Hypothalamic Control

• Hypothalamus and pituitary are in diencephalon
• Hypothalamus contains control centres for many biological systems
• hypothalamic control crucial for feeding, plasma osmolarity, body temp, and sexual and stress responses
• hypothalamic control always involves negative feedback → processing chemical and neural signals from the body to monitor how well things are working and to detect disturbances
• some control systems maintain homeostasis, other vary things through time ex. circadian rhythms
• Hypothalamus exerts its influence neurally and hormonally
• nuclei within hypothalamus send neural signals to each other and other parts of the brain
• the hypothalamus also synthesizes hormones which it transports down axons to the posterior lobe of the pituitary, where they are released into the blood
• the hypothalamus makes releasing hormones that travel through capillaries to the anterior pituitary, where they trigger the release into the blood of other hormones, made in the pituitary
• hypothalamus is crucial to feeding control. mice with lesions in ventromedial hypothalamus overeat and become obese, those with lesions in the lateral hypothalamus get thin
• In fasting state, arcuate NPY neurons encourage feeding

  • these neurons in the arcuate nucleus of the hypothalamus which release neuropeptide Y (NPY), GABA and (in some cells) also agouti-related peptide (AgRP)