Anatomy & Physiology Concept 2: Homeostasis & Regulation

Homeostasis

stability of internal environment & mechanisms that maintain the stability

Receptor

receives stimulus

Stimulus

action that evokes response

Effector

organ that does response

Response

effect caused by stimulus

Feedback Inhibition

output of process used as input to control the behavior of the overall process

Passive Transport

no extra energy needed, molecules moved down the concentration gradient

Active Transport

extra energy needed, molecules go against the concentration gradient

Hypertonic Solution

water concentration lower than cell's cytoplasm (more solute)

Hypotonic solution

water concentration higher than cell's cytoplasm (less solute)

Isotonic Solution

identical water concentration to cytoplasm

Ligand

molecules that bind to receptor proteins for signaling purposes

Signal transduction pathway

sequence of events initiated by a signal, leads to a cellular response (signal to message transduced to desired response)

inhibitor

block normal ligands to prevent communication

transduction

passing along a signal until the desired response is reached

phosphorylation

adding phosphate groups by kinases

dephosphorylation

removing phosphate groups by phosphatases

second messenger

key for regulation; intermediate between the receptor and cascade of responses after (distribute/amplify initial signal received at the receptor)

Types of passive transport

simple diffusion, facilitated diffusion, osmosis

Types of active transport

molecular pumps, endocytosis, exocytosis

Simple diffusion

molecules spread out across membrane until equilibrium (O2, CO2, small, non-polar, lipid-soluble)

facilitated diffusion

transport protein (channel or carrier) helps facilitate diffusion of molecules (large & polar)

osmosis

simple diffusion of water across cell membrane (from high water concentration to low water concentration)

molecular pumps

ATP used to pump molecules across membrane (low to high concentration)

endocytosis

bringing large particles into the cell

exocytosis

export materials out of the cell