Physiology Ch. 3-5
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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
Name three different body cavities:
What is the lumen?
The hollow part of the organ
Give an example of a lumen connected to the outside environment:
Give an example of a lumen that is NOT external
Within the heart, filled w/ blood
What are the two basic fluid compartments inside the body?
- Intracellular Fluid Compartment (IFC)
- Extracellular Fluid Compartment (EFC)
Name the two sub-compartments located within the EFC, and describe each.
- Interstitial Fluid- fluid surrounding cells
- Plasma- fluid component of blood
What seperates the fluids of cells?
The cell membrane!
What selects substances to move into and out of the three body fluid compartments?
The cell membrane
Define the word membrane:
A tissue that lines a cavity or seperates two compartments
List at least 4 things cell membranes are responsible for
- Seperation of external and internal enviornments
- Provides shape
- Mediates communication
- Controls exchanges of material
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.
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
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.
Name the various functions of membrane protiens
- Cell Junctions
- Cell recognition
- Immune response
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
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)
What is Simple Diffusion?
Molecules move across the Phospholipid bi-layer without the help of a transport protien
What molecules can pass through Simple diffusion?
- Small molecules WITHOUT a charge
- Examples: Oxygen, Carbon dioxide, small amounts of water
What is Fick's law?
Rate of diffusion = surface area • concentration gradient • membrane permeability / membrane thickness
Define passive protein mediated diffusion
Diffusion of a substance across the membrane with the help of a specific protien
What substances and types of substances are transported by passive protien mediated diffusion?
- Charged Polar molecules
- Uncharged large molecules
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.
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.
- 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
- Assist polar and/or charged molecules
- large molecules
- allows very little water through
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
When salt is dissolved in water, which is the solute and which is the solvent?
- Salt is the solute
- Water is the solvent
What is Osmosis?
The net movement of water through a selective perm. membrane towards a higher concentrate until equalibrium is reached within the concentrate.
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"
water channel protiens
amount of solute
Equal solute concentrate
Solution with the higher concentration of solutes
Solution with the lower concentration of solutes
Presure required to counteract osmosis
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
What substances are transported through active protein mediated transport?
- Molecules the cell needs
- "Important molecules"
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)
In which direction does Sodium (K+) go?
- pumpK-in, or Pumpkin.
- Sodium gets pumped in, potassium gets pumped out
small membrane bound sac
Why do cells form vesicles?
To move out or bring inside large amounts or a substance or large particles
pushes material out
brings material IN
Cell engulfs large particles using pseudopods
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