In cell biology, extracellular fluid ( ECF) denotes all body fluid outside the cells of any multicellular organism. ![]() Only a very thin shell of charge difference is needed to establish a membrane potential.The distribution of the total body water in mammals between the intracellular compartment and the extracellular compartment, which is, in turn, subdivided into interstitial fluid and smaller components, such as the blood plasma, the cerebrospinal fluid and lymph Several types of stimuli control the opening and closing of ion channels Gates: voltage-gated channels, ligand-gated channels, mechanically gated channels, non-gated channels.They open and close in response to specific electrical, mechanical, or chemical signals. They recognize and select specific ions3. Ion channels have three important properties1.Ion Channels Are Important for Signaling in the Nervous System Neuron as the functional units of nervous system Structure of a neuron 1x Neuron: carrying signals 50x Supporting cells: protect, insulate, reinforce, assist neurons Multiple sclerosis (MS): immune system-myelin sheath loss of signal conduction, muscle control, brain function Active Electrical Properties of the Neuron Synaptic Transmission.Hyposmotic (100 mOsm): particles suck, so cell will suck water from the solution and burst.Hyperosmotic (600 mOsm): particles suck, so solution will suck the water from the cell, which will shrink.Isosmotic (300 mOsm): no net gain or loss of water.What will happen to a cell placed in the following solutions? Osmotic Pressure: the amount of hydrostatic pressure (force of fluid exerted on the vessel wall) required to counter osmosis Osmotic pressure is attributed to the osmolarity of a solution Isosmotic - has same osmolarity as body fluids Hyperosmotic - higher osmolarity than body fluids Hyposmotic- lower osmolarity than body fluids Figure 4-10 Guyton & Hall The solution with the highest number of particles will have the highest hydrostatic pressure. Osmotic pressure is attributed to the osmolarity of a solution. Osmotic pressure is the amount of hydrostatic pressure required to stop osmosis from moving water from low to high concentration across a cell membrane. ![]() IT IS a driving force for moving plasma water across walls of capillaries.Animal cell membranes are “flexible” so it is not a driving force across cell membranes.The pressure of the fluid exerted on the vessels, or container (change in energy/mole).Driving force for water movement across cell membranes.a chemical potential energy difference dependent on the water concentration on two sides of the membrane.Only small uncharged molecules or fat soluble molecules can pass through membrane without help- diffusion (passive transport).Selectively permeable- allows some substances to pass.Lipids and lipid-loving (hydrophobic or lipophylic) substances, such as alcoholįunctions of Membrane- Selective Permeability and Transport.What particles can cross the cell membrane? The particles in the cell will suck water into the cell until the cell bursts. If you have a cell containing 300 mOsm of potassium (K+) immersed in pure water, will it shrink or burst? The potassium cannot flow out of the cell to equalize its numbers inside and outside of the cell because it is blocked in by the cell membrane.Won’t the potassium ions want to move down their concentration gradient towards equilibrium? Yes, they will want to, but the cell membranes are semi-permeable and will prevent the potassium (and other particles) from crossing.If the numbers of particles are always the same, how can we have higher numbers of potassium ions inside of the cell compared to the outside of the cell?.Same osmolalities (total number of particles) 0.3 Osmolal = 300 mOsmolal (actually closer to 280mOsmolal) Plasma Interstitial Intracellularĭifferent compositions across the membrane:.Different compositions (different amounts of individual particles). ![]() in all the compartments you should get the same number of particles: 300 million particles per liter,.If you manipulate one body fluid compartment, it has an effect on another compartment.Body fluid compartments have different sizes and volumes, and different compositions.ECF Blood plasma Interstitial fluid Lymph fluid.Intra cellular fluid (ICF) 2/3 of body fluid.Extra cellular fluid ( ECF) 1/3 of body fluid.15% Fats (Females have 10 % less body water – relatively greater amount of adipose tissue).Cell PhysiologyBDS lecture -3(Body Fluid Compartments) Dr Pradeep Kumar Professor in Physiology KGMU, Lko
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