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Biology HL

SLHL

Chapter 7: Cell Control and Communication

Explain how cells detect, transmit and integrate information through receptors, neurons, synapses, hormones, feedback systems and plant growth regulators.

Estimated chapter time: 881 minutes

IB syllabus: C2.1 · C2.2 · SL and HL

Chapter Topics

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  1. 1How to Read This Cell Communication Chapter
    1. 1.1Communication Turns Cells into Systems
    2. 1.2Keep Signal, Messenger and Response Separate
    3. 1.3Use Quantitative Thresholds Carefully
  2. 2Principles and Modes of Cell Signalling
    1. 2.1A Receptor Defines the Target
    2. 2.2Five Signalling Ranges Solve Different Problems
    3. 2.3Quorum Sensing Measures Population Context
    4. 2.4Coordination Creates Emergent Function
  3. 3Receptors, Transduction and Feedback
    1. 3.1Membrane Permeability Predicts Receptor Location
    2. 3.2Channels Convert Binding Directly into Ion Flow
    3. 3.3G Proteins and cAMP Relay and Amplify
    4. 3.4Receptor Kinases Assemble Phosphorylation Cascades
    5. 3.5Intracellular Receptors Couple Ligands to DNA
    6. 3.6Feedback Regulates the Pathway, Not Just Its Output
  4. 4Nervous Systems and Neuron Structure
    1. 4.1Nervous Systems Receive, Integrate and Act
    2. 4.2Neuron Shape Reflects Signal Direction
    3. 4.3Consciousness Is an Emergent Neural Property
  5. 5Action Potentials and Impulse Conduction
    1. 5.1Resting Potential Is a Maintained Electrochemical State
    2. 5.2Threshold Opens a Regenerative Sodium Current
    3. 5.3Local Currents Propagate the Spike
    4. 5.4Myelin Changes Continuous Conduction into Saltatory Conduction
    5. 5.5Read an Action-Potential Trace as Events
  6. 6Synapses and Neural Integration
    1. 6.1A Chemical Synapse Converts the Signal Twice
    2. 6.2Acetylcholine Must Be Released and Removed
    3. 6.3Excitation and Inhibition Describe Effects on Threshold
    4. 6.4Neural Computation Is Weighted, Not a Simple Vote
  7. 7Drugs, Pain and Consciousness
    1. 7.1Chemicals Can Alter Every Synaptic Step
    2. 7.2Addiction Is Circuit Adaptation, Not Simply Strong Pleasure
    3. 7.3Nociception Begins in Free Nerve Endings
    4. 7.4Conscious Experience Emerges from Interacting Networks
  8. 8Animal Hormones and Blood-Glucose Control
    1. 8.1Hormones Are Blood-Borne First Messengers
    2. 8.2Insulin and Glucagon Form an Antagonistic Control System
    3. 8.3Diabetes Can Reflect Missing Signal or Reduced Response
    4. 8.4Correlation Alone Does Not Establish Hormonal Cause
  9. 9Hormone Action and Medical Use
    1. 9.1Steroids Regulate Selected Genes
    2. 9.2Epinephrine Uses a Second-Messenger Cascade
    3. 9.3Insulin Uses Receptor Tyrosine Kinase Activity
    4. 9.4Medical Hormones Replace or Redirect Signals
  10. 10Plant Growth Regulators and Phototropism
    1. 10.1Plants Coordinate Growth without Endocrine Glands
    2. 10.2Light Direction Is Converted into Unequal Growth
    3. 10.3Experiments Must Separate Perception from Response
    4. 10.4Ethylene Can Coordinate Ripening by Positive Feedback
  11. 11Chapter Synthesis: From Detection to Coordinated Response
    1. 11.1Different Signals Share One Information Logic
    2. 11.2Thresholds Make Decisions; Feedback Shapes Trajectories
    3. 11.3Trace Matter and Information Separately

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