1 Human Physiology Bio 5 Denise Lim, Instructor

2 ParScore Scantrons for Lecture Tests  Orange, 8.5" X 11"  Do not wait until the day of the exam to buy them

3 Use Your Textbook Wisely  Glossary/Index  Concept Reviews (Blue Headings)  "Focus On…” in Chapter 1 –Concept Mapping –Graphing  Concept Checks –Answers at end of chapter  Running Problems (case studies)  Chapter Summaries  Chapter Questions (Answers in Appendix A)  Appendix B: Physics and Math basics

Some other words of advice  Manage your time well  Pay attention to detail  Learn to be a good communicator  Be professional 4

5 Introduction Chapter 1 What is Physiology?

6 Why is physiology so hard to study?  Complexity –Conditions both inside and outside the body constantly change –Interplay between body systems change as conditions change  Variation –Genetic predisposition, life style  Safety, ethics –Investigative methods can be invasive

7 Function and Mechanism: "Why" versus "How"  "Why" = Purpose  "How" = Mechanism  Need to understand both purpose and mechanistic, but focus on mechanism –Teleology = purpose

8 Organization: small to big  Atoms  Molecules  Cells  Tissues  Organs  Organ systems

9 Important physiological themes  Structure/Function relationships  Energy –Metabolism  Communication  Homeostasis & Regulation –Maintaining the constancy of the internal environment within a range of tolerance

 What goes in must go out  What is lost must be replaced 10 Homeostasis is maintained through mass balance and mass flow Fig. 1.5, pg. 12

Flow of exchange between the body’s external and internal environment 11 Fig. 1.4, pg 12

12 Local and long- distance control of homeostasis  Local response: intrinsic control  Reflex response: extrinsic control Fig. 1-8, pg. 15

13 Homeostasis depends on communication and feedback  Stimulus  Receptor or sensor –Detects the stimulus  Integrating center determines setpoint  Effector produces response Fig. 1-9, pg. 14

Activity 1 14

15 Negative feedback counteracts the stimulus, maintains conditions within a range around a setpoint (range of tolerance) Fig. 1-10, pg. 17

16 Example: blood glucose  Glucose levels drop after fasting: hungry  Glucose rises after a meal  Insulin brings levels back to setpoint  May overshoot Fig , pg. 761

Glucose Homeostasis  Stimulus –Increased blood glucose  Receptor –Beta cells in pancreas  Afferent Pathway –ATP production increases when more glucose is available  Integrating Center –Pancreas: releases insulin when ATP in beta cells is high  Efferent Pathway –Insulin  Effector –Liver and muscle cells: insulin triggers glucose uptake  Response –Decreases blood glucose 17

18 Positive feedback amplifies body’s response; NOT homeostatic  Inflammatory response  Childbirth Fig. 1-11b, pg. 17

Figure 1.12 A positive feedback loop Baby drops lower in uterus to initiate labor Push baby against cervix Cervical stretch causing stimulates Uterine contractions Oxytocin release causes Positive feedback loop Delivery of baby stops the cycle Fig. 1.12, pg 18

20  Presence of food in stomach activates pepsin  Emptying stomach shuts it off HCl production in stomach