1. Membrane Potentials / Membrane Polarity
Today’s Topics
Membrane Potentials / Membrane Polarity
What you must know first …
ECF vs. ICF
Normal distribution of electrolytes
Permeabilities to Na+ and K+
RMP (resting mem. potential)
Is the result of …
The Cardinal Rule
Altering RMP for Communication & Contraction
Chemical Synapses
Components of… & Events at chemical synapses

2. Neuromuscular Junctions (Chemical Synapses) - The Big Picture
Fig 9.10

3. Neuromuscular Junctions (Chemical Synapses) - The Big Picture
Focus Fig 9.2
Fig 9.10

4. Must know first… ECF vs. ICF (extracellular vs. intracellular)
Normal distribution of Na+, K+, Ca++, & proteins(A-)
Permeability to K+ vs. Na+
Composition not same but concentration and osmolality =
Both fluids electrically neutral and isotonic

5. RMP (Resting Membrane Potential)
Definition…
All body cells have an RMP of -50mV to -100mV
Some cells are “electrically excitable”…
e.g. neurons and muscle
To get a response we must alter RMPs

6. RMP is due to:
Na+/K+ pump.
Mem. is more permeable to K+ leaking out than Na+ leaking in
Proteins (-) are pulled to inner surface of membrane

7. The Cardinal Rule about RMP:
“The tendency for K+ to diffuse out of the cell is the #1 factor determining RMP…
The greater the conc gradient of K+ the greater the tendency …
The greater the permeability of the mem. to K+, the greater the tendency…
The greater the tendency for K+ to diffuse out the more Pro- pulled to the inner surface of the mem. and therefore the greater the RMP (farther from 0) (more negative)

8. Altering RMP at Chemical Synapses
Focus Fig 9.2
Altering RMP at Chemical Synapses
Fig 9.10

9. Video: events at a chemical synapse

10. Video: events at a chemical synapse

11. Text version…
Focus
Fig 9.1

12. Q&A

13. Remember the Big Picture
Focus Fig 9.2
Remember the Big Picture
Fig 9.13

14. RMP – The cardinal rule explained
Fig 3.14
RMP – The cardinal rule explained

15. Depolarization vs. Hyperpolarization
Fig 11.9

16. An Action Potential traveling
Fig 11.11

17. What if…?

18. Graded (Local) Potentials and Summation
Only on neurons
Strength varies with amount of NT released
Strength declines/weakens as it travels
Can be combined with others via summation

19. Q&A

20. Q&A

21. Q&A

22. Q&A

23. Inflammation, local

24. Inflammation, systemic

25. S&S of local Inflammation?-

26. Inflammation, local Fig 4.12
S&S are result of inflammatory chemicals, 3 big ones:
Histamine (from Mast cells)
a) Binds to H1 receptors on arterioles causing vasodilation
-  BF…
-  permeability…
b) Escaped proteins cause…
c) Tissue edema then causes …

27. Inflammation, local Fig 4.12 Kinins - Activated when cells damaged
- Bind to chemoreceptors …

28. Inflammation, local Fig 4.12 Prostaglandins
- Produced in and released from leukocytes (WBCs)
- Bind to arterioles causing vasodilation…
- Bind to chemoreceptors causing pain – ouch!

29. Clinical Applications
Benadryl
Aspirin & Ibuprofen
Cortisone cream
-Blocks the histamine (H1) receptor sites on arterioles
-called an “antihistamine”
- Inhibits the formation and/or action of prostaglandins
Inhibits the release and/or action of a variety of inflammatory chemicals
Fig 4.12

30. Tissue Repair: Organization, Regeneration, & Fibrosis
Blood clot replaced w granulation tissue
Capillaries “bud” and grow
Fibroblasts synthesize collagen fibers …
Macrophages “clean up the mess”
Regeneration…
Fibrosis…
Regenerative Capabilities
Well / Moderately well
Skin, mucous mem., adipose, bone, smooth muscle
Poorly
Tendons, ligaments, cartilage, skeletal muscle
None
Cardiac muscle, neurons of the CNS

31. Fibrosis cont’d: Adhesions