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What is osmotic equilibrium? How does it arise?
- -Fluid in two compartments are equal
- -expressed as amount of solute/vol.
- example: ECF and ICF fluids are equal
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What is chemical disequilibrium? Give some examples of specific solutes that exist in a state of chemical disequilibrium in your body.
- -when solutes are unequal in two compartments
- example: ICF is high in K+ & proteins while ECF is high in Na and Cl.
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Why is water movement such an important aspect of physiology?
- -it is the solvent for all living matter
- -maintains osmotic equilibrium
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Define and describe osmosis.
- -diffusion of H2O (99% right)
- -water moving across a membrane/barrier in response to a solute concentration
- -water will stop moving when net movement is 0
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What is osmotic pressure?
-the applied pressure to oppose osmosis
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How does osmolarity differ from molarity?
- -osmolarity is the number of active particles in solution
- -expressed in osmoses per liter
- -osmol/L or OsM
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- -molarity is the number of active particles when started
- -mol/L x number of active particles/molecules
- -the concentration when started
-osmolaity-osmoles of solute/kg of water
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Distinguish between the terms isosmotic, hyposmotic, and hyperosmotic.
- -used shen comparing two solutions
- isosmotic-refering to two solutions with the same osmolarity
- hyposmotic-one solution's osmolarity is lower than the other
- hyperosmotic-one solution's osmolarity is higher than the other
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Contrast osmolarity and tonicity.
- -osmolarity is measuring active particle in a solution
- -tonicity is predicting where water will move
- how will a cell react if placed in a specific solution

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Contrast penetrating and nonpenetrating solutes. What does it mean when a solute is considered "functionally nonpenetrating?
- penetrating-when solute particles (ions or particles) enter a cell
- nonpenetrating-when solute particles can't enter a cell
- functionally non penetrating-NaCl
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What are the rules for predicting tonicity?
- 1. if the cell has a high concentration of nonpenetrating solutes than the solution, water will move into the cell making the solution hypotonic
- 2. if the cell has a lower concentration of nonnpenetrating solutes than the solution, the water will move outside the cell making the solution hypertonic.
- 3. if both are the same, then the solution is isotonic.
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How can a solution be isosmotic and hypotonic?
????
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What is bulk flow? Give examples in the body.
- -bulk flow refers to the movement of fluids in a compartment weather its liquid or gas
- -pressure gradients make fluid move from high to low pressure
- example: circulatory sys., heart pump and moves blood. Also the air flow of lungs.
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What qualities of a cell membrane contribute to its permeability? Give examples of substances that typically are permeable and impermeable to human cell membrane.
- -size and lipid solubility
- -O2, CO2, and move easily across the cell membrane
- -ions, a large molecules like proteins move with more difficultly or not all
- -some require specific transport protein membranes(vesicles)
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What two properties of a molecule determine whether it can diffuse across a membrane?
-Passive and active transport
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What is the difference between passive and active transport?
- -passive transport does not require energy
- -active transport requires energy(ATP)
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What are the different ways a molecule can move across a membrane?
- -simple diffusion
- -facilitated diffusion
- -primary active transport
- -secondary active transport(uses APT from primary)
- -endo-, exo-, and phagocytosis
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Define diffusion.
the movement of molecules from a higher concentration to a lower concentration
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List seven properties of diffusion.
- 1. Passive process
- 2. Molecule movement of higher to lower concentration
- 3. net movement of molecules continues until concentration is equal
- 4. diffusion is faster over short distance and slower over long dist.
- 5. Diffusion is directly related to temperature
- 6. inversely related to size and weight
- 7. can occur in an open system or particles that separate two compartments
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Define simple diffusion. Beyond the seven properties, what additional properties influence rate of diffusion?
The rate diffusion depends on how permeable the membrane is to the diffusing molecules.
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What factors influence membrane permeability?
- -surface area
- -thickness of membrane
- -larger concentration gradient
- -solubility
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Why is simple diffusion not an option for most molecules in our body?
Most of the molecules are either lipophobic or electrically charged, so they can't cross by simple diffusion.
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Differentiate between mediated transport, facilitated diffusion, and active transport.
- -mediated transport requires a membrane protein to enter
- -facilitated diffusion-does not require energy(ATP) to diffuse
- -active transport-requires ATP
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What are the three major roles of structural proteins? Fig 5.8
- 1. maintain shape by connecting the cytoskeleton to the membrane. i.e. microvilli transporting epithelia
- 2. create cell junctions like gap and tight junctions that hold tissues together.
- 3. attach ECF matrix membrane fibers to ECF collagen and protein fibers.
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What are membrane enzymes? How are they different in function from intracellular enzymes?
