01 14 2014 HYPOTHALAMUS HYPOTHALAMUS responses Center that integrates autonomic endocrine and behavioral Regulates the internal environment homeostasis Makes survival and propagation more likely Combination of neural and endocrine inputs and outputs Plays a major role in function as diverse as o Feeding drinking temp regulation sexual responses and determining How you feel Via release of hormones and activation of the ANS hypothalamus influences how you feel Location o Superior brain stem posterior to pituitary gland optic chiasm Above pituitary Behind optic chiasm Bottom of brain Live in wall of 3rd ventricle o Made of tiny nuclei Compete against each other Homeostasis Close tolerances necessary for life o We have low tolerance for variation Small change in body temp electrolytes and blood pH can cause death Interface b t external and internal environment o Endocrine system o Autonomic nervous system Autonomic Nervous System Parasympathetic NS o Acetylcholine Relaxed Wetter mouth Release bladders Sympathetic NS o Driven by our mind o Norepinephrine o Scared to death from parasympathetic NS Fight or flight system Aroused attentive salivation heart rate faster nervous bladders when sympathetic turns off quickly parasympathetic turns on quickly intensely cocaine meth heroine Via release of hormones and activation of ANS the hypothalamus influences how we feel o I feel fear Stress activates hypothalamus triggers pituitary gland release NE and ACTH through blood stream trickle down effects on respective organs and body systems Regulation Body Temperature o Involves autonomic nervous endocrine and skeletomotor systems o Body temperature detectors Peripheral skin spinal cord viscera Sends info to anterior hypothalamus Central anterior hypothalamus o Body temp effectors Heat retention or generation posterior hypothalamus Heat conserving mechanisms Vasoconstriction of blood vessels in skin Shivering Increased secretion of hormones Thermogenesis production of uncoupling protein 1 UCP 1 allows mitochondria in brown adipose tissue to convert waster ATP into heat Muscles can do same thing in response to testosterone Heat dissipation ant Hypothalamus Detection how fast neurons are firing The faster they fire the hotter we are Heat dissipating mechanisms Dilation of blood vessels in skin Inhibition of shivering Anterior cools you down Posterior warms you up o Lower body temp leads to longer life span Optimum temp for ward off infection w o expend too Our bodies would never get sick if we were constantly at much E is 36 7 C 101 degrees Can t do this bc we don t have enough energy Can t eat that many calories We would age too quickly o Hypothalamus extends to different organs HEATING Thyroid hormone Released from thyroid gland Helps warm you up Brown fat Brown due to mitochondria o Great for burning energy Shivering Moving muscles Burns fat mitochondria constricting blood vessels COOLING Panting Blow off heat Sweating Want to be as cool as room Wont lose heat if it s too humid We can over heat very easily Dilation of vessels Thermogenesis o Production of uncoupling protein 1 UPC allows mitochondria in brown adipose tissue waste to convert ATP into heat Muscles do same thing in response to testosterone Thyroxin does this too Men warm themselves up easily with more muscles Generate a lot of heat Even more heat with uncoupling protein o Another reason men die before women Disorders of Thermo regulation o Lesions of heat conserving mechanisms Lesion of post hypothalamus Causes hypothermia o Lesions of heat dissipating mechanisms Lesion of ant hypothalamus Causes hyperthermia Ecstasy overdose o Disconnection syndrome during REM sleep Causes piokoliothermia cold blooded Inability to regulate own temperature o Some drugs may make us feel cold or warm Drinking o Body fluids are mostly located inside your cells Interstitial fluid Plasma Intracellular fluid Minor components o Thirst Determined by serum osmolality and blood volume Osmolality what is concentration of salts Osmotic receptors in the hypothalamus Volume receptors in the right atrium of the heart and great veins Volume of water Vasopressin release from hypothalamus o Increases water reabsorption from the kidney o Inhibited by ethanol consumption o Stops loss of water from kidneys Ethanol inhibits vasopresson for us to concentrate our urine o Hypovolemic thirst Vascular leaking Bleeding Veins of body losing fluid Doctors give you saline o Osmotic thirst Salt concentration too high Doctors give you water o Environmental effects upon fluid consumption Shorter stay more drinks hour Drinking alone more drinks hour Rhythm equals heart rate more drink Lyrics sad songs more drinking More men than women more drinking Live band more drinking Action photo more drinking Circadian Rhythm o Oscillations during the course of the day Corticosteroids Feeding and drinking behavior Growth hormone secretion disrupts these oscillations o Suprachiasmatic nucleus Controls all circadian rhythms Lives near nuclei that wake us up o Lesions of the suprachiasmatic nuclei of the hypothalamus Each nucleus contains about 20k neurons o Biological clocks may exist in all cells of the body Feeding o Arcuate nucleus in the hypothalamus Job is to decide how much food is stored how much food available for brain sugar and how much food have we just eaten We eat very sweet high fat foods during dessert o Ghrelin We are empty Feed us o Leptin Comes from our fat Regulates if we eat or not eat How much stored fat do we have We have lots of fat No more food If we are fat this system should tell us not to eat Obesity is inherited o Inability to respond to leptin POMC tells us not to eat AGRP tells us to eat o Insulin Goes back to brain KNOW GHRELIN LEPTIN AND INSULIN AND STARS o Lesion of POMC neurons leads to over eating Gaining weight o Orexin Neurons Located only in lateral hypothalamus projects widely Controls circadian rhythms Activating arousal systems Norepinephrine Serotonin Dopamine Exploring environment moving Helps your metabolism start in the morning Stimulation produces arousal foraging Mutations produce narcolepsy symptoms Functionally distinct groups Reward inputs Project upward to reward systems Morphine cocaine food LH projections to limbic areas o forebrain and midbrain reward areas VTA NAc Amy o reward centers amygdala dopamine area THIS IS HOW A PERSON Arousal inputs BECEOMES ADDICTED TO FOOD Waking stress DMH PFA project to brainstem arousal areas Locus Coeruleus