Transcript Week 1, Introductionx

Introductory Physiology
Biol 141
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Instructor: Lara LaDage
Office: 214 Hawthorn
Phone: 949-5772
Email: [email protected]
Office hours: Tuesdays 1-2pm, or by
appointment
My background
Why are you here?
• It fit my schedule
Bad idea
• I need it to graduate
Bad idea
• Dr. LaDage is too cool for words
Lie
You should be here if you…
• Are interested in integrating biological
disciplines
• Are academically inclined
• Enjoy working hard
What does your future hold?
I hope you can appreciate the value
of showing up to class.
100
Average grade percentage
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Zero
One
Two
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Number of absences
Five
Six
Seven
How to succeed in this class…
• Be in class, on time, every day
• Prep for class by reading and reviewing book
and previous material
• Take effective notes
• Actively participate in class and ask questions
• Rework class notes within 24 hours of class
• Use practice questions as self quizzes
• Come to office hours if you need help!
Course management
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Syllabus
Tour of Canvas
Register your iClicker
Pre-assessment
In this course, you will…
• Become familiar with the mechanisms that
underlie physiological systems
In this course, you will…
• Understand how different physiological
systems integrate with others
What is physiology?
• The study of the normal functioning of living
organisms, including all chemical and physical
processes
Why study physiology?
Why study physiology?
• Integration across disciplines
– e.g., biochemistry, genetics, ecology, evolution
PHYSIOLOGY
ECOLOGY
CHEMISTRY
Atoms
Molecules
MOLECULAR
BIOLOGY
Cells
CELL
BIOLOGY
Tissues
Organs
Organ
systems
Organisms
Populations of
one species
Ecosystem of
different species
Biosphere
Why study physiology?
• Integration across
systems
Why study physiology?
• Emergent properties of complex systems
Themes in Physiology
• Structure and function are closely related
Themes in Physiology
• Pathways/transformation of energy
Themes in Physiology
• Information flow coordinates body function
Themes in Physiology
• Homeostasis maintains internal stability
Homeostasis
• Maintains internal balance- a
rough status quo
• Keeps parameters more or less
constant
• Does not mean “no change” or
equilibrium
Homeostasis
• Regulation of the body’s internal environment
• Keeping internal environment stable
Why?
• Why keep the internal environment relatively
constant?
Biological reactions have optima
Biological reactions have optima
• Maintaining optima requires regulation
• How systems regulate is one of the key
concerns of physiology
Regulating homeostasis
• External or internal change
• Loss of homeostasis
• Body senses this and physiologically attempts
to compensate
Homeostasis
Organism in
homeostasis
• Successful compensation
– Homeostasis
reestablished
Internal
change
External
change
Internal change
results in loss
of homeostasis
• Failure to compensate
– Disease
• Study of failure to
compensate is
pathophysiology
Organism attempts
to compensate
Compensation fails
Illness or disease
Compensation succeeds
Wellness
How is homeostasis maintained?
• Regulated variables are kept within normal
range by control mechanisms
– Keeps near set point, or optimum value
• Control systems
– Input signal
– Integrating center
– Output signal
Reflex steps
Water temperature is
below the setpoint.
Water temperature
is 25° C
Feedback loop
STIMULUS
Thermometer
senses temperature
decrease.
SENSOR
Signal passes from
sensor to control
box through the wire.
INPUT
SIGNAL
Thermometer
Water
temperature
increases
Wire
Control box is
programmed
to respond to
temperature below
29 degrees.
Signal passes
through wire to
heater.
Control
box
Heater turns on.
Wire to heater
Feedback
loop
INTEGRATING
CENTER
OUTPUT
SIGNAL
TARGET
Heater
Water temperature
increases.
RESPONSE
But why doesn’t the temperature just
keep going up???
Feedback loops
• Response to perturbations in the system
• Two types:
– Negative feedback stabilizes variable
– Positive feedback reinforces stimulus
Negative feedback loops
• Dampen/decrease amount of change
• Maintain parameters at or near optimum
levels
Negative feedback loops
• Permit only small fluctuations around a set
point (optimum)
• When fluctuations get too large, response
dampens fluctuations
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Setpoint
of function
Negative feedback turns
response loop off
Temperature (°C)
31
30
Normal
range of
function
29
Response loop
turns on
28
Time
Set point- your optimum
Set point- your optimum
Another example…
Body temperature- Too Hot!
Body temperature- Too Cold!
Positive feedback loop
• Change is accentuated rather than opposed
(pushes beyond set point and normal range)
• Enhances the response, keeps building
• Drives a process to completion
• Fairly rare, unstable
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