1. Chapter 6b Communication, Integration, and Homeostasis

2. Figure 6-15 Novel Signal Molecules: Calcium Calcium as an intracellular messenger Extracellular fluid Intracellular fluid Electrical signal released from intracellular Ca 2+ stores Ca 2+ binds to proteins Calmodulin Other Ca 2+ - binding proteins Alters protein activity ExocytosisMovement Chemical signal Ca 2+ in cytosol increases. Voltage-gated Ca 2+ channel opens.

3. Novel Signal Molecules: Calcium Figure 6-15 (1 of 5) Extracellular fluid Intracellular fluid Electrical signal Voltage-gated Ca 2+ channel opens.

4. Novel Signal Molecules: Calcium Figure 6-15 (2 of 5) Extracellular fluid Intracellular fluid Electrical signal released from intracellular Ca 2+ stores Chemical signal Voltage-gated Ca 2+ channel opens.

5. Novel Signal Molecules: Calcium Figure 6-15 (3 of 5) Extracellular fluid Intracellular fluid Electrical signal released from intracellular Ca 2+ stores Chemical signal Ca 2+ in cytosol increases. Voltage-gated Ca 2+ channel opens.

6. Novel Signal Molecules: Calcium Figure 6-15 (4 of 5) Extracellular fluid Intracellular fluid Electrical signal released from intracellular Ca 2+ stores Ca 2+ binds proteins Calmodulin Other Ca 2+ - binding proteins Chemical signal Ca 2+ in cytosol increases. Voltage-gated Ca 2+ channel opens.

7. Novel Signal Molecules: Calcium Figure 6-15 (5 of 5) Extracellular fluid Intracellular fluid Electrical signal released from intracellular Ca 2+ stores Ca 2+ binds proteins Calmodulin Other Ca 2+ - binding proteins Alters protein activity ExocytosisMovement Chemical signal Ca 2+ in cytosol increases. Voltage-gated Ca 2+ channel opens.

8. Novel Signal Molecules: Gases Nitric oxide (NO) Activates guanylyl cyclase Formation of cGMP Acts as neurotransmitter and neuromodulator in brain Produced by endothelial cells Diffuses into smooth muscle and causes vasodilation

9. Novel Signal Molecules: Gases Carbon monoxide (CO) Also activates guanylyl cyclase and cGMP Targets smooth muscle and neural tissue Hydrogen Sulfide (H 2 S) Targets cardiovascular system Garlic is major source of precursors

10. Novel Signal Molecules: Lipids The arachidonic acid cascade produces lipid messengers Figure 6-16

11. Novel Signal Molecules: Lipids Leukotrienes Role in asthma and anaphylaxis Prostanoids Prostaglandins Sleep, inflammation, pain, fever Thromboxanes Nonsteroidal anti-inflammatory drugs (NSAIDs) help prevent inflammation by inhibiting cyclooxygenase (COX)

12. Modulation of Signal Pathways Specificity and competition Agonist versus antagonist Multiple receptors for one ligand Alpha receptor Vasoconstriction Beta receptor Vasodilation

13. Modulation of Signal Pathways Agonist versus antagonist Figure 6-17 The primary ligand activates a receptor. An agonist also activates the receptor. An antagonist blocks receptor activity. Response No response

14. Modulation of Signal Pathways Target response depends on the target receptor Figure 6-18 Intestinal blood vessel Skeletal muscle blood vessel  - Receptor response  2 - Receptor response Epinephrine +  -Receptor  2 -Receptor  -Receptor Epinephrine +  2 -Receptor Vessel constricts Vessel dilates

15. Modulation of Signal Pathway Up-regulation Down-regulation By decreasing the number of receptors By decreasing the binding affinity One explanation for drug tolerance Termination mechanism Disease and drugs

16. Modulation of Signal Pathway Disease and drugs target signal transduction proteins Table 6-3

17. Control Pathways: Overview Physiological control systems keep regulated variables within a desired range during homeostasis Figure 6-19 Regulated variable Within desired range No action required Outside desired range Sensor is activated Effectors Integrating center CONTROL SYSTEM sends signal to influence alters

