Endocrinology Overview

Flashcards covering the basics of endocrinology, including hormone functions, classifications, mechanisms, and reflex pathways.

What is endocrinology?

The study of hormones, their synthesis, secretion, transport, and mode of action.

What is the difference between endocrine and exocrine secretion?

Endocrine secretion is into the bloodstream (ductless), whereas exocrine secretion is into ducts.

What are the major types of hormones?

Protein hormones and steroid hormones.

How do hormones primarily exert their effects?

Through receptor-mediated responses at very low concentrations.

What is negative feedback in hormone regulation?

A major control system where the output of a process inhibits its own production.

What discovery did Bayliss and Starling make in 1902?

They discovered secretin, demonstrating that chemical messengers (hormones) convey signals between organs.

What defines a hormone?

A biologically-active compound that acts on target tissues distant from its site of synthesis/storage.

What is the role of receptors in hormone action?

Hormones can only act on cells that have specific receptors for them.

What are ectohormones?

Hormones secreted into the external environment, such as pheromones.

What is the significance of receptor affinity?

Cells with high-affinity receptors respond more strongly to the same concentration of hormone.

What happens during downregulation of hormone receptors?

High levels of a hormone lead to a reduction in the number of receptors and a diminished cell response.

What are the differences between steroid and protein hormones?

Steroid hormones are lipid-soluble, synthesized from cholesterol and have receptors in the nucleus; protein hormones are water-soluble, composed of amino acids, and have receptors in the plasma membrane.

How are steroid hormones transported in the body?

They are usually transported by carrier proteins to enhance their solubility in blood.

What effect does hyperthyroidism have on hormone receptors?

It can increase adrenaline receptors, leading to symptoms like tachycardia.

What is the importance of hormone half-life?

It indicates the duration of hormone activity and influences how the body responds to changes.

What triggers the activation of steroid hormones?

Binding to cytosolic receptors, allowing them to enter the nucleus and affect gene activity.

Define autocrines and paracrines in hormonal signaling.

Autocrines act on the same cell that produces them, and paracrines influence nearby cells.

What process do protein hormones undergo before they are secreted?

They are synthesized, packaged, stored, and secreted from the cell.

What is the example of a simple reflex control in hormone regulation?

Control of Parathyroid Hormone release.

What are the components of a reflex pathway in endocrine regulation?

Stimulus, sensor, integrating center, output signal, target, and response.