dischange of cell particles, which are packaged in membrane- bound vesicles, by fusion of the vesicular membrane w/ the plasma membrane and subsequent release of the particles to the exsterior of the cell
Red Blood Cells Start Out with all the organelles:
as they grow they:
produce hemoglobin
have enlarged endoplasmic reticulum (b/c it needs to produce the large hemo)
have small golgi bodies (b/c their holding alot and not sending it out)
Red Blood Cells Start Out with all the organelles:
When they are mature, they:
lose their endoplasmic reticulum (b/c they made their prduct and aren't making more)
lose their mitochondia (b/c they dont make ATP b/c they get energy from anaerobic metabolizom)
lose lysosomes (they don't create free radicals)
passive diffusion
molecules move randomly away from the area where they are most concentrated
osmosis
movement of water from region of greater concentration to a region of lesser concentration
depends on particle concentration
What way will water move if in the blood there is lots of water and in the cell there is less water?
moves into the cell
water diffuses from the place with lots of water to the place with less water
water follows solutes the "pull" of the particles is oncotic or colloid osmotic
If Na diffuse into the cell, what will water do?
What will water do if the Na/K pump sends Na back out?
water will follow Na
Facilitated Diffusion
molecules diffuse across a membrane WITH HELP by forming a vacuole or attaching to protein
Pinocytosis
need something in cell
vaccums it in
moves it across membrane
let it out inside the cell
carrier/transport protein
non- lipid soluble molecules need help through the membrane
they combine w/ a carrier protein and are carried across in the cell
Active Transport
diffusion results in uniform concentration
cell processes requires uneven concentration
-high concentrations of K are needed to carry out intercellular processes
energy (ATP) is used to move substances into or out of the cell for use
Primary Active Transport
ATP is used directly to move a substance against the concentration gradient
Secondary Active Transport
the energy created by primary active transport is harnessed and used to facilitate the transport of a second substance
usu involves Na b/c large Na gradients occur frequently in normal metabolism
cell communication
a messeneger molecule attaches to receptor proteins on cells surface
receptors span the cells membrane (messengers hook up and send message)
signal tansduction
message is converted and moved across the membrane to effect a change w/in the cell
up- regulation
more receptors are present when low levels of messengers are available
down- regulation
few receptors are available when high levels of messengers are present
G- protein linked receptors
second messenger- turn on internal cellular systems
(activate receptors of membrane and that activates something in the cell)
Enzyme linked receptors
mediate cellular responses (hormones)
ion channel linked receptors
rapid synaptic signaling (neurotransmitters)
Ion Channels
rapid ion exchange is needed for cellular process
the electical change of ions such as Na and K make it difficult for these to pass through the lipid membrane
special protein channels span the width of the lipid membrane
the proteins undergo conformational changes to form open channels for a selected ion
non- gated (leak) channel
open and about the gradient
ligand gated channel
need something to open ligand and let things in
ex. hormone
cell metabolism
the processs that provdies fuel for cellular processes. Converts proteins, carbs, and fats to ATP: ENERGY