18. Control Systems: Cannon’s Postulates 1.Nervous regulation of internal environment 2.Tonic control 3.Antagonistic control 4.One chemical signal can have different effects in different tissues

19. Control Systems: Tonic Control Tonic control of blood vessel diameter Figure 6-20 Time Electrical signals from neuron Change in signal rate Time Tonic control regulates physiological parameters in an up-down fashion. Increased signal rateDecreased signal rate

20. Control Systems: Antagonistic Control Figure 6-21 Antagonistic neurons control heart rate: some speed it up, while others slow it down. Stimulation by parasympathetic nerves decreases heart rate. Stimulation by sympathetic nerves increases heart rate. Heart beats Sympathetic neuron Parasympathetic neuron

21. Control Pathways Comparison of local and reflex control Figure 6-22 Brain Blood vessels Brain evaluates the change and initiates a response. LOCAL CHANGE LOCAL RESPONSE REFLEX RESPONSE is initiated by cells at a distant site. Systemic change in blood pressure sensed here. Stimulus Integrating center Response KEY

22. STIMULUS SENSOR or RECEPTOR AFFERENT PATHWAY INTEGRATING CENTER EFFERENT PATHWAY TARGET or EFFECTOR RESPONSE Feedback loop Response loop Control Pathways: Reflex Control Steps in a reflex control pathway Figure 6-23

23. Chemoreceptor (pH, gases, chemicals) Eyes (vision) Nose (smell) Tongue (taste) Ears (hearing, equilibrium) Osmoreceptor (osmolarity) Thermoreceptor (temperature) Baroreceptor (pressure) Proprioceptor (body position) Other mechanoreceptors (pain, vibration, touch) RECEPTORS Specialized cells or structures that convert various stimuli into electrical signals Cell membrane or intracellular receptor proteins Peripheral receptors lie outside the brain. Central receptors are in or close to the brain. can be Control Pathways: Receptors Multiple meanings of the word receptor Figure 6-24

24. Thermometer Wire Water temperature increases Heater Wire to heater Water temperature is 25° C Control box Water temperature is below the setpoint. Thermometer senses temperature decrease. Signal passes through wire to heater. Water temperature increases. Heater turns on. Signal passes from sensor to control box through the wire. Control box is programmed to respond to temperature below 29 degrees. STIMULUS SENSOR or RECEPTOR AFFERENT PATHWAY INTEGRATING CENTER EFFERENT PATHWAY TARGET or EFFECTOR RESPONSE Reflex steps 1 1 2 3 4 5 6 7 2 3 4 5 6 7 Control Pathways: Response Loop A nonbiological response loop Figure 6-25

25. Control Pathways: Response Loop Figure 6-25, step 1 Water temperature is 25° C Water temperature is below the setpoint. STIMULUS Reflex steps 1 1

26. Control Pathways: Response Loop Figure 6-25, steps 1–2 Thermometer Water temperature is 25° C Water temperature is below the setpoint. Thermometer senses temperature decrease. STIMULUS SENSOR or RECEPTOR Reflex steps 1 1 2 2

27. Control Pathways: Response Loop Figure 6-25, steps 1–3 Thermometer Wire Water temperature is 25° C Water temperature is below the setpoint. Thermometer senses temperature decrease. Signal passes from sensor to control box through the wire. STIMULUS SENSOR or RECEPTOR AFFERENT PATHWAY Reflex steps 1 1 2 3 2 3

28. Control Pathways: Response Loop Figure 6-25, steps 1–4 Thermometer Wire Water temperature is 25° C Control box Water temperature is below the setpoint. Thermometer senses temperature decrease. Signal passes from sensor to control box through the wire. Control box is programmed to respond to temperature below 29 degrees. STIMULUS SENSOR or RECEPTOR INTEGRATING CENTER Reflex steps 1 1 2 3 4 2 3 4 AFFERENT PATHWAY

