endocrinesystem

endocrinesystem - Animal Hormones Hormones and Their Actions

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Animal Hormones
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Hormones and Their Actions Hormone-secreting cells are called endocrine cells . Cells receiving the hormonal message are called target cells and must have appropriate receptors. The binding of the receptor activates a response. The distance over which the signal operates distinguishes hormone groups; some act close to the release site, others
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Hormones and Their Actions Hormones can be classified into three main groups: Peptides or proteins. They are water soluble and transported by vesicles out of the cell that made them. Steroid hormones are lipid-soluble and can diffuse out of the cell that made them but in the blood they must be bound to carrier proteins. Amine hormones are derivatives of the amino acid tyrosine. Some are water-
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Hormones and Their Actions The receptors for lipid-soluble hormones are inside cells, either in the cytoplasm or in the nucleus. The action of lipid-soluble hormones is mediated by intracellular hormone receptors that usually alter gene expression.
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Figure 42.1 Chemical Signaling Systems
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Hormones and Their Actions The epinephrine acts on different cells in the body: In the heart, it stimulates faster and stronger heartbeat. Blood vessels in some areas constrict to send more blood to muscles. In the liver, glycogen is broken down to glucose to provide quick energy. In fat tissue, fats are mobilized as another energy source.
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Hormones and Their Actions Growth factors , which stimulate growth and differentiation of cells, are a major class of paracrine hormones. Growth factors also act as autocrine hormones: Some of the hormone influences the cell that secreted it, preventing the cell from secreting too much hormone. Neurons may also be considered to be paracrine cells because they use
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Figure 42.2 The Endocrine System of Humans
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Vertebrate Endocrine Systems The pituitary gland of mammals is a link between the nervous system and many endocrine glands and plays a crucial role in the endocrine system. The pituitary gland sits in a depression at the bottom of the skull and is attached to the hypothalamus. The pituitary is made of two parts: anterior and posterior.
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Vertebrate Endocrine Systems The posterior pituitary releases two hormones: antidiuretic hormone and oxytocin. They are made by neurons in the
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This note was uploaded on 04/02/2008 for the course BIO 188 taught by Professor Capco during the Fall '08 term at ASU.

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endocrinesystem - Animal Hormones Hormones and Their Actions

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