Introduction to Human Physiology

1. Introduction to Human Physiology XIA Qiang（夏强）, MD & PhD Department of Physiology Room 518, Block C, Research Building School of Medicine, Zijingang Campus Email: xiaqiang@zju.edu.cn Tel: ☆88206417 (Undergraduate School), 88208252 (Medical School)

2. Graduate Attributes and Capabilities Attitudes Knowledge Skills

3. Learning Philosophy I hear and I forget, I see and I remember, I do and I understand.

4. Handheld device software • Epocrates: drugs manual • >3300drugs • More than 45% medical doctors used • DynaMed: evidence based medicine database

5. https://www.medsch.ucla.edu/mobile/requirement/req-2014.htm

6. http://guides.library.harvard.edu/hms/mobileApps

7. Course Structure • Lectures: 80 academic hours • 5 a.h./week • 2 a.h. on Mon., 3 a.h. on Wed. • Practicals: 64 a.h. • 4 a.h./week • Begin from second week

8. Evaluation • “Double pass” policy: • Total >= 60 • Final examination >= 60 • Weekly assessments & midterm exam >= 60 Participation: 5% Practical reports: 15% Weekly assessments (from Summer Week 2 on), mini-tests at lecture & midterm exam: 30% Final examination: 50%

9. Recommended textbook Widmaier EP, Raff H, Strang KT (2010 or later) Vander’s Human Physiology: The Mechanisms of Body Function, McGraw-Hill.

10. Course website • Course website: • http://m-learning.zju.edu.cn • Demo

11. Human Physiology • Specificcharacteristics, functions and mechanisms of the human body that make it a living being What ? How ?

12. Body Components skin = barrier entry = respiratory & GI transport = CV & diffusion exit = renal & GI Differentiated Cells - specialized function Tissues - groups of cells with related function (muscle, nervous, connective, & epithelium) Organ- functional unit Organ system – several organs act together to perform specific function

13. ICF ISF plasma organs external environment internal environment Fluid Compartments

14. Body Fluid = 60% of Body Weight (BW) Plasma 5% of BW Extracellular Fluid 1/3, 20% of BW Interstitial Fluid 15% of BW 70 kg Male, 42 L Intracellular Fluid 2/3, 40% of BW Internal environment

15. Extracellular Fluid= Internal Environment

16. Homeostasis • Homeostasis(from the Greek words for “same” and “steady”): maintenance of static or constant conditions in the internal environment • Central theme of physiology Walter B. Cannon

17. Components of Homeostasis: • Concentration of O2 and CO2 • pH of the internal environment • Concentration of nutrients and waste products • Concentration of salt and other electrolytes • Volume and pressure of extracellular fluid

18. How is homeostasis achieved? ----Regulation Body's systems operate together to maintain homeostasis: Skin system Skeletal and muscular system Circulatory system Respiratory system Digestive system Urinary system Nervous system Endocrine system Lymphatic system Reproductive system

19. Homeostasis and Illness

20. Regulation of body functions • Nervous Regulation • Humoral Regulation • Autoregulation

21. Nervous regulation Reflex Knee jerk reflex

22. Reflex Arc • Receptor • Afferent (sensory) nerve • Reflex center (brain or spinal cord) • Efferent (motor) nerve • Effector

23. Hormone Endocrine cells Receptor Hormone Humoral regulation Traditional description of humoral regulation by hormone

24. Endocrine action:the hormone is distributed in blood and binds to distant target cells • Paracrine action:the hormone acts locally by diffusing from its source to target cells in the neighborhood • Autocrine action:the hormone acts on the same cell that produced it

25. Neuroendocrine (Neurosecretion) Vasopressin Oxytocin

27. Autoregulation Definition:Intrinsic (independent of any neural or humoral influences) ability of an organ to maintain a constant blood flow despite changes in perfusion pressure Mechanism: Stretch-activated constriction of vessels Significance: Maintenance of near-constant cerebral, renal and coronary blood flow

28. 80~180 mmHg

29. Control systems of the body CYBERNETICS or Control and Communicationin the Animal and the Machine (MIT Press 1948) Norbert Wiener (1894-1964) Originator of Cybernetics

30. Stimulus Response Control Center Effectors 1. Non-automatic Control System Open-loop system Seldom seen under physiological conditions Stress

32. Stimulus Response Control Center Effectors 2. Feedback Control System Closed-loop system Automatic control Negative feedback Positive feedback

33. Negative feedback:common A change in a condition leads to responses from the effectors which counteracts that change

34. Examples: Regulation of blood pressure, Regulation of body temperature, Regulation of hormone release…

35. Correction Gain= Error Gain of the negative feedback: The degree of effectiveness with which a control system maintains conditions

36. + Positive feedback:uncommon A change in a condition leads to responses from the effectors which amplifies that change

37. Examples: Child birth Micturition Blood coagulation Vicious circle under pathophysiological conditions…

38. Disturbance Monitor Stimulus Response Control Center Effectors 3. Feed-forward Control Often seen in nervous system Rapid Adaptive control Examples: some muscle contraction, conditioned reflex

40. Summary • Terms: • Internal environment • Homeostasis • Negative feedback • Positive feedback • Regulation of body functions

41. THANK YOU FOR YOUR ATTENTION!