1 / 40

Chapter 5c

Chapter 5c. Membrane Dynamics. The Body Is Mostly Water. Distribution of water volume in the three body fluid compartments 1 liter water weighs 1 kg or 2.2 lbs 70 kg X 60% = 42 liters for avg 154 lb male. Figure 5-25. Aquaporin.

carter
Download Presentation

Chapter 5c

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 5c Membrane Dynamics

  2. The Body Is Mostly Water • Distribution of water volume in the three body fluid compartments • 1 liter water weighs 1 kg or 2.2 lbs • 70 kg X 60% = 42 liters for avg 154 lb male Figure 5-25

  3. Aquaporin • Moves freely through cells by special channels of aquaporin

  4. Osmosis and Osmotic Pressure A B Volume increased • Osmolarity describes the number of particles in solution Selectively permeable membrane Volume decreased Glucose molecules 1 2 Two compartments are separated by a membrane that is permeable to water but not glucose. Water moves by osmosis into the more concentrated solution. Volumes equal 3 Osmotic pressure is the pressure that must be applied to B to oppose osmosis. Figure 5-26

  5. Osmolarity: Comparing Solutions Hyper / Hypo / Iso are relative terms Osmolarityis total particles in solution Normal Human body around 280 – 300 mOsM Table 5-5

  6. Tonicity • Solute concentration = tonicity • Tonicity describes the volume change of a cell placed in a solution Table 5-6

  7. Tonicity • Tonicity depends on the relative concentrations of nonpenetrating solutes Figure 5-27a

  8. Tonicity • Tonicity depends on nonpenetrating solutes only Figure 5-27b

  9. Cell H2O Solution (a) (c) (d) (b) Tonicity • Tonicity depends on nonpenetrating solutes only Figure 5-28

  10. Plasmolysis and Crenation • RBC’s

  11. Osmolarity and Tonicity Table 5-7

  12. Intravenous Solutions Table 5-8

  13. Electricity Review • Law of conservation of electrical charges • Opposite charges attract; like charges repel each other • Separating positive charges from negative charges requires energy • Conductor versus insulator

  14. (b) Cell and solution in chemical and electrical disequilbrium. Intracellular fluid Extracellular fluid Separation of Electrical Charges • Resting membrane potential is the electrical gradient between ECF and ICF Figure 5-29b

  15. Separation of Electrical Charges • Resting membrane potential is the electrical gradient between ECF and ICF Figure 5-29c

  16. Measuring Membrane Potential Difference The voltmeter A recording electrode Input Output The ground ( ) or reference electrode Cell Saline bath The chart recorder Figure 5-30

  17. Potassium Equilibrium Potential Artificial cell (a) Figure 5-31a

  18. Potassium Equilibrium Potential K+ leak channel (b) Figure 5-31b

  19. Potassium Equilibrium Potential • Resting membrane potential is due mostly to potassium • K+ can exit due to [ ] gradient, but electrical gradient will pull back; when equal resting membrane potential Concentration gradient Electrical gradient (c) Figure 5-31c

  20. 15 mM +60 mV 150 mM 0 mV Sodium Equilibrium Potential • Single ion can be calculated using the Nernst Equation • Eion = 61/z log ([ion] out / [ion] in) Figure 5-32

  21. Resting Membrane Potential Intracellular fluid -70 mV Extracellular fluid 0 mV Figure 5-33

  22. Changes in Membrane Potential • Terminology associated with changes in membrane potential PLAY Interactive Physiology® Animation: Nervous I: The Membrane Potential Figure 5-34

  23. 3 2 4 5 1 KATP channels open. Metabolism slows. ATP decreases. Low glucose levels in blood. Cell at resting membrane potential. No insulin is released. K+ leaks out of cell Voltage-gated Ca2+ channel closed Glucose ATP Metabolism GLUT transporter No insulin secretion Insulin in secretory vesicles (a) Beta cell at rest Insulin Secretion and Membrane Transport Processes Figure 5-35a

  24. 1 Low glucose levels in blood. Glucose (a) Beta cell at rest Insulin Secretion and Membrane Transport Processes Figure 5-35a, step 1

  25. 2 1 Metabolism slows. Low glucose levels in blood. Glucose Metabolism GLUT transporter (a) Beta cell at rest Insulin Secretion and Membrane Transport Processes Figure 5-35a, steps 1–2

