HTHSCI 1I06 Lecture Notes - Lecture 1: Coronary Artery Disease, Transmission Electron Microscopy, Scanning Electron Microscope
20 Mar 2019
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Document Summary
Signaling between cells / signaling within cells. Distance and stability of molecules stability of the messenger molecules. Signals are produced by specialized cells and released into the bloodstream, which carries them to target cells in distant parts of the body. Signals that are produced in one part of the body and travel through the circulation to reach far away targets are known as hormones. In humans, endocrine glands that release hormones include the thyroid, the hypothalamus, and the pituitary, as well as the gonads (testes and ovaries) and the pancreas. Neurotransmitters are chemicals secreted by neurons that diffuse across a small gap to the target cell. The neuron is the cell that produces the signal and the target cell can be close to the neuron: e. g. a muscle responding to acetylcholine signals which make the muscle contract. Neurohormones are chemicals released by neurons into the blood for action at distance targets.
