lecture 2 Flashcards
describe simple diffusion
move freely with no help.
e.g. O2 + CO2 between blood, body cells, and lungs
this is because if the body had to wait for a carrier, would die
is a route for absorption/excretion
describe facilitated diffusion
uses membrane proteins- channel or carrier
faster then simple diffusion
for bigger molecules
describe the glucose transporter carrier
glucose binds to specific type of carrier protein (glucose transporter) on the outside surface of membrane
transport undergoes change in shape, allowing glucose to pass through membrane
transporter releases on other side
describe osmosis
movement of water
goes from high conc. to low conc.
uses aquaporins- are integral membrane proteins, regulate water influx using osmotic gradient
uses water to maintain cellular integrity
in humans, found in kidney, brain, astrocytes
describe primary active transport
energy from ATP changes shape of transport protein
pumps substance across membrane, AGAINST conc. gradient
describe the sodium potassium pump + what type of diffusion is it
expels Na+ and brings in K+ ions to maintain low intracellular conc. of sodium ions
3 sodium ions form cytosol bind to inside surface of pump
Na+ binding triggers ATP to bind to pump, splitting it into ADP + phosphate
energy from ATP splitting causes protein to change shape, moving Na+ INSIDE
2 K+ ions attached to outside surface of pump, causing phosphate to be released
release of phosphate causes pump to return to original shape, which moves the K+ into cell
active, primary
describe secondary active diffusion
energy stored is used to drive other substances against their own conc. gradient
important for glucose reabsorption in kidneys
antiporters- 2 substances, across membrane, OPPOSITE directions
supporters- 2 substances, across membrane, SAME direction
what is vesicular transport?
how large molecules enter/exist cell
2 types
endocytosis- materials move IN
exocytosis- materials move OUT
what is phagocytosis
means cell eating
form of endocytosis
cell engulfs large solid particles, eats + destroys it
2 main types- macrophages (located in body tissue) + neutrophils (type of white blood cell)
steps of phagocytosis
phagocytosis white blood cells encounter bacteria that binds to cell membrane
phagocyte uses it cytoskeleton to push its cell membrane around the bacteria, creating a large vesicle (phagosome)
phagosome containing bacteria separates from cell membrane + moves into cytoplasm
phagosome fuses with lysosomes containing digestive enzymes
bacteria is killed + digested within vesicles
describe exocytosis
membrane enclosed secretory vesicles fuse with membrane, release contents outside
materials move out
used in removal of waste materials from cell, transport of hormones + proteins, chemical signalling between cells + membrane
factors affecting transport
Saturation of transporters
No. Of transporters
Electrochemical gradient
Physical changes of transporter
what is tonicity: hypertonic vs hypotonic
is how the solution influences the shape of body cells
can be measures as solutes dissolved in solvents
in human body, is isotonic (same ) = 0.9% saline
More water = hypertonic, water goes out, shrinks, lower % salt, higher solute conc., higher conc. Of solutes outside, water molecules move OUT faster then in, causing shrinking- called erenation
Less water = hypotonic, water goes in, bursts, higher % salt, lower solute conc., water molecules enter faster then they leave leading to swelling + bursting
haemolysis vs lysis
Haemolysis- rupture of red blood cells
Lysis- rupture of other types of cells due to placement in hypotonic solution
Note: pure water is VERY hypotonic + causes rapid haemolysis
describe the effect of alcohol on blood tonicity
when drinking alcohol, blood tonicity increases (means more salt and less water in blood)- creates a decrease in saliva + dry mouth
Osmoreceptors (regulate water/salt conc.) in hypothalamus + kidneys detect it
makes you feel thirsty
drinking water moistens mouth/throat, and gets absorbed into GI tract
blood tonicity decreases
also decreases AHD- responsible for controlling urination (when eat salt, AHD decreases, makes you want to pee)
