ch. 45—hormones and the endocrine system
DESCRIPTION
Ch. 45—Hormones and the Endocrine System. The Endocrine System. Includes hormones-secreting cells and tissues Endocrine glands secrete hormones into body fluids Hormones cause a response in target cells. Positive Feedback. ‘A’ produces more of ‘B’ which produces more of ‘A’ - PowerPoint PPT PresentationTRANSCRIPT
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Ch. 45—Hormones and the Endocrine System
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The Endocrine System
• Includes hormones-secreting cells and tissues• Endocrine glands secrete hormones into body
fluids• Hormonescause a response intarget cells
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Positive Feedback
• ‘A’ produces more of ‘B’ which produces more of ‘A’
• More gets you more• See bottom of pg. 254
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Negative Feedback
• More gets you less• See top of pg. 254
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Cell Surface Receptors• Integral membrane proteins• Communication between cell and outside• Triggers a signal transduction pathway– Series of events
that respond to the signal
– Ex: binding of epinephrine toliver cells which leads to conversion of glycogen to glucose
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Intracellular Receptors• Located inside the cell (rather than on its cell
membrane)• Acts as a transcription factor – a protein that binds to specific DNA sequences and controls the flow of DNA to mRNA (transcription)
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Hypothalamus
• Portion of the brain• Link the nervous system to the endocrine
system via the pituitary gland• Responsible for metabolic processes
(autonomic nervous system)– Controls body temp, hunger, thirst, fatigue, sleep
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Posterior Pituitary
• Stores and secretes oxytocin and vasopressin (or antidiuretic hormone)– synthesized by the hypothalamus– See table 9.1
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Anterior Pituitary
• Secretes hormones that act on target organs (adrenal gland, liver, bond, thyroid, gonads)
• Regulates several physiological processes– Stress, growth, reproduction, lactation
*See FSH and LH in Table 9.1