Agony and Ecstasy Norris Armstrong University of Georgia-Athens Susan, a new intern at the local hospital, was working the admissions desk one Monday.
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Agony and Ecstasy Norris Armstrong University of Georgia-Athens 1 Susan, a new intern at the local hospital, was working the admissions desk one Monday morning. A man and a woman rushed through the doors, carrying a second woman. “Help! Can you help us?” one called. Susan and a nurse rushed them into an exam room. “What happened?” Susan asked while examining the patient. “We don’t know!” the female student sobbed. “Brittany started feeling sick at a party last night. She came home and went to sleep, but then couldn’t wake up this morning. She was acting so weird we decided to bring her here.” Susan carefully observed the woman lying on the table. She was rolling her head and clearly seemed confused. However, there were no obvious signs of trauma. “Has Brittany taken any drugs recently?” Susan asked. The two students hesitated and looked at each other. Finally one of them nodded. “I think she took some Ecstasy last night.” 2 Susan thought for a moment. Ecstasy had been fairly popular on the party scene for several years now. She had seen people on the drug become somewhat confused, but not delirious. Maybe Brittany was having an adverse reaction to the drug. It was a start. To be safe, Susan ordered a series of blood tests. In the meantime, she checked her medical references to find out as much as she could about how Ecstasy affected the body. 3 Ecstasy (MDMA) Animation http://learn.genetics.utah.edu/content/addiction/drugs/mouse.html Animation describing the neurological/molecular mechanisms by which ecstasy works 4 Ecstasy (MDMA) Fact Sheet • MDMA (3,4 methylenedioxymethamphetamine) is a synthetic, psychoactive drug chemically similar to the stimulant methamphetamine and the hallucinogen mescaline. MDMA acts as both a stimulant and psychedelic. It produces an energizing effect, distorts both physical and cognitive sensations, and may impair memory. • MDMA affects a neuron’s ability to use the chemical serotonin. Serotonin plays an important role in regulating mood, aggression, sexual activity, sleep, and sensitivity to pain. Research in animals indicates that MDMA is a neurotoxin. MDMA is potentially harmful to health and, on rare occasions, may be lethal. 5 Ideas why Brittany is ill? MDMA may affect: • Blood pressure • Pulse rate • Body temperature • Hyperthermia • Hypothermia • Water Balance • Dehydration • Excess water • Blood sugar level • Vision 6 Brittany’s Test Results Item and measure Normal Brittany Heart Rate (beats/min) 60-100 90 Blood Pressure (mmHg) 90/50 - 140/90 135/87 98.6 100.2 Temperature (°F) Glucose (mg/dl) 60-109 72 Sodium-Na+ (mM/L) 135-146 115 Potassium-K+ (mM/L) 3.5-5.5 2.9 Chloride-Cl- (mM/L) 95-109 88 O2 (mmHg) 80-100 93 CO2 (mM/L) 22-32 24 7 CQ#1: What do the test results suggest is causing Brittany’s illness? A. B. C. D. E. F. High blood pressure or rapid heart rate Hypoglycemia (too little blood sugar water) Hyperthermia (too hot) Hypothermia (too cold) Excess water (too much water) Dehydration (too little water) 8 Concentration: Amount of one substance (solute, ) dissolved in given volume of another substance (solvent, ). Side A Side B 9 Ecstasy Case Continued Susan spoke to the students in the waiting area. “Did Brittany have much to drink last evening?” “Just one beer,” replied one. “She had a test today and wanted to study. She did drink a lot of water. You’re supposed to do that to prevent a hangover aren’t you? She seemed really thirsty.” Susan thought for a minute. Normally, Brittany’s kidneys would respond to drinking a lot of water by producing large amounts of dilute urine. However, Ecstasy acts as an antidiuretic and forces the kidneys to make concentrated urine instead. This would prevent Brittany’s body from getting rid of excess water and could cause her electrolytes to fall. Could this be causing her symptoms? 