Homeostasis

We have discuss Definition of homeostasis which is state of balance .then The scope of human physiology in homeostasis means the feature and characteristics of homeostasis control system and feedback system. Negative and positive feedback when and where it place . Also components of homeostasis control system which include reflex arc, local homeostatic response . And intercellular chemical messengers .

1. HOMEOSTASIS Jamilah saad Alqahtani CNS,MSN,NS,RGN,BSN, OR Specialist hemostasis jamilah saad Alqahtani 1

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3. Objectives The student will be able to understand: Def homeostasis The scope of human physiology Homeostasis: defining feature of physiology General characteristics of homeostatic control system: Homeostasis Control system Feedback system Components of homeostasis control system Process related to homeostasis Nursing and homeostasis

4. Outlines Introduction Def homeostasis The scope of human physiology Homeostasis: defining feature of physiology General characteristics of homeostatic control system: Homeostasis Control system Feedback system Components of homeostasis control system Process related to homeostasis Nursing and homeostasis Summary

5. Homeostasis Homeo –same Astasis -standing still Dynamic equilibrium hemostasis jamilah saad Alqahtani 5

6. Homeostasis Is the most fundamental of physiology

7. Homeostasis Homeostasis is the maintenance of the body's internal environment within a narrow range of normal values. It is an ongoing process, with changes constantly occurring in the body. In health, normal homeostatic mechanisms function to maintain fluid, electrolyte, and acid-base balance. In illness, one or more of the regulating mechanisms may be affected, or an imbalance may become too great for the body to correct without treatment. hemostasis jamilah saad Alqahtani 7

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9. The scope of human physiology how is the body organized ? Cell(the basic unit of living organisms ) Tissue Organs and organ system Body fluid compartments

10. Many organs are organized into small similar subunits referred to as functional units Example: nephrons are function in kideny hemostasis jamilah saad Alqahtani 10

11. Body Fluid compartments H2o present within and around the cells of the body and within blood vessels

12. Fluid in the body hemostasis jamilah saad Alqahtani 12

13. This led to concept that homeostasis is state of dynamic constancy hemostasis jamilah saad Alqahtani 13

14. Homeostasis: defining feature of physiology The body’s internal environment is the extracellular fluid. The function of organ systems is to maintain a stable internal environment-homeostasis. Numerous variables within the body must be maintained homeostatically. When homeostasis is lost for one variable , it may trigger a series of changes in other variables. Example (consider swing in blood glucose level over the course of day hemostasis jamilah saad Alqahtani 14

15. Homeostasis denotes the stable condition of the internal environment that results from operation of compensatory homeostatic control system. General characteristics of homeostatic control system:

16. General characteristics of homeostatic control system: Homeostasis control system Feedback system

17. Homeostasis control system The activities of cells, tissue and organs must be regulated and integrated with each other so that any change in extra cellular fluid initiates a reaction to correct the change. The compensating mechanisms that mediate such response are performed by homeostasis control system

18. Example1, Regulation of body temperature

19. The body undergoes no net gain or loss of heat and body temp remains constant (a steady stat) Intake = Output

20. Stability of internal environment variables is a achieved by balancing of input and outputs.

21. Example2, Regulation of body glucose level hemostasis jamilah saad Alqahtani 21

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23. Feed back system Negative positive

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25. Negative feedback Is a change in the variable being regulated brings about responses that tend to push the variable in the direction opposite to the original change. Negative feedback minimizes changes from set point of the system leading to stability.

26. Negative feed back

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28. Positive feedback Positive feedback accelerates a process leading to explosive system ( in positive feedback no means of stopping ) hemostasis jamilah saad Alqahtani 28

29. Resetting of set point Change in the external environment can displace variable from its set point . In additional the set point for many regulated variables can be physiologically reset to new value. Common example : fever - high body temp response to - infection is some what analogous - to raising the home’s thermostat homeostatic control system still working during fever - by maintain temp at a higher value .

30. That is why This regulated rise in the body temp is adaptive for fighting the infection, because elevated temp inhibits proliferation of some pathogens . In fact; this is why fever often preceded by chills and shivering.

