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--- neurotransmitters [2025/02/12 17:25] – created andrewtaustin
+++ neurotransmitters [2025/02/13 07:07] (current) – [Neurotransmitters as Hormones] andrewtaustin
@@ Line 104: / Line 104: @@
 ===== Notes =====
   * Neurotransmitter systems are highly interconnected, and imbalances often involve multiple chemicals.
-  * Conditions listed are simplified associations; actual etiology may involve receptors, reuptake, or genetic factors.
+  * Conditions listed are simplified associations; actual aetiology may involve receptors, reuptake, or genetic factors.
   * Always consult a healthcare professional for diagnosis and treatment.
+===== Neurotransmitters as Hormones =====
+Neurotransmitters are primarily known for their role in neuronal communication within the central nervous system (CNS). However, when they are released into the bloodstream or act outside the blood-brain barrier, they can function as hormones, influencing various physiological processes throughout the body.
+**Norepinephrine**:
+    * In the CNS, norepinephrine acts as a neurotransmitter, regulating attention and arousal.
+    * Outside the CNS, it is released by the adrenal medulla as a hormone, contributing to the "fight-or-flight" response by increasing heart rate, blood pressure, and blood flow to muscles.
+**Dopamine**:
+    * In the brain, dopamine regulates reward, motivation, and movement.
+    * In the periphery, dopamine acts as a hormone in the kidneys, where it helps regulate sodium excretion and blood pressure.
+**Serotonin**:
+    * In the CNS, serotonin modulates mood, appetite, and sleep.
+    * In the gut (where 90% of serotonin is produced), it acts as a hormone to regulate intestinal motility and blood flow.
+**Acetylcholine**:
+    * In the CNS, acetylcholine is involved in memory and learning.
+    * Outside the CNS, it acts as a hormone in the autonomic nervous system, controlling heart rate, digestion, and muscle contraction.
+**Histamine**:
+    * In the brain, histamine regulates wakefulness and appetite.
+    * In the body, it acts as a hormone in immune responses, triggering inflammation and allergic reactions.
+**Glutamate and GABA**:
+    * These are primarily CNS neurotransmitters, but small amounts in the periphery may influence hormone release (e.g., glutamate stimulates insulin secretion in the pancreas).
+===== Key Points =====
+  * Neurotransmitters can have dual roles: as chemical messengers in the brain and as hormones in the body.
+  * Their effects depend on location: CNS (neuronal signaling) vs. periphery (hormonal action).
+  * The blood-brain barrier restricts their movement, but peripheral production allows them to act systemically.
+===== Example Table =====
+| Neurotransmitter | CNS Role (Neurotransmitter) | Peripheral Role (Hormone)               |
+|-------------------|-----------------------------|-----------------------------------------|
+| Norepinephrine    | Attention, arousal          | Fight-or-flight response                |
+| Dopamine          | Reward, movement            | Kidney function, blood pressure         |
+| Serotonin         | Mood, sleep                 | Gut motility, blood flow                |
+| Acetylcholine     | Memory, learning            | Heart rate, digestion, muscle control   |
+| Histamine         | Wakefulness, appetite       | Immune response, inflammation           |