10 Diffusion / Osmosis Animations http://physioweb.med.uvm.edu/diffusion/ 11 CQ#2: Assume movement of a molecule is limited. It can move to the opposite side of a container or stay where it is. If movement is random, what is the probability (0-100%) that the molecule will move to the opposite side? Side A Side B 12 CQ#3: Assume there are 10 molecules on one side of a container. How many would you expect to move to the opposite side? A. 10 B. 5 C. 0 D. It is impossible to predict Side A Side B 13 Diffusion with Many Particles http://physioweb.med.uvm.edu/diffusion/tocpage.htm (Animation) 14 CQ#4: Which statement best describes how these molecules will behave over time due to random movement? Side A Side B A. Red molecules will move from side A to B. B. Blue molecules will move from side B to A. C. All of the molecules will move so that red and blue will become equal on both sides. D. More molecules will move from side A to B than from side B to A. 15 Solutions and Transport • Solution – homogeneous mixture of two or more components – Solvent – dissolving medium – Solutes – components in smaller quantities within a solution • Intracellular fluid – nucleoplasm and cytosol • Interstitial fluid – fluid on the exterior of the cell Brittany’s cells Inside Cells Outside Cells 300 mM Salt 250 mM Salt 17 CQ#5: Which of the following molecules could move through a phospholipid membrane with the least difficulty? A. H2O B. Glucose C. Na+ D. O2 E. An amino acid 18 Cell Membrane Cell Membrane Outside of cell Proteins Carbohydrate chains Cell membrane Inside of cell (cytoplasm) Protein channel Copyright Pearson Prentice Hall Lipid bilayer 20 Figure 5.13 Two structures formed by self-assembly of phospholipids in aqueous environments HOW DO MOLECULES CROSS? Hydrophobic Hydrophilic 22 Figure 8.7 The structure of a transmembrane protein Aquaporins 24 Brittany’s Tissues Aquaporin Inside the cells Outside the cells 25 CQ#6: What do you expect to happen over time in Brittany’s cells? Inside Cells 300 mM Salt Outside Cells 250 mM Salt A. Water will move from inside to outside ONLY. B. Water will move from outside to inside ONLY. C. Water will move in both directions, but more water will move inside. D. Water will move in both directions, but more water will move outside. E. Water will not move. 26 So what happened to Brittany? Brittany was treated for hyponatremia. The treatment included giving her an IV of fluids with normal or slightly higher sodium concentrations to correct the salt imbalance in her tissues. A problem associated with acute (sudden) hyponatremia, or water intoxication, is swelling of tissues due to osmotic uptake of water by cells. Fortunately, because she received treatment, they were able to reverse the swelling effects before her brain stem was damaged. Hyponatremia can be very serious because of the possibility of brain damage. 27 Problems with Hyponatremia • Brittney Chambers of Colorado (2001), Leah Betts of Great Britain (1995), and Anna Wood of Australia (1995) died after reportedly taking Ecstasy and drinking large amounts of water. • Fraternity hazing killed Matthew Carrington, a student at California State Chico February 2005. • In Sacramento, Jennifer Strange died after a water-drinking contest "Hold your wee for a Wii” sponsored by a local radio station, January 2007. • A 28-year-old female Boston marathoner died in 2002. • Artist Andy Warhol died after hospital staff accidentally administered excess water after gall bladder surgery (1987). • Infants fed diluted formula for extended periods of time can suffer from hyponatremia. 28 Cell Membrane Cell Membrane The cell membrane regulates what enters and leaves the cell and also provides protection and support. Copyright Pearson Prentice Hall Diffusion Through Cell Boundaries Measuring Concentration A solution is a mixture of two or more substances. The substances dissolved in the solution are called solutes. The concentration of a solution is the mass of solute in a given volume of solution, or mass/volume. Copyright Pearson Prentice Hall Diffusion Through Cell Boundaries Diffusion Particles in a solution tend to move from an area where they are more concentrated to an area where they are less concentrated. This process is called diffusion. When the concentration of the solute is the same throughout a system, the system has reached equilibrium. Copyright Pearson Prentice Hall Diffusion Through Cell Boundaries Copyright Pearson Prentice Hall Cellular Physiology: Membrane Transport • Membrane Transport – movement of substance into and out of the cell • Transport is by two basic methods – Passive transport • No energy is required – Active transport • The cell must provide metabolic energy