A&P 12- Transport across plasma membrane (passive and active transport)

passive transport

no energy/ATP required diffusion with concentrated gradient

examples of passive transport

simple diffusion, osmosis, and facilitated/channel diffusion

simple diffusion

the movement of molecules through phospholipid bilayer from an area of high concentration to an area of low concentration until the molecules are equally distributed

example of simple diffusion

oxygen into the lungs and carbon dioxide out of lungs are carried by simple diffusion

what are some factors that affect the rate of diffusion

increased temperatures, smaller molecules, and increasing the concentration gradient

increased temperatures (simple diffusion)

increases kinetic molecular motion and so increases rate of diffusion

what is the optimal temperature for fatest diffusion is normal body temperature

37 degrees celcius

what are cell membranes. permeable to (small or large molecules) and example

cell membranes are permable to small molecules only eg unit molecules

increasing the concentration gradient (simple diffusion)

will increase rate of diffusion e.g mountain climbing at exxtreme altidutes

osmosis

the diffusion of water through phospholipid bilayer- the movement of water molecules from an area of high concentration to an area of low concentration across a differntially permeable membrane

example of osmosis

water moves in and out of plasma membrane through phospholipid bilayer freely, energy/ATP is not needed

example of channel mediated transport

sodium and potassium gates in neuron

are proteins channels through which sodium and potassium ions cross the plasma membrane according to their concentration gradients. Energy/ATP is not needed 

(important concept for nervous system as well)  

active transport

energy/ATP required movement against concentration gradient

examples of active transport

transport using a plasma membrane protein and ATP, exocytosis, endocytosis

example of transport using a plamsa membrane protein and ATP

Na/K pump requires ATp and carrier protein

exocytosis and endocytosis

transport by vesicles formation and using ATP, plamsa membrane involved

endocytosis

brings substances INTO the cell, uses cell membrane to form vesicle, requires ATP

steps of endocytosis

cell membrane begins to wrap around substance to be engulfed, a vacoule forms around substance engulfed, the vacoule membrane forms from the original phospholipid bilayer membrane

what are the two types of endocytosis

phagocytosis and pinocytosis

phagocytosis

cell eating, process of engulfing large materials like bacteria and cell debris

pinocytosis

cell drinking, process of engulfing large molecules like protein

what is the difference between phagocytosis and pinocytosis

the size of the material being engulfed (phago= bigger while pino= smaller)

exocytosis

substances secreted from cell when vesicle fuses with inner side of cell membrane, requires ATP