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Chapter 2 1. The relationship between the distance and time of diffusion is d ; that is, the distance diffused is proportional to the square root of time (e.g., for three-dimensional diffusion, ). One way to solve the problem is to plug numbers in: first, second, . The first equation allows us to solve for D : squaring the first equation gives 25 μm 2 =…

Cell membranes are modeled with electrical circuits The plasma membrane can be modeled as an electrical circuit. Fig. AppD.1 A is a schematic view of the structure of a biological membrane with a single open K + –selective ion channel. This physical entity is electrically equivalent to the circuit shown in Fig. AppD.1 B. The circuit consists of a resistor in series with a battery, and…

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Exponents Definition of exponentiation Multiplying the number 3 by itself four times gives 3×3×3×3= 81 3 × 3 × 3 × 3 = 81 which can be written more simply with the shorthand notation 34= 81 3 4 = 81 The notation 3 4 is read as “3 raised to the fourth power” or “3 to the fourth power.” In this example, the number 3 is…

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Objectives 1. Explain how a skeletal muscle twitch and a tetanus are generated. 2. Describe how muscle contractile force can be varied. 3. Describe the mechanical properties of muscle that are characterized by the length-tension relationship and the force-velocity relationship. 4. Describe the roles of the three main types of phasic skeletal muscle. 5. Explain how the mechanical properties of skeletal muscle, cardiac muscle, and smooth…

Objectives 1. Compare and contrast the mechanisms of excitation-contraction coupling in skeletal, cardiac, and smooth muscle cells. 2. For skeletal muscle, describe: a. How movement of a voltage sensor couples sarcolemmal depolarization to the opening of SR Ca 2+ release channels. b. The source of the Ca 2+ required for the activation of contraction. c. What happens to the Ca 2+ to effect relaxation. 3. Describe…

Objectives 1. List the common principles that apply to all molecular motors: myosin, kinesin, and dynein. 2. Describe the structure of a skeletal muscle cell and the organization of its contractile elements, and compare and contrast this with the structure of cardiac and smooth muscle. 3. Describe the sliding filament mechanism of muscle contraction. 4. Describe the coupling between the mechanical motions of the myosin motor…

Objectives 1. Explain the concept of a chemical neurotransmitter and its receptor. 2. Describe the mechanism of neurotransmission at the neuromuscular junction. 3. List the major classes of neurotransmitters and their actions. 4. Explain the difference between ionotropic and metabotropic receptors. 5. Describe how excitatory and inhibitory neurotransmitters influence postsynaptic activity, and how synaptic transmission is terminated. 6. Describe how synaptic responses are integrated. 7. Describe…

Objectives 1. Describe the structure and function of electrical synapses. 2. Describe the structure of a representative chemical synapse. 3. Explain the quantal nature of neurotransmitter release. 4. Describe the mechanism of transmitter release and the role of calcium. 5. Describe the synaptic vesicle cycle. 6. List the mechanisms that underlie short-term synaptic plasticity. The synapse is a junction between cells that is specialized for cell-cell…

Objectives 1. Explain how the Na + pump uses energy from ATP to keep [Na + ] i low and [K + ] i high by transporting Na + and K + against their electrochemical gradients. 2. Explain how Ca 2+ is sequestered in the sarcoplasmic and endoplasmic reticulum and transported across the plasma membrane by ATP-dependent active transport systems. 3. Describe how intracellular Ca 2+…

Objectives 1. Explain how the distribution of lipids and proteins in the cell membrane influences the membrane permeability to hydrophobic and hydrophilic solutes and ions. 2. Differentiate the following mechanisms based on the source of energy driving the process and the necessity for an integral cell membrane protein: diffusion, mediated (facilitated) transport, and secondary active transport. 3. Explain how the transport rates of certain molecules and…

Objectives 1. Recognize that concentration gradients and electrical potential gradients store chemical and electrical potential energy, respectively. 2. Recognize that electrochemical potential energy drives all transport processes. 3. Use the concept of electrochemical potential energy to analyze transport processes. Electrochemical potential energy drives all transport processes In Chapter 2 , by examining the permeability of biological membranes to various solutes, we concluded that, with the exception…

Objectives 1. Compare and contrast the properties of voltage-gated Ca 2+ and Na + channels. 2. Describe the mechanism of action of Ca 2+ antagonist drugs, and describe their use as therapeutic agents. 3. Describe the properties of TRP channels. 4. Describe the role of A-type K + channels and Ca 2+ -activated K + channels in regulating the AP firing pattern in a bursting neuron.…

Objectives 1. Describe the properties of the voltage clamp, and explain why it is useful for the study of ion channels. 2. Describe the properties of voltage-gated Na + and K + channels. 3. Define the terms “conductance,” “ionic current,” and “driving force,” and calculate these quantities using Ohm’s Law. 4. Define inactivation and describe some functional properties of neurons that result from Na + channel…

Objectives 1. Define passive membrane electrical properties as those due to parameters that are constant near the resting potential of the cell. 2. Explain why membranes behave, electrically, like a resistor in parallel with a capacitor. 3. Explain why open ion channels are electrically equivalent to conductors (or resistors). 4. Use Ohm’s Law to calculate current flow through ion channels. 5. Explain why membranes have capacitive…

Objectives 1. Describe how ion channels function as gated, water-filled pores that selectively increase the permeability of the membrane to certain ions. 2. Describe the function of the selectivity filter in an ion channel. 3. Describe the grouping of ion channels into gene families on the basis of structural homology. 4. Describe the structural features of the voltage-gated channel superfamily. Ion channels are critical determinants of…

Objectives 1. Recognize that the movement of ions can generate an electrical potential difference across a membrane. 2. Define the concept of the equilibrium potential and apply the Nernst equation to calculate it. 3. Describe how the resting membrane potential is generated in a cell and use the Goldman-Hodgkin-Katz (GHK) equation to calculate membrane potential. 4. Explain the relationship between the GHK equation and the Nernst…