Bio unit 8 - Hormones and the Endocrine System Endocrine...

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Hormones and the Endocrine System Endocrine glands are ductless b/c they secrete chemical messengers directy into the extracellular fluid Neurosecretory cells: nerve cells that release hormones, “neurohormones” o Epinephrine Alpha receptor in interstitial blood vessels – causes constriction Beta receptor in skeletal muscle vessels – causes constriction Beta receptors in liver cells – causes breakdown of glycogen and release of glucose into blood Receptor/Sensor control center Effector o Negative feedback o Positive feedback – lactation, controlled by Oxytocin 3 major classes of hormones o proteins / peptides o amines o steroids – not water soluble signal transduction pathway – series of changes that creates an intracellular response to an extracellular signal cells have intracellular receptors for lipid-soluble hormones o usually a transcription factor that triggers a change in gene expression local regulators convey messages between neighboring cells – paracrine signaling o neurotransmitters are amino acid derivatives, act as local regulators in nervous system o protein/peptide local regulators: Cytokines (play a role in immune responses), and growth factors (stimulate cell proliferation) o Nitric oxide (NO) – when blood oxygen levels fall, NO is released by endothelial cells in blood vessel walls, which dilates blood vessels and increases blood flow to tissues Also increases blood flow to penis in males Viagra interferes with breakdown of NO o Prostoglandins – modified fatty acids, regulate nearby cells in various ways Regulate muscles that help to induce labor, induce fever and inflammation in immune system, intensify sensation of pain, also help regulate the aggregation of platelets Respiratory system: Prostoglandin E signals muscle cells to relax, dilates blood vessels, and increases blood flow to the lungs. Prostoglandin F contracts muscle cells, constricts blood vessels, and reduces blood flow to the lungs HYPOTHALMUS AND PITUITARY Hormone Name Function Class/Produced By Oxytocin Contraction of uterus and mammary gland cells, lactation Peptide / Hypothalamus ADH Promotes retention of water in kidneys Peptide / Hypothalamus
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Growth Hormone Stimulates growth and metabolic functions Peptide / Pituitary FSH Stimulates production of eggs and sperm Glycoprotein / Pituitary LH Stimulates ovaries and testes Glycoprotein / Pituitary TSH Stimulates thyroid Glycoprotein / Pituitary T 3 and T 4 Stimulate and maintain metabolic processes Amine / Thyroid Calcitonin Lowers blood calcium level Peptide / Thyroid Parathyroid Hormone Raises blood calcium level Peptide / Parathyroid Insulin Lowers blood glucose level Protein / Pancreas Glucagon Raises blood glucose level Protein / Pancreas Epinephrine / Norepinephrine Raise blood glucose level, increase metabolic activities, constrict certain blood vessels Amine / Adrenal Glands Glucocorticoids Raise blood glucose level Steroid / Adrenal Glands
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This note was uploaded on 04/05/2008 for the course BIO G 105 taught by Professor Campbell,d. during the Spring '08 term at Cornell University (Engineering School).

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Bio unit 8 - Hormones and the Endocrine System Endocrine...

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