For example, the hormones released when you are confronted with a dangerous or frightening situation, called the fight-or-flight response, occur by the release of adrenal hormones-epinephrine and norepinephrine-within seconds. As a result, endocrine signaling requires more time than neural signaling to prompt a response in target cells, though the precise amount of time varies with different hormones. Hormones are transported primarily via the bloodstream throughout the body, where they bind to receptors on target cells, inducing a characteristic response. These signals are sent by the endocrine organs, which secrete chemicals-the hormone-into the extracellular fluid. In this way, neural communication enables body functions that involve quick, brief actions, such as movement, sensation, and cognition.In contrast, the endocrine system uses just one method of communication: chemical signaling. The target cell responds within milliseconds of receiving the chemical “message” this response then ceases very quickly once the neural signaling ends. Once the neurotransmitters interact (bind) with receptors on the receiving (post-synaptic) cell, the receptor stimulation is transduced into a response such as continued electrical signaling or modification of cellular response. When an electrical signal in the form of an action potential arrives at the synaptic terminal, they diffuse across the synaptic cleft (the gap between a sending neuron and a receiving neuron or muscle cell). Neurotransmitters act locally and rapidly. The nervous system uses two types of intercellular communication-electrical and chemical signaling-either by the direct action of an electrical potential, or in the latter case, through the action of chemical neurotransmitters such as serotonin or norepinephrine. Identify the major organs and tissues of the endocrine system and their location in the body.Distinguish the types of intercellular communication, their importance, mechanisms, and effects.By the end of this section, you will be able to:
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