beng100chapter6

beng100chapter6 - BENG 100 Frontiers of Biomedical...

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1 BENG 100 Frontiers of Biomedical Engineering Professor Mark Saltzman Chapter 6 SUMMARY In this chapter, cell signaling was presented within the context of three physiological systems that utilize communication extensively: the nervous system, endocrine system, and immune system. • The nervous and endocrine systems are the main control systems of the body, helping to maintain homeostasis. • The immune system constantly monitors for the presence of foreign invaders and acts to rid them from our bodies. • Cells are capable of executing controlled responses to internal and external changes in the environment through intricate signal transduction pathways. • Cells communicate with each other via signaling ligands which interact with receptors located on the surface or inside the target cell. • Receptor-ligand binding can activate different signal transduction pathways depending on the type of ligand, receptor, and target cell. • Although the signal transduction pathways and responses may differ, all cellular communication proceeds in a cascade fashion: a ligand binds to receptor; enzymes and 2 nd messengers transduce and amplify the signal inside the cell; the cell responds to the signal. • The consequences of signal transduction pathways (or cellular response) vary, ranging from opening or closing of an ion channel to activating transcription of target genes. Many diseases are the result of failures or alterations in signal transduction. Any component of a signaling pathway can be affected. Understanding these pathways has also enabled development of therapeutic drugs that can inhibit or enhance the biological responses. Biomedical engineers can use the knowledge of receptor-ligand interactions in the design of new therapeutics, diagnostic methods, and biosensors. KEY CONCEPTS AND DEFINITIONS action potential – electrical signal or nerve impulse affinity – strength of binding of one molecule to another at a single site agonist – molecule which can bind to a receptor and activates a receptor amplifier – a device that increases the magnitude of an input
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2 antagonist – a molecule that competes with a ligand and inhibits receptor activation antigen presenting cells – cells that display peptide fragments from antigens on their surface along with other molecules required for the activation of T cells apoptosis – an active process of programmed cell death, characterized by cleavage of chromosomal DNA, chromatin condensation, and fragmentation of both the nucleus and the cell; also referred to a cell suicide autocrine signaling – a type of cell signaling in which a cell secretes a molecule to which it also responds axon - long process extending from the cell body of a neuron that conducts an electric impulse (action potential ) away from the neuron CD4 – co-receptor protein on helper T cells which recognizes antigens bound to MHC class II molecules
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This note was uploaded on 02/06/2012 for the course BENG 100 taught by Professor Marksaltzman during the Spring '08 term at Yale.

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beng100chapter6 - BENG 100 Frontiers of Biomedical...

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