Chapter 6b Communication Integration and Homeostasis 2013 Pearson Education Inc CRASH COURSE https www youtube com watch v WVrlHH14q3o Figure 6 11 Calcium As an Intracellular Messenger Extracellular fluid Ca2 Electrical signal Voltage gated Ca2 channel opens Ca2 released from intracellular Ca2 stores Ca2 Ca2 in cytosol increases Chemical signal Ca2 binds to proteins Calmodulin Other Ca2 binding proteins Intracellular fluid Alters protein activity Exocytosis Movement Figure 6 11 Slide 1 Calcium As an Intracellular Messenger Extracellular fluid Ca2 Electrical signal Voltage gated Ca2 channel opens Intracellular fluid 2013 Pearson Education Inc Figure 6 11 Slide 2 Calcium As an Intracellular Messenger Extracellular fluid Ca2 Electrical signal Voltage gated Ca2 channel opens Ca2 released from intracellular Ca2 stores Chemical signal Intracellular fluid 2013 Pearson Education Inc Figure 6 11 Slide 3 Calcium As an Intracellular Messenger Extracellular fluid Ca2 Electrical signal Voltage gated Ca2 channel opens Ca2 released from intracellular Ca2 stores Ca2 Ca2 in cytosol increases Chemical signal Intracellular fluid 2013 Pearson Education Inc Figure 6 11 Slide 4 Calcium As an Intracellular Messenger Extracellular fluid Ca2 Electrical signal Voltage gated Ca2 channel opens Ca2 released from intracellular Ca2 stores Ca2 Ca2 in cytosol increases Chemical signal Ca2 binds to proteins Calmodulin Other Ca2 binding proteins Intracellular fluid 2013 Pearson Education Inc Figure 6 11 Slide 5 Calcium As an Intracellular Messenger Extracellular fluid Ca2 Electrical signal Voltage gated Ca2 channel opens Ca2 released from intracellular Ca2 stores Ca2 Ca2 in cytosol increases Chemical signal Ca2 binds to proteins Calmodulin Other Ca2 binding proteins Intracellular fluid Alters protein activity Exocytosis Movement 2013 Pearson Education Inc Gases Are Ephemeral Signal Molecules Nitric oxide NO Produced by endothelial cells type of tissue Diffuses into smooth muscle and causes vasodilation Synthesized by the action of nitric oxide synthase NOS Activates guanylyl cyclase Formation of cGMP Acts as neurotransmitter and neuromodulator in brain 2013 Pearson Education Inc Gases Are Ephemeral Signal Molecules Carbon monoxide CO Also activates guanylyl cyclase and cGMP Targets smooth muscle and neural tissue Hydrogen sulfide H2S Targets cardiovascular system to relax blood vessels Garlic is major dietary source of precursors 2013 Pearson Education Inc Figure 6 12 The Arachidonic Acid Cascade Extracellular fluid Intracellular fluid Membrane phospholipids PLA2 Arachidonic acid Second messenger activity lipoxygenase cycloxygenase COX 1 COX 2 Leukotrienes Lipid soluble paracrines Prostaglandins Thromboxanes KEY PLA2 phospholipase A2 Some Lipids Are Important Paracrine Signals Leukotrienes Role in asthma and anaphylaxis Prostanoids Prostaglandins Thromboxanes Sphingolipids 2013 Pearson Education Inc Sleep inflammation pain fever Nonsteroidal anti inflammatory drugs NSAIDs help prevent inflammation by inhibiting cyclooxygenase COX Help regulate inflammation cell adhesion and migration and cell growth and death Figure 6 13 Target response depends on the target receptor In this example blood vessels dilate or constrict depending on their receptor type Epinephrine can bind to different isoforms of the adrenergic receptor Receptor Response 2 Receptor Response Receptor 2 Receptor Intestinal blood vessel Skeletal muscle blood vessel Epinephrine Receptor Epinephrine 2 Receptor Vessel constricts Vessel dilates Modulation of Signal Pathways Specificity and competition Agonist versus antagonist 2013 Pearson Education Inc Figure 6 14 The primary ligand activates a receptor An agonist also activates the receptor An antagonist blocks receptor activity Response No response Modulation of Signal Pathway Responses Down regulation Decrease in receptor number Desensitization By binding a chemical modulator to receptor Up regulation Inserts more receptors in cell membrane Termination mechanism Disease and drugs 2013 Pearson Education Inc Table 6 1 Some Diseases or Conditions Linked to Abnormal Signaling Mechanisms Disease and drugs target signal transduction proteins Control Systems Cannon s Postulates 1 Nervous regulation of internal environment Regulates parameters 2 Tonic control 3 Antagonistic control 4 One chemical signal can have different effects in different tissues 2013 Pearson Education Inc Figure 6 15a Tonic and antagonist control of regulated variables 1 of 6 TONIC CONTROL Tonic control regulates physiological parameters in an up down fashion The signal is always present but changes in intensity Electrical signals from neuron Time Moderate signal rate results in a blood vessel of intermediate diameter Decreased signal rate vessel dilates Change in signal rate Time If the signal rate decreases the blood vessel dilates Increased signal rate vessel constricts Time If the signal rate increases the blood vessel constricts Figure 6 16 Steps of a reflex pathway Reflex Steps STIMULUS SENSOR INPUT SIGNAL INTEGRATING CENTER OUTPUT SIGNAL TARGET RESPONSE Feedback loop Reflex Pathway Response Loops Stimulus Sensor or receptor Threshold minimum reflex needed to set reflex in motion Input signal or afferent pathway Integrating center In endocrine pathways also the sensor Output signal or efferent pathway Target or effector Response 2013 Pearson Education Inc Figure 6 17 Multiple meanings of the word receptor RECEPTORS can be Cell Membrane or Intracellular Receptor Proteins Sensors Specialized Cells or Structures That Convert Various Stimuli into Electrical Signals Central receptors are in or close to the brain Peripheral receptors lie outside the brain Eyes vision Ears hearing equilibrium Nose smell Tongue taste Central chemoreceptors osmoreceptors and thermoreceptors Chemoreceptor pH gases chemicals Osmoreceptor osmolarity Thermoreceptor temperature Baroreceptor pressure Proprioceptor body position Other mechanoreceptors pain vibration touch Figure 6 18 Endocrine neural and neuroendocrine control pathways A Simple Endocrine Reflex A Simple Neural Reflex A Complex Neuro endocrine Reflex Internal or external change Internal or external change Internal or external change Receptor Receptor Input signal sensory neuron Input signal sensory neuron Endocrine system sensor integrating center Nervous system integrating center Output signal hormone Efferent neuron Target Target Response Response Nervous system integrating center Efferent neuron