Introductory Physiology Biol 141 Instructor: Lara LaDage Office: 214 Hawthorn Phone: 949-5772 Email: ldl18@psu.edu 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 Dr. LaDage is too cool for words Bad idea Bad idea 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.

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 CHEMISTRY Atoms Cells Tissues Molecules Organs PHYSIOLOGY CELL BIOLOGY MOLECULAR BIOLOGY ECOLOGY 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 Successful compensation Failure to compensate Compensation fails Internal change results in loss of homeostasis Organism in homeostasis Organism attempts to compensate External change Internal Compensation succeeds Wellness Illness or disease Successful compensation Homeostasis reestablished Failure to compensate Disease Study of failure to compensate is pathophysiology

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 RESPONSE Water temperature increases. TARGET OUTPUT SIGNAL Signal passes through wire to heater. Heater turns on. INTEGRATING CENTER Control box is programmed to respond to temperature below 29 degrees. INPUT Signal passes from sensor to control box through the wire. STIMULUS Water temperature is below the setpoint. SENSOR Thermometer senses temperature decrease. Reflex steps Feedback loop is 25° C Water temperature increases Control box Wire Wire to heater Heater Feedback loop

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

Time Response loop turns on Setpoint of function Normal range of function Negative feedback turns response loop off Temperature (°C) 28 29 30 31 32

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