exam 5 bio notes

exam 5 bio notes - Animal Cell Signaling Chemical Signaling...

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Animal Cell Signaling Chemical Signaling in Animals ( at a distance ) Two majors systems : Endocrine system : hormones secreted into the blood stream Nervous system : neurotransmitters secreted into the synapse (junction) between neurons Major differences: Endocrine system : broadcasts the signal throughout a broad area (via blood stream) Nervous system : sends the signal directly to a target cell (via neurons) Major Similarities : Many hormones are neurotransmitters Some neurons secrete hormones Both systems involve ells communicating with other cells Hormones Types of hormones: Steroid : bind to the cytoplasmic receptors, regulate gene activity Protein or amino acid derived : bind to membrane bound receptors, activate signal transduction pathways
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Endocrine Glands Glands that secrete (release) hormones into the blood stream. Table 45.5 Pituitary Anterior: largest list of hormones Posterior Thyroid Gland Parathyroid Pancreas Adrenal Glands : only gland that produces both hormones simultaneously (protein based and steroid) Gonads Pineal Gland Thymus Integration of Endocrine and Nervous system (45.15) Hypothalamus : An extension of the brain, 2 types of hormones: ADH and Oxytocin Pituitary : Posterior : 2 hormones, secreted by neurosecretory cells in the hypothalamus Anterior: 7 hormones, 4 hormones control other endocrine glands (master gland) Portal system : artery capillary bed portal capillary bed vein Allows body to somewhat direct where hormones go even though it is deposited into the bloodstream
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Neurosecretory cells : Neurons that secrete hormones. Form an important link between endocrine and nervous system Endocrine System Regulation Antagonistic Pairs Example: Blood glucose levels two hormones involved--glucagon and insulin both produced by the pancreas (misregulation leads to diabetes) Glucagon : stimulates the breakdown of glycogen to glucose Insulin : stimulates the conversion of glucose to glycogen When blood glucose levels rise this stimulates the pancreas to create insulin and the insulin stimulates the liver to convert glucose into glycogen. When blood glucose levels decrease it stimulates the pancreas to releases glucagon. Questions 1. If you eat a big mean and blood glucose levels rise sharply, what happens? -Insulin release increases 2. Six hours after that meal blood glucose levels are dropping, what happens? -Glucagon release increases
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Negative Feedback System The last thing produced negatively feeds back to turn the system off. Example: Thyroid hormones, regulate overall metabolism and Goiter. Goiter: not enough iodine in your diet. Question What would be expected to happen to levels of TSH if the TRH receptors in the thyroid are constantly bound and stimulated with TRH-like active molecules?
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exam 5 bio notes - Animal Cell Signaling Chemical Signaling...

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