Cells and the internal environment Flashcards
1. Describe major fluid parts - intra & extra cellular 2. Explain composition and function of cell membrane 3. Describe conc. of ions in intra/extracellular fluids 4. Describe diffusion, filtration, carrier mediated transport, exo/endocytosis and osmosis
What are the 3 major fluid compartments in the body?
Blood plasma, interstitial fluid, intracellular fluid
What is the body weight % of blood plasma?
5%
What is the body weight % of interstitial fluid?
15%
What is the body weight % of intracellular fluid?
40%
What is the body weight % of extracellular fluid?
20%
What are the 3 internal environments that we absorb water from?
Blood vessels, stomach, intestine
From the internal environment, where does the fluid pass through first?
Blood plasma
From the blood plasma, where does the fluid pass too?
Lungs, kidneys, interstitial fluid
What separates the blood plasma and interstitial fluid?
Two compartment capillary wall
What separates the interstitial fluid and intracellular fluid?
Cell membrane
What does the process of having a cell membrane achieve?
Osmotic equilibrium
What is the general trend in extra vs intra fluids ion concentrations?
Extracellular has high concentrations of Na and Cl but low concentrations of K and protein. Intracellular has low concentrations of Na and Cl but a high concentration of K and protein.
Why does intracellular fluid have a high protein concentration?
Enzyme reactions
What is the composition of intra vs extra cellular fluids called?
Chemical disequilibrium
Why does a chemical disequilibrium occur?
Differences in the composition and cell membranes permeability to molecules
What molecule properties makes it hard to cross a membrane?
Large size, low lipid solubility, high charge
What is the most important factor that affects permeability?
Charge
What is a membrane impermeable to?
Sugars, amino acids, peptides, proteins and inorganic ions
What is diffusion?
Diffusion is the process of random collisions causing molecules to move down a gradient from a high to low concentration to make an equilibrium
What is filtration?
Filtration occurs under a high pressure and a porous membrane which will only allow molecules of a certain size through
What is an example of filtration?
Kidney
What is osmosis?
Osmosis is the movement of water across a membrane in response to a solute concentration gradient. It moves from low to high solute gradient
What is osmotic pressure?
Pressure which would prevent water moving
What is protein mediated transport?
PMT is where proteins act as carriers and channels to facilitate the flow of substances that cannot permeate through the lipid bilayer
What are 2 examples of molecules which us PMT?
Ions and large unionised molecules
What process happens to allow PMT
Facilitated diffusion down a concentration gradient. No energy is required. Active transport against a concentration gradient, ATP is used
Describe endocytosis:
Endocytosis is the process of a molecule being engulfed by the cell membrane into the cell
What 2 ways are there for endocytosis:
Pinocytosis - pinches off pockets
Phagocytosis - engulfing
What is exocytosis?
The process of hormones and neurotransmitters leaving the cell
