4 Lujain Al_Adayleh Amani Nofal Mohammad khatatbeh
Recap : Filtration: the movement according to the differences of pressure. **note: not all particles have the same solubility through plasma membrane. For example : the diffusion of CO2 is more than O2. How to measure the osmotic pressure of a solution? by using the osmometer. It consists of a tube filled with solution, distilled water in a bath and a membrane separating two compartments with different concentration of water. *Because of osmosis, water moves from the bath to the tube, and then we are getting increasing of the water level in the tube, and then a pressure is created (hydrostatic pressure ), once equilibrium is reached,no more movement of water, so the hydrostatic pressure which is created can oppose the osmosis, and it s equal to the osmotic pressure.we can calculate the osmotic pressure by Van t Hoff equation (II = RTC). Osmolarity : the number of moles of particles- regardless the type of particles per liter. Osmolality : the number of moles of particles per Kg.(in one kg of medium) *The difference between osmolarity and osmolality is that 1 kg of oil for example is not equal to 1 liter of oil (but this is not including water because the density of water=1000kg/m3 )water has less differences,so the differences occur if we are using mediums other than water. Definitions related to osmolarity (tonicity) *Isotonic : having the same osmolarity,as our body fluid. * hypertonic : higher osmolarity. 1 P a g e Distilled water in a bath A tube filled with solution Membrane
*Hypotonic : lower osmolarity. # if we know the osmolarity we can identify the tonicity. The solution of the task in sheet 3 We first calculate the number of moles for each solution (9/58.43) 150 millimoles, (50/180)280 millimoles. Then we calculate the molarity 150, 280 Then the osmolarity (150*2)300, 280 The osmolarity of glucose remains the same as the molarity because it doesn t dissociate in water ( the number of particles remain the same ). So both solutions are almost isotonic because the osmolarity of the intracellular fluid is 300 mm. *if we have 1 mole of CaCl2 we get 3 molar of osmolarity. There s another type of pressure which is called oncotic pressure (colloid-osmotic ) results by the presence of proteins in the solution. We know that protein s weight is very high, so to get 1 molar solution of albumin for example, you need to dissolve 66 kg of the protein in 1 liter( which is impossible almost) to get the molarty = 1, now you are combining the osmolarity that results from particles ( ions for example) plus the presence of the proteins in that solution, in this case we refer to the oncotic pressure ( colloid-osmotic pressure ). In our extracellular fluid even though we have two compartments of the extracellular fluid (refer to the picture below ). In the compartment that we have in the vascular bath ( intravascular fluid) we have high concentration of protein(albumin), and we have very low concentration between cells (in the interstitial fluid), if -in some medical conditions- happens to have lower concentration of proteins in the intravascular fluid, what happens to fluids? they will move from the intravascular fluid toward the interstitial fluid ( the fluid between cells ). Extracellular fluid divides into: 1- Plasma fluid or blood in the blood vessels. 2- Fluids between cells in the tissue which is called the interstitial fluid. 2 P a g e
Low concentration of proteins High concentration of proteins(albumin) The importance of colloid-osmotic pressure in capillaries Note : capillary divides into arteriolar and venous part. First in the arteriole capillary we have high hydrostatic pressure and high colloidosmotic pressure but the hydrostatic pressure is higher so we are getting filtration of the fluids (move from the intravascular fluid to the interstitial fluid ), then in the venous capillary the hydrostatic pressure becomes lower than the colloid-osmotic pressure so we get osmosis in this case (fluids move from the interstitial fluid to the intravascular fluid ). The concentration of sodium is almost equal inside the vessels (intravascular fluid) and inside the interstitial fluid but very low concentration of sodium inside the cells. We have high concentration of potassium inside the cells but very low outside the cells( either inside the vessels or the interstitial fluid). We have very low concentration of proteins in the interstitial fluid but much higher concentration of proteins inside the intravascular fluid (vessels) and higher concentration of proteins inside the cells. Don t forget the osmolarity of the extracellular fluid, intracellular fluid and inside vessels (intravascular fluid ) is the same but the difference is in the type particles. We have for example in our bodies 140 millimoles and 140 millimolar in the extracellular fluid of sodium, but sometimes in hospitals, some tests show you the concentration of these ions in equivalent concentration, what do we mean by equivalent concentration? in any reaction you can replace 1 mole of sodium with 3 P a g e
