Cellular Communication

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Cellular Communication

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University of Southern California
Bisc 307l - General Physiology
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BISC 307L 1st Edition Lecture 5 Cell Communication- CH 6  Cellular Communication- Slide 1 o Chemicals can be used as signals  1. Endocrine signaling  Goes through the blood  Hormones  2. Paracrine  Same as endocrine but affects cells in the area  3. Autocrine  The cell that sent the signal is the one that receives it  4. Pheromone  Affects cell in another individual  5. Contact dependent  6. Synaptic transmission  7. Gap junctional coupling  Mechanisms of hormone action- Slide 2 o 1. Hydrophilic hormones-  water soluble (cannot cross membrane)  need plasma membrane receptor to carry across the plasma membrane  1. Peptides  2. Proteins  3. Amines o 2. Lipophillic hormones-  not water soluble (can cross the membrane) carrier proteins in the plasma to transport around  The most abundant protein in the plasma is albumin  1. Steroids  2. Thyroid o Plasma membrane receptors  Lipophillic hormone  Use intracellular messengers to alter enzymes, channels, or gene expression  Recently discovered- previously unknown pathway  Signal Transduction- Slide 3 o o Where it says proteins kinases that also includes phosphatases o Shows the general mechanism of signal transduction- summary o How does this amplify the signal?  A single molecule binding to a receptor can cause a response because of amplification  Types of Membrane receptors (4)- Slide 4 o 1. Ligand-gated ion channels o 2. Receptor enzymes o 3. G-protein coupled  progesterone membrane receptor is this type o 4. Integrin receptors  Ionic Basis of Resting Membrane potential- Slide 5 o 1. Na/K ATPase creates ionic concentration gradients o 2. Membrane selectively permeable to K+ due to open K+ channels o 3. K+ diffuses outward down the concentration gradient o 4. Since Na+ and Cl- cannot move to compensate, inside becomes negative o 5. K+ diffuses inward, down its electrical gradient o 6. System comes to equilibrium when flux of K+ out = Flux of K+ in o 7. Na+ and Cl- are not in equilibrium o 8. Electrochemical gradients (especially for Na+) represent stored potential energy o 9. Under condition 6, The resting voltage potential (Vm) = RT/zF(ln([K+]out/ [K+]in))  Three things to remember  1. Na+/K+ important low concentration of Na+ inside the cell and high concentration of K+ inside the cell (Pump)  2. Resulting distribution of ions  3. Almost all cells have open K+ selective ion channels in their membranes  Almost all animal cells have the inside negative compared to the outside  1. Ligand-Gated Ion Channels- Slide 6

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