Lecture 3 - Osmosis and Membrane Dynamics

What are the two types of body fluid compartmets?

• intracellular

• extracellular

What is intracellular fluid?

• Makes up 2/3 of the total water volume

• high in K+ and Proteins

What is Extracellular fluid?

• high in Na+ and Cl- and potentially protein

What does chemical disequilibrium mean

• ions aren’t equally distributed across the cell-membrane

What is Electric disequilibrium

• when the inside of the cell is more negatively charged than the inside

What is osmosis

• The movement of water across a membrane from a gradient

What is equilibrium?

• contents are in equal concentrations and levels

What is osmotic pressure?

• the difference in water levels/concentrations

What is osmolality

• measured in kg rather than liters (osmolarity)

What is tonicity?

• describes the solution concentrations volume of a cell

• ex) isotonic

What is isotonic?

• 
  

What is a hypotonic solution?

• when the solution contents move into the cell (there is lower concentration in the cell)

What is a hypertonic solution?

• when concentration moves out of the cell (the cell has more concentration)

What is diffusion?

• it is a passive process

• moves from high to low concentration until its equal

What determines the speed of diffusion?

• faster if its;

  • a larger surface area

  • thinner membrane

  • concentration gradient is larger

  • the membrane is more permeable

What determines membrane permeability

• the lipids solub

What is protein-mediated transport?

• facilitated diffusion

• active transport

What is the structure and function of channel proteins?

• made of several protein subunits

• lined with hydrophilic amino acids

• filled with water

• allow ion and water passage

• selective based on molecule size and charge

What are some different types of carrier proteins?

• uniport carriers

• symport carriers

• antiport

What are uniport carriers?

What are symport carriers?

What are antiport carriers?

how do carrier proteins work?

• the substrate binds to the active site

• this then activates the carrier protein

• and moves the substrate into the cell

What is facilitated diffusion?

• brings concentration into a cell using the concentration gradient and GLUT transporter

What is the difference between simple and facilitated diffusion?

• simple diffusion rate is linear

• protein mediated facilitated diffusion stops when there maximum saturation