chapter 5 Flashcards
what is osmotic equilibrium
free movement between cells and the ECF
- water is only molecule with free movement
what is electrical disequilibrium
the inside of cells is negative relative to the outside
what is chemical disequilibrium
major solutes in the body are more concentrated in one of the two body compartments
how can the body be in osmotic equilibrium but electrical and chemical disequilibrium
osmotic equilibrium because water can move in and out of cells at a constant rate but the solutes in the body are still concentrated and and charged differently
what is the distribution of water among compartments
- intracellular fluid volume: 2/3 of volume
- extracellular fluid volume: 1/3 of volume
define and describe molarity
the number of moles of dissolves solute per liter (mol/L)
define and describe osmolarity
concentration for biological solutions
- number of osmostically active particles (ions and molecules that can’t easily cross the cell membrane) per liter (osmol/L)
define and describe osmotic pressure
pressure that must be applied to oppose osmosis
- not let concentrations be equal?
define and describe tonicity
allows prediction of how solution will affect cell volume
what is bulk flow
biological transport
- fluid and gas movement driven by pressure or temperature gradients
describe solute movement across compartment membranes
membranes have selective permeability which can be specifically altered with membrane proteins
compare bulk flow to solute movement across membranes
bulk flow is transport of fluid and gases due to pressure or gradients, while solute movement is when urea or gases can freely cross membranes and enter the cell
describe simple diffusion
diffusion directly across phospholipid bilayer of membrane
- unaided diffusion
describe vesicular transport
molecules that are too large for channels and carriers use vesicles
- bubble like formations made rom cell membrane
describe diffusion in open system
molecules move from an area of higher concentration to area with lower concentration
what are the seven properties diffusion follows
- passive process
- molecules move from high to low concentrations (chemical gradient)
- net movement occurs until concentration is equal
- rapid over short distances and slow over long distances
- directly related to temperature
- inversely related to molecule size (larger=slower)
- occurs in open system or across partition between two separate systems
describe movement on facilitated diffusion
molecule needs channel/transport protein to cross membrane
describe active transport carriers
carriers on move one molecule or group of closely related molecule at a time
compare movement through channels to movement on facilitated diffusion and active transport carriers
define specificity
carriers only move one molecule or group of closely related molecules
define competition
molecules with similar shape compete for binding sites on transporters and stop or slow down transport
define saturation
rate of transport will increase as substrate concentration increases or until all carriers are full (transport maximum)
describe trans cellular transport
describe paracellular transport
describe transcytosis
- plasma proteins are concentrated in caveolae then undergo endocytosis and for vesicles
- vesicle cross cell
- vessicle contents are released into ECF by exocytosis
how do trans cellular transport, paracellular transport and transcytosis apply to epithelial transport
if molecule is too large so vesicular transport is used and energy is needed for movement across both membranes
what is resting membrane potential
electrical gradient formed between ECF and ICF
what does it mean for a cell to have resting membrane potential
when cells don’t actively electrically signaling, electrical gradient reaches steady state, the steady state is RMP
describe ion permeabiity
ability of ions to pass through membrane
describe membrane potenial
electrical potential difference across cell membrane
- uneven distribution of ions between ECF and ICF
how do changes in ion permeability change membrane potential (give example)
membrane potential is determined by movement of ions across membrane. if one of the ions that is highly concentrated inside the cell flows outside it will make the inside of the cell more negatively charged
what is the sequence of membrane transport-asscoiated steps that link increased blood glucose to insulin secretion from pancreatic beta cells
- high glucose in blood
- metabolism increases
- ATP increases
- Kate channels close
- cell depolarizes and calcium channels open
- Ca entry acts as an intracellular signal
- Ca signal triggers exocytosis and insulin is secreted
define homestasis
stability of the body internal environment
are ICF and ECF same
no they are stable not the same they are at a dynamic disequilibrium
define dynamic disequilibrium
maintain balance while in motion (things moving in and out)
define osmosis
water moves from an area of lower solute concentration to higher solute concentration
define semi-permeable
cells have membranes that allow water to move freely but solute movement is more restrictive
what does it mean for solutions to be isosmotic what does it relate to
two solution with the same number of solute particles per volume
- osmolarity
what does it mean for a solution to be hyperosmotic what does it relate to
a solution with higher osmolarity
what does it mean for a solution to be hypoosmotic and what does it relate to
solution with lower osmolarity
what is hypotonic and what does it relate to
cell gains water after being placed in solution (water goes in cell)
- tonicity
what is hypertonic and what does it relate to
cell loses water
- tonicity
what is isotonic and what does it relate to
no change in cell volume (water goes in and leaves cell keeping it constant)
- tonicity
what are non-penetrating solutes
solutes unable to cross membrane freely (need specific transport)
(ions, protein, glucose and lipids)
what are penetrating solutes
solutes freely crossing membrane into cell
(urea and gases)
- doesn’t impact water movement (achieves chemical equilibrium)
what properties will dictate if a molecule can pass through a membrane
- size (small molecules pass through more freely)
- lipid solubility (lipid soluble molecules can pass through)
- water, O2 and Co2 can move freely
what is used to facilitate transport through impermeable membranes
membrane proteins
what is passive transport
uses potential energy stored in gradient to move molecules across membrane
- with the gradient
- uses simple and facilitated diffusion
what is active transport
requires and input of energy from outside source to move molecule across membrane
- against the gradient
- uses primary and secondary active transport
what are additional considerations for simple diffusion
rate of diffusion depends on nature of the molecule
- molecular size
- lipid content
- water is exception
- rate of diffusion is proportional to membrane surface area
what is Fick’s law of diffusion
rate of diffusion is proportional to:
surface area x concentration gradient x membrane permeability
what are the three types of vesicular transport
- phagocytosis: import
- endocytosis: import
- exocytosis: export
