Lecture 04

• What is the primary focus of transport across membranes?

  How molecules cross biological membranes
• What are the two main transport routes mentioned?

  Transcellular and paracellular diffusion
• What are the main transport mechanisms across membranes?

  • Passive diffusion
  • Facilitated diffusion
  • Active transport
  • Vesicular transport (pinocytosis)
  • Cell to cell transport

  
• What is an example of an antiport transport mechanism?

  Sodium-potassium pump

  
• What is the characteristic of biological membranes regarding permeability?

  They are hydrophobic and selectively permeable
• How do hydrophilic and hydrophobic drugs differ in passive diffusion?

  Hydrophilic drugs diffuse poorly, hydrophobic well
• How can membrane permeability of drugs be improved?

  By removing polar functional groups
• Name three examples of drugs that can increase passive diffusion.

  Epinephrine, ephedrine, methamphetamine

  
• What are the characteristics of facilitated diffusion?

  • Selectively allows substances to cross membranes
  • Transport proteins span the membrane
  • Channels facilitate diffusion
  • Specific to certain molecules
  • Types: channel proteins (aquaporin) and carrier proteins
• What is the function of aquaporin?

  Allows quick diffusion of water
• How do membrane carrier proteins function?

  They change shape to translocate solutes
• What is GLUT1?

  A carrier protein for glucose transport
• What is required for active transport?

  Energy to pump molecules against gradients
• What does Na, K-ATPase do?

  Transports sodium and potassium ions

  
• What is the role of ATP in active transport?

  Supplies energy for transport systems
• How does co-transport utilise an electrochemical gradient?

  It transports two molecules using one solute's gradient
• What are the two types of glucose transporters?

  GLUT and SGLT
• What is the role of GLUT in glucose transport?

  Facilitates passive diffusion across barriers

  
• What is the function of SGLT?

  Key role in glucose absorption from intestines

  
• What are the differences between symport and antiport transport?

  • Symport: 2 substances move in the same direction
  • Antiport: 2 substances move in opposite directions

  
• What is vesicular transport?

  Active movement via a vesicle
• What is the term for a signal traveling between cells?

  Intercellularly
• What is the most common route of entry for drugs?

  Passive diffusion
• What is true about the resting potential of cells?

  Inside a cell is negative compared to outside
• What are the definitions of symport, uniport, and antiport?

  • Symport: 2 substances move in the same direction
  • Uniport: single substance moves in a single direction
  • Antiport: 2 substances move in opposite directions