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  1. 1. Neurotransmitters<br />Properties of neurotransmitters:<br />synthesized in the presynapticneuron<br />2) Localized to vesicles in the presynaptic neuron<br />3) Released from the presynaptic neuron under physiological conditions<br />4) Rabidly removed from the synaptic cleft by uptake or degradation<br />5) Presence of receptor on the post-synaptic neuron.<br />6) Binding to the receptor elicits a biological response<br />
  2. 2.
  3. 3. Neurotransmitter<br />Neurotransmitters are endogenouschemicals which relay, amplify, and modulate signals between a neuron and another cell.[1] Neurotransmitters are packaged into synaptic vesicles that cluster beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to receptors in the membrane on the postsynaptic side of the synapse. Release of neurotransmitters usually follows arrival of an action potential at the synapse, but may follow graded electrical potentials. Low level "baseline" release also occurs without electrical stimulation.<br />
  4. 4. Discovery<br />In the early 20th century, scientists assumed that synaptic communication was electrical. However, through the careful histological examinations of Ramón y Cajal (1852-1934), a 20 to 40 nm gap between neurons, known today as the synaptic cleft, was discovered and cast doubt on the possibility of electrical transmission. In 1921, German pharmacologist Otto Loewi (1873-1961) confirmed the notion that neurons communicate by releasing chemicals. Furthermore, Otto Loewi is accredited with discovering acetylcholine—the first known neurotransmitter. [2]<br />
  5. 5. Neurotransmitters found in the nervous system<br />EXCITATORY<br />Acetylcholine<br />Aspartate<br /> Dopamine<br /> Histamine<br />Norepinephrine<br /> Epinephrine<br /> Glutamate<br /> Serotonin<br />INHIBITORY<br />GABA <br />Glycine<br />
  6. 6. What kinds of neurotransmitters are there?<br />AMINO ACID transmitters<br />Glutamate<br />GABA (γ-aminobutyric acid)<br />
  7. 7. Neurotransmitter<br />Derived from<br />Enzyme<br />Histamine<br />Histidine<br />Histidine decarboxylase<br />GABA<br />(γ-Amino butyrate)<br />Glutamate<br />Glutamate decarboxylase<br />Nitric Oxide<br />Arginine<br />Nitric Oxide Synthase <br />Other Neurotransmitters:<br />
  8. 8. Neurotransmitter Molecule<br />Derived From<br />Site of Synthesis<br />Acetylcholine<br />Choline<br />CNS, parasympathetic nerves<br />Serotonin5-Hydroxytryptamine (5-HT)<br />Tryptophan<br />CNS, chromaffin cells of the gut, enteric cells<br />GABA<br />Glutamate<br />CNS<br />Histamine<br />Histidine<br />hypothalamus<br />Epinephrine<br />synthesis pathway<br />Tyrosine<br />adrenal medulla, some CNS cells<br />Norpinephrine<br />synthesis pathway<br />Tyrosine<br />CNS, sympathetic nerves<br />Dopamine<br />synthesis pathway<br />Tyrosine<br />CNS<br />Nitric oxide, NO<br />Arginine<br />CNS, gastrointestinal tract<br />
  9. 9. Buffers<br /><ul><li>Buffer Solutions resist a change in pH
  10. 10. Buffers contain relatively large concentrations of either
  11. 11. An acid, HA and its conjugate base A-
  12. 12. A base, B, and its conjugate acid (BH+) </li></li></ul><li>Buffers<br />
  13. 13. Buffers<br />NH3 to react with H+<br />
  14. 14. <ul><li>When H+ is added, it reacts essentially to completion with the weak base present</li></ul>H+ + A- HA or<br />H+ + B  BH+<br />
  15. 15. <ul><li>When OH- is added, it reacts essentially to completion with the weak acid present</li></ul>OH- + HA  H2O + A-<br />OH- + BH+  H2O + B<br />
  16. 16. <ul><li>pH = pKa + log (base/acid)
  17. 17. Want pH  pKa  1
  18. 18. pH determined by </li></ul>Ka of acid and ratio of acid/conjugate base<br />or <br />Kb of base and ratio base/conjugate acid<br />
  19. 19. Buffer Table<br />
  20. 20. Buffer Choice<br /><ul><li>Choose a pKa near the desired pH
  21. 21. pH = pKa + log (base/acid)
  22. 22. 4.0 = 3.74 + log (base/acid)
  23. 23. 0.26 = log (base/acid)
  24. 24. 10.26 = 1.8 = (Na formate / formic acid)
  25. 25. Ammonia pKb = 4.74 </li></ul>pKa = 14.00 – 4.74 = 9.26<br />NH3 / NH4Cl used to buffer around pH 9.26<br />
  26. 26. Biological Uses<br /> In biological systems (saliva, stomach, and blood) it is essential that<br /> the pH stays ‘constant’ in order for any processes to work properly.<br /> e.g. If the pH of blood varies by 0.5 it can lead to unconsciousness and coma<br /> Most enzymes work best at particular pH values.<br />Other Uses Many household and cosmetic products need to control their pH values.<br />Shampoo Buffer solutions counteract the alkalinity of the soap and prevent irritation<br />Baby lotion Buffer solutions maintain a pH of about 6 to prevent bacteria multiplying<br />Others Washing powder, eye drops, fizzy lemonade<br />
  27. 27. THANK YOU<br />BY:DEEPIKA TRIPATHI<br />