Selective Permeability • The plasma membrane allows some materials to pass while excluding others • This permeability includes movement into and out of the cell 35 Simple diffusion Facilitated diffusion Passive Transport Processes • Types of diffusion – Simple diffusion • Unassisted process • Solutes are lipid-soluble materials or small enough to pass through membrane pores Passive Transport Processes • Types of diffusion – Facilitated diffusion • Substances require a protein carrier for passive transport – Osmosis – facilitated diffusion of water • Highly polar water easily crosses the plasma membrane through protein channels Diffusion through the Plasma Membrane Figure 3.10 Osmosis Osmosis Osmosis is the diffusion of water through a selectively permeable membrane. Copyright Pearson Prentice Hall Osmosis How Osmosis Works Concentrated sugar solution (Water less concentrated) Dilute sugar solution (Water more concentrated) Sugar molecules Selectively permeable membrane Copyright Pearson Prentice Hall Movement of water Osmosis Water tends to diffuse from a highly concentrated region to a less concentrated region. If you compare two solutions, three terms can be used to describe the concentrations: hypertonic (“above strength”). hypotonic (“below strength”). isotonic (”same strength”) Copyright Pearson Prentice Hall Figure 8.12 The water balance of living cells Active Transport Processes • Transport substances that are unable to pass by diffusion – They may be too large – They may not be able to dissolve in the fat core of the membrane – They may have to move against a concentration gradient • Two common forms of active transport – Solute pumping – Bulk transport Active Transport Energy Active Transport Processes • Solute pumping – Amino acids, some sugars and ions are transported by solute pumps – ATP energizes protein carriers, and in most cases, moves substances against concentration gradients PRESS TO PLAY ACTIVE TRANSPORT ANIMATION Active Transport Processes Figure 3.11 Endocytosis Figure 3.13a Active Transport Processes • Bulk transport – Endocytosis • Extracellular substances are engulfed by being enclosed in a membranous vescicle – Types of endocytosis • Phagocytosis – cell eating • Pinocytosis – cell drinking Active Transport Processes • Bulk transport – Exocytosis • • • • • Moves materials out of the cell Material is carried in a membranous vesicle Vesicle migrates to plasma membrane Vesicle combines with plasma membrane Material is emptied to the outside Exocytosis Figure 3.12a Endo & Exocytosis Golgi Apparatus Vesicle Cell Membrane 52 Passive Transport Processes • Filtration – Water and solutes are forced through a membrane by fluid, or hydrostatic pressure – A pressure gradient must exist • Solute-containing fluid is pushed from a high pressure area to a lower pressure area 7-3 Unlike a cell wall, a cell membrane • • is composed of a lipid bilayer. provides rigid support for the surrounding cell. • allows most small molecules and ions to pass through easily. is found only in plants, fungi, algae, and many prokaryotes. • Copyright Pearson Prentice Hall 7-3 The concentration of a solution is defined as the • • • • volume of solute in a given mass of solution. mass of solute in a given volume of solution. mass of solution in a given volume of solute. volume of solution in a given mass of solute. Copyright Pearson Prentice Hall 7-3 If a substance is more highly concentrated outside the cell than inside the cell and the substance can move through the cell membrane, the substance will • move by diffusion from inside the cell to outside. • remain in high concentration outside the cell. • move by diffusion from outside to inside the cell. • cause water to enter the cell by osmosis. Copyright Pearson Prentice Hall 7-3 The movement of materials in a cell against a concentration difference is called • • • • facilitated diffusion. active transport. osmosis. diffusion. Copyright Pearson Prentice Hall 7-3 The process by which molecules diffuse across a membrane through protein channels is called • • • • active transport. endocytosis. facilitated diffusion. osmosis. Copyright Pearson Prentice Hall Figure 44.14a Osmoregulation in a saltwater fish Figure 44.14b Osmoregulation in a freshwater fish Figure 44.13 Nitrogenous wastes 62 Figure 44.17 Key functions of excretory systems: an overview 64 65 66 67