Chapter 4 Flashcards
(49 cards)
Diffusion of small particles
Moves DOWN its concentration gradient (electrochemical). Requires no additional energy
Simple diffusion
No binding needed (not carrier mediated)
What affects simple diffusion?
Concentration difference, electrical gradient, pressure, and temperature
Simple diffusion through phospholipid bilayer
The more lipid soluble the higher the concentration difference, the faster the diffusion rate
What passes through a phospholipid bilayer using simple diffusion?
Gasses (CO2, O2, NO), alcohol, and small lipid solubles (steroid hormones, testosterone, estrogen, progesterone, cortisol)
Simple diffusion through a pore
Usually for water and are always open
What are the simple diffusion pores for water called?
Aquaporins
Simple diffusion through a channel
Can be opened or closed. Selective permeability based on charge, shape, & diameter
Mechanically gated channels
Opened or closed in response to changes in pressure
What is another name for mechanically gated channels?
Pressure gated
What uses mechanically gated simple diffusion channels?
Most mechanoreceptors. Baroreceptors, joint proprioceptors, muscle spindles, golgi tendon organs, meisner’s, meckel’s, pacinian
Ligand gated channels
Opened or closed when a molecule binds to a membrane receptor
What are examples of ligand gated channels?
Nicotinic & muscarinic receptors, neurotransmitters, protein hormones, chemoreceptors, & chemical senses (taste and smell)
Voltage gated channels
Opened or closed in response to a change in the electrical charge/potential of the nearby membrane
Where are voltage gated channels used (location)?
Axon hillock & along the axon during action potential
How does a voltage gated channel work?
They are shocked open or are on a timer. When opened they are snapped open. Na+ rushes in causing depolarization which then snaps the channel closed + triggers K+ channels
Facilitated diffusion
Binding required. Carrier mediated which is limited by stereospecificity
Examples of facilitated diffusion
Glucose uptake into cells using a GLUT4 protein
What activates facilitated diffusion in all cells EXCEPT neurons?
Insulin
Is simple or facilitated diffusion faster?
Facilitated until you hit V max
Active transport
Moves a molecule against its concentration gradient. Requires an energy source. Carrier mediated. Subject to saturation/transport max, stereospecificity + competition
Primary active transport
Uses ATP to pull molecules against their concentration gradient (pumps)
Sodium potassium pump (ATPase pump)
Moves Na+ and K+ against concentration gradient. Slightly electrogenic.
How many and in what direction does the ATPase pump move sodium and potassium?
3 Na+ OUT. 2 K+ IN
