Weeks 1 and 2 Notes

Weeks 1 and 2 Notes - Diffussion, Ion Pumps Resting...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Diffussion, Ion Pumps Resting Potentials: Graded and Action Potentials I. Diffusion Exchange between intracellular and extracellular compartments is restricted by cell membrane. Selectively permeable: lipid and protein composition of cell membrane determines which molecules enter/leave Impermeable: doesn’t allow substance to pass through. Permeability can be changed by altering proteins, lipids of membrane Moves easily: oxygen, carbon dioxide, lipids Moves with difficulty: ions, most polar molecules, very large molecules Permeability influenced by: 1) size of molecule 2) lipid solubility - smaller molecules and lipid soluble crosses directly through phosolipid bilayer Membrane proteins are usually mediator cells used to transport molecules across membranes Passive transport: doesn’t require use of energy Active transport: required input of energy from outside source, high-energy phosphate bond of ATP Diffusion uses only the energy of molecular movement Passive transports required kinetic energy Diffusion: movement of molecules from an area of higher concentration to an area of lower concentration of molecules Seven properties of Diffusion: 1) passive process: a. doesn’t require the input of energy from outside source 2) molecules move from high concentration area to lower concentration area a. concentration gradient: difference in concentration of a substance between two places i. also known as chemical gradient b. down the gradient: from higher concentration to lower concentration c. rate of diffusion: depends on magnitude of concentration gradient i. larger concentration gradients differences- FASTER it takes place d. net movement of molecules occurs until concentration is equal everywhere: i. after molecules of substances have distributed evenly, system reaches equilibrium and diffusion stops ii. dynamic equilibrium state: concentration has equalized through system but molecules continue to move e. diffusion is rapid over short distances but much slower over longer distances f. diffusion is directly related to temperature
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
i. diffusion results from molecular movement so rate of diffusion increases as temperature increases ii. in humans: no significant impact because maintain relatively constant body temperature g. diffusion rate is inversely related to molecular size
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 6

Weeks 1 and 2 Notes - Diffussion, Ion Pumps Resting...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online