Introduction to Physiology

Table of Contents

Cytoskeleton, Molecular Motors, and Cell Motility

CHARLES ASBURY

Introduction: What is Cell Motility?

Learning Objective #1. Compare molecular architectures of the three types of cytoskeletal filaments, microtubules, actin filaments, and intermediate filaments. Understand the structural polarity of microtubules and actin filaments, and why intermediate filaments are not polar.

Learning Objective #2. Describe how cytoskeletal filaments provide frameworks that underlie specialized structures within cells, including the role of cell-cell and cell-matrix junctions for transmitting forces between cells. Describe how junctional defects can cause human disease.

Learning Objective #3. Describe how a molecular motor produces movement and force via its chemo-mechanical cycle. Understand how filament polarity determines the directionality of motor movement.

Learning Objective #4. Understand how the molecular motor dynein drives the beating motions of cilia and flagella. Describe how dysfunctional cilia can cause human disease.

Learning Objective #5. Describe the dynamics of microtubules. Understand the importance of microtubule dynamics for mitosis, and why drugs that inhibit microtubule disassembly are used to treat cancer.

Extra Q&A from past students that might be helpful

Cell Membranes and Transport

FRED RIEKE AND BERTIL HILLE

Cell membranes

Learning Objective #1. Describe the structure and topology of cellular membranes.

Learning Objective #2. Contrast ion channels and ion transporters and the forces that drive them.

Learning Objective #3. Know the normal balance of Na+, K+, Cl– and Ca2+ with respect to the plasma membrane.

Learning Objective #4. Describe the elements of ionic electricity: ions, charge, potential gradients, forces, current, and conductance.

Practice questions and review topics

G Protein Coupled Receptors

MARK BOTHWELL

Introduction:  What is Cellular Signaling?

Learning Objective #1. Describe in detail the activation of GPCR signaling including receptors, ligands & heterotrimeric G-proteins.

Learning Objective #2. Know different G-proteins coupling to different second messengers.

Learning Objective #3. Describe two effector pathways: cAMP and PLC.

Learning Objective #4. Know how GPCR signaling is terminated.

Receptor tyrosine kinases and nuclear hormone receptors

MARK BOTHWELL

Introduction

Learning objective #1. Describe the structure and function of RTKs.

Learning objective #2. Describe signaling mechanisms used by RTK signaling (MAPK cascades).

Learning objective #3. Describe crosstalk and interactions between pathways.

Learning objective #4. Describe steroid hormone receptors.

Learning objective #5. Describe steroid hormone receptor mechanisms of activity.

Conclusion

Membrane Potentials

FRED RIEKE AND BERTIL HILLE

Learning Objective #1. Know how ion diffusion in ion channels establishes membrane potentials.

Learning Objective #2. Recognize that fluxes needed to make typical membrane potentials are extremely small: membrane capacitance.

Learning Objective #3. Explain with Na+, K+, Cl–, and Ca2+ what contribution each could make individually to electrical potential changes in the plasma membrane of excitable cells.

Review questions

Practice questions

Action Potential, Threshold, Refractory Period

FRED RIEKE

Overview

Key properties of action potentials

Quick review of membranes, ions and channels (see also Membrane Transport
and Membrane Potentials chapters)

Resting potential

Learning Objective #1. Explain the ionic basis of the action potential

Learning Objective #2. Explain the concept of threshold in terms of the underlying ion channel activity

Learning Objective #3. Describe the refractory period and how it is produced mechanistically

Practice questions

Action Potential Propagation

FRED RIEKE

Overview

Learning Objective #1. Describe how changes in resting membrane potential affect the action potential.

Learning Objective #2. Explain the propagation of an action potential down an axon and describe how the refractory period contributes to this.

Learning Objective #3. Describe the importance of myelination for action potential propagation.

Practice questions

Synapses and Neurotransmitter Receptors

JOHN TUTHILL

Overall Summary

Learning Objective 1: Describe how neurotransmitter is released at chemical synapses, including the role of calcium.

