Cell Membrane Transport Flashcards
Lipid bilayer consists of ____ and ____
Polar (hydrophilic) heads
Hydrocarbon fatty acid (hydrophobic) tails
Most common lipid in cell membrane
Phospholipids
Simple diffusion - Water soluble
Occurs through…
Through pore or gated ion channel
Simple diffusion - Lipid soluble
Substance
CO2, O2, ethanol, lipid soluble substances
Location of lipid soluble diffusion
All cells
Simple diffusion - lipid soluble
Occurs through…
Through lipid bilayer
Simple diffusion - water soluble
Substances
Water & ions
Location of water soluble simple diffusion
All cells, nerve cells
Function of cholesterol in cell membrane
Makes membrane less fluid
Glycolipids location
Only on outside of cell
Function of proteins in cell membrane
Responsible for membrane function
Types of membrane proteins
Integral & peripheral
Simple diffusion, osmosis and facilitated diffusion are examples of ____
Passive transport
What is passive transport?
Substances move with concentration gradient
What is active transport?
Substances move against concentration gradient
Diffusion is proportional to ____, ____, ____
Surface area
Concentration gradient
Number and size of openings
____ surface area will increase diffusion
Higher
____ number & size of openings will increase diffusion
Increased
2 types of diffusion
Simple
Facilitated
Simple diffusion =
No carrier protein
Facilitated diffusion =
Requires carrier protein
Facilitated diffusion - Glucose transporters
Glut 1: one way
Glut 2: both ways
Glut 4: one way
SGlut1: Sodium symport
Glut 1 transporter - insulin
Insulin independent
Glut 2 transporter - insulin
Insulin independent
Glut 4 transporter - insulin
Insulin dependent
SGlut1 transporter - insulin
Insulin independent
Glut 1 - location
Brain & RBC
Glut 2 location
Liver
Glut 4 location
Muscle & adipose
SGlut1 location
GI tract & kidney
Which glucose transporter goes both ways?
Glut 2
Which glucose transporter is insulin dependent?
Glut 4
Define osmosis
Movement of water from area of low to higher solute concentration
____ are perfect osmometers
RBCs
Osmosis depends on ____ not ____ of particles
Number, not size
osmosis
Glucose - number of particles
1 particle
osmosis
Albumin - number of particles
1 particle
osmosis
NaCl - number of particles
2 particles
CaCl2 - number of particles
3 particles
Osmosis calculation
Calculated out by using osmotic pressure:
Number of particles x molar concentration
osmosis
Isotonic solution - RBC
RBC stays the same size
osmosis
Hypotonic solution - RBC
RBC swells & bursts (lyses)
osmosis
Hypertonic solution - RBC
RBC shrinks (crenate)
Why is facilitated diffusion similar to active transport?
Requires a transporter so has similar kinetics to active transport
Primary active transport pumps
Na/K ATPase pump
Ca pump
H ion pump (proton pump)
Primary active transport contains…
ATPase in the transporter
2 types of Secondary active transport
- Symport/co-transport (with another molecule)
- anti-port/counter transport (against another molecule)
Na/K ATPase pump
Function
Maintain/re-establish RMP
- 3 Na out
- 2 K in
Na/K ATPase pump
Location
- all cell membranes (maintains volume)
- nerve/skeletal muscle & heart muscle (maintain RMP)
calcium pump
Function
Pump Ca out of cytoplasm (sarcoplasm) into SR or ECF
calcium pump
Location
Cell membrane of nerve & muscle
Membrane of SR
H+ (proton) pump
Function
- decrease pH of stomach
- decrease pH of urine
H+ (proton) pump
Location
Parietal cells (stomach)
Distal convoluted tubule of kidney (intercalated discs)
Co-transport
Function
move Na+glucose or Na+amino acids out of cell into blood
Co-transport
Location
small intestine (jejunum)
Proximal convoluted tubule of kidney
Counter-transport/anti-port
Function
- Na pumped into cell, Ca pumped out
- Na pumped into cell, H pumped out of cell into urine
counter-transport/anti-port
Na/Ca - location
Most cells
T tubules of heart
counter-transport/anti-port
Na/H - location
Proximal convoluted tubule (kidney)
Differentiate primary & secondary active transport
Both require energy
Primary has ATP in pump
types of endocytosis
pinocytosis
phagocytosis
receptor mediated
types of exocytosis
constitutive
regulated
describe pinocytosis
cell drinking
requires actin
describe phagocytosis
cell eating
requires ATP
requires actin
describe receptor mediated endocytosis
requires receptor and Clathrin coated pits
describe consitutive exocytosis
golgi apparatus to vesicles
describe regulated exocytosis
from clathrin coated pits
pinocytosis cell types
all cells
phagocytosis cell types
ONLY neutrophils & macrophages
examples of receptor mediated endocytosis
- LDL receptor in liver
- reuptake of NTs by presynaptic membrane
constitutive exocytosis examples
cell membrane constituents,
collagen & elastin
example of regulated exocytosis
mechanism for hormone & NT release