Module 1: Cell Transport and Signaling Flashcards
Carrier-mediated: Active vs Passive
Yes; Yes or No
Concentration gradient: Active vs Passive
Uphill; Downhill
Energy expenditure: Active vs Passive
Yes; No
Types of Passive Transport
Diffusion
Facilitated diffusion
Osmosis
Simple movement through the membrane, caused by the random motion or kinetic movement of the molecules
Diffusion
Kinetic movement of molecules or ions via membrane opening or or intermolecular spaces
Simple diffusion
T or F: Simple diffusion uses carrier proteins.
F
Rate of diffusion is determined by:
Amount of substance
Velocity of kinetic motion
Number and sizes of openings
Simple diffusion is governed by what law?
Fick’s Law
Law that predicts the rate of diffusion of molecules across a biological membrane
Fick’s Law
T or F: Diffusion is SLOW at higher concentration gradient.
F, FAST
T or F: Diffusion is FAST at higher permeability.
T
T or F: Diffusion is SLOW at higher areas for diffusion.
F, FAST
T or F: Diffusion is SLOW when diffusing membrane is thicker.
T
Paths of simple diffusion
Via interstices of lipid bilayer if diffusing substance is lipid soluble
Through water channels
T or F: Protein pores
A. Always open
B. Non selective with size and charge
A. T
B. F, selective
Molecular conformation of of the gate or its chemical bonds responds to the electrical potential across the cell membrane
Voltage-gated channels
These channels are opened by a chemical substance with the protein
Ligand-gated channels
Ligand-gated channels are also called
Chemical gating
T or F: Facilitated diffusion requires carrier protein.
T
T or F: Facilitated diffusion also follows Fick’s Law.
F, does not follow
T or F: Rate at which molecules can be transported via facilitated diffusion cannot exceed the rate at which carrier protein molecule can undergo change back and forth between its two state
T
Acetylcholine channel is an example of?
Ligand-gated channels
Na and K channels are of what type?
Voltage-gated channels
Factors that affect net diffusion
Net diffusion
Concentration
Charge
Energy
The process of net movement of water through a selective membrane caused by a concentration
Osmosis
A _______ undergoes osmosis from an area of low solute concentration to an area of high solute concentration.
Solvent (water)
A solute undergoes ________ from an area of high solute concentration to an area of low solute concentration.
Diffusion
Homogenous mixture composed of two or more substances
Solution
Substance dissolved
Solute
Substance that dissolves the solute
Solvent
Concentration of all osmotically active particles (osmoles) per liter of solution (osmol/L)
OsmolaRity
OsmolaRity is a colligative property that can be measured by
Freezing point depression
Concentration of all osmotically active particles (osmoles) per kilogram of solvent (osmol/kg)
Osmolality
Determines osmotic pressure between solutions
Osmolality
Two solutions that have the same osmolarity
Isosmotic
Solution with the higher osmolarity
Hyperosmotic
Solution with the lower osmolarity
Hyposmotic
The exact amount of pressure required to stop osmosis
Osmotic pressure
Osmotic pressure is calculated using
Van’t Hoff’s Law or Morse Law
T or F: Osmotic pressure is HIGHER with higher osmolality
T
T or F: Osmotic pressure is LOWER at higher temperature.
F, HIGHER
T or F: The higher the osmotic pressure of a solution, the greater the tendency for water to flow into the solution.
T
Measure of the osmotic pressure of two solutions separated by a semi permeable membrane
Tonicity
T or F: Tonicity is influenced by solutes that can cross the membrane.
F, cannot cross
T or F: Osmolarity is not the same as Tonicity.
