Physiology Chapter 1 Quiz

Chapter 1: Physiology

• Physiology is the study of the normal functioning of a living organism and its parts.
• Levels of organization range from atoms to molecules, cells, tissues, organs, organ systems, and finally, the organism.

Homeostasis

• Homeostasis is maintaining a stable internal environment, despite external fluctuations.

• Homeostasis is a dynamic steady state, not static equilibrium.

• Sickness or disease occurs when homeostasis is disrupted for an extended time.

• Negative feedback: Reverses a change to return to a set point.

  • Example: Regulating body temperature; when body temperature rises, sweating occurs to cool you down.

• Positive feedback: Amplifies a change, pushing the system further away from a set point.

  • Example: Childbirth, where oxytocin release triggers uterine contractions, which cause more oxytocin release.

• Feedforward control: Anticipates changes and activates mechanisms to prevent deviations.

  • Example: Salivation before eating.

Chapter 5: Osmotic and Electrical Equilibrium

• Osmotic Equilibrium: The total solute concentration is the same on both sides of the cell membrane, preventing net water movement.

• Chemical Disequilibrium: Ions and other solutes have unequal concentration across cell membranes.

• Electrical Disequilibrium: An uneven distribution of ions creates a difference in electrical charge across the cell membrane, creating a resting membrane potential (typically -70 mV). This is maintained by ion channels and pumps.

• Example of a primary active transport carrier: Sodium-potassium ATPase pump (Na+/K+ ATPase).

  • This pump moves 3 sodium ions out of the cell and 2 potassium ions into the cell, using energy from ATP.

Membrane Transport

• Simple Diffusion: Passive movement of molecules down their concentration gradient. Examples include oxygen and carbon dioxide.

• Protein-Mediated Transport:

  • Facilitated Diffusion: Passive transport with carrier proteins.
  • Active Transport: Requires energy to move molecules against their concentration gradient, using carrier proteins or pumps.
  • Ion Channels: Passive transport allowing specific ions to pass based on electrochemical gradient.

• Vesicular Transport: Active transport involving vesicles for moving large molecules or substances, like in exocytosis (releasing molecules) and endocytosis (taking molecules into the cell structures).

Comparing Transport Mechanisms

• Channels: Passive, fast, have selectivity based on size and charge.
• Facilitated Diffusion Carriers: Passive, slower, conformational changes involved.
• Active Transport Carriers: Active, requires energy, usually moves molecules against their concentration gradient.

Carrier-Mediated Transport

• Specificity: Carriers are selective (e.g., glucose transporters).
• Competition: Similar molecules compete for the same carrier.
• Saturation: Maximum transport rate.

Membrane Potential

• Changing ion permeability alters membrane potential.
  • Increased Na+ permeability depolarizes the membrane (e.g., during action potential).
  • Increased K+ permeability repolarizes the membrane
  • Increased Cl- permeability may also depolarize the membrane.