BIO 106 Lecture Notes - Lecture 9: Salivary Gland, Skeletal Muscle, Acetylcholine
17 Oct 2016
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Document Summary
The conversion of an external signal to an amplified internal signal (one signal type is converted to another) Cell signaling-a weak external signal amplified internally as a second message. Extracellular signal (a) converted to amplified intracellular signal (b) Different types of signaling pathways: endocrine, paracrine, synaptic, contact-dependent. One signaling molecule can induce different responses in different target cells. Receptor protein decrease heart rate: salivary gland cell secretion, skeletal muscle cell contraction. Cells depend on multiple extracellular signals: signals work in combinations to regulate the behavior of the cell. Cells bind extracellularly or intracellularly: cell surface receptors. Signals unable to cross the plasma membrane bind to a surface receptor to then create and internal signal: intracellular receptors. Small hydrophobic signals diffuse across and act as a signal. Some signals alter gene expression: cortisol, a hormone secreted in response to stress, diffuses across the membrane and binds to its receptor. Together, they can enter the nucleus and alter gene expression.
