1 / 19

ANIMAL PHYSIOLOGY AND ENDOCRINOLOGY

ANIMAL PHYSIOLOGY AND ENDOCRINOLOGY. Nervous System Physiology. PHYSIOLOGICAL BASIS OF NEURONAL FUNCTION. VARIOUS TYPES OF NEURONS FOUND IN ANIMALS. STRUCTURE OF A NEURON. A NEURON SHOWING DIRECTION OF NERVE IMPULSE. RESTING MEMBRANE POTENTIAL.

helened
Download Presentation

ANIMAL PHYSIOLOGY AND ENDOCRINOLOGY

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. ANIMAL PHYSIOLOGY AND ENDOCRINOLOGY Nervous System Physiology Zool 303 (Dr Saba Butt)

  2. PHYSIOLOGICAL BASIS OF NEURONAL FUNCTION Zool 303 (Dr Saba Butt)

  3. VARIOUS TYPES OF NEURONS FOUND IN ANIMALS Zool 303 (Dr Saba Butt)

  4. STRUCTURE OF A NEURON Zool 303 (Dr Saba Butt)

  5. A NEURON SHOWING DIRECTION OF NERVE IMPULSE Zool 303 (Dr Saba Butt)

  6. Zool 303 (Dr Saba Butt)

  7. RESTING MEMBRANE POTENTIAL RMP is “normal membrane potential of an un-stimulated cell”. In most cells, it is – 90 mV (range is – 70 to – 90 mV). Zool 303 (Dr Saba Butt)

  8. MECHANISMS RESPONSIBLE FOR RMP Essentially there are three (3) mechanisms contribute in RMP, these are: • The Electrogenic ion Pump (Na+-K+ pump) • Donnan Equilibrium • Diffusion potentials Zool 303 (Dr Saba Butt)

  9. Zool 303 (Dr Saba Butt)

  10. DONNAN EQUILIBRIUM • Biological membranes vary greatly in their permeability to different solutes thus they are complex semipermeable membranes. The semipermeability of biological membrane has far reaching consequences. These create equilibrium on their both sides with distribution of permeable and impermeable ions, which is called as Donnan equilibrium. Zool 303 (Dr Saba Butt)

  11. DONNAN EQULIBRIUM Zool 303 (Dr Saba Butt)

  12. Zool 303 (Dr Saba Butt)

  13. RESTING MEMBRANE POTENTIAL • Three mechanisms contribute to these potentials: The electrogenic pump, Donnan equilibrium (small contribution) and diffusion potentials (most important). • Diffusion Potentials: There are three important aspects to the electrical contribution of ions to membrane potentials: Ion mobility, Ionic permeability and ionic concentration difference. • Ion Mobility:Different ions have varied mobility due to different sizes and charge density because of varying hydration layer. Zool 303 (Dr Saba Butt)

  14. RESTING MEMBRANE POTENTIAL CONTD • Ion permeability: There is selective permeabilities of the membranes to the different ions. The ion channels impart this characteristic. Na+, K+, Ca2+ & Cl- channels are specific for their respective ions. These channels work variedly for the ions permeabilities at different times. Channels action is understood by their channel blocking agents e.g. Tetrodotoxin from puffer fish blocks Na+ channels. Saxitoxin blocks Na+ channel in dinoflagellate, passed to shell fish. • Ionic concentration difference: Inside of the cell has lower Na+& Cl- concentration and higher K+ concentration. There are similar conc. differences of other ions across membrane. Zool 303 (Dr Saba Butt)

  15. Zool 303 (Dr Saba Butt)

  16. Zool 303 (Dr Saba Butt)

  17. Zool 303 (Dr Saba Butt)

  18. Zool 303 (Dr Saba Butt)

  19. The plasma membranes of RBCs with Hereditary spherocytosis is 3X more permeable than normal. The level of Na+, K+ ATPase also remains elevated there. Consequently anemia is caused in these patients. • Cardiac glycosides such as digitalis increase heart’s strength of contraction as these inhibit Na+, K+ pump, thus increase intracellular Na+ and Ca2+ to cause forceful contraction. • Changes in intracellular K+ cause serious cardiac arrhythmias. Hypokalemia by long term use of diuretics hyperpolarizes a cells and Hyperkalemia in acute renal failure causes partial depolarization. Zool 303 (Dr Saba Butt)

More Related