allostatic regulation Bernard Claude Canon Walter B closed loop cybernetics delay emergence feed forward gain homeostasis negative feedback open loop oscillation positive feedback regulatory cascade set point homeostasis set point can vary depending on conditions allostatic changed conditions the sum of everything portraying homeostasis 1865 regulation of internal enviorment in the body within a relatively narrow range first to suggest the idea we now call homeostasis 1929 coined homeostasis four postulates 1 Role of nervous system and how it preserves the fitness of the internal enviorment blood preassure bodyemp 2 tonic regulation wide range of response in the body with one control blood vessel diameter 3 Antagonistic control sympathetic vs parasympathetic percise control opposing affects 4 chemical signals have different effect in different tissue receptors epinephrine affects everyones heart differently feed back loop one input one output and a response output affects feedback signal continuous regulation science control communications in animal and machine norbert weiner 1948 usually detectable in a feedback system depends on anatomy or processing bases off simple functional elements large number of elements new complex macro behavior unpredictable yet derived from the behavior of simple elements bottom up control open loop starts a response before a stimulus does involves learning prediction expresses intnesity or magnuitude of effector action amount of change from stimulus to effector response regulation tendency of a system to maintian internal stability reponse opposite direction of the change closed loop oppose change and return to set point homeostatic operate in a narrow range input action output no self regulation system has control but its is not automatic only response long delay high gain movement of a parameter around a desired range setpoint negative feedback feedback keeps response loop going making change greater wave of stimuli passes over chain of intermediates initial trigger of an inactive precursor to an active form desired target value for a parameter oscillations occur around set point homeostasis see Negative or Positive feedback present in all physiological systems can be large or smal nervoussystem ant hill pavlovs dog salivating before eating using rate of change information to predict changing conditions HCG and pre pregnancy gently blowing on the fur of an animal cause large action pH body temp etc shivering see feed forward ship steerer long delay in turning large response body temp milk secretion due to increased suckling not being able to stop in the middle of peeing protein kinase cascade 98 6 normal body attractor cell body endocrine non linear chaotic systems point in chaos system that system wants to go to zero momentum zero velocity nucleus and much of the synthetic apparatus of the cell includes nucleus rough ER golgi complex mitochondria long distance regulation signaling uses chemical hormones that go into bloodstream 1960 s discovery of new manifestations of complex nonlinear systems need new graphical mathmatical techniques to analyze small changes in initial conditions lead to big changes in system function paracrine local chemical signaling effects cells in immediate vicinity phase space diagram autocrine position vs momemtum plot does not display time values for nonlinear systems tell velocity patterns that you cant see on traditional time series graph self regulation reflex requires sensory input and integrating center and effector functions smallest unit of regulatory function pendulums eventually go to endpoint big part of cell not dendrite or extremities growth hormones during puberty weather butterfly effect diffusion histamine diffuses into capiliaries at point of injury dodging a ball by ducking star shaped part of blood brain barrier system contact with both neurons and blood vessels most abundant type of glial cell non neuronal support cells of the CNS regulate and protect the nervous system brain spinal cord more specialized complex regulation complexity centralization PNS Ogliodendrocytes Schwann Cells everything else extremities some regulation in the parts that are close to CNS only regulation in the PNS is in the ganglia form myelin sheaths in the CNS affects several axons form myelin sheaths in the PNS only effect one neuron extension of neuron that carries signal to target cell each neuron has ONE axon has branches collaterals along it length can be covered myelin sheaths distal end of a neuron where a neurotransmitter is released in the synapse signal is being released from this point presynaptic neuron have two extensions 1 dendrite 1 axon primitive first neuron in development rare in adult many become pseudounipolar centerline of the body more complex regulation by NS common in vertabrae leading towards the head aka head centrilzation thin branched extension that receive and transport incoming info to an integrating region within the neuron usually multiple and highly branched astrocytes glial cells CNS axon axon terminal bipolar centralization cephalization dendrites dorsal root ganglia ganglion concentrated collection of cell neurons outside the CNS on the dorsal root before the spinal cord no synapses no processing of information contains cell bodies of psuedounipolor sensory nuerons afferent signal cluster of nerve cell bodies in PNS may carry out simple processing integrate multiple inputs generate other patterns many functions everything that s not sensory motor nuerons CNS send signal from internueron to a response target muscle or gland efferant pathway interneuron motor neurons multipolar nueron many dendrites 1 axon myelin layers of cell membrane that insulate axons speed up signals along axon primitve arangements of neurons little or no spacial organization little or no specialization of neurons potentially many pathways of activity through the net only bipolar after the synapse contains receptor proteins on surface before the synapse contains nuerotransmitters to be send across the synapse axon terminals use axon terminal and contains vesicles nerve net post synaptic pre synaptic psuedounipolar one cell body one extension fused dendrite and axon often develop from bipolar neruons receptor sensory neuron synapse synaptic vessicles continually monitor changes in internal external enviroment of cell protein or sensory receptor all have a threshold minimum value that must be achieved to set reflex in