Hypothalamus and Its Connections

• Hypothalamus − comprised of 0.3 % of the total brain − important part of the CNS − controls Autonomic Nervous System & Endocrine System − lies below the thalamus and forms the floor of the 3rd ventricle − has 3 regions
• Hypothalamus parts: a.) Optic Chiasma b.) Tuber Cinereum c.) Mammillary Bodies
• Functions of The Hypothalamus: a) Autonomic Control b) Regulates Feeding and Drinking Behavior c) Temperature Regulation d) Emotion & Behavior e) Control of Circadian Rhythms f) Regulates Endocrine Activity g) Regulates Sexual Behavior h) Neurosecretion
• Autonomic Control - preserving body HOMEOSTASIS
• Regulates Feeding and Drinking Behavior - stimulation of lateral region of hypothalamus => feeling of hunger; ↑ Food Intake • Lateral region of hypothalamus sometimes referred as the Hunger Center • Bilateral destruction of Hunger Center of hypothalamus => Anorexia • Stimulation of medial region of hypothalamus => inhibits Eating; ↓ Food Intake • Medial region of hypothalamus sometimes referred as the Satiety Center • Bilateral destruction of Satiety Center of hypothalamus => uncontrolled voracious appetite causing extreme OBESITY • Stimulation of other areas of lateral region of hypothalamus => ↑ desire to Drink (Thirst Center)
• stimulation of lateral region - of hypothalamus => feeling of hunger; ↑ Food Intake
• Lateral region of hypothalamus sometimes referred as the - Hunger Center
• Bilateral destruction of Hunger Center of hypothalamus - Anorexia
• Stimulation of medial region of hypothalamus - inhibits Eating; ↓ Food Intake
• Medial region of hypothalamus sometimes referred as the - Satiety Center
• Bilateral destruction of Satiety Center of hypothalamus => uncontrolled voracious appetite causing extreme - OBESITY
• Stimulation of other areas of lateral region of hypothalamus => ↑ desire to - Drink (Thirst Center)
• Emotion & Behavior - Emotion and Behavior are function of the Hypothalamus, Limbic system and the Prefrontal Cortex - Hypothalamus is the integrator of Afferent information received from other areas of nervous system ✓ Physical expression of emotion ✓ ↑ HR ✓ ↑ BP ✓ (+) Dryness of mouth ✓ Pallor of the skin ✓ Sweating ✓ Massive peristaltic activity of GIT
• Control of Circadian Rhythms - Controls body temperature, Adrenocortical activity, Eosinophil count and renal secretion • Lesion: interfere Rhythm of Sleeping & Waking
• Hypothalamic Nuclei parts: a) Preoptic Area (Rostral to Hypothalamus) b) Supraoptic Region c) Tuberal Region (Tuber Cinereum) d) Mammillary Region
• Preoptic Area (Rostral to Hypothalamus) parts: a) Medial Preoptic Area b) Lateral Preoptic Area
• Supraoptic Region parts: a) Suprachiasmatic Nucleus b) Supraoptic Nucleus c) Paraventricular Nucleus d) Anterior Hypothalamic Nucleus e) Lateral Hypothalamic Nucleus
• Tuberal Region (Tuber Cinereum) parts: a) Dorsomedial Nucleus b) Ventromedial Nucleus c) Arcuate Nucleus 5) Lateral Hypothalamic Nucleus
• Mammillary Region parts: a) Mammillary Nuclei b) Posterior Nucleus
• hypothalamus receives information from the rest of the body parts: a) Nervous Connections b.) Bloodstream c.) Cerebrospinal Fluid
• Hypothalamic Lines of Connections − The hypothalamus receives information from the rest of the body through the following: a. Nervous Connections b. Bloodstream c. Cerebrospinal Fluid- serves as a conduit between the neurosecretory cells of the hypothalamus and distant site of the brain
• Cerebrospinal Fluid - serves as a conduit between the neurosecretory cells of the hypothalamus and distant site of the brain
• Hypothalamohypophseal Tract − Supraoptic & Paraventricular Nuclei responsible for the producing the 2 hormones: Vasopressin & Oxytocin
• Supraoptic & Paraventricular Nuclei producing hormone: a) Vasopressin b) Oxytocin
• Vasopressin - Antidiuretic Hormone - produced mainly by Supraoptic nucleus - Function: Vasoconstriction - increased absorption of H2O in the distal convoluted tubules and collecting tubules of the kidney
• Oxytocin - produced mainly by Paraventricular Nucleus - stimulates contraction of the smooth muscles of the uterus
• Connections of The Hypothalamus with The Hypophysis Cerebri − The hypothalamus is connected to the HYPOPHYSIS CEREBRI (Pituitary Gland) by two pathways: 1. Nerve fibers that travel from the supraoptic and paraventricular nuclei to the posterior lobe of the hypophysis 2. Long and short portal blood vessels that connect sinusoids in the median eminence and infundibulum with capillary plexuses in the anterior lobe of the hypophysis