Exam 1 Flashcards
Integral protein
channels, pores, carriers, enzymes, that go all the way through the membrane (extracellular– intracellular)
Peripheral protein
enzymes, intracellular signal mediators; protein on only one side of the membrane
Glycolipid
carbohydrate attached directly to the lipid bilayer
Glycoprotein
carbohydrate attached to integral protein, majority of integral proteins and glycocalyx
Proteoglycans
protein core between two carbohydrates but not connected to membrane or integral protein– attached via a charge (membrane + and molecule -)
Glycocalyx
protects the cell by surrounding it with a negative charge– repels other negatively charged molecules; involved in cell-cell attachment/interactions; play role in immune reactions
Cholesterol
increases membrane flexibility
Rough endoplasmic reticulum
outer membrane covered in ribosomes (processing protiens) and newly synthesized proteins are extruded into the ER matrix from the nucleus
–proteins processed inside ER matrix: crosslinked, folded, glycosated, cleaved
Golgi apparatus
4 or more stacked layers of flat vesicular structures, creates vesicles to secrete contents into extracellular space– bloodstream– target cell; some release contents into lysosomes
- receives vesicles from smooth ER and processes them (phosphorylated/glycosylated); contents are concentrated, sorted, and packaged for secretion
– provides enzymes for lysosomes to use
Smooth endoplasmic reticulum
site of lipid synthesis, growing ER membrane buds continuously to form vesicles that travel to the Golgi apparatus
Constitutive vs stimulated secretion
constitutive= random
stimulated= requires a stimulus to occur
Lysosomes
contain hydrolytic enzymes (acid hydrolases); fuse with pinocytotic/phagocytotic vesicles to form digestive vesicles
– issues with enzymes= lysosomes become engorged with undigested substrate– disease
Peroxisomes
similar to lysosomes except for formed by self replication and contain oxidases
Chromatin
condensed DNA found in the nucleoplasm, functions to form the granular subunits of ribosomes
clathrin-coated pits
receptors coated in pits and receptor binding causes cell to change shape around material to form vesicle, endocytosis is ATP-dependent and involves recruitment of actin and myosin
Cytoskeleton
Intermediate filaments (keratins), microtubules, thin filaments (f-actin), thick filaments (myosin)S
Simple diffusion
molecules move readily across the membrane based on their concentration gradient (water soluble molecules require channels/pores/transport protein)
Ungated channels
example of simple diffusion- transport based on size, shape, and charge of channel and ion
Gated channels
voltage: membrane potential reaches correct value– opens and falls below– closed (action potential)
chemical: neuromuscular junction (substrate binds to receptor–opens)
-facilitated diffusion
Facilitated vs simple diffusion rate
simple=linear
facilitated= starts out linear and plateaus because proteins can only bind so fast (limited by Vmax of carrier proteins)
Active transport
occurs against a concentration gradient, required energy (ATP)
Primary vs secondary active transport
Primary= required ATP
Secondary=energy from electrochemical gradient (usually Na)
Na- K ATPase
–antiporter, sodium ions (3) out and potassium ions (2) in
–uses about 20% typical cells energy and 67% neurons energy
Ca ATPase
present on cell membrane and sarcoplasmic reticulum– maintains a low cytosolic Ca concentration– pumps Ca from cytosol back into sarcoplasmic reticulum
H ATPase
-parietal cells of stomach (HCl secretion) and intercalated cells of renal tubules (controls blood pH)
-pumps H ions
symporters vs antiporters
–symporters= molecules traveling in same direction (driver must bind first- down concentration gradient- where energy comes from)
–antiporters= ions moving in opposite directions (both must bind before moving– driver first)
Digoxin
–cardiac glycoside, increase cardiac muscle performance in patients with heart failure
–blocks Na/K pump– increase Na concentration in cell– decrease Na ability to lower Ca levels in cell– facilitate a stronger more forceful contraction of muscle because more Ca available
Transcellular Transport of Glucose/AA
-AA and glucose pulled from lumen into epithelial cell- Na symporter (diffusion to get into extracellular fluid)
-Na/K pump pumping Na against conc. gradient- creating it so other side can pull in AA/glucose
Osmosis
net diffusion of water– water moves toward higher salt concentration (down gradient)
Osmotic pressure
the minimum amount of pressure required to halt the flow of water down conc. gradient/ to counter osmosis; higher concentration of solute= higher pressure of osmotic pressure to move against conc. gradient; water moves down concentration gradient until reach equilibrium
Osmolarity
–mOsm= index of the concentration of PARTICLES per liter solution (molecules disassociate: NaCl –> Na/Cl
–if the molecule disassociates then multiple mM by how many particles it disassociates into
Molarity
–mM= index of concentration of MOLECULES per liter solution
Tonicity (effective osmotic pressure)
depends on the properties of both the membrane and the solute
Steady state cell volume
–dependent upon the concentration of IMPERMEANT particles in the extracellular fluid
–higher permeability= more transient the change
Hypernatremia
-increased plasma Na– water leaves cells– cells shrink
-central/nephrogenic diabetes insipidus
-decreased release/response to ADH
Hyponatremia
-decreased plasma Na– water enters cells– cells swell
-syndrome of inappropriate ADH secretion
-too much ADH
K equilibrium potential (Ek)
-electrochemical potential that counters net diffusion of K
-Ek= -94 mV
-Ek= -61 x log (Ki/Ko)
Na equilibrium potential (ENa)
- electrical potential that counters net diffusion of Na
-ENa= +61 mV
-ENa= -61 x log (Nai/Nao)
Resting membrane potential (Vm)
–the membrane is more permeable to K than Na– more potassium leak channels– favors loss of K over uptake of Na
– Vm= -90 to -70
Resting membrane potentials of various cells
Skeletal muscle fibers= -85 to -90
Smooth muscle fibers= -50 to -60
Neurons= -60 to -70
Net driving force of ions
the difference in millivolts between the membrane potential and the equilibrium potential for that ion (Eion)
Depolarized
-membrane potential moves toward 0 mV (becomes more positive)
-Na leak channels opening cause– close in downshoot
Hyperpolarization
goes below resting membrane potential
Overshoot
membrane goes above 0mV
Repolarization
-membrane goes back down toward Vm– towards resting potential
-K leak channels open and cause– open in downshoot
Excitability
ability of membrane to increase in mV
Threshold
-cutoff for cell of where we see action potential– membrane potential must exceed
-Na volted gated (leak) channels open when membrane potential reaches threshold
Na/K activation gate
Na= activation gate opens when membrane potential reaches certain voltage–closes when membrane reaches Vm– inactivation gate opens and activation gate closes
K= K has slow activation when Na inactivation gate closes
Absolute refractory period
a second response isn’t possible no matter the strength or duration of stimulus
Relative refractory period
a second response can be elicited, but requires a stronger stimulus
