biol ch 48 - Biol 1108 I Chapter 48 Endocrine regulation...

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Biol 1108 Chapter 48 Endocrine regulation I. Endocrine system is responsible for regulating many essential processes A. Includes growth, development, stress response, reproduction, etc. B. Endocrine glands are an important component 1. 10 distinct endocrine glands a. Specialized cells in other tissues also act as endocrine tissue 2. Secrete hormones a. Chemical messengers b. Cause changes in target tissues 3. Hormones travel through interstitial fluid/blood to reach target cells a. Often several hormones work to modulate a response C. Nervous system works with endocrine system 1. Nervous responses are fast and short lived a. Chemical or electrical signals b. Send messages to endocrine cells 2. Endocrine system responds more slowly a. Response is longer lasting 3. Distinction between nervous and endocrine system isn’t complete a. Some nerve cells release hormones b. Some hormones also act as neurotransmitters i. Ex, norepinephrine D. Endocrine system is regulated by negative feedback 1. The response to a stimulus is in the opposite direction a. Organ X produces molecule B in response to signal A i. When A is low, lots of B made
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ii. When A is high, low B production 2. Negative feedback works to keep levels intermediate 3. Ex, parathyroid gland produces parathyroid hormone a. Increases blood Ca ++ b. Blood Ca ++ high, gland decreases hormone release i. Lowers blood Ca ++ c. Blood Ca ++ low, gland increases hormone release i. Stimulates Ca ++ release from bones ii. Increases blood Ca ++ 4. Positive feedback much less common in biology II. Types of hormone A. Fatty-acid derivatives – fatty acids are long hydrocarbon chains 1. Prostaglandins a. Synthesized from arachidonic acid i. Essential fatty acid b. Used in autocrine and paracrine signaling B. Steroids – based off of 4 ring structures-carried by plasma proteins 1. All have same basic rings a. Differ in side groups attached 2. Ex, testosterone, estrogens, etc. C. Amino acid derivatives – modified amino acids-carried by plasma proteins 1. Epinephrine (adrenaline) – modified tyrosine 2. Melatonin – modified tryptophan D. Peptide hormones – also includes protein hormones
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1. Neuropeptides – short (~7 amino acid) peptides produced by neurons 2. Insulin – small protein made in pancreas that helps control blood glucose 3. Growth hormone – protein hormone made in pituitary III. Hormone distribution and delivery A. Classical endocrine signaling 1. Endocrine gland secretes hormone into blood 2. Blood carries hormones throughout body a. Steroid,fatty acid derived, and amino-acid derived hormones are not H 2 O soluble i. Carried by plasma proteins b. Peptide hormones are dissolved in plasma 3. Hormones diffuse out of blood into interstitial fluid a. Diffuses to reach target cells B. Neurohormones – produced by neurons 1. Function like classical signaling except:
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