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What is the role of a compartment?
- To seperate biochemical processes that might conflict with one another.
- Examples: Pepsin in thw stomach works well because of acidic environment, but is practically useless in the intestines
- Think: Kitchen vs. Bathroom
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Name three different body cavities:
- Cranial
- Thracic
- Abdominopelvic
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What is the lumen?
The hollow part of the organ
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Give an example of a lumen connected to the outside environment:
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Give an example of a lumen that is NOT external
Within the heart, filled w/ blood
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Organelles are:
Cell compartments
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What are the two basic fluid compartments inside the body?
- Intracellular Fluid Compartment (IFC)
- Extracellular Fluid Compartment (EFC)
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Name the two sub-compartments located within the EFC, and describe each.
- Interstitial Fluid- fluid surrounding cells
- Plasma- fluid component of blood
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What seperates the fluids of cells?
The cell membrane!
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What selects substances to move into and out of the three body fluid compartments?
The cell membrane
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Define the word membrane:
A tissue that lines a cavity or seperates two compartments
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List at least 4 things cell membranes are responsible for
- Seperation of external and internal enviornments
- Provides shape
- Mediates communication
- Controls exchanges of material
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Briefly describe the "Fluid Mosaic Model"
- Comprised of a phopholipid bilayer of polarized molecules. The eternal heads are hydrophylic and the fatty tails are hydrophopic so they face inwards.
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Describe general structure of one phospholipid molecule and what makes them suitable as major component of cell membranes.
- Polar “head” region interacts with water molecules
- Nonpolar “tails” region will not interact with water molecules
- Phospholipids spontaneously form bilayers
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Explain the behavior of phospholipidmolecules in water.
Phospholipids arrange themselves so that their nonpolar tails are not in contact with aqueous solutions such as extracellular fluid.
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Name the various functions of membrane protiens
- Enzymes
- Cell Junctions
- Cytoskeleton
- Cell recognition
- Immune response
- Transporters
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Define fundamental differences between active and passive transport processes.
- Active transport requires energy from the cell (usually ATP)
- Passive transport does NOT require cell energy
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Name the seven properties of diffusion
- Passive process
- DOWN gradient-net high to low concentration
- Net movement until movement in all directions at about equal rate (EQUILIBREUM)
- Rapid over short distances-slower over long distance.
- Directly related to temperature
- Inversely related to molecular size
- In open system or across a partition (e.g. membrane)
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What is Simple Diffusion?
Molecules move across the Phospholipid bi-layer without the help of a transport protien
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What molecules can pass through Simple diffusion?
- Small molecules WITHOUT a charge
- Examples: Oxygen, Carbon dioxide, small amounts of water
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What is Fick's law?
Rate of diffusion = surface area • concentration gradient • membrane permeability / membrane thickness
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Define passive protein mediated diffusion
Diffusion of a substance across the membrane with the help of a specific protien
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What substances and types of substances are transported by passive protien mediated diffusion?
- Ions
- Charged Polar molecules
- Uncharged large molecules
- Water
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What is the importance of specificity and saturation of transport proteins?
- Specificity means that the transport protien will only transport one specific molecule + water
- And saturation will increase the rate of transfer UNTIL it reaches the transport maximum and then it will NOT increase the rate of transfer.
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What is the difference between channel protiens and carrier protiens?
- Channel protiens are open/leakage channels or gated channels that that move the molecule across the membrane
- Carrier protiens require the binding of a specific molecule to the protien which then changes it's shape allowing the transfer to happen.
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Channel Protien
- Open/leakage allow a continuous movemnet of water and one specific molecule
- Gated- can be opend or closed, allows movement of one molecule and water
- Both allow more water than carrier protines
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Carrier Protiens
- Assist polar and/or charged molecules
- large molecules
- allows very little water through
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What can cause a gated ion protien channel to open?
- A specific stimulus such as
- chemical binding, change in voltage, specific temp, mechanical bend/pressure, light wavelengths
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When salt is dissolved in water, which is the solute and which is the solvent?
- Salt is the solute
- Water is the solvent
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What is Osmosis?
The net movement of water through a selective perm. membrane towards a higher concentrate until equalibrium is reached within the concentrate.
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How does water move by osmosis through a cell membrane?
- Small amounts through simple diffusion
- Cotransported with channel protiens
- Most moves through water channel protiens "Aquaporins"
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Aquaporins
water channel protiens
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Tonicity
amount of solute
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Isotonic
Equal solute concentrate
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Hypertonic
Solution with the higher concentration of solutes
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Hypotonic
Solution with the lower concentration of solutes
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Osmotic pressure
Presure required to counteract osmosis
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Define active protein mediated transport (facilitated difusion)
- Requires energy (ATP) from the cell
- Moves from low to high concentration
- "pumped against the gradient" through a protien membrane
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What substances are transported through active protein mediated transport?
- Ions
- Molecules the cell needs
- "Important molecules"
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Define Sodium-Potassium Pump
- Always a co-transport of Sodium(Na+) & Potassium (K+)
- Moves ions at the same time in opposite directions
- 3 Na+ for every 2 K+ (or 3:2 ratio)
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In which direction does Sodium (K+) go?
- pumpK-in, or Pumpkin.
- Sodium gets pumped in, potassium gets pumped out
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Vesicle:
small membrane bound sac
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Why do cells form vesicles?
To move out or bring inside large amounts or a substance or large particles
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Exocytosis
pushes material out
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Endocytosis
brings material IN
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Phagocytosis
Cell engulfs large particles using pseudopods
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