Physiology exam 1, slide 4 and extra notes

• What is cytosol?

  Intracellular fluid, composition is tightly controlled by cells, plasma membrane separates from the outside.
• What is Interstitial fluid?

  extracellular fluid that surrounds cells in any tissue; can be specialized in some tissues
• What is plasma?

  extracellular fluid of the blood, separated from ISF by endothelial cells of capillaries and vessel walls; mixes with ISF
• label

  label this

  A) plasma

  B) interstitial fluid

  C) cytosol (inside)

  
• what is the phospholipid bilayer considered?

  amphipathic
• what are the watery environments the polar heads hang out with?

  cytosol, plasma, interstitial fluid
• where do the hydrophobic molecules face in the bilayer?

  nonpolar tails face the middle
• What can pass through the bilayer?

  Small nonpolar molecules, such as oxygen and carbon dioxide, can pass through the bilayer.
• What can't pass through the bilayer?

  large polar molecules that are charged
• Characteristics of passive transport

  • Powered by a concentration gradient
  • No ATP/energy required
  • Transports from high to low concentration
• what does simple diffusion transport?

  small, non-charged molecules
• what does facilitated diffusion transport?

  charged molecules and larger molecules with the help of a protein
• characteristics of active transport

  • transports low to high concentration
  • ATP/energy required
  • requires membrane proteins
• examples of passive transport

  simple diffusion and ion channels, glucose can be passed through
• examples of active transport

  Sodium-Potassium pumps, neurons
• what can be passed in simple diffusion?

  small gases (O2, CO2, NH3), steroids, small lipids, thyroid hormone, water IN SMALL AMOUNTS
• Given what you know about diffusion, how can this loss of essential solutes be prevented?

  By having the diasylate contain an equal number of those solutes as the blood.
• General carrier properties

  • transmembrane proteins
  • specific for molecule(s) they carry
  • have a binding site with precise 3D shape
  • exhibit saturation kinetics
• what is saturation kinetics?

  the limit to how quick things can move. The rate is limited by a carrier protein
• If you have saturated the carrier for molecule X on the membrane, what is the only way to move more of X?

  Add more of the carrier for X to the membrane (can't speed up by adding more of X, you need more proteins)
• What is an example of a turnstile carrier?

  glucose carriers (GLUTs)
• What does GLUTs do?

  • Carrier protein that has binding sites for glucose
  • Conforms change in the carrier and creates a pathway to transport glucose
  • always moves down gradient (bi-directional)
  • can be removed from the surface if not needed
• What happens in the presence of insulin?

  GLUTs goes onto the plasma membrane
• Ungated channel definition

  constitutively (always) open
• examples of ungated channels

  aquaporins and ion leakage channels
• gated channel definition

  conditionally open

  stimulus opens it, closes when stimulus is gone
• example of a gated channel

  many ion channels
• what are the 3 gate stimuli?

  ligand, stretch, and voltage
• how many complexes are on the ETC?

  4
• where can amino acids enter in respiration?

  CA cycle, pyruvate or acetyl CoA
• where and how does glycerol enter respiration?

  can enter as phosphoglyceraldehyde between glucose and pyruvate
• where do 3 fatty acids enter respiration?

  can enter in a prep reaction of its own (makes 1 NADH still and 1 CO2)
• what do ion channels do?

  pass ions
• what common ions do ion channels pass?

  Na+, K+, Ca2+, Mg2+, Cl-
• Where do you see ion channels?

  neurons, muscles, and many cell types
• What is the most common leakage ion channel?

  Na+
• Are ion channels gated or ungated?

  both
• Are aquaporins ungated or gated?

  ungated
• What do aquaporins do?

  • ICF<->ISF
  • Pass H2O
  • Found in the kidneys
• What happens if aquaporins aren't present?

  H2O can't cross quickly and in significant amounts