Learning Objective 2: Compare excitatory and inhibitory neurotransmitters and identify the major examples of each neurotransmitter type in the CNS.

Learning Objective 3: Compare ionotropic and metabotropic receptors.

Learning Objective 4: Describe the mechanism by which neurotransmitter is cleared at chemical synapses.

Learning Objective 5: Describe how temporal and spatial summation of synaptic potentials affect postsynaptic responses

Learning Objective 6: Outline the key differences between chemical and electrical synapses

Conclusion

Terms used in ionic electricity

Sensory Receptors

JOHN TUTHILL

Learning Objective #1: To know the general properties of sensory receptors

Learning Objective #2. To understand the labeled-line principle of signal detection

Learning Objective #3: To compare the mechanisms of sensory transduction in different types of sensory receptors

Light Receptors (Vision)

Chemoreceptors (Smell and Taste)

Mechanoreceptors (Touch and Proprioception)

Hair Cell Receptors (Hearing and Balance)

Learning Objective #4: To appreciate how the intensity and duration of a stimulus are reflected in the receptor potential and action potential discharge rate of a sensory neuron.

Learning objective #5. To understand how sensory receptors adapt to a constant stimulus.

Autonomic Nervous System Physiology

JOHN TUTHILL

Learning objective #1: Compare and contrast the neurotransmitters and receptor types in the somatic motor division, parasympathetic autonomic efferent division, and sympathetic autonomic efferent division of the nervous system. Include the neurotransmitter / receptor pairs in the ANS two-neuron pathways.

Learning objective #2: Identify epinephrine / norepinephrine receptor types and their effects on various target organs.

Learning Objective #3: Compare nicotinic and muscarinic acetylcholine receptor (AChR) activation and identify acetylcholine receptor types and their effects on various target organs.

Learning objective #4: Identify the role of ATP and nitric oxide in smooth muscle relaxation and blood vessel-dilation.

Learning objective #5: Describe the baroceptor reflex in response to high or low blood pressure.

Learning objective #6: Define orthostatic hypotension and discuss how the baroreflex counters it in healthy patients.

Nociception and Spinal Reflexes

JOHN TUTHILL

Summary: Nociception and Spinal Reflexes

Learning Objective #1: To know how nociceptors are activated and sensitized.

Learning Objective #2: To understand the difference between reflexes and other types of movements.

Learning Objective #3: To differentiate the neural circuits underlying the flexion and stretch reflexes.

Learning Objective #4: To understand how reflex testing can be used clinically to diagnose neuropathologies that affect motor and sensory function.

Muscle Physiology

CHARLES ASBURY

Introduction: Why is muscle physiology important?

Learning Objective #1: Explain the mechanism by which muscle contracts, outlining how the sliding of actin filaments in sarcomeres is driven by ATP-dependent chemo-mechanical cycling of myosin motor proteins.

Learning Objective #2: Explain excitation-contraction coupling and relaxation in skeletal muscle by identifying the roles of the t-tubules, calcium channels (Cav1.1 and the ryanodine receptor), thin filament regulators (troponin and tropomyosin), and ATP-dependent calcium pumps.

Learning Objective #3: Compare twitch contractions for slow/type 1 and fast/type 2 skeletal muscle fibers and explain the molecular bases for the differences in twitch behavior. Define isometric and isotonic contractions.

Learning Objective #4: Explain how smooth, graded contractions of a skeletal muscle are produced by changes in stimulus intensity and by the size principle of motor unit recruitment.

Learning Objective #5: Understand the differences in excitation-contraction coupling between skeletal, cardiac, and smooth muscle. Describe the two-stage phospho-regulatory cascade that initiates smooth muscle contraction.

Learning Objective #6: Compare and contrast how skeletal, cardiac and smooth muscle are controlled by the nervous system. Define single-unit vs. multi-unit smooth muscle types.

Extra Q&A from past students that might be helpful