4 Endocrine System 1 Homeostasis

4 Endocrine System 1 Homeostasis - vessel Response(a...

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Homeostasis and Endocrine Signaling I. Homeostasis - control systems and feedback regulation II. What is a hormone - principles of endocrinology A. Types of chemical messengers B. Major endocrine organs C. Mechanisms of action D. Amplification of hormonal signals E. Insulin/glucagon and glucose homeostasis F. Anterior pituitary hormones III. Endocrine disorders
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Homeostasis - “steady state” or internal balance depends on feedback circuits • relies on “control systems” Fig. 40.8: Negative Feedback Circuit Response: Heater turned off Stimulus: Control center (thermostat) reads too hot Room temperature decreases Set point: 20ºC Room temperature increases Stimulus: Control center (thermostat) reads too cold Response: Heater turned on
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Fig. 11.6 EXTRACELLULAR FLUID Plasma membrane CYTOPLASM Receptor Signaling molecule Relay molecules in a signal transduction pathway Activation of cellular response Reception Transduction Response 1 2 3 Biological Control Systems Rely on Cellular Signaling
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Fig. 40.6 Stimulus Hormone Endocrine cell Signal travels everywhere via the bloodstream. Blood
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Unformatted text preview: vessel Response (a) Signaling by hormones Stimulus Neuron Axon Signal Signal travels along axon to a specific location. Signal Axons Response (b) Signaling by neurons Signaling in the endocrine and nervous systems negative feedback positive feedback Pathway Stimulus Endocrine cell Blood vessel Target cells Response N e g a t i v f d b c k – low pH in intestine cells of intestine secrete hormone “secretin” secretin binds receptors on cells of pancreas bicarbonate released from pancreas into intestine ( increases pH ) Pathway Stimulus Hypothalamus/ posterior pituitary Positive feedback Sensory neuron Neurosecretory cell Blood vessel Target cells Response + Feedback Circuits in the Endocrine System infant’s suckling sensory nerve in nipple sends signal to hypothalamus hypothalamus/ posterior pituitary produce oxytocin oxytocin binds receptors on breast smooth muscle cells milk release (stimulates suckling) Fig 45.16 Fig. 45.11...
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This note was uploaded on 10/21/2011 for the course BIO 102 taught by Professor Robinson during the Spring '09 term at UPenn.

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4 Endocrine System 1 Homeostasis - vessel Response(a...

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