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22 Cards in this Set
- Front
- Back
Autocrine
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Means that the cell secretes a chemical that affects activity in the same cell
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Paracrine
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means that the cell secretes a chemical that affects activity in adjacent cells
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Endocrine
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means that the cell secretes a chemical that affects activity in distant cells
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Ectocrine
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means that the organism secretes a chemical that affects another organism
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Definition of Endocrine Gland
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A ductless gland ...
1. From which hormones are released 2. Into the bloodstream 3. In response to physiological signals |
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Definition of Hormone
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A chemical that...
1. Is effective in minute quantities 2. is released from endocrine cells 3. is secreted into the circulatory system 4. interacts with specific target cells some distance away 5. exerts a specific regulatory action on the target cell |
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Definition of a Receptor
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A chemical structure that...
1. Is on the surface of the cell or inside it 2. has affinity for a specific chemical compound |
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What are the classes of hormones?
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1. Peptide
2. Steroids 3. Amines a. Catecholarmines b. Indoleamines c. Thyroid hormones |
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Structure of Peptide hormones
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1. Water soluble
2. 3 - 40 amino acids 3. Polypeptide = 50 - 200 amino acids |
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Action and Metabolism of Peptide Hormones
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1. Modify existing proteins
2. Affects synthesis of new proteins |
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Structure of Steroids
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1. Three 6C rings + 1 conjugated 5C ring
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Steroid Hormone Synthesis
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1. Made from cholesterol by tissue-specific enzymes
2. synthesized in smooth endoplasmic reticulum 3. Cholesterol is present in tissue or taken up from the blood |
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Steroid hormone secretion
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1. Secretion is coupled with synthesis
2. Secretion happens in pulses because pituitary hormones that activate it are pulsatile |
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Steroid Transport
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1. Inactive while bound to CPs
2. At target tissues, dissociate from CPs and diffuse into cells |
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General Features of Hormone Receptors
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1. Proteins or glycoproteins
2. Lock and key analogy 3. High affinity 4. High specificity 5. Embedded in cell membrane, cytosol, or nucleus 6. Undergo conformational change when bound to hormone 7. Receptor number and affinity are critical determinants of hormone effects 8. Receptor numbers are dynamic |
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Peptide Hormone Receptors
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1. Embedded in plasma membrane
2. 3 major domains: extracellular, transmembrane, and cytoplasmic domain 3. two major types: intrinsic enzymatic activity act via a G protein and an intracellular 2nd messenger |
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G protein sample pathway
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1. signal molecule binds to G-protein linked receptor
2. G protein turns on adenylyl cyclase 3. Adenylyl cyclase converts ATP to cAMP 4. cAMP activates protein kinase A 5. Protein kinase A phosphorylates other proteins |
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Steroid Hormone Receptors sample pathway
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1. Hormone receptor located in cell nucleus or cytoplasm
2. Hormone-Receptor complex translocates to nucleus 3. H-R binds to hormone response elements to stimulate or inhibit transcription |
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What are the actual effects of hormones on cells?
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1. Change the rate of normal cellular functions
2. Affects size or morphology of cells 3. Affect growth, development, and death of cells 4. Alter sensitivity to other chemical messengers |
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What does the posterior pituitary store and secrete?
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Vasopressin and Oxytocin
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Vasopressin effect
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1. Acts on kidney to reabsorb water
2. Acts on blood vessels to tighten tone 3. released in response to increased blood osmolarity, decreased blood volume, or decreased blood pressure |
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Oxytocin effect
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1. Acts on uterus to increase contractions
2. Acts on breast to release milk |