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Human Physiology
Bio 5
Denise Lim, Instructor
1
ParScore Scantrons for
Lecture Tests
z Orange, 8.5" X 11"
z Do not wait until the day of the exam
to buy them
2
Use Your Textbook Wisely
Glossary/Index
Concept Reviews (Blue Headings)
"Focus On…” in Chapter 1
– Concept Mapping
– Graphing
Concept Checks
– (Answers in Appendix A)
Running Problems (case studies)
Chapter Summaries
Review Questions (Answers in Appendix A)
Appendix B: Physics and Math basics
3
Some other words of advice
Manage your time well
Pay attention to detail
Learn to be a good communicator
Be professional
4
Introduction
Chapter 1
What is Physiology?
The integration of function across
many levels of organization
5
Organization: small to big
Atoms
Molecules
Cells
Tissues
Organs
Organ
systems
6
Function and Mechanism:
"Why" versus "How"
"Why" = Purpose
"How" = Mechanism
Need to understand both purpose and
mechanistic, but focus on mechanism
7
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 between individuals
– Genetic predisposition, life style
Safety, ethics
– Investigative methods can be invasive
8
Important physiological themes
Structure/Function relationships
Energy
–Metabolism
Communication coordinates
function
Homeostasis & Regulation
–Maintaining the constancy or
stability of the internal environment
within a range of tolerance
9
Homeostasis is maintained
through mass balance and mass
flow
What goes in must go out
What is lost must be replaced
Fig. 1.5, pg. 11
10
Flow of exchange between
the body’s external and
internal environment
Fig. 1.4, pg 11
11
Local versus
longdistance
control of
homeostasis
Fig. 1-9, pg. 14
Local response: intrinsic control
Reflex response: extrinsic control
12
Homeostasis depends on
communication and feedback
Stimulus
Receptor or sensor
– Detects the stimulus
Integrating center
determines setpoint
Effector produces
response
Fig. 1-10, pg. 15
13
Activity 1
14
Negative feedback counteracts the
stimulus, maintains conditions within
a range around a setpoint
(range of tolerance)
Fig. 1-11, pg. 16
15
Example: blood glucose
Glucose levels
drop after
fasting: hungry
Glucose rises
after a meal
Insulin brings
levels back to
setpoint
May overshoot
Fig. 22-19, pg. 716
16
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
Positive feedback amplifies
body’s response; NOT
homeostatic
Inflammatory
response
Childbirth
Fig. 1-12b, pg. 16
18
Figure 1.12 A positive feedback loop
Baby drops
lower in uterus to
initiate labor
Cervical
stretch
causing
stimulates
Push baby
against
cervix
Oxytocin
release
Positive feedback loop
causes
Uterine
contractions
Delivery of baby
stops the cycle
Fig. 1.13, pg 17
HCl production in stomach
Presence of
food in
stomach
activates
pepsin
Emptying
stomach
shuts it off 20