Chapter 6/8: Homeostasis & Transport

Homeostasis is...

the biological balance between a cell or an organism and its environment (ex: temperature, water levels, glucose)

homeo-

same

-stasis

remain constant

Concentration

a measurement of the amount of solute (substance that is being dissolved) dissolved in a fixed amount of solvent (substance that is being dissolved)

concentration gradient

the difference in concentration of a substance across a space (not the same)

equilibrium

a state that exists when the concentration of a substance is the same throughout the space (same solution inside and outside of the cell)

Brownian Motion

the molecules never hold still, they're constantly moving in a straight line (the random movement of molecules)

Permeable

refers to a membrane through which molecules can pass

Selectively Permeable

not all molecules can diffuse through all membranes (depends on: size of molecule, type of molecule, molecular structure of cell membrane)

Simple Diffusion

the process by which molecules (solutes) move from an area of greater concentration to an area of lesser concentration (passive, can occure outside cell, ex: oxygen in lungs to our blood)

Factors that affect the rate of diffusion

temperature, higher concentration gradient, & pressure

Types of Diffusion

Simple diffusion & Facilitated diffusion

Osmosis

the diffusion of water through a membrane from high to low

Types of Solutions

Isotonic solution, Hypertonic solution, & Hypotonic solution

Isotonic Solution

the condition when the concentration of solute molecule inside & outside of a cell are equal and move at the same rate (passive, water moves, ex: plant that has enough water)

iso-

same

Turgor Pressure

water pressure within a cell

Hypotonic Solution

the solute concentration in the environment is lower than in the cell (lots of turgor pressure, passive, water moves in, ex: paramecium in water)

Cytolysis

the intake by a cell of lots of water that the cell membrane ruptures (plant cells don't rupture)

Contractile Vacuole

an organelle in microorganisms that excretes excess water

Plasmolysis

the shrinking or wilting of a cell from low turgor pressure

Hypertonic Solution

solute concentration in the environment is higher than in the cell (no turgor pressure, passive, water moves out, ex: when you're dehydrated)

Facilitated Diffusion

when carrier molecules (proteins) transport molecules through a membrane without expending energy (uses transport proteins, passive, solutes move, high to low, ex: glucose)

Carrier Protein

changes shape to allow particles to pass

Channel Protein

tube that allows specific molecule to flow through (doesn't change shape)

Active Transport

moving particles from a low to high concentration using energy; ATP is the primary source of energy (against a concentration gradient, must be alive, carrier protein used, ex: NA+/K+ pump nerve impulses & muscle contractions

Endocytosis

process by which cells engulf substances that are too large to enter the cell by passing through the cell membrane (into cell, active, 2 types, ex: white blood cell engulfing a microorganism)

Exocytosis

passage of large molecules out of the cell (vesicle comes from Golgi body, active, ex: transport of glucagon -hormone that opposes insulin- from the pancreas to the liver)

Phagocytosis

movement of large food particles or whole microorganisms into the cell "cell eating" (ex: amoeba eating food)

Pinocytosis

movement of solutes or fluids into the cell "cell drinking" (ex: small intestine absorbing nutrients)