Hormone Synthesis and Structure Flashcards
What are the basic components of the endocrine system?
3 basic components:
* Endocrine gland/cell
* Hormone
* Target organ
Endocrine glands/cells secrete hormones, hormones are chemical products released upon stimulation, and target organs express hormone-specific receptors to show biological response.
Define a hormone.
Physiological organic substance produced by specialized cells and released into blood or lymph for transport to target tissues.
What are the classical characteristics of hormones?
- Synthesized by endocrine cells
- Secreted into circulation
- Interact with receptors
- Have specific effects on target cells.
How are hormones classified?
- Type of signaling
- Chemical structure
- Solubility.
What is the difference between water-soluble and fat-soluble hormones?
Water-soluble hormones bind to surface receptors, while fat-soluble hormones can diffuse through cell membranes.
What is endocrine signaling?
When hormones enter the bloodstream and bind to receptors in distant target cells.
Provide an example of endocrine signaling.
Insulin produced by beta cells in the pancreas travels through the blood to target tissues.
What is paracrine signaling?
When hormones bind to nearby cells in the same organ or tissue.
Provide an example of paracrine signaling.
Testosterone from Leydig cells stimulates spermatogenesis in adjacent seminiferous tubules.
What is autocrine signaling?
When a hormone acts on the same cell that released it.
Provide an example of autocrine signaling.
The endometrium responds to oxytocin to produce prostaglandins.
What is intracrine signaling?
When a hormone is synthesized and acts within the same cell.
Provide an example of intracrine signaling.
Precursor sex steroid hormones are converted to active androgens/estrogens within the same cell.
What is neuroendocrine signaling?
When a chemical produced by a neuron is released into the bloodstream to act on another cell type.
What are pheromones?
Chemicals released externally to communicate with another organism.
What are the types of pheromones?
- Primer
- Signaler
- Modulator
- Releaser.
What is the role of primer pheromones?
Cause a shift in the endocrine system of the receiving animal.
What is the role of signaler pheromones?
Relay information, such as olfactory recognition.
What are the four structural groups of hormones?
- Peptides and proteins
- Amino acid derivatives
- Steroids
- Eicosanoids.
Define peptide hormones.
Hormones that range from 3 to 200 amino acids and are synthesized as preprohormones.
What is the processing pathway for peptide hormones?
- Preprohormone
- Prohormone
- Active hormone.
What are amino acid-derived hormones?
Hormones derived from amino acids, primarily tyrosine.
List examples of amino acid-derived hormones.
- Norepinephrine
- Epinephrine
- Thyroid hormones
- Melatonin.
What are steroid hormones characterized by?
Cholesterol-derived, lipophilic, bind to carrier proteins, and have longer half-lives.
