1

Human Physiology

Bio 5Denise 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 WiselyGlossary/IndexConcept Reviews (Blue Headings) "Focus On…” in Chapter 1

– Concept Mapping– Graphing

Concept Checks– Answers at end of chapter

Running Problems (case studies)Chapter SummariesChapter Questions (Answers in Appendix A)Appendix B: Physics and Math basics

Some other words of advice

Manage your time wellPay attention to detailLearn to be a good communicatorBe professional

4

5

IntroductionChapter 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 changeVariation

– Genetic predisposition, life styleSafety, ethics

– Investigative methods can be invasive

7

Function and Mechanism:"Why" versus "How"

"Why" = Purpose"How" = MechanismNeed to understand both purpose and

mechanistic, but focus on mechanism– Teleology = purpose

8

Organization: small to big

AtomsMoleculesCellsTissuesOrgansOrgan

systems

9

Important physiological themes

Structure/Function relationshipsEnergy

–Metabolism CommunicationHomeostasis & Regulation

–Maintaining the constancy of the internal environment within a range of tolerance

What goes in must go outWhat 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

11Fig. 1.4, pg 12

12

Local and long-

distance control of

homeostasis

Local response: intrinsic controlReflex response: extrinsic control

Fig. 1-8, pg. 15

13

Homeostasis depends on communication and feedback

StimulusReceptor or sensor

– Detects the stimulusIntegrating center

determines setpointEffector 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 glucoseGlucose levels

drop after fasting: hungry

Glucose rises after a meal

Insulin brings levels back to setpoint

May overshoot Fig. 22-19, 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

Cervicalstretch

causing stimulates

Uterine contractions

Oxytocinrelease

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 offHCl production in stomach