【正文】 – signs of paralysis in his upper body and arms. 6 The Physicians… ? kept his airway open. ? administered drugs to bring his heart back to a normal rhythm. ? put a mixture of charcoal into his stomach to help absorb any chemicals that might still be there. Within a few hours, Dr. Westwood39。Thaut Images Source: Clearance: Licensed, royalty free image. Slide 6 Description: Surgeons. Author: 169。Benjamin Mercer Source: Clearance: Licensed, royalty free image. Slide Credits Slide 5 Description: Ambulance. Author: 169。Bad Fish, Bad Bird Kristi Hannam, SUNYGeneseo Adapted from a case by James A. Hewlett 2 One evening during a trip to Indonesia to study the recent sightings of a coelacanth, Dr. Marshall Westwood from the Montana Technical Institute ate a meal of pufferfish. Local Cuisine 3 Within an hour of returning to his hotel room, he: ? felt numbness in his lips and tongue – which quickly spread to his face and neck. ? began to feel pains in his stomach and throat – which produced feelings of nausea and eventually severe vomiting. Dr. Westwood called a local hospital. Numbness in his lips and face made it almost impossible for him to municate, but the hospital staff sent an ambulance. 4 5 As Dr. Westwood was rushed to the hospital, he had: – trouble breathing。s condition improved and he was on his way to a full recovery. 7 After discussing his case with his physician, he learned that he had probably been the victim of a pufferfish poisoning. 8 POISONED! ? The active toxin in the tissues of this fish is a chemical called tetrodotoxin. ? Tetrodotoxin is a neurotoxin it affects nerve cells (neurons). ? Specifically, tetrodotoxin blocks voltagegated sodium ion channels. 9 CQ1: The symptoms Dr. Westwood suffered included all of the following EXCEPT: A. Fever and chills B. Numbness C. Paralysis D. Difficulty breathing E. Nausea and vomiting 10 CQ2: According to what you know so far, voltagegated sodium ion channels are found in: A. Cells of pufferfish B. All living cells C. Epithelial cells D. Nerve cells E. None of the above 11 CQ3: If tetrodotoxin (TXX) blocks voltagegated sodium ion channels, which part of the action potential graph would be impacted? A. Part A B. Part B C. Part C D. Part D E. Part E TIME Membrane Voltage (mV) 70 55 0 30 A B C D E 12 The Charge Across Cell Membranes ? All cells have an electrical potential difference across their plasma membrane. – Called a MEMBRANE POTENTIAL ? The cell’s inside is negative relative to the outside. ? Sodium (Na+) potassium (K+) and large anions (A) are important in maintaining the membrane potential. Extracellular Intracellular Neuron Cell Membrane Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ K+ A A A A A A A A A A A A A A A A A 13 The Charge Across Cell Membranes ? The interior of a cell’s membrane is hydrophobic and repels ions and molecules with