Classes of Hormones Flashcards

Study Notes

Classes of Hormones

Four primary classes: proteins and peptides, steroids, monoamines, and lipid-based hormones (prostaglandins).

Steroid Hormone Synthesis

Main sources: adrenal glands, gonads, and brain.
All steroid hormones feature a structure of three six-carbon rings and one five-carbon ring, consistent across all vertebrates.
Variations exist among steroid hormones in the number and types of atoms attached to their rings.
Steroids are derived from cholesterol, synthesized from acetate in the liver.

Steroid Hormones

Fat soluble, allowing easy movement through cell membranes.
Not water soluble; require carrier proteins for blood transport to target tissues.
Receptors can be embedded in cell membranes or found in the cytosol/nucleus.
Effects are slow to manifest but tend to last longer.

Non-genomic Effects of Steroid Hormones

Steroids can induce rapid effects on neurons without altering gene expression.
These effects modify neuronal excitability and involve membrane-bound receptors.

Receptor Isoforms

Slight structural variations exist among hormone receptors, resulting in different functional properties.

Protein and Peptide Hormones

Composed of amino acids, categorized as small peptides or larger proteins/polypeptides.
Include neurohormones from the hypothalamus, tropic hormones from the anterior pituitary, and various hormones from the posterior pituitary, parathyroid, gastrointestinal tract, and pancreas.

Protein and Peptide Hormones (continued)

Stored within vesicles in endocrine cells, released via exocytosis into circulation.
Soluble in blood, eliminating the need for carrier proteins.
Act quickly, with effects observable in seconds to minutes.

Protein and Peptide Hormone Receptors

Located in the cell membrane, characterized by three domains: extracellular (hormone binding), transmembrane, and cytoplasmic.
Utilize intracellular second messengers like cyclic AMP (cAMP) for signaling.

Monoamines

Derived from single amino acids, classified into two types:
- Catecholamines: include epinephrine and norepinephrine produced in the adrenal medulla.
- Indole amines: include melatonin produced in the pineal gland.
Thyroid hormones are also considered monoamines, as they are derived from the amino acid tyrosine.

Description

Test your knowledge on the various classes of hormones, including proteins, peptides, steroids, monoamines, and lipid-based hormones. This flashcard set also covers steroid hormone synthesis and its sources. Perfect for students studying biology or endocrinology.