1 Hypothalamus (Master Homeostasis Center)
The Hypothalamus connects brain, hormones, and autonomic nerves.
| Hypothalamic nucleus | Function | Neurotransmitter / hormone | Target organ | Body regulation |
|---|---|---|---|---|
| Paraventricular nucleus | stress response | CRH | pituitary ? adrenal | cortisol release |
| Suprachiasmatic nucleus | circadian rhythm | melatonin regulation | pineal gland | sleep cycle |
| Arcuate nucleus | hunger control | neuropeptide Y | stomach / pancreas | appetite |
| Ventromedial nucleus | satiety | leptin signaling | digestive system | stop eating |
| Lateral hypothalamus | feeding behaviour | orexin | GI tract | hunger |
Main body functions controlled:
-
hunger
-
thirst
-
temperature
-
sexual behaviour
-
stress hormones
2. Amygdala (Threat Detection System)
The Amygdala processes fear and emotional salience.
| Amygdala nucleus | Function | Neurotransmitter | Target body system | Effect |
|---|---|---|---|---|
| Basolateral nucleus | emotional learning | glutamate | cortex | memory encoding |
| Central nucleus | fear response | norepinephrine | adrenal glands | adrenaline release |
| Medial nucleus | social behaviour | serotonin | limbic system | aggression control |
Body effects:
-
heart rate increase
-
sweating
-
fight-or-flight response
3. Hippocampus (Memory Integration)
The Hippocampus integrates memory with emotional context.
| Subregion | Function | Neurotransmitter | Target system | Regulation |
|---|---|---|---|---|
| CA1 | memory consolidation | glutamate | cortex | long-term memory |
| CA3 | pattern completion | acetylcholine | limbic network | associative memory |
| Dentate gyrus | new memory formation | GABA | hippocampal circuit | learning |
Body-level influence:
-
learning behaviour
-
stress adaptation
4. Prefrontal Cortex (Executive Control)
The Prefrontal cortex regulates reasoning and impulse control.
| Subregion | Function | Neurotransmitter | Target body system | Effect |
|---|---|---|---|---|
| Dorsolateral PFC | reasoning | dopamine | cortex networks | planning |
| Ventromedial PFC | emotional regulation | serotonin | limbic system | emotional control |
| Orbitofrontal cortex | impulse inhibition | dopamine | basal ganglia | behavioural control |
Body influence:
-
decision making
-
impulse suppression
-
social judgement
5.Basal Ganglia (Movement & Reward)
Key structures include Basal ganglia nuclei.
| Structure | Function | Neurotransmitter | Target system | Effect |
|---|---|---|---|---|
| Caudate nucleus | cognition loop | dopamine | cortex | planning |
| Putamen | motor control | dopamine | muscles | movement |
| Globus pallidus | inhibition | GABA | motor circuits | movement control |
| Substantia nigra | dopamine production | dopamine | basal ganglia | reward |
Body functions:
-
voluntary movement
-
motivation
-
habit formation
6. Brainstem Autonomic Centers
The Brainstem controls life-support systems.
| Structure | Function | Neurotransmitter | Target organ | Regulation |
|---|---|---|---|---|
| Medulla | breathing | acetylcholine | lungs | respiration |
| Medulla | heart control | norepinephrine | heart | heart rate |
| Pons | sleep cycles | serotonin | brain networks | sleep |
| Reticular formation | alertness | norepinephrine | cortex | consciousness |
7. Cerebellum (Motor Precision)
The Cerebellum refines movement.
| Structure | Function | Neurotransmitter | Target system | Effect |
|---|---|---|---|---|
| Vermis | posture | GABA | spinal cord | balance |
| Cerebellar hemispheres | coordination | glutamate | muscles | motor precision |
8. Dopamine Reward Circuit
Major pathway:
| Brain region | Function | Target body system |
|---|---|---|
| Ventral tegmental area | dopamine release | motivation |
| Nucleus accumbens | reward sensation | behaviour reinforcement |
| Prefrontal cortex | decision making | goal-directed behaviour |
Body outcome:
-
pleasure
-
addiction
-
motivation
9. Stress Axis (Brain–Endocrine Loop)
The stress response uses the HPA axis.
Sequence:
Hypothalamus ? Pituitary ? Adrenal glands
Hormones released:
-
CRH
-
ACTH
-
cortisol
Body effects:
-
increased glucose
-
elevated heart rate
-
immune suppression
Brain–Body Integration Map
Simplified chain:
| Brain part | Neurotransmitter | Target organ | Function |
|---|---|---|---|
| Hypothalamus | CRH | adrenal glands | stress response |
| Amygdala | norepinephrine | heart | fear reaction |
| Hippocampus | glutamate | cortex | memory |
| Prefrontal cortex | dopamine | cortex | reasoning |
| Basal ganglia | dopamine | muscles | movement |
| Brainstem | acetylcholine | lungs | breathing |