  26. 3 2 1 Metabolism slows. ATP decreases. Low glucose levels in blood. Glucose ATP Metabolism GLUT transporter (a) Beta cell at rest Insulin Secretion and Membrane Transport Processes Figure 5-35a, steps 1–3

  27. 3 2 4 1 KATP channels open. Metabolism slows. ATP decreases. Low glucose levels in blood. K+ leaks out of cell Glucose ATP Metabolism GLUT transporter (a) Beta cell at rest Insulin Secretion and Membrane Transport Processes Figure 5-35a, steps 1–4

  28. 3 2 4 5 1 KATP channels open. Metabolism slows. ATP decreases. Low glucose levels in blood. Cell at resting membrane potential. No insulin is released. K+ leaks out of cell Voltage-gated Ca2+ channel closed Glucose ATP Metabolism GLUT transporter No insulin secretion Insulin in secretory vesicles (a) Beta cell at rest Insulin Secretion and Membrane Transport Processes Figure 5-35a, steps 1–5

  29. Insulin Secretion and Membrane Transport Processes 5 2 3 4 1 KATP channels close. Metabolism increases. ATP increases. High glucose levels in blood. Cell depolarizes and calcium channels open. 6 Ca2+ entry acts as an intracellular signal. Ca2+ Glucose Glycolysis and citric acid cycle ATP Ca2+ 7 GLUT transporter Ca2+ signal triggers exocytosis and insulin is secreted. (b) Beta cell secretes insulin Figure 5-35b

  30. Insulin Secretion and Membrane Transport Processes 1 High glucose levels in blood. Glucose (b) Beta cell secretes insulin Figure 5-35b, step 1

  31. Insulin Secretion and Membrane Transport Processes 2 1 Metabolism increases. High glucose levels in blood. Glucose Glycolysis and citric acid cycle GLUT transporter (b) Beta cell secretes insulin Figure 5-35b, steps 1–2

  32. Insulin Secretion and Membrane Transport Processes 2 3 1 Metabolism increases. ATP increases. High glucose levels in blood. Glucose Glycolysis and citric acid cycle ATP GLUT transporter (b) Beta cell secretes insulin Figure 5-35b, steps 1–3

  33. Insulin Secretion and Membrane Transport Processes 2 3 4 1 KATP channels close. Metabolism increases. ATP increases. High glucose levels in blood. Glucose Glycolysis and citric acid cycle ATP GLUT transporter (b) Beta cell secretes insulin Figure 5-35b, steps 1–4

  34. Insulin Secretion and Membrane Transport Processes 5 2 3 4 1 KATP channels close. Metabolism increases. ATP increases. High glucose levels in blood. Cell depolarizes and calcium channels open. Ca2+ Glucose Glycolysis and citric acid cycle ATP GLUT transporter (b) Beta cell secretes insulin Figure 5-35b, steps 1–5

  35. Insulin Secretion and Membrane Transport Processes 5 2 3 4 1 KATP channels close. Metabolism increases. ATP increases. High glucose levels in blood. Cell depolarizes and calcium channels open. 6 Ca2+ entry acts as an intracellular signal. Ca2+ Glucose Glycolysis and citric acid cycle ATP Ca2+ GLUT transporter (b) Beta cell secretes insulin Figure 5-35b, steps 1–6

  36. Insulin Secretion and Membrane Transport Processes 5 2 3 4 1 KATP channels close. Metabolism increases. ATP increases. High glucose levels in blood. Cell depolarizes and calcium channels open. 6 Ca2+ entry acts as an intracellular signal. Ca2+ Glucose Glycolysis and citric acid cycle ATP Ca2+ 7 GLUT transporter Ca2+ signal triggers exocytosis and insulin is secreted. (b) Beta cell secretes insulin Figure 5-35b, steps 1–7

  37. Summary • Mass balance and homeostasis • Law of mass balance • Excretion • Metabolism • Clearance • Chemical disequilibrium • Electrical disequilibrium • Osmotic equilibrium

  38. Summary • Diffusion • Protein-mediated transport • Roles of membrane proteins • Channel proteins • Carrier proteins • Active transport

  39. Summary • Vesicular transport • Phagocytosis • Endocytosis • Exocytosis • Transepithelial transport

  40. Summary • Osmosis and tonicity • Osmolarity • Nonpenetrating solutes • Tonicity • The resting membrane potential • Insulin secretion

More Related