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Acid-base physiology

Acid-base balance is concerned with maintaining a normal hydrogen ion concentration in the body fluids. This balance is achieved by utilization of buffers in extracellular fluid (ECF) and intracellular fluid (ICF), by respiratory mechanisms that excrete carbon dioxide, and by renal mechanisms that reabsorb bicarbonate and secrete hydrogen ions. pH of body fluids The hydrogen ion (H + ) concentration of the body fluids is extremely…

Renal physiology

The kidneys function in several capacities. As excretory organs, the kidneys ensure that those substances in excess or that are harmful are excreted in urine in appropriate amounts. As regulatory organs, the kidneys maintain a constant volume and composition of the body fluids by varying the excretion of solutes and water. Finally, as endocrine organs, the kidneys synthesize and secrete three hormones: renin, erythropoietin, 1,25-dihydroxycholecalciferol, and…

Respiratory physiology

The function of the respiratory system is the exchange of oxygen and carbon dioxide between the environment and the cells of the body. Fresh air is brought into the lungs during the inspiratory phase of the breathing cycle, oxygen and carbon dioxide are exchanged between inspired air and pulmonary capillary blood, and the air is then expired. Structure of the respiratory system Airways The respiratory system…

Cardiovascular physiology

The primary function of the cardiovascular system is to deliver blood to the tissues, which provides essential nutrients to the cells for metabolism and removes waste products from the cells. The heart serves as the pump, which, by contracting, generates the pressure to drive blood through a series of blood vessels. The vessels that carry blood from the heart to the tissues are the arteries, which…

Neurophysiology

The nervous system is a complex network that allows an organism to communicate with its environment. The network includes sensory components, which detect changes in environmental stimuli, and motor components, which generate movement, contraction of skeletal and smooth muscle, and glandular secretions. Integrative components of the nervous system receive, store, and process sensory information and then orchestrate the appropriate motor responses. Organization of the nervous system…

Autonomic nervous system

The motor (efferent) nervous system has two components: the somatic and the autonomic. These two systems differ in a number of ways but are chiefly distinguished by the types of effector organs they innervate and the types of functions they control. The somatic nervous system is a voluntary motor system under conscious control. Each of its pathways consists of a single motoneuron and the skeletal muscle…

Cellular physiology

Understanding the functions of the organ systems requires profound knowledge of basic cellular mechanisms. Although each organ system differs in its overall function, all are undergirded by a common set of physiologic principles. The following basic principles of physiology are introduced in this chapter: body fluids, with particular emphasis on the differences in composition of intracellular fluid and extracellular fluid (ECF); creation of these concentration differences…

Answers to study problems

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 =…

Summary of elementary circuit theory

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…

A mathematical refresher

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…

Mechanics of muscle contraction

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…

Excitation-contraction coupling in muscle

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…

Molecular motors and the mechanism of muscle contraction

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…

Synaptic physiology II

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…

Synaptic physiology I

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…

Active transport

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+…