Lecture Outline

CHAPTER OVERVIEW: This chapter covers the electrical activity associated with cell membranes in terms of the movements of ions. Electrical potentials are defined and explained within the context of charge differences across living membranes. The cellular mechanisms responsible for the existence and maintenance of each of the types of membrane potentials are discussed. The phases of the action potential are described in some detail. External stimuli are characterized based on the type and/or magnitude of the response potential they evoke in the cell.

OUTLINE (two or three fifty-min. lectures):

 Chapt. Object.

Topic Outline, Chapter 9

 

Figures & Tables

Trnspcy. Acetates

Trnspcy.

Masters

1

 I. Chemical Signals
      1. Receptor Specificity for Communication Between Cells
        a. Membrane-Bound Receptors
        b. Intracellular Receptors

 

Fig. 9.1, p.246

 

Fig. 9.2a, p.247

Fig. 9.2b, p.247

  

 

TM-27

 

2

 

 

3

 

 

 

 

 

4

 

 

 

 

 

5

    A. Ligands and Membrane-Bound Receptors

      1. Receptors That Directly Alter Membrane Permeability
        a. Ligand-Gated Ion Channels
      2. Receptors That Synthesize Intracellular Mediator Molecules
        a. First-Messenger Molecules
        b. Intracellular Mediators (Second Messengers); cGMP
      3. Receptors and the Function of G Proteins
        a. G Proteins (Three Subunits)
          1) cAMP
          2) Adenylyl Cyclase: cAMP to ATP
          3) DAG and IP3
          4) Cyclic GMP
      4. Receptors That Phosphorylate Intracellular Proteins

 

 

Fig. 9.3, p.247

 

 

 

 

Fig. 9.4, p.248

 

 

Fig. 9.5, p.249

Fig. 9.6, p.250

Predict Quest. 1

Fig. 9.7, p.251

Table 9.1, p.251

Fig. 9.8, p.252

 

Fig. 9.9, p.252

 

 

TA-112

 

 

 

 

TA-113

 

 

 

TA-114

 

 

 

 

 

 

TA-115

 

  

6
    B. Ligands and Intracellular Receptors
      1. Cytoplasmic & Nuclear Receptors Interact with DNA

Fig. 9.10, p.253

Predict Quest. 2

TA-116

 

  
 

II Electric Signals

      1. Action Potentials
      

7, 8

    A. Concentration Differences Across the Plasma Membrane

Table 9.2, p.254

    
 

      1. The Sodium-Potassium Exchange Pump

Fig. 9.11, p.255

    

 

 

 

 

14
      2. Permeability Characteristics of the Plasma Membrane
      3. Nongated Ion Channels (Always Open)
      4. Gated Ion Channels
        a. Voltage-Gated Ion Channels
        b. Ligand-Gated Ion Channels
        c. Other Gated Ion Channels

Fig. 9.12, p.256

TA-117

  

9

    B. The Resting Membrane Potential (RMP)

Fig. 9.13, p.256

    

 

 

10

11
      1. Establishment of the Resting Membrane Potential
        a. Due to Outflow of K+
        b. Potential Difference Across Membrane
      2. Changing the Resting Membrane Potential
        a. Depolarization
        b. Hyperpolarization

Table 9.3, p.257

 

Fig. 9.14, p.257

 

 

 

Fig. 9.15, p.258

Predict Quest. 3

Predict Quest. 4

 

 

TA-118

  
 

    C. Electrically Excitable Cells

 

Fig. 9.16, p.259

Predict Quest. 5

TA-119

  

12

 

 

 

13, 15
      1. Local Potential
        a. Graded
        b. Summate
        c. Temporal Summation
      2. Action Potentials

Table 9.4, p.260

Fig. 9.17a, p.259

Fig. 9.17b, p.259

Predict Quest. 6

Table 9.5, p.260

    
 

        a. Threshold Potential

Fig. 9.18, p.260

TA-120

  
 

        b.All-or-None Principle

          1) Depolarization Phase
          2) Repolarization Phase
          3) Afterpotential

Fig. 9.19, p.261

Fig. 9.20a, p.262

Fig. 9.20b, p.262

Predict Quest. 7

Clinical Focus, p.263

TA-121

TA-120

 

 

 

  

16

 

 

17

 

 

 

 

 

 

 

18

 

 

19

 

20

 

 
      3. Refractory Period
        a. Absolute Refractory Period
        b. Relative Refractory Period
      4. Propagation of Action Potentials
        a. Along Membrane of One Cell
        b. From Cell to Cell
          1) Chemical Synapses and Neurotransmittrers
          2) Gap Junctions
      5. Action Potential Frequency
        a. Action Potential Frequency Defined
        b. Substhreshold Stimulus
        c. Threshold Stimulus
        d. Maximal Stimulus
        e. Supramaximal Stimulus
        f. Submaximal Stimulus
      6. Accommodation
        a. Without Accommodation - Frequency Proportional to Stimulus Strength
        b. With Accommodation - Frequency Proportional to Changes in Stimulus Strength

Fig. 9-8, p.270

Fig. 9.21, p.264

Predict Quest. 8

Fig. 9.22, p.264

 

 

Fig. 9.23a, p.265

 

Fig. 9.23b, p.265

Table 9.5, p.260

 

Fig. 9.24, p.266

 

 

 

Predict Quest. 9

Predict Quest. 10

Fig. 9.25, p.266

 

 

TA-122

 

TA-123

 

 

TA-124

  

 

IMPORTANT CONSIDERATIONS: This set of topics is crucial to the understanding of muscle and nerve cell functioning and so is worth the time invested in ensuring that students are able to explain these events. The logical break is between the general cell and membrane properties responsible for the resting membrane potential and the characteristics of other potentials in excitable cells. Students with weaker backgrounds in chemistry will need assistance as they attempt to visualize what is happening and exactly where the events are occurring.

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