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Ch. 45 The Endocrine System. The Body’s Long Distance Regulators. One chemical Signal Different Effect. Epinephrine “Flight or Fight” Hormone Produces different responses in different cells .
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Ch. 45 The Endocrine System The Body’s Long Distance Regulators
One chemical Signal Different Effect Epinephrine “Flight or Fight” Hormone Produces different responses in different cells . How is this? They the target cells either have different receptors for a specific hormone (a) and (b) or they have different signal transduction pathways and or effector proteins (b) and (c). So when Epi binds to the smooth muscle cells of the intestine the response is decreased blood flow to the intestines When Epi binds to skeletal muscle cells they dialate increasing the blood flow. In addition extra sugar from the liver cells all ramp up the body to swing or duck!
A nonliving example of negative feedback: control of room temperature (pg.832) Functional Units of Homeostatic Control: Receptor, control center and an effector. Receptor detects a change in the organisms body. Control Center processes in formation it receives from the receptor and directs an appropriate response by the effector. Ex. Control of Room Temp( note: the receptor is in the control center) not true for living systems. Negative Feedback: A change in the variable being monitored triggers the control mechanism to counteract any further change. It prevents small changes from becoming too large.
The thermostat function of the hypothalamus in human thermoregulation (pg. 839)
Feed back regulation of T3 and T4 secretion from the thyroid Gland The thyroid gland plays a crucial role in vertebrate development and maturation. Control is by the secretion of T3 and T4 The main component of these hormones is iodine Homeostatic Functions: blood pressure, heart rate, muscle tone, digestion, reproductive features. Increase oxygen consumption and cellular metabolism when needed 2 Negative Feedback loops: T3 shuts off Anterior Pituitary. T4 shuts off Hypothalamus. Too much or too little results in serious metabolic disorders. Hyperthyroidism-(Grave’s Disease)high blood pressure, bulging eyes. Hypothryrodism-opposite conditions, cretinism in infants( skull doesn’t form right, mental retardation)/, weight gain and lethargy in adults. Deficient in Iodine =Goiter (enlarged thyroid gland) no iodine not enough T3 and T4 no negative feedback loop
Parathyroid Horomone and Calcitonin: Control of Blood Calcium
Stress and the Adrenal Glands Stress can cause the hypothlamus to speak to the adrenal medulla via nerve impulses and to the adrenal cortex via hormones. Adrenal Medulla handles short term Stress. Adrenal Cortex Handles Long Term Stress