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208 Cards in this Set
- Front
- Back
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What are the fourchemical messengers that cells use to communicate with eachother?
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endocrine, paracrine, direct, synaptic
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What are the 5 types of extracellular signaling?
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1. contact dependent
2. paracrine 3. autocrine 4. synaptic 5. endocrine |
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What occurse in contact dependent signaling?
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signal molecules remain bound to the signaling cell surface
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How does paracrine signaling occur?
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secreted as local mediators
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What cells does paracrine signaling effect?
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neighboring cells
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What are autocrine signals secreted as?
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local mediators
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What cells does autocrine signaling effect?
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the secreting cell
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What occurs at synaptic signaling?
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neurotransmitters are transmitted across the synaptic cleft
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How does endocrine signaling work?
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secreted into the blood stream
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What cells does endocrine signaling effect?
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distant targets
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Compare endocrine signaling to neuronal signaling.
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endocrine is slower but just as specific; the only cells that respond are the ones that recieved the message
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How does endocrine system achieve homeostatic balance?
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through communication
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How is the endocrine system turned off?
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negative feedback system
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What are the three groups that hormones and paracrine factors of the body can be divided into?
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1. amino acid derivatives
2. peptide hormones 3. lipid derivatives |
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What is the difference between a polypeptide and protein hormone?
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a polypeptide hormone has less than 100 amino acids; protein hormone has more than 100
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What are polypeptide and protein hormones synthesized on?
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the rough endoplasmic reticulum of endocrine cells
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What does the amino acid group consist of?
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1. thyroid hormones
2. epinephrine, norepinephrine, dopamine 3. melatonin |
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What is a prohormone?
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what is sent to the Golgi Apparatus, smaller, biologically inactive
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What is a preprohormone?
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Larger than a prohormone, biologically inactive
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Where are hormone receptors located?
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in the plasma membrane or inside the cell
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Does the hormone have a direct effect on activities under way inside the cell?
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NO
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How does a hormone effect activies in the cell?
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the hormone (first messenger) uses an intracellular intermediary (second messenger) to exert the hormones effects in the cytoplasm
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What are the three things the second messenger can act as?
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enzyme activator, inhibitor, cofactor
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What are the two most important second messengers?
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cyclic-AMP and calcium ions
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What does the link between the first messenger and second messenger usually involve?
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G protein
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What are the two possible effects of cAMP levels rising
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enzymes are activated or ion channels may be opened
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What has an inhibitory effect on cells?
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G protein activation resulting in decreased levels of cAMP in the cytoplasm
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How do steroid hormones effect a cell?
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diffuse across the phospholipid bilayer of teh plasma membrane and bind to receptors in the cytoplasm or nucleus
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What are steroid hormones stimulated from?
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cholesterol stored in vacules
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What are amine hormones derived from?
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tyrosine
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What are amine hormones formed by?
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enzymatic action in cytoplasmic compartments of glandular cells
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Where are amine hormones stored?
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in the cells (follicles or vesicles)
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Are amine hormones lipid or water soluble?
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both
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How are amine hormones distributed?
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diffusion for lipid soluble; exocytosis for water soluble
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Where are polypeptide and protein hormones?
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biologically active hormones stored in vesicles within the cytoplasm
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What is the controlled variable with negative feedback control?
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the degree of activity of the target tissue, not how much hormone is secreted
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How are water soluble hormones transported?
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they are dissolved in plasma; they diffuse out of capillkaries into interstitial fluid to the target cells
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How do steroid and thyroid hormones circulate?
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bound to the plasma protiens because they cant travel through the blood
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What are hormone receptors?
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specific protein or glycoprotein receptors
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What are the four ways hormone receptors decrease?
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1. inactivation of receptor molecules or intracellular signaling molecules
2. temporary sequestration of receptor to inside 3. destruction of receptors by lysosomes 4. decreased production |
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How does hormone receptor number increase?
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in response to deficiency
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What 2 factors increase or decrease blood concentration?
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rate of secretion and rate of removal (metabolic clearance rate)
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How do you calculate the metabolic clearance rate?
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the rate of dissapearance from plasma/concentration of hormones
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What are the four ways hormones are cleared?
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1. metabolic destruction by tissues
2. binding with tissues 3. excretion by the liver into bile 4. excretion by kidneys into urine |
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How are peptide hormones removed from the blood?
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rapid enzymatic degradation and excretion
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How are plasma bound hormones removed from the blood?
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only 10% are unbound at a time; slower
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Whath are the four possible outcomes when a cell recieves two hormones at the same time?
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1. antagonistic
2. additive 3. permissive 4. integrative |
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What occurs in an antagonistic hormone interaction?
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one hormone opposes the action of another
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What occurs in a permissive hormone interaction?
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actions of one hormone require simultaneous or recent exposure to a second hormone; a hormone has an action it performs well but performs it better in the presence of another
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What occurs in a synergistic or additive hormone interaction?
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the effects of the two hormones together is stronger than either alone
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What occurs in an integrative effect?
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hormones produce different but complementary effects in specific tissues and organs
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How many organs are there whose primary function is endocrine?
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seven
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What are the seven hormones whose main function is endocrine activities?
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-hypothalamus
-pituitary gland -thyroid gland -adrenal gland -pacreas -pineal gland -parathyroid glands |
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What organs have secondary endocrine functions (5)
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-heart
-thymus -digestive tract -kidneys -gonads |
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What structure has the highest endocrine control?
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the hypothalamus
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What two hormones do hypothalamic neurons synthesize?
