Hypothalamus and Pituitary Gland

1.2. Functions of the Hypothalamus

The hypothalamus serves as the control center linking the nervous system and endocrine system. Its major functions include:

1. Autonomic Nervous System Regulation

• Controls sympathetic and parasympathetic activity
• Influences heart rate, blood pressure, gastrointestinal motility, pupil size, sweating, and thermoregulation

2. Endocrine Control via the Pituitary

• Anterior pituitary: Releasing and inhibiting hormones from the arcuate and paraventricular nuclei regulate hormone secretion (e.g., CRH → ACTH; TRH → TSH; GnRH → LH/FSH).
• Posterior pituitary: ADH and oxytocin produced in the supraoptic and paraventricular nuclei are transported via axons to be released into circulation.

3. Thermoregulation

• Anterior region: Heat loss center (vasodilation, sweating)
• Posterior region: Heat conservation (vasoconstriction, shivering)

4. Regulation of Food and Water Intake

• Lateral zone: Feeding center – stimulation induces eating
• Ventromedial nucleus: Satiety center – stimulation inhibits eating
• Osmoreceptors in the anterior hypothalamus regulate thirst and ADH secretion

5. Circadian Rhythms

• Suprachiasmatic nucleus synchronizes body rhythms (sleep–wake cycles, hormone secretion) with the light–dark cycle

6. Emotional and Behavioral Responses

• Connections with the limbic system influence emotional expression, sexual behavior, and stress responses

7. Memory and Learning

• Mammillary bodies are part of the Papez circuit, essential for memory consolidation