1 mole of hydrogen but if you are talking calcium as an ion to replace that calcium with hydrogen how many moles of hydrogen we are needing? 2 moles, in this case the 1 mole of calcium is equal to 2 equivalent concentration but 1 mole of sodium is equal to 1 equivalent concentration, so the molar concentration of hydrogen that can replace ( react with any other ion ) we are considering it the equivalent concentration for that ion. The molar concentration of the ion * the valence electron of the ion = the equivalent concentration for that ion The equivalent concentration refers to the amount of hydrogen or the molar of concentration of hydrogen that can react with or replace the molar concentration of that ion. Last lecture we talked about types of transport ( the passive transport and the active transport ), we discussed the details of the passive transport now we are going to talk about the active transport. Active transport Active transport modalities : 1- Primary active transport 2- Secondary active transport 3- Vesicular transport For the active transport modalities we need ATP to phosphorylate that protein structure to transport particles from the low concentration to the high concentration (against concentration gradient ). These protein structures have sites for binding of these particles that will be transported. 1- Primary active transport Primary means that it consumes ATP directly. Pumps are used only with the primary active transport,they are protein structures which consume ATP to get the transport of particles from the low concentration to the high, they have sites to get the binding of particles to be transported. 4 P a g e
There are four types of pumps : 1- Na+/K+ pump 2- H+ pump 3- H+/K+ pump 4- Ca++ pump Na+/K+ pump For example in Na+/K+ pump, we have 3 binding sites for sodium, and 2 binding sites for potassium, when sodium binding sites are filled with sodium ions then the protein is phosphorylated and by phosphorylation we are getting the transport of these ions of sodium from inside toward the outside, and then 2 potassium ions bind to the carrier, then the carrier changes its shape to transport these 2 potassium ions from outside toward the inside. But when that pump isn t functioning( for example it doesn t transport sodium, It only transport 2 potassium ions from outside toward the inside), the sodium will diffuse from outside toward the inside down the concentration gradient by other means of transport ( channels ), with time,the concentration gradient for sodium inside the cell will increase ( the osmolarity inside increases ), that increasing of osmolarity attracts to other change that,the water ( osmosis is going to happen ) and water will move from outside toward the inside,and the cell will swell (lysis ). So the carriers are important to keep the cell volume not to be changed( to keep certain number of particles inside the cell ). H+ pumps(proton pump) transport hydrogen from the low concentration toward the high concentration, for example there are some cells in the stomach release HCL,how? the cells transport protons form inside the cell where they are found in low concentration toward the lumen of the stomach where they accumulate and found in a high concentration.this pump is responsible for decreasing the ph inside the stomach. H+/K+ pumps can transport hydrogen from the low concentration to the high concentration also potassium from the low ( outside the cell) to the high ( inside the cell ). 5 P a g e
ca++ pumps, in cardiovascular system for example, calcium is needed to enter inside the cell to get the heart contraction.and to get relaxation, calcium has to be removed, how to remove it? one of the modalities ( because there are more than one modality for the transport of calcium ) moves that calcium from inside where it s found in the low concentration toward the outside ( high concentration ) with the help of ca++ pumps. And in the ER (endoplasmic reticulum ) we have a high concentration of calcium, how to keep the high concentration of calcium inside the ER? there are at the membranes of the ER calcium pumps which pump calcium ions from the cytosol toward the inside of the ER. pumps primary active transport some of the lectures called the pumps: type of the ion + ATP-ase. Like Calcium ATP_ase which depend on ATP to transport calcium ( they split ATP into ADP and P). 6 P a g e