Amino acid-derived hormones

Definition

Amino acid-derived hormones are a class of hormones that are synthesized from single amino acids, primarily tyrosine and tryptophan. These hormones play vital roles in various physiological processes, including growth, metabolism, and stress response, and they function as signaling molecules that facilitate communication between different cells and organs in the body.

5 Must Know Facts For Your Next Test

1. Amino acid-derived hormones include important examples such as thyroxine (T4) and epinephrine, which regulate metabolism and the body's response to stress, respectively.
2. These hormones are usually water-soluble and can be stored in secretory vesicles before being released into the bloodstream.
3. They act on target cells by binding to specific receptors on the cell surface, triggering a cascade of intracellular signaling pathways.
4. The synthesis of amino acid-derived hormones is tightly regulated by various factors, including feedback mechanisms that maintain hormonal balance in the body.
5. Examples of conditions related to abnormal levels of these hormones include hyperthyroidism due to excess thyroxine or pheochromocytoma leading to excess catecholamines.

Review Questions

• How do amino acid-derived hormones differ from peptide and steroid hormones in terms of their synthesis and action?
  • Amino acid-derived hormones are synthesized from single amino acids, specifically tyrosine and tryptophan, while peptide hormones are composed of short chains of amino acids and steroid hormones are derived from cholesterol. Unlike steroid hormones, which can directly influence gene expression by crossing cell membranes, amino acid-derived hormones typically act by binding to receptors on the cell surface, initiating intracellular signaling pathways. This distinction affects how these hormones interact with target cells and elicit physiological responses.
• Discuss the role of catecholamines as amino acid-derived hormones and their impact on the body's stress response.
  • Catecholamines such as epinephrine and norepinephrine are key amino acid-derived hormones produced by the adrenal medulla in response to stress. They play a crucial role in preparing the body for 'fight or flight' by increasing heart rate, elevating blood pressure, and mobilizing energy stores. This rapid hormonal response enables the body to react quickly to perceived threats or stressors, highlighting the importance of catecholamines in acute stress management and survival.
• Evaluate the physiological consequences of dysregulation in amino acid-derived hormone levels, using thyroid hormones as an example.
  • Dysregulation of amino acid-derived hormones can lead to significant physiological consequences. For instance, an overproduction of thyroid hormones like thyroxine (T4) results in hyperthyroidism, characterized by symptoms such as weight loss, increased heart rate, and anxiety due to heightened metabolic activity. Conversely, underproduction can lead to hypothyroidism, causing fatigue, weight gain, and depression. These disorders underscore how critical balanced levels of amino acid-derived hormones are for maintaining overall health and homeostasis in the body.

Related terms

Peptide hormones:

Hormones that consist of short chains of amino acids and are involved in a wide range of physiological functions, often requiring receptors on target cells for their action.

Steroid hormones: Hormones derived from cholesterol that can easily pass through cell membranes and typically act by directly influencing gene expression in target cells.

Catecholamines:

A group of amino acid-derived hormones, including epinephrine and norepinephrine, which are involved in the body's fight-or-flight response.