29. Control Pathways: Response Loop Figure 6-25, steps 1–5 Thermometer Wire Wire to heater Water temperature is 25° C Control box Water temperature is below the setpoint. Thermometer senses temperature decrease. Signal passes through wire to heater. Signal passes from sensor to control box through the wire. Control box is programmed to respond to temperature below 29 degrees. STIMULUS SENSOR or RECEPTOR INTEGRATING CENTER EFFERENT PATHWAY Reflex steps 1 1 2 3 4 5 2 3 4 5 AFFERENT PATHWAY

30. Control Pathways: Response Loop Figure 6-25, steps 1–6 Thermometer Wire Heater Wire to heater Water temperature is 25° C Control box Water temperature is below the setpoint. Thermometer senses temperature decrease. Signal passes through wire to heater. Heater turns on. Signal passes from sensor to control box through the wire. Control box is programmed to respond to temperature below 29 degrees. STIMULUS SENSOR or RECEPTOR INTEGRATING CENTER EFFERENT PATHWAY TARGET or EFFECTOR Reflex steps 1 1 2 3 4 5 6 2 3 4 5 6 AFFERENT PATHWAY

31. Control Pathways: Response Loop Figure 6-25, steps 1–7 Thermometer Wire Water temperature increases Heater Wire to heater Water temperature is 25° C Control box Water temperature is below the setpoint. Thermometer senses temperature decrease. Signal passes through wire to heater. Water temperature increases. Heater turns on. Signal passes from sensor to control box through the wire. Control box is programmed to respond to temperature below 29 degrees. STIMULUS SENSOR or RECEPTOR AFFERENT PATHWAY INTEGRATING CENTER EFFERENT PATHWAY TARGET or EFFECTOR RESPONSE Reflex steps 1 1 2 3 4 5 6 7 2 3 4 5 6 7

32. Control Pathways: Setpoints Oscillation around the setpoint Acclimatization refers to natural adaptation Acclimation refers to induced adaptation Figure 6-26 Setpoint of function Negative feedback turns response loop off Response loop turns on Normal range of function

33. Control Pathways: Feedback Loops Negative and positive feedback Feedforward control refers to anticipatory responses The response counteracts the stimulus, shutting off the response loop Figure 6-27a (a) Negative feedback Response Stimulus Response loop shuts off Initial stimulus

34. (b) Positive feedback Response Stimulus Feedback cycle An outside factor is required to shut off feedback cycle. Initial stimulus Control Pathways: Feedback Loops The response reinforces the stimulus, sending the varible farther from the setpoint Figure 6-27b

35. Control Pathways: Feedback Loops Figure 6-28 Baby drops lower in uterus to initiate labor Cervical stretch stimulates causing Oxytocin release causes Uterine contractions Push baby against cervix Positive feedback loop Delivery of baby stops the cycle

36. (a) Control Pathways: Setpoints Circadian rhythms Figure 6-29a

37. Control Pathways: Setpoints Figure 6-29b (b) 9:00 A.M.

38. Control Systems: Speed and Specificity Table 6-4

39. Control Pathways: Review Figure 6-30 A simple endocrine reflex A simple neural reflex A complex neuroendocrine reflex Internal or external change Internal or external change Internal or external change Receptor Afferent path: sensory neuron Afferent path: sensory neuron Endocrine system sensor- integrating center Neural system integrating center Neural system integrating center Endocrine integrating center Efferent signal: hormone Efferent signal # 2: hormone Efferent neuron or neurohormone Efferent neuron Effectors Response

40. Control Pathways: Review Some basic patterns of neural, endocrine, and neuro-endocrine control pathways Figure 6-31 Neuroendocrine reflexes Simple endocrine reflex Endocrine cells Response Hormone Neurohormone Neurotransmitter Hormone #2 Stimulus Simple neural reflex Neurohormone reflex Receptor Afferent neuron Efferent neuron Neuro- transmitter Target cell Blood vessel Response Stimulus KEY Stimulus Neurotransmitter Neurohormone Classic hormone Endocrine integrating center Receptor (sensor)Efferent neuron Sensory neuron (afferent pathway) CNS integrating center Target cell (effector) Efferent pathways 123 4 5 6

