You will eventually have to get back to the restingpotential, involving the sodium-potassium pump. The cell is polarized at-70mv. Sodium comes in through depolarization. The process of thepotassium channel opening and all the events that follow is calledrepolarization. Three sodium to two potassium ratio.
Microvilli, Cilia, and Flagellamicrovilli: extensions of the plasma membrane that serve primarily toincrease a cell’s surface area; best developed in cells specialized forabsorption such as the epithelial cells of the intestines and kidneytubules cilia: hairlike processes about 7-10 µm long; sensory, serving as thecells “antenna” for monitoring nearby conditions; sense of balance;monitor the flow of fluids as it is processed to urineflagellum: whiplike tail of a spermNeurotransmittersneurotransmitter: chemical released at the distal end of an axon thatstimulates and adjacent cell examples: acetylcholine (ACH), norepinephrine, and serotonin action/graded potential steps (take 1/1000thof a second to do):ACH makes peripheral protein move out of the way so the gatecan opensodium comes in; as it comes in -70mv gets closer to 0sodium keeps coming in until -70mv reaches +30mv; then thegate closes and the ACH is destroyed (depolarization)because it reaches +30mv, voltage disruption makes aperipheral protein move off the potassium channel andpotassiumexitsthecelluntilitreaches-90mv(hyperpolarization)to get back to -70mv a pumper molecule will pump 3 sodium to 2potassium The Nucleus largest organelle of the cell and visible with the light microscope contains the cell’s chromosomes and is the genetic control center ofcellular activity a few cell types are multinucleate, they have 2 to 50 nuclei nuclear envelope: formed by two unit membranes surrounding thenucleus and is perforated with nuclear pores, formed by a ring ofproteins nuclear lamina: narrow, but dense fibrous zone inside the nuclearenvelope nucleoplasm: material inside the nucleus chromatin: fine thread-like matter composed of DNA and protein nucleoli: dark-staining mass where ribosomes are producedEndoplasmic Reticulum (ER)literally means “little network within the cytoplasm”
endoplasmic reticulum: system of interconnected channels calledcisternae enclosed by a unit membrane made to compartmentalize synthesizes steroid & other lipids, detoxifies alcohol and other drugs,and manufactures all membranes of the cell rough endoplasmic reticulum cisternae are parallel, flattened sacs covered with granules calledribosomescontinuous with the outer membrane of the nuclear envelope,and adjacent cisternae are connected by perpendicular bridges produces the phospholipids and proteins of plasma membrane &synthesizes proteins that are either packaged in other organellesor secreted from the cellabundant in cells that synthesize large amount of protein(digestive gland)smooth endoplasmic reticulum