Intercellular commication and signal transduction
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Intercellular Commication and Signal Transduction. Chapter 4. Intercellular Communication. Cells of body must communicate with one another Coordinates organ systems Takes place directly: Physical contact between cells Gap junctions Direct linkage of surface markers Or indirectly

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Intercellular communication
Intercellular Communication

  • Cells of body must communicate with one another

  • Coordinates organ systems

  • Takes place directly:

    • Physical contact between cells

      • Gap junctions

      • Direct linkage of surface markers

  • Or indirectly

    • Extracellular chemical messengers or signal molecules

    • Specific to target cell receptors


Chemical messengers
Chemical Messengers

  • Four types of chemical messengers

    • Paracrines

      • Local chemical messengers

      • Exert effect only on neighboring cells in immediate environment of secretion site

    • Neurotransmitters

      • Short-range chemical messengers

      • Diffuse across narrow space to act locally on adjoining target cell (another neuron, a muscle, or a gland)


Chemical messengers1
Chemical Messengers

  • Hormones

    • Long-range messengers

    • Secreted into blood by endocrine glands in response to appropriate signal

    • Exert effect on target cells some distance away from release site

  • Neurohormones

    • Hormones released into blood by neurosecretory neurons

    • Distributed through blood to distant target cells


Chemical messengers2
Chemical Messengers

  • Cell responses brought about primarily by signal transduction

    • Incoming signals conveyed to target cell’s interior

  • Binding of extracellular messenger (first messenger) to receptor brings about intracellular response by either

    • Opening or closing channels

      • Chemically gated receptor channel

    • Activating second-messenger systems

      • Activated by first messenger

        • Receptor-enzyme

      • Relays message to intracellular proteins that carry out dictated response

        • G-protein coupled receptor



Intercellular commication and signal transduction

Receptor-enzyme:

Tyrosine kinase pathway


Hormones
Hormones

  • Endocrinology

    • Study of homeostatic activities accomplished by hormones

  • Two distinct groups of hormones based on their solubility properties

    • Hydrophilic hormones

      • Highly water soluble

      • Low lipid solubility

    • Lipophilic hormones

      • High lipid solubility

      • Poorly soluble in water






Class questions
Class Questions messenger pathway

  • There are 3 ways cells communicate. The 2 direct means of communication is through ___________ and _______________. Cells indirectly communicate through _______________.

  • Name and describe the 4 types of chemical messengers. Include which fluid medium they travel through: blood, extracellular fluid, intracellular fluid.

  • Why is a neurotransmitter different than paracrine signalling?

  • What is a syncytium?

  • What is a ligand? What is a receptor?

  • How does a chemical messenger “know” which organ to affect?

  • Name 3 ways that an extracellular chemical messenger can bring about an intracellular response.

  • Is the response between a chemical messenger and a particular receptor always the same?

  • How can a chemical receptor elicit a different response inside a cell?

  • In a second messenger system, where does the first messenger bind? Where is the second messenger?


Class questions1
Class Questions messenger pathway

  • There are 2 major 2nd messengers: cyclic AMP and Ca2+ . Describe the action of a hydrophilic hormone via activation of the cyclic AMP 2nd messenger pathway. If you draw pictures, you must label everything and explain what is happening.

  • How does using an 2nd messenger system amplify the response inside the cell?

  • How do some chemical messengers affect gene activity (hence, protein synthesis) within a cell?

  • Which type of hormone can affect gene activity, hydrophilic or lipophilic? Why?