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Endocrine System Hormones & Homeostasis. Regulation. How we maintain homeostasis nervous system nerve signals control body functions endocrine system hormones chemical signals control body functions. OBJ 47. Nervous vs. Chemical Regulation of Homeostasis. A few glands…. Pituitary
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Endocrine System Hormones& Homeostasis
Regulation • How we maintain homeostasis • nervous system • nerve signals control body functions • endocrine system • hormones • chemical signals control body functions
OBJ 47 Nervous vs. Chemical Regulation of Homeostasis
A few glands… • Pituitary • many hormones: master gland • Controlled by the hypothalamus • Pancreas • insulin, glucagon • Stomach • gastrin • Ovary • Estrogen, progesterone • Testes • testosterone
Responding to hormones • Lock and key system • hormone fits receptor on “target” cell targetcell secretingcell non-targetcells can’treadsignal can’treadsignal
Protein hormones Hydrophilic/water-soluble Bind to a receptor on cell membrane Activate secondary messengers Steroid hormones Hydrophobic/lipid-soluble Go through cell membrane Bind to receptors INSIDE the cell OBJ 48 2 Hormone Signaling Pathways
OBJ 48 Hormone Signaling Pathways Steroid hormones Protein hormones
OBJ 49 Regulation of Hormone Secretion • Antagonistic hormone pairs maintain homeostasis through negative feedback • Analogy: thermostat • Examples: blood sugar level, blood calcium level, acid in stomach.
pancreas high liver low pancreas liver Endocrine System Control Negative Feedback Regulation of Blood Glucose insulin liver storesglucose as glycogen (dehydration synthesis) liver cells takeup glucosefrom blood blood glucose level (90mg/100ml) liver breaks glycogen into glucose (degradation hydrolysis) and releases into blood glucagon