Cell Transport Flashcards
What is passive transport?
- movement down the force
- no energy required
- downhill
What is active transport?
movement against the force
Name 2 characteristics of chemical driving forces.
- The gradient “pushes” particles from higher to lower concentration areas
- Force acts from higher to lower concentration areas
What is Concentration gradient (ΔC)?
Difference in particle concentration between the inside and outside of the cell
Describe the direction of chemical driving forces.
- Down the chemical gradient
- From higher to lower concentration
Define cation.
particle with a positive (+) charge
Define anion.
particle with a negative (-) charge
What are the 3 types of passive transport?
- Simple diffusion
- Facilitated diffusion
- Diffusion through channels
Describe simple diffusion.
- passive
- through the lipid bilayer
Simple diffusion is influenced by:
- Surface area
- Permeability
- Concentration gradient
Give 2 examples of facilitated diffusion.
- GLUT4 insertion: primary exercise effect
- GLUT4 activity (intrinsic): secondary exercise effect
Name 3 characteristics of diffusion through channels.
- Transmembrane protein
- Passageway or pore (Aquaporin)
- Substance specific
Describe aquaporin channels.
- Selective pores that permit water movement by diffusion
- Urinary system
- Hormonal influence
Name 3 types of ion channels.
- Leak channels
- Gated channels
- Bidirectional
Describe leak channels.
Allow Na+ and K+ to move down conc. Gradients to maintain stable resting membrane potential
Describe gated channels.
Chemical messenger binds, then channel allows ion through
Describe bidirectional channels.
Allows movement of ions in both directions
Where does primary active transport get it’s energy?
- energy requiring
- usually from ATP hydrolysis
Describe ATP hydrolysis.
- Water breaks down ATP
- Liberates phosphate, energy
- Energy used to drive the pump
Give an example of primary active transport.
Sodium potassium pump is AKA ATPase
Where does secondary active transport get it’s energy?
- Energy released from ion diffusion
- Energy used to drive a pump
- Diffusion due to previous active transport of an ion
What is symport?
Moving things together in one direction
What is antiport?
one goes in, one goes out. Opposite directions.
What is osmolarity?
Drives movement of substances into capillary bed and v.v
What is iso-osmotic?
- balanced
- All we need is a difference across the membrane to move it
What is hyper osmotic?
- high solute concentration means low water concentration
- Hyperosmotic inside cell, water will move inside the cell
- Moving down concentration gradient, even if it is against pressure
What is hypo osmotic?
High water, low solute concentration
What is osmotic pressure?
- Total solute concentration
- Determines the pull on water
When solute concentration increases, osmotic pressure ______.
increases
Give an example of solute concentration affecting osmotic pressure.
- Total solute concentration: kidneys, urinary system
- Long loop of Henley: dips far down into centre of kidney, salty = high concentration of solutes in medulla of kidney
- Water is pulled out of tubule into the medulla = concentrates urine
What is transcytosis?
moving something across the cell
Define endocytosis.
bringing something into the cell
Define exocytosis.
moving something out of the cell.
