Lecture #1: What is Physiology

Q: What is the origin of the word "physiology"?

From Greek PHUSIOLOGIA, meaning “knowledge of nature.”

Q: Define physiology.

The study of the normal functioning of living organisms and their parts, including chemical and physical interactions.

Q: What are emergent properties?

Properties that arise from non-linear interactions between components; the whole is greater than the sum of its parts.

Q: What are the 4 characteristics that define life?

1) Made of one or more cells
2) Regulate internal environment
3) Respond to stimuli
4) Capable of reproduction

Q: Why aren’t viruses considered alive?

They cannot reproduce on their own.

Q: Why is physiology important?

Helps treat disease (pathophysiology), understand environmental stress coping, and explore the question “What is life?”

Q: Why is physiology exciting today?

Advances in genomics, personalized medicine, molecular evolution, drug discovery, bioinformatics, bioengineering, robotics, and nanotechnology.

Q: Name the main themes in physiology.

1) Structure and function are related
2) Information flow coordinates body function
3) Need for energy
4) Evolution (Dobzhansky: “Nothing in Biology Makes Sense Except in the Light of Evolution”)

Q: What is a key theme in physiology regarding structure and function?

Structure and function are closely related at the organ, cell, and molecular levels.

Q: How does information flow coordinate body function?

Through homeostasis and control systems.

Q: Why is energy a theme in physiology?

Living organisms require energy to maintain life and perform functions.

Q: How is evolution a theme in physiology?

Evolution explains why organisms are structured and function as they do; Dobzhansky: “Nothing in Biology Makes Sense Except in the Light of Evolution.”

Q: Define homeostasis.

Ability to maintain a relatively constant internal environment despite external changes.

Q: Who coined “homeostasis” and when?

Walter Cannon, 1929.

Q: Who introduced the concept of the internal environment?

Claude Bernard, 1800s (“la fixité du milieu intérieur”).

Q: Give examples of regulated variables in homeostasis.

Temperature, pH, salinity, oxygen/CO₂, nutrients.

Q: Does homeostasis mean equilibrium?

No; it’s a dynamic steady state, not absolute equilibrium.

Q: Does homeostasis mean never changing?

No; internal parameters change in response to challenges (some prefer “homeodynamics”).

Q: What is required for homeostasis?

Control systems that monitor and adjust regulated variables.

Q: What are examples of control system types?

Local (cell/tissue level) and long-distance (endocrine or nervous system).

Q: Name three control system mechanisms mentioned.

Negative feedback, positive feedback, feedforward

Q: What is the role of a control system in physiology?

To monitor and adjust regulated variables like internal temperature, pH, and salt balance.

Q: What are the types of control systems based on communication distance?

Local (cell/tissue level) and long-distance (endocrine or nervous system).

Q: What is negative feedback?

A response that counteracts a change to restore homeostasis.

Q: Example of negative feedback?

Insulin lowering blood glucose after a meal.

Q: What is positive feedback?

A response that amplifies a change, moving system away from baseline.

Q: Example of positive feedback?

Oxytocin during childbirth increasing contractions.

Q: What is feedforward control?

Anticipatory response to a predicted change before it occurs.

Q: Example of feedforward?

Salivation at the smell of food.