled receptor (GPCR) family.

Recent Discovery about Kinin B1 Receptor

The B1 receptor shows increased expression during inflammation, highlighting its role in pathological processes.

Function of Platelet-Activating Factor Acetylhydrolase

This enzyme inactivates platelet-activating factor (PAF), regulating its activity in inflammatory processes.

Cells Involved in Producing PAF

Primarily produced by platelets, macrophages, and neutrophils during inflammatory responses.

Effects of PAF on Vascular Permeability

PAF increases vascular permeability, contributing to inflammation and edema.

Role of PAF in Inflammation

PAF plays a crucial role in mediating inflammatory responses, enhancing leukocyte recruitment.

Effects of PAF on Platelets

PAF activates platelets and enhances their aggregation during clot formation.

Function of CV-3988

CV-3988 acts as a selective B2 receptor antagonist, blocking bradykinin-mediated effects.

Enzyme Involved in Metabolism of SM-12502

Metabolized by aldehyde dehydrogenase, impacting its pharmacological activity.

Clinical Significance of High PAF Levels

Elevated PAF levels are linked to various inflammatory disorders, including asthma and sepsis.

Rupatadine

Rupatadine is an antihistamine with additional anti-inflammatory properties used to treat allergic conditions.

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Description

Learn about autacoids, locally produced modulating factors that influence cell and tissue function. Understand their production, action, and metabolism, as well as their autocrine and paracrine effects. Test your knowledge of these important biological compounds!

Autacoids: Definition and Function

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