Diffusion including Osmosis Flashcards
Define Osmosis
The flow of solvent (in most cases, water), across a selectively permeable membrane from a dilute to a more concentrated solution.
Define diffusion
Passage of chemicals from regions of high concentration to regions of low concentration resulting in an even or equal distribution.
What types of substances are involved in simple diffusion
Small uncharged lipid soluble subtances
Does simple cell diffusion allow the movement of substances into and out of the cell?
Yes
What role does the direction of the concentration gradient play in simple diffusion?
It determines the net passage of the chemical
How do oxygen and Carbon dioxide move in and out of interstitial fluid from and to the blood?
By the process of simple diffusion
What process enables the movement of lip soluble materials such as steroid hormones, oestrogens and progestrones through the cell membrane?
Simple diffusion
How do charged particles that aren’t lipid soluble manage to move through the cell membrane?
Through protein pores
What 3 conditions promote a faster rate of simple diffusion?
1) A greater surface area (of the cell) is available
2) Greater Permeability of the membrane to specific substances
3) Increased concentration gradients
How do urea and ethanol move across a cell membrane?
Simple diffusion
What is facilitated diffusion?
It is when a carrier chemical (normally an integral protein)transports relatively large chemicals across the membrane
Which process is faster, facilitated or simple diffusion?
Facilitated
When a molecule combines with a carrier chemical during facilitated diffusion, how does that allow transport across the cell membrane?
It normally changes the shape of the molecule being carried which means a channel opens up in the membrane to allow it to pass through
What are the four factors that contribute to the rate of facilitated diffusion? (Tip: 3 are the same as for simple diffusion)
1) A greater surface area (of the cell) is available
2) Greater Permeability of the membrane to specific substances
3) Increased concentration gradients
4) Amount and availability of Carrier chemicals
What is an isotonic solution?
Equal in pressure and strength
