13-15;Fick's/Osmosis/Transport/Cohesion/Surface tension Flashcards
describe the kinetic energy of molecules
at ordinary room temp, solids, liquids and gases move continuously at v high speeds
gas=make billions of collisions w/ walls each sec = causes P of gas on walls of container
liquids=move about w/ mutual attraction but no preferred order
solids= molecules vibrate back and fourth rapidly in their limited space
liquids and solids motion of molecules is limited by mutual attractive forces and less empty space for movement
random kinetic energy
energy that accomplishes net transfer of molecules
osmosis
diffusion of solvent across semi-permeable membrane, down conc gradient
semi permeable membrane
membrane permeable to solvent molecules, blocks passage of solutes
osmotic pressure
pressure required to prevent diffusion from pure sol into that sol
net migration of solvent molecules yields difference in height proportional to osmotic pressure diff
hypertonic
sol is less conc, cell is more conc so water moves out of cell, shrivels, dies
hypotonic
sol is more conc, cell is less conc, water moves into cell, swells and dies
dialysis
process involving diffusion of several types of molecules through a selectively permeable membrane
mostly in kidneys of removal of water from blood in nephrons
dialysis in kidneys
via nephrons to remove water from blood, 2 main parts: glomerulus and bowman’s capsule
glomerulus is coiled shape of thin-walled capillaries enclosed by bowman’s capsule, water reabsorption is process is via GLOMERULAR FILTRATION
Reabsorption proceeds by DIFFUSION = dialysis
dialysate
controlled sol of electrolytes
often subjected to -ive P to speed removal of XS water from blood
regulate so osmotic P diff across membrane isn’t too large
AT
Molecules transported against conc gradient, required ATP
are selectively permeable membranes subject to +ive or -ive pressure
+ive BP to force plasma out
describe molecular transfer across capillary system
outflow from capillary on arteriole end is almost balanced by return on venule end = maintain almost constant vol of circulating blood
more slight outward XS = balanced by fluid return via lymphatic circulation
blood molecules and effect on osmotic pressure
blood albumin = large molecule stays in capillaries to contribute osmotic P diff
loss of albumin = more fluid leaves capillaries in arteriole end, less return in venule end = oedema = collection of fluid in tissues
loss of salt = blood and interstitial fluid becomes hypotonic = water diffuses into cells = depletes interstitial fluid
cohesion vs adhesion, give EG
cohesion = strong internal attractive forces between like molecules, adhesion= forces between unlike molecules
EG curved surface of WATER meniscus, curved up = water molecules at edge adhere to glass wall more strongly than they cohere to each other.
of MERCURY Curved down = since cohesion atoms stronger than adhesion to wall
surface tension
cohesive forces between liquid molecules more strongly those on surface = forms shape of liquid droplets of a spherical shape
how does surface tension affect function of liquid
high surface tension = water can be nebulised/placed in aerosol form
low surface tension = good cleansing agent = spreads out and wets surface readily == hot water is better cleaning agent than cold water = hotter = molecules more agitated at surface = reduces cohesive forces = lower surface tension
why is surface tension needed in respiration
provides necessary membrane strength to maintain the bubble like alveoli, where oxygen exchange from air to blood occurs.
T=Pr/2
if T increases=more P needed to keep radius same otherwise bubble collapses
If P is constant and r decreases = bubble is unstable = collapses
If r increases too much and P isn’t enough to stabilise it = will rupture since required T is too great
what is the challenge for newborn baby relating to laplace law
premature infants haven’t developed a sufficient amount of needed surfactant layer on alveoli, so as r increases = surfactant layer gets thinner = tension will halt expansion
also when r gets smaller = surfactant gets more conc on surface = lowers T = halts expansion
so exhaling is done by the elastic recoil of chest, helped by the deflation of alveoli = decreased r = increased T
capillary action
ability of liquid to flow in narrow spaces w/o assistance of gravity, result of adhesion and surface tension
viscosity
determines flow rate of fluid through tube due to internal friction due to mutual cohesive forces of fluid molecules
adsorption
molecular attractive force that causes outside substances to attach to liquid/solid
absorption
when outside substances penetrates into substances EG gas/liquid condenses and attaches to surface of solid
