Chapter 5 Hormones

Chapter 5 Hormones - 1 Chapter 5: Hormones and the Brain I....

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I. Hormones Act in a Great Variety of Ways through the Body a. Hormones are chemicals secreted by one group of cells and carried through the bloodstream to other parts of the body, where thy act on specific target tissues to produce specific physiologic effects. b. Any hormones are produced by endocrine glands (a gland that secretes produces into the blood stream to act on distant targets), because they release their hormones within the body. c. Exocrine glands (a gland who secretions exit the body via ducts) such as treat glands, salivary glands, swat glands. d. Our current understanding of hormones developed in stages. i. Castration: removal of the gonads, usually the testes. ii. Greeks emphasized humors, or fluids as an explanation for temperament and emotions. Thee are phlegm, blood, black bile, and yellow bile (choler) which all interacted to produce health or disease. Phlegmatic (sluggish), sanguine (cheerful), sanguis is Latin for blood, bilious (irritable), and choleric (hot tempered). iii. Endocrines come in variety of shapes and sizes located in the body. iv. Homeostasis is the maintenance of a relatively constant internal environment by an array of mechanisms in the body. v. Thyroid, the adrenal cortex, and the pituitary are important hormones from several glands that mains this constant environment inside out body. e. Organisms use several types of chemical communication i. Synaptic communication. In synaptic transmissions, sometimes called neurocrine function, the released chemical signal diffused across the synaptic cleft and causes a change in polarization of the postsynaptic membrane. The synaptic transmitter function is highly localized. ii. Autocrine communication. In autocrine communication, a released chemical acts on the releasing cell itself and thereby affects its own activity. Ex: common for neuron to contain autoreceptors that detect NT molecules released by that neuron; the cell can thus monitor its own activity. Thus, the NT serves as both the autocrine and a synaptic communication function. iii. Paracrine communication. The released chemical signal diffuses to nearby target cells; strongest impact is on its nearest cells. iv. Endocrine communication. The chemical signal is a hormone released into the bloodstream to selectively effect distant target organs. v. Pheromone communication. Hormones can be use for communication not only within an individual, but also between individuals. Pheromones are released into the outside environment to affect other individuals of the same species. vi. Allomone communication. Some chemicals are released by members of one species to affect the behavior of individuals in another species called allomones . Allomones can carry messages between animal species or from plants to animals. 1
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Chapter 5 Hormones - 1 Chapter 5: Hormones and the Brain I....

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