PHYSIOL 1 Lecture Notes - Lecture 5: Signal Transduction, Paracrine Signalling, Autocrine Signalling
Document Summary
Physiological signal: electrical signal: changes in membrane potential of a cell (movement of ions in and out of icf/ecf, chemical signal, secreted by cells into ecf, responsible for most communication, signal is ligands. Target cells respond to ligand or electrical signals. Local communication: (1) gap junctions create cytoplasmic bridges between adjacent cells to allow molecules to flow from cell to cell, (2) chemicals diffuse through ecf to act on nearby cells (paracrine signal) Long distance communication: uses chemical and electrical signals, hormones: come into contact with target tissues with receptor & when they bind a signal transduction system occurs, neurocrine molecules are chemical signals secreted by neurons, neurotransmitter, neuromodulators, neurohormones. Cytokines may act as both local and long distance signals. Cytokines = peptides synthesized & secreted by all cells w nuclei in response to stimuli. In development & differentiation, cytokines function as autocrine or paracrine signals. In stress & inflammation, some cytokines may act on relatively distant targets.
