Dynamic vs static equilibrium
Dynamic: things change but stay within a range
Static: things stay the same
Relationship between response to stimuli and homeostasis
Organisms take in stimuli and respond to them to maintain homeostasis
Positive vs. negative feedback loops
Positive feedback loops: output intensifies the response
1. human child birth
2. fruit ripening
Negative feedback loops: output causes counter response to return to set point
1. human body temp
2. blood pressure regulation
Role of cell membrane in maintaining homeostasis
Controls movement of things in and out of the cell (passive/active transport)
Passive vs active transport
Passive: high to low concentration (down concentration gradient)
Active: low to high concentration (against concentration gradient)
Simple diffusion
spreading of molecules across membrane till equilibrium is reached
Facilitated diffusion
transport protein helps facilitate diffusion of molecules that normally couldn’t pass through cell membrane
Osmosis
simple diffusion of water across cell membrane
Molecular pumps
cell uses energy to pump molecules across membrane
Endocytosis
uses vesicles to move large particles into the cell
Exocytosis
uses vesicles to export materials out of the cell
Hypotonic solution
water higher than cell’s cytoplasm, cell swells
Isotonic solution
identical water to cell’s cytoplasm, cell stays the same
Hypertonic solution
water lower than cell’s cytoplasm, cell shrivels
Homeostasis
need of an organism to stay stable by regulating internal conditions
Solute
what gets dissolved
Solvent
does the dissolving
Solution
uniform mixture of two or more substances
Concentration []
amount of solute dissolved in solvent