hypothalamic arcuate nucleus ARC Arcuate nucleus of the hypothalamus projects to LH and VMH Melanocortin cells are here Neuropeptide Y is a potent inducer of consummatory behavior Appetite suppressing POMC CART neurons are anorexigenic less hunger excited by leptin and insulin not affected by ghrelin and PYY release inject MSH to inhibit orexigenic signals in LH Appetite enhancing AgRP NPY neurons are orexigenic more hunger excited by ghrelin inhibited by insulin leptin and PYY release NPY to inhibit anorexigenic neurons in paraventricular nucleus PVN release AgRP to block effects of MSH in LH by acting as a competitive antagonist at its receptor less promotion of satiety more hunger Only case where one neurotransmitter impedes the effects of another AgRP agouti related protein Ectopic expression of AgRP in transgenic mice obesity ft of tII diabetes yellow fur Send signals to regions of the brain other than just the hypothalamus Ex If you are hungry but now I get scared then hunger is suppressed AGRP cells are influencing many behaviors in the brain integration of appetite signals by the ARC 1 Peptide hormones leptin insulin ghrelin PYY from the gut or 4 leptin from body fat cells are carried to brain to regulate appetite inhibiting NPY neurons and stimulating POMC neurons Ghrelin and PYY thought to exert minute to minute control on appetite and they have opposing effects on NPY neurons ghrelin stimulates eating PYY inhibits appetite 2 3 Visceral and somatosensory information travels via vagus nerves and spinal nerves Lateral hypothalamus orexigenic are second order neurons Paraventricular nucleus anorexigenic ARC contains POMC neurons and NPY inhibits anorexic neurons Afferent a for away takes signals from GI tract to the brain Gut brain communication through vagus nerve Vagal afferent nerve terminals innervate organs involved in nutrient sensing stomach where hormone hunger signal ghrelin is produced by enteroendocrine cells blood levels of ghrelin are highest before meals and dip to lower levels post meal ghrelin increases food intake by activating AgRP NPY neurons in the ARC nucleus GHSR1A sl 23 ghrelin also participates in regulation of gastric motility learning and memory taste sensation reward behavior and glucose metabolism intestines where hormone PYY is made when intestines are filled with food acting to signal that the gut is full and no more eating liver where glycogen is stored glycogen also stored in muscle tissue pancreas where insulin is produced where glucagon is produced sometimes PYY is produced here too Vagal network senses both nutrient related hormonal and mechanical signals and trigger neuronal transmission to the CNS to affect feeding behavior and energy balance Manipulation of gut nutrient dependent and vagal dependent afferent firing rates potential novel therapeutic strategy for obesity and diabetes satiety signals 1 Insulin needed to convert glucose glycogen secreted by pancreas post meal medium Essential in normal functioning of glucose transporters that bring glucose across the membrane into cells of the body but not the brain Cannot make insulin Type I diabetic must take insulin to get energy from food Body doesn t respond normally to insulin Type II diabetic Insulin acts on hypothalamus to suppress appetite 2 3 Leptin greek for thin produced and secreted by adipose tissue when tissue expands more leptin is produced when tissue size decreases less leptin is produced slow PYY peptide tyrosine tyrosine when intestines are filled with food acting to signal the gut is full fast Leptin deficient mice are morbidly obese and diabetic gut derived hormones released by digestive system to tell brain about food consumption can either be satiety signals or hunger signals PYY released from intestines satiety signal suppressing appetite Ghrelin produced in stomach when stomach is empty glucose metabolism hunger for sugars and fats Excess glucose can be converted into glycogen Glycogen can be converted back to glucose by glucagon pancreatic hormone Umami tastes fatty foods evolved hunger Lipids can be stored for a long time in adipose tissue and converted back into glycogen and glucose via gluconeogenesis KEY Yellow vocab and key concepts Orange organs Pink hormones Blue structures in brain Purple proteins joints and movements Two Antagonistic muscles Flexors contractions bends the joint ex bicep Extensors contraction straightens the joint ex tricep Muscles are connected by tendons to bone Tendons pulling bone when muscle contracts cannot push limbs Contracting shortening of the fibers muscle fibers and myofibrils Each muscle fiber is one large cell with many nuclei Myofibril at the center of the muscle fibers Actin cytoskeleton protein Leptin provides info on current energy stores decreasing feeding behavior by hunger signal Myosin spends ATP grab actin pull toward middle of fiber Muscle Contraction Sarcomere structure that has myosin and actin filaments The contraction is the pulling of the actin by the myosin heads Motor nerve unit Collection of fibers innervated by a single motor neuron Contraction happening because of the synapse at neuromuscular junction NMJs ACh is being released nicotinic ionotropic ONLY Na enters Ca enters myosin pull actin filaments together Spinal cord Maintain but not initiate ongoing repetitive movements Ventral roots carry motor commands from brain to body Each pair sends axons to different muscle groups kind of like dermatome Motor neurons reside in gray matter of ventral horn of the sc Cell body is inside of spinal cord axons go out Brainstem motor nuclei Cranial motor neuron cell bodies reside in the brainstem motor nuclei Motor axons exit brainstem through cranial nerves to contract muscles in the head and face final common pathway Motor neurons are the final common pathway through which the b and sc control muscles Every single time the motor neuron fires an ap the muscle will contract with nearly 100 efficiency Basal ganglia I just drove to work but i was trying to the coffee shop Initiation and termination of movement Storing motor patterns that you have done many times Cortex Start walking Go there Simpler actions too hold this primary Sequences of supplementary Starting and stopping Cerebellum Movement more fluid and accurate Drunk cerebellum this simple feedback inhibition allows for generation of motor rhythms 2 Pyramidal motor system control voluntary movements initiating voluntary movement NOT reflexive Decussate