Week 1 Flashcards
what is the extracellular environment
includes all constituents of the body located outside of the cells. Cells receive nourishment from and release waste into the extracellular environment. Cells interact with each other via chemical regulators secreted into extracellular environment
What are primary cilia
non-motile cilia are on every type of cell except blood cells. They have important functions in communication, signal transduction, and cell growth control. They can have huge effects on growth and development, kidney disease, obesity, wound healing, and cancer
what are some ciliopathies
Diseases cause by dysfunction of cilia include polycystic kidney disease, congenital heart disease, mitral valve prolapse, retinal degeneration.
Describe the water content of the body
67% of total body water is WITHIN cells. 33% is extracellular. About 20% of the extracellular fluid is in blood plasma and the remaining 80% is the interstitial fluid in tissues
describe the interstitial fluid (where is it)
it is contained in the gel-like extracellular matrix. Molecules must pass through the interstitial fluid to get between blood and body cells
What composes the extracellular matrix and what does each component do
collagen, elastin, and gel-like ground substance (contains glycoproteins and proteoglycans with high content of water bound molecules)
collagen and elastin provide structural strength to the connective tissues (Collagen IV contributes to the basement membrane)
glycoproteins and proteoglycans form bonds with carbohydrates on membrane of cells making a basement membrane which weds the epithelium to its connective tissues
What are integrins
a class of glycoproteins that extend from the cytoskeleton in a cell through its plasma membrane and into the extracellular matrix. Serve to provide adhesion, polarity, signaling, and motility
“Integrate” the two compartments
why is it called the plasma membrane?
because the extracellular fluid is either blood plasma or derived from it. The membrane separates extracellular from intracellular
explain how the plasma membrane is selectively permeable
It only allows some molecules to penetrate the membrane because it has a large non polar region so only non polar molecules can pass. Generally proteins, nucleic acids, and other large polar molecules are not permeable. But certain ions or small non polar molecules are permeable
This is relevant to PHARMACOLOGY
categories of transport through the plasma membrane
Carrier-mediated transport includes facilitated diffusion and active transport
Non-carrier-mediated transport includes simple diffusion, simple diffusion through channel proteins, and aquaporin channels
Can also categorize by PASSIVE and ACTIVE transport. Passive moves with concentration gradient and uses no energy. Active moves agains gradient and requires energy (PUMPS!)
difference between carrier and channel proteins
carrier proteins are membrane proteins that change their configuration (3D structure) in some way to ferry a molecule or ion across the membrane
channel proteins are membrane proteins with structures that provide selective channels for the movement of specific ions or water molecules across the membrane
what are the components of an aqueous solution
solvent: liquid doing the dissolving (usually water)
solute: molecule being dissolved (like salt, sugar, etc)
What is Brownian Motion
the visible manifestation of random electromotion of a solution. The molecules of a solution are in a constant state of random motion as a result of their thermal energy
This is the driving force for diffusion!
define diffusion
If there is a concentration difference or concentration gradient between two regions of a solution, random motion (Brownian motion) tends to eliminate the concentration difference as the molecule become more diffuses spread out
define NET diffusion
as a result of random molecular motion, molecules in the part of the solution with a higher concentration will enter the area of lower concentration. There is motion in both directions, but more move in the high to low direction so there is a NET MOVEMENT from the region of higher concentration to lower until the difference no longer exists
when does net diffusion occur?
whenever there is a concentration difference across a membrane AND that membrane is permeable to the diffusing substance
what molecules can pass through the plasma membrane easily and why?
PM has a thick non polar core, so non polar molecules can easily pass through it. This includes oxygen gas and steroid hormones. Small, uncharged, polar molecules such as CO2 and H2O can also pass through.
explain the distribution of O2 and CO2 concentrations inside and outside cells
Oxygen concentration is high in the extracellular fluid because oxygen is carried from lungs to tissues in blood. During cell respiration (metabolism, ETC) oxygen is constantly being depleted and made into water, so intracellular oxygen is low.
Carbon dioxide is higher inside the cell. Cells produce CO2 during cell respiration (metabolism, CAC) so intracellular CO2 is constantly being produced.
This contributes to Gas Exchange
how does water diffuse through the membrane
water can diffuse through membrane to a limited degree because of the small size and lack of net charge. However, most membranes have greatly aided water passage through AQUAPORIN water channels.
define osmosis
Net diffusion of water molecules (the solvent instead of solute) across membrane
define ion channels
transmembrane proteins that provide passage for impermeable charged inorganic ions (Na+ and K+ for example). They are relatively selective. Some are always open and many are gated so they can open or close
What determines the rate of diffusion (4 things)
- The magnitude of the concentration difference across the membrane
- the permeability of the membrane to the substance
- the temperature of the solution
- the surface area of the membrane
Can you explain why all of these things contribute to diffusion rate? Page 008
what are microvilli
tiny fingerlike projections in the epithelial membranes in the small intestine which aid in increasing cell surface area and therefore increasing rapid diffusion of digestion products across membranes
2 criteria for osmosis to occur
- There must be a difference in the concentration of a solute on the two sides of a selectively permeable membrane
- The membrane must be relatively impermeable to the solute
define osmotically active
solutes that cannot freely pass through the membrane can promote the osmotic movement of water are osmotically active. Basically if they cause osmosis
when are aquaporins present? what organ as special importance in aquaporin regulation
some cells always have aquaporins present while others have those channels inserted into the membrane in response to regulatory molecules. This regulation is especially important to the KIDNEYS which are the major organs regulating total body water balance
IMPORTANT: aquaporins do not open and close, they are inserted and removed!
explain osmotic pressure
The pressure needed to stop osmosis. E.g. in plant cells, the cell walls provide a rigid box that will prevent further expansion. Animal cells don’t have this and will LYSE (burst) if placed in pure water
the greater the solute concentration of a solution, the greater its osmotic pressure. Measures the force required to stop osmosis, so measures how strongly a solution draws water by osmosis
explain molarity and molality
molarity is a measure of mol/liter so when making a solution you add the weight of 1 mol to a total volume of 1 liter. This means you DO NOT KNOW the exact ratio of solute to water because you don’t know how much water exactly is added
molality is a measure of mol/kg water so you would add the weight of 1 mol to 1 kg of water. Now you know the EXACT ratio of solute to solvent because you know how much water is added!
what is osmolality
the TOTAL MOLALITY of a solution. Depends on ratio of solute to solvent, NOT chemical nature of solute molecules. Add the molality of everything in the solution together for osmolality.
NOTE: for electrolytes like NaCl, they will ionize in water and dissociate. So if a solution is 1 molal NaCl it ends up being 2 osmolal because the Na and Cl ionize
how to measure osmolality
freezing point depression occurs because the freezing point of a solution is affected by total concentration. So by seeing how much freezing point is changed from 0 C, we know the osmolality!
Through this we know that plasma is 0.3 Osm or 300 milliosmolal (mOsm)
describe 2 common isosmotic solutions
5% dextrose or D5W: 0.3 m glucose solution is 0.3 Osm. made by 5 g of glucose per 100 ml.
physiologic saline or normal saline: 0.15 m NaCl solution is 0.3 Osm. made by 0.85 g of NaCl per 100 ml. (NOTE: 0.9 g NaCl is commonly used but 0.85 is the exact number!)
