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Introductory Physiology Biol 141 • • • • • 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 90 80 70 60 50 40 30 20 10 0 Zero One Two Three Four 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 • • • • 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 32 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