T
______ accounts for all solutes while, _______ accounts for only non-permeating solutes.
Osmolarity; Tonicity
Isosmotic volume expansion (eg. Isotonic NaCl infusion)
Gain of water and Na in the ECF, no change in ECF osmolarity, inc ECF volume, no change in ICF volume
Isosmotic volume contraction (eg. Diarrhea)
Loss of water and Na in the ECF, No change in ECF osmolarity, dec ECF volume, No change in ICF volume
Hyperosmotic volume expansion (eg. High NaCl intake, Conn’s)
Gain of Na in the ECF, Inc ECF osmolarity, Inc ECF volume, Dec ICF volume
Hyperosmotic volume contraction (eg. Sweating, fever, DI)
Loss of water in the ECF, Inc ECF osmolarity, Dec ECF volume, Dec ICF volume
Hypoosmotic volume expansion (eg. SIADH)
Gain of water in the ECF, Dec ECF osmolarity, Inc ECF volume, Inc ICF volume
Hypoosmotic volume contraction (eg. Adrenal insufficiency, Diuretics overuse)
Loss of Na in the ECF, Dec ECF osmolarity, Dec ECF volume, Inc ICF volume
Types of vehicular transport
Exocytosis
Endocytosis
Secretory vehicles fuse with cell membrane, extruding their contents outside the cell
Exocytosis
Molecules are absorbed and internalized by coating with membrane phospholipids forming a vesicle that detaches form cell membrane
Endocytosis
Calcium-dependent: Exocytosis or Endocytosis
Exocytosis
Cell drinking
Pinocytosis
T or F: Pinocytosis does not require ATP and calcium in the ECF.
F, requires
Cell eating
Phagocytosis
Events in phagocytosis
Contact..
Invagination..
Pinching off..
Vacuole formation
Receptor-mediated endocytosis
Clathrin-mediated Endocytosis
Transport of glucose, amino acids, and other polar molecules through the cell membrand
Carrier-mediated Transport
Characteristics of Carrier-mediated Transport
Stereospecificity
Saturation
Competition
Types of Active Transport
Primary Active Transport
Secondary Active Transport
Occurs UPHILL against an electrochemical gradient, requires direct input of metabolic energy, carrier-mediated transport
Primary Active Transport
Give examples of Primary Active Transport
Na/K-ATPase in virtually all cells
Ca-ATPase in sarcoplasmic reticulum
H/K-ATPase in parietal cells of stomach
H-ATPase in intercalated cells of kidneys
Transport of Na from ICF to ECF and K from ECF to ICF against electrochemical gradient
Na/K-ATPase
Usual stoichiometry in Na/K-ATPase
3 Na/2 K
Transport of two or more solutes is coupled
Secondary Active Transport
T or F: One of the solutes (usually Na) is transported UPHILL and provides energy for the DOWNHILL transport of other solutes
F, DOWNHILL; UPHILL
Types of Secondary Active Transport
Co-transport
Countertransport
Co-transport is also called
Symport
Occurs if the solutes move in the same direction across the cell membrane
Co-transport
Examples of co-transport
Na glucose co-transport in the intestines
Na/K/2Cl co-transport in loop of Henle
Na/Cl co-transport in distal convoluted tubule
Also called exchange transport or antiport
Countertransport
Occurs if the solutes move in opposite directions across the cell membrane
Countertransport
Examples of countertransport
Na-Ca countertransport in virtually all cells
Na/H countertransport in proximal tubule
Signaling molecules
Peptides and proteins Catecholamines Steroid hormones Iodothyronines Eicosanoids
Mechanisms of cellular communication
Endocrine Neurocrine Paracrine Autocrine Juxtacrine
Transport of hormones along the bloodstream to a distant target organ
Endocrine Signaling
Transport of neuro-transmitters from a presynaptic cell to a postsynaptic cell
Neurocrine Signaling
Release and diffusion of local hormones with regulatory action on neighboring target cells
Paracrine Signaling
A cell secretes hormones or chemical messengers that bind to the same cell
Autocrine Signaling
Contact-dependent signaling
Juxtacrine Signaling
Types of receptors
Signal transducers
Membrane receptors
Nuclear receptors
Plasma membrane receptors
Ion-channel linked
G-protein coupled receptors
Catalytic receptors
Transmembrane receptors
Types of signal transduction pathways
G proteins
Ion channels
Protein kinases
Mediate direct and rapid synaptic signaling between electrically excitable cells
Ion-channel linked signal transduction pathways
Heterotimeric complexes - alpha, beta, gamma subunits
G protein-coupled signal transduction pathways
Active or Inactive: GTP with alpha subunit, activation via guanine nucleotide exchange factors
Active
Active or Inactive: GDP, inactivation via GTPase-accelerating proteins and RGS proteins
Inactive
An enzyme that modifies other proteins by phosphorylation
Kinase