31. In fact the points can be reset adaptive as in the case of fever . Highly important challenges for medicine

32. Some important generalizations about homeostatic control systems 1- stability of an internal environmental variable is achieved by balancing inputs and outputs. It is not the absolute magnitudes of the inputs and outputs that matter but the balance between them. 2-in negative feedback systems a change in variable being regulated brings about responses that end to move the variable in the direction opposite the original change- that Is back toward the initial value (set point) 3-homeostasis control systems cannot maintain complete constancy of any given feature of internal environment. Therefore, any regulated variable will have a more-or – less narrow range of normal values depending on the external environmental conditions 4-the set point of some variables regulated by homeostatic control systems can be reset—that is physiologically raised or lowered 5-it is not always possible for homeostasis control systems to maintain constancy in every variable in response to an environmental challenges. There is hierarchy of importance so that the constancy of certain variables may be altered marked to maintain others within their normal range

33. Feed forward regulation It anticipates changes in regulated variable, improves the speed of the body’s homeostatic responses and minimizes fluctuations in the level of the variable being regulated. Work in conjunction with feedback system

34. Feed forward regulation Example temp sensitive nerve cells trigger negative feedback regulation of body temp when it beings to fails are located inside the body . In additional there are temp sensitive nerve cells in skin and it is in effect.

35. Components of homeostatic control system Reflexes Local homeostatic responses Intercellular chemical messengers

36. Components of homeostatic control system the components of a reflex arc are receptor, afferent pathway, integrating center, efferent pathway and effector . The pathway may be neural or hormonal.

37. Local homeostatic responses are also stimulus-response sequences, but they occur only in the area of stimulus, with neither nerves nor hormones involved. Components of homeostatic control system hemostasis jamilah saad Alqahtani 37

38. Components of homeostatic control system Intercellular communication is essential to reflexes and local responses and is achieved by neurotransmitters, hormones and paracrine or autocrine agents . Less common is interecellular communication through either gap junctions or cell-bound messengers.

39. Processes related to homeostasis Acclimatization Biological rhythms Balance in homeostasis of chemical substances in the body

40. Acclimatization Acclimatization is an improved ability to respond to an environmental stress. The improvement is induced by prolonged exposure to the stress with no change in genetic endowment. If acclimatization occurs early in life, it may be irreversible and is known as developmental acclimatization.

41. Biological rhythms Provide a feed forward component to homeostatic control systems. The rhythms are internally driven by brain pacemakers, but are entrained by environmental cues, such as light, which also serve to phase-shift (reset)the rhythms when necessary. In the absence of cues, rhythms free run.

42. Balance in homeostasis of chemical substances in the body Is achieved by matching inputs and outputs. Total-body balance of substance may be negative, positive, or stable.

43. Nursing and homeostasis Homeostasis is important in nursing because the body mobilizes its fight-or-flight reaction in an attempt to maintain homeostasis. This can result in sweating, breathlessness, rapid heartbeat, shivering, and trembling. The internal equilibrium of the body is the gauge of whether it is functioning properly or not. With homeostasis, the body's systems are stable and self-perpetuating. Many of the tests that a nurse performs on a patient, such as taking a temperature or a blood pressure, are tests to determine whether the patient's body is in homeostasis or in distress. Homeostasis is highly desirable, because it keeps the body functioning as it should be. hemostasis jamilah saad Alqahtani 43

44. The body as a homeostatic system maintains its structure and functions by means of: a multiplicity of dynamic equilibriums rigorously controlled by interdependent regulation mechanisms. Such a system reacts to every change in the environment, or to every random disturbance, through a series of modifications of equal size and opposite direction to those that created . hemostasis jamilah saad Alqahtani 44

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46. S ummary We have discuss Definition of homeostasis which is state of balance .then The scope of human physiology in homeostasis means the feature and characteristics of homeostasis control system and feedback system. Negative and positive feedback when and where it place . Also components of homeostasis control system which include reflex arc, local homeostatic response . And intercellular chemical messengers . Process related to homeostasis like acclimatization , biological rhythms and the balance of substances in the body .At last Nursing and homeostasis hemostasis jamilah saad Alqahtani 46

47. Any questions hemostasis jamilah saad Alqahtani 47

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49. Thank you hemostasis jamilah saad Alqahtani 49