Read the summary and the most important questions on Principles of Human Physiology International Edition | 9780321884619 | Cindy L. Stanfield

• 1 Introduction to physiology

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• 1.1.1 Cells, Tissues, Organs, and organ systems

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• What is the difference between absorption and reabsorption?

  Absorption takes in nutrients from the external environment for the first time wheras reabsorption takes useful substances back into the body for reuse

• 1.2 Homeostasis: A Central Organizing Principle of Physiology

• How does the body adapt to changing internal or external environments?

  many organ systems and negative feedback loops

• 1.2.1 Negative feedback control in Homeostasis

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• what is a good example of negative feedback?

  cruise control in a car going uphill

• 7 Nerve Cells and Electrical Signaling

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• 7.4.2.1 Graded potentials are decremental

• Why are graded potentials decremental?

  The current is spread over a large area and some currents leak across the plasma membrane

• 7.4.2.2 graded potentials can be depolarisations or hyperpolarisations

• what effects do depolarisations and hyperpolarisations have?

  Depolarisations (when sodium channels open) are exitatory. Hyperpolarisations (when potassium channels open) are inhibitory

• 7.4.2.3 Summation of Graded Potentials

• What is the difference between temporal and spatial summation?

  in temporal summation a stimulus is applied repeatedly in rapid succession such that the graded potential from the first application does not dissipate before the next graded potential occurs. In spatial summation the effects of stimuli from different sources occuring close together in time are summed up.

• 7.4.3.1 Ionic Basis of an Action Potential

• What are the three distinct phases of an action potential in a neuron and what causes each phase?

  Rapid depolarization - cause d by a sudden increase in permeability to sodium. Sodium ions move into the cell.

  Repolarization - after 1 msec permeability to sodium decreases and increases to potassium. Sodium doesn't move into the cell, but Potassium moves out.

  After-hyperpolarization - All Potassium still moves out beyond the resting potential as Potassium channels slowly close.

• 7.4.3.2 The Role of Voltage-Gated Ion Channels in Action Potentials

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• What is the function of inactivation gates?

  They are responsible for the closing of sodium channels during the repolarization phase of an action potential

• What are the three possible conformations of sodium channels?

  Closed but capable of opening

  Open

  Closed and incapable of opening

• 7.4.3.3 The All-or-None Principle of Action Potentials

• Define the all-or-none principle

  Whether a membrane is depolarized to threshold or greater, the amplitude of the resulting action potential is the same; if the membrane is nog depolarized to threshold, no action potential occurs.