Olga Vajnerová 2. LF UK Praha Hypothalamus Olga Vajnerová 2. LF UK Praha

Hypothalamus, a major control headquarters for the limbic system Cortex Thalamus Temporal lobe Basal ganglia Septum Paraolfactory area cingulate gyrus Parahippocampal gyrus Orbitofrontal cortex Anterior nuclei Hippocampus Amygdala

Functions of hypothalamus Neurosecretion – oxytocin, ADH Statins, liberins Temperature control Homeostasis Biorhythms Transmission of emotions Hunger, thirst

Functions of hypothalamus

Relation to autonomic function Parasympathetic responses Urinary bladder contraction Sympathetic responses Increased adrenal medullary secretion Vasoconstriction Stress – fight or flight

Cardiovascular regulation Arterial pressure Heart rate Specific cardiovascular control centres are in…. Reticular regions of the pons and medulla Cardioexcitatory area Cardioinhibitory area Vasomotor area Via Sympathetic and Parasympathetic nerves

Influence on respiratory and gastointestinal reflexes Olfactory stimulus – from paleocortex Signals to visceromotor centres i medulla – nausea, vomiting

Transmission of emotions from limbic system Rage, anxiety and fear, joy, sadness Is connected with visceromotor and somatomotor reaction Hear rate, breathig rate, vasomotor reaction – pale or red skin, sweat glands, gastrointestinal motility and secretion, smooth muscle in skin, shivering

Biological rhythms Suprachiasmaticus nuclei – retinohypothalamic tract Pacemaker of circadian rhythms Sleep – wake cycle ACTH secretion Melatonin secretion Body temperature rhythm Activity patterns of animals

Regulation of body water Thirst center Lateral hypothalamus Osmoreceptors – when the EF is too concetrated – develops intense desire to drink water 2. Antidiuretic hormone

Gastrointestinal and feeding regulation Hunger Lateral hypothalamic area, stimulation – extreme hunger, appetite, desire to search for food Damage to this area – lethal starvation Satiety Ventromedial nuclei Stimulation – stop eating Destruction – hunger centers overactive, obesity

Regulation of body temperature Temperature regulating centers Temperature receptors 1. Peripheral Skin receptors (cold and warm) Deep body temperature receptors Spinal cord, abdominal viscera and great veins 2. Central Temperature detectors in hypothalamus Heat sensitive neurons, cold sensitiv neurons Praeoptic area

Posterior hypothalamus integrates the central and peripheral temperature sensory signals Control Heat-producing Heat- conserving reaction of the body Set point – crucial temperature level 37.1ºC Feedback gain for body temperature control

Temperature-decreasing mechanisms Vasodilation of skin blood vessels Inhibition of the sympathetic centers in the posterior hypothalamus Sweating Praeoptic area, via autonomic pathways to the spinal cord Sympathetic but cholinergic Decrease in heat production Inhibition of shivering and thermogenesis

Temperature-decreasing mechanisms Vasodilation of skin blood vessels Inhibition of the sympathetic centers in the posterior hypothalamus Sweating Praeoptic area, via autonomic pathways to the spinal cord Sympathetic but cholinergic Decrease in heat production Inhibition of shivering and thermogenesis

Temperature-decreasing mechanisms Vasodilation of skin blood vessels Inhibition of the sympathetic centers in the posterior hypothalamus Sweating Praeoptic area, via autonomic pathways to the spinal cord Sympathetic but cholinergic Decrease in heat production Inhibition of shivering and thermogenesis

Temperature-increasing mechanisms When the body is too cold 1. Vasoconstriction of skin blood vessels Stimulation of the sympathetic centers in the posterior hypothalamus 2. Piloerection via autonomic pathways to the spinal cord Sympathetic stimulation causes arrector pili muscles to contract 3. Increase in heat production, thermogenesis Shivering, sympathetic excitation of heat production, Thyroxin secretion

3. Increase in heat production, thermogenesis Shivering Primary motor center for shivering in the dorsomedial portion of the posterior hypothalamus Excited by cold signals from the skin and spinal cord Tr hypothalamoreticularis, hypothalamospinalis to spinal motoneurons Non rhytmical signals, increase the tone of the skeletal muscles Probably feedback oscillation of the muscle spindle stretch reflex Sympathetic excitation of heat production Chemical thermogenesis, E and NE uncouple oxidative phosphorylation, energy in the form of heat but do not cause ATP to be formed Thyroxin secretion

Sympathetic excitation of heat production Chemical thermogenesis, E and NE uncouple oxidative phosphorylation, energy in the form of heat but do not cause ATP to be formed Thyroxin secretion

Olga Vajnerová using Mital Patel presentation Hypothalamic-hypophysial system. Olga Vajnerová using Mital Patel presentation

Structure of hypothalamus and pituitary gland The pituitary gland together with the hypothalamus provide endocrine control of many major physiological function Hypothalamus: Located below the thalamus just above the brain stem Subdivided into a number of nuclei = paraventricular, supraoptic, arcuate, Pituitary gland: Located inside skull below hypothalamus Has 3 divisions = Adenohypophysis (ant), Neurohypophysis (post) and the pars intermedia

Adenohypophysis Linked to hypothalamus via hypophyseal-portal system in the infundibulum Connection allows hypothalamus to stimulate/inhibit 5 distinct pituitary cell types: 1. somatotropes -human growth hormone 2. corticotropes - adrenocortictropin 3. Thyrotropes - TSH 4. Gonadotropes – LH and FSH 5. Lactotropes - Prolactin

Negative feedback (autoregulation)

Hypothalamic hormones Adenohypophysis

Blue – peptides yellow - steroids Light blue – glycoproteins orange – tyrosine derivates

Neurohypophysis Connected to the hypothalamus via infundibulum Hormones made in nerve cell bodies in the hypothalamus, are transported down the nerve to the neurohypophysis Secretes two peptide hormones: oxytocin – from paraventricular nucles ADH – from supraoptic nucleus Axons reach terminal on inf hypophyseal artery to enter general circulation

Hypothalamic hormones Neurohypophysis

QUESTION PATIENT : EXTREME THIRST EXCESSIVE DILUTED URINATION DAY AND NIGHT DEHYDRATION WHATS THE DIAGNOSIS?

QUESTION PATIENT : EXTREME THIRST EXCESSIVE DILUTED URINATION DAY AND NIGHT DEHYDRATION WHATS THE DIAGNOSIS? DIABETES INSIPIDUS ADH DEFICIENCY