- -membrane enzymes are active in metabolism and signal transfer.
- -intracellular enzymes transfer signals from ECF to cytoplasm
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Describe membrane receptor proteins.
Receptors proteins can activate membrane enzymes, open and close chemically gated channels, and are active in receptor mediated endocytosis.
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The current classification scheme recognizes two types of transporters:____and _____.
carrier and channel proteins
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Describe and draw a typical protein channel. What type of molecules pass through channel proteins? Give examples of channel proteins.
 - There are gated and open channels.
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What factors determine the channel protein's specificity?
by the size of the pore and the electric charge of the amino acids that line it.
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Distinguish between an open and gated channel.
- -open channels are typically open with no regulation, also know as leak channels or pores
- -gated channels spend most of the time closed, they can be controlled chemically, mechanically, or by voltage.
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List three types of gated channels and indicate the stimulus that opens each type.
- -chemically gated channels controlled by intracellular molecules or extracellular ligands that bind to the channel protein.
- -voltage-gated channels are controlled through the electrical state of the cell
- -mechanically gated channels respond to physical forces, like increased temperature or pressure
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Give examples of molecules that might cross a membrane by using a carrier protein.
Na+, K+, ATPase, sodium potassium pump, Ca2+, H+, Glucose
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Define the following terms: uniport carriers, cotransporters, symport carriers, and anti port carriers.
- -uniport can only move one molecule
- -cotransporter refers to a carrier that moves more than one molecule
- -symport moves more than one molecule in the same direction
- -antiport moves more than one molecule in opposite directions
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Compare and contrast facilitated diffusion and simple diffusion.
- Simple diffusion can directly cross the phosopholipid bilayer of a membrane.
- Facilitated diffusion is a mediated transport.
- Both are passive and move molecules down their concentration gradient.
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Give example of molecules that might cross a membrane by facilitated diffusion.
- Sugars and amino acids
- GLUT transporters
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What is active transport? What does it accomplish? Why does it require the input of energy?
Molecules moving against their gradient which requires a lot of energy. It creates a state of disequilibrium. Moving m In the sodium potassium pump, Na is getting pumped out while K is getting pumped in. In a neuron this would result in a neuron firing.
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Distinguish between primary active transport and secondary active transport.
- -primary active transport also known as ATPase(enzyme)
- -secondary active transport uses ATP from primary active transport and usually is Na dependent
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Diagram the structure and mechanism of the Na+-K+-ATPase as an example of primary active transport.
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How is the relativity high extracellular Na+ used to drive transport of other molecule against their concentration gradient across a membrane?
By using cotransporters molecule will piggy back with it.
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Give examples of how specificity applies to carrier-mediated transport.
The transporter(membrane protein) only allows a certain family of molecule through like GLUT.
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How does competition relate to specificity?
Since transporters can move a family of molecules, the particular type that it wants could get beat out by a different molecule in the family.
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Give an example of competitive inhibition.
- When one molecule prevents the needed molecule from binding to a transporter.
- example: maltose and glucose are in the same family(disaccharides) but compete with each other for binding sites.
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Describe how the principle of saturation applies to carrier-mediated transport. Included a description of transport maximum.
As the substrate concentration increases the rate of transport increases until to reaches a max like the check out stands at the super market.
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How can cells increase their transport capacity and avoid saturation?
Increase the number of carriers in the membrane.
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The two primary modes of vesicular transport are _____ and _____.
phagocytosis and endocytosis
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Describe the process of phagocytosis. What is a phagosome?
phagocytosis is the process of engulfing a bacteria or particle. A phagosome is the membrane bound vesicle that brings the particle to lyosomes.
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How does endocytosis differ from phagocytosis?
- -in endocytosis the membrane indents
- -vesicles in endocytosis are much smaller
- -endocytosis is an essential process alway occurring while phagocytosis must be triggered.
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What is pinocytosis?
Active process that can be nonselective or selective, sucks in water
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Explain the process of receptor-mediated endocytosis. What role does clathrin play? What is an endosome?
- 1. Ligand binds to membrane receptor
- 2. Receptor-ligand move toward clathrin coated pit.
- 3. Endocytosis
- 4. vesicle losses clathrin coat(gets recycled)
- 5. receptor and ligand separate
- 6. Ligands go to lysosomes or Golgi for processing
- 7. Vesicle and receptors move towards membrane.
- 8. vesicle fuse to membrane(recycling of membrane.
- 9. Exocytosis.
- -clathrin is an indentation of the membrane where it is high in protein
- -endosome is the vesicle the ligands take when there separated from the receptors.
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Describe the movement of glucose across a transporting epithelial cell. Include in your diagram all membrane proteins ions, and directionality of transport.
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