41. Control Pathways: Review Figure 6-31, step 1 Simple neural reflex Receptor Afferent neuron Efferent neuron Neuro- transmitter Target cell Response Stimulus KEY Stimulus Neurotransmitter Neurohormone Classic hormone Endocrine integrating center Receptor (sensor) Efferent neuron Sensory neuron (afferent pathway) CNS integrating center Target cell (effector) Efferent pathways 1

42. Control Pathways: Review Figure 6-31, steps 1–2 Simple neural reflex Neurohormone reflex Receptor Afferent neuron Efferent neuron Neuro- transmitter Target cell Blood vessel Response Stimulus KEY Stimulus Neurotransmitter Neurohormone Classic hormone Endocrine integrating center Receptor (sensor) Efferent neuron Sensory neuron (afferent pathway) CNS integrating center Target cell (effector) Efferent pathways 12

43. Control Pathways: Review Figure 6-31, steps 1–3 Neuroendocrine reflexes Simple neural reflex Neurohormone reflex Receptor Afferent neuron Efferent neuron Neuro- transmitter Target cell Blood vessel Response Stimulus KEY Stimulus Neurotransmitter Neurohormone Classic hormone Endocrine integrating center Receptor (sensor) Efferent neuron Sensory neuron (afferent pathway) CNS integrating center Target cell (effector) Efferent pathways 123

44. Control Pathways: Review Figure 6-31, steps 1–4 Neuroendocrine reflexes Endocrine cells Response Hormone Neurohormone Neurotransmitter Stimulus Simple neural reflex Neurohormone reflex Receptor Afferent neuron Efferent neuron Neuro- transmitter Target cell Blood vessel Response Stimulus KEY Stimulus Neurotransmitter Neurohormone Classic hormone Endocrine integrating center Receptor (sensor) Efferent neuron Sensory neuron (afferent pathway) CNS integrating center Target cell (effector) Efferent pathways 123 4

45. Control Pathways: Review Figure 6-31, steps 1–5 Neuroendocrine reflexes Endocrine cells Response Hormone Neurohormone Neurotransmitter Hormone #2 Stimulus Simple neural reflex Neurohormone reflex Receptor Afferent neuron Efferent neuron Neuro- transmitter Target cell Blood vessel Response Stimulus KEY Stimulus Neurotransmitter Neurohormone Classic hormone Endocrine integrating center Receptor (sensor) Efferent neuron Sensory neuron (afferent pathway) CNS integrating center Target cell (effector) Efferent pathways 123 4 5

46. Control Pathways: Review Figure 6-31, steps 1–6 Neuroendocrine reflexes Simple endocrine reflex Endocrine cells Response Hormone Neurohormone Neurotransmitter Hormone #2 Stimulus Simple neural reflex Neurohormone reflex Receptor Afferent neuron Efferent neuron Neuro- transmitter Target cell Blood vessel Response Stimulus KEY Stimulus Neurotransmitter Neurohormone Classic hormone Endocrine integrating center Receptor (sensor) Efferent neuron Sensory neuron (afferent pathway) CNS integrating center Target cell (effector) Efferent pathways 123 4 5 6

47. Control Pathways: Review Table 6-5

48. Summary Cell-to-cell communication Electrical signals Chemical signals Four methods

49. Summary Signal pathways Signal transduction Amplification Second messengers Receptor-enzymes G-proteins Integrin Ligand-gated ion channels

50. Summary Novel signal molecules Calcium NO CO H 2 S Lipids Modulation of signal pathways Agonist versus antagonist Up-regulation and down-regulation

51. Summary Control pathways Cannon’s postulates Local control Reflex control Feedback loops Negative feedback Positive feedback Feedforward control Circadian rhythms