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ADH and OXT; antidiuretic and oxytocin
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What are regulatory hormones?
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hormones that control endocrine cells in the pituitary gland
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What do the regulatory hormones control in the pituitary gland?
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the secretory activities of endocrine cells n the anterior lobe of the pituitary gland
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The hypothalamus has autonomic centers that control endocrine cells in what part of the body?
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adrenal medullae
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What does the endocrine system include?
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all cells and body tisssues that produce or secrete hormones and paracrine factors
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What are endocrine cells?
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glandular secretory cells that release their secretions into extracellular fluid
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Do endocrine cells contain ducts?
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no
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What supplies blood to the adenohypophysis?
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the hypophyseal portal system
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What is the anterior lobe of the pituitary called?
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adenohypophysis
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What is the posterior lobe of the pituitary lobe called?
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neurohypophysis
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What functions do the hypothalamus and pituitary work together to perform?
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regulate growth, development, metabolism, homeostatis
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What are the three functions of the hypothalamus?
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1. synthesize releasing and inhibiting hormones that control endocrine cells of the anterior pituitary
2. synthesizes ADH and OXT that are released by the posterior pituitary 3. contains autonomic centers that exert neural control over the adrenal medullae |
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At what part of the infundibulum do hypothalamic neurons release regulatory factors?
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median eminence
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Are the endotheliall cells permeable?
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yes
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What part of the posterior lobe of the pituitary gland makes ADH?
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supraoptic nuclei
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What part oof the posterior pituitary gland makes oxytocin?
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paraventricular nuclei
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Can the communication go both ways in the hypophyseal portal system?
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NO
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How is the hypophyseal portal system structured?
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ccapillary network in the median eminence, portal veins, second capillary netowrk in anterior lbe
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How are the regulatory hormones secretged at the hypothalamus transported to the anterior lobe of the pituitary gland?
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hypophyseal portal system
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What is the purpose of releasing hormones?
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stimulate the synthesis and secretion of one or more hormones in at the anterior lobe
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What is the purpose of inhibiting hormones?
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prevent the synthesis and secretion of hormones from the anterior lobe
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What are the two types of hypothalamic regulatory hormones?
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releasing hormones; inhibiting hormones
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What hormones are released by the adenohypophysis? (7)
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-TSH (thyroid stimulating hormone)
-ACTH (adrenocorticotropic hormone -FSH (gonadotropin) -LH (gonadotropin) -GH (growth hormone) -PRL (prolactin) -MSH (melanocyte stimulating hormone) |
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Does the adenohypophysis secrete the end hormone?
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no
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What hormones are secreted by the posterior lobe? (2)
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ADH and OXT
-antidiuretic and oxytocin |
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What is the infundibulum?
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funnel shaped stalk that connets the pituitary gland to the inferior surface of they hypothalamus
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How many peptide hormones are released by the pituitary gland?
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nine
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What do the hormones released by the pituitary gland bind to?
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-membrane receptors
-use cAMP as a second messenger |
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What are the hormones of the anterior lobe called?
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tropic hormones
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Why are the hormones in the anterior lobe called tropic hormones?
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they "turn on" endocrine glands or support the functions of other organs
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What does TSH target?
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the thyroid gland where it triggers the release of thyroid hormones
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What causes the release of TSH and where does it come from?
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TRH (thyrotropin releasing hormone) and it comes from hypothalamus
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What happens when there are high levels of T3 and T4?
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the rates of TRH and TSH production decline-->negative feedback
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What is ACTH release triggered by and where does it come from?
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CRH (corticotropin releasing hormone) and it comes from the hypothalamus
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What does ACTH stimulate the release of?
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production and secretion of cortisol by the adrenal cortex that affect glucose metabolism
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What type of feedback occurs from rising levels of CRH and ACTH?
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negative feedback
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What are FSH and Lh release triggered by and where does it come from?
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GnRH (gonadotropin releasing hormone) from the hypothalamus
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What is the role of FSH?
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promotes ovarieal follicle development in females and stimulates estrogen secretion; sperm production in males
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What happes to FSH from increasing levels of estrogen and testosterone?
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negative feedack
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What is the function of LH?
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initiates ovulation, when present with FSH it stimulates estrogen secretion
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What happens with increasing levels of estrogens, progestins, and androgens?
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negative feedback
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What does prolactin initiate?
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lactation and mammary gland development
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When does the hypothalamus make PRL or PIH?
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any time when there are increased estrogen levels
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What inhibits the production of prolactin?
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PIH (prolactin inhibiting hormone)
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During pregnancy,, what triggers the release of prolactin?
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PRF
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What does hypersecretion of prolactin cause in males?
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erectile dysfunction
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What does hypersecretion of prolactin cause in females?
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galactorrhea (overproduction of milk) and amenorrhea (cessation of menstrual cycle)
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Where is MSH released from in the anterior lobe?
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the pars intermedia in development, children, and pregnant woemn
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what is the role of MSH in adults?
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unknown
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What stimulates the release of MSH
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excessive leves of CRH
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What inhibits the release of MSH?
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dopamine
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What is the function of MSH?
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stimulates melanocytes of the skin to increase their production in melanin
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What is the function of growth hormone?
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stimulates cell growth and reproduction by accelerating the rate of protein synthesis
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What stimulates GH release?
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GHRH from the hypothalamus
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What does GH promote synthesis and secretion of?
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somatomedins (IGF's)
increase growth rate (children) maintain mass and repair (adults) |
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When does negative feedback of GH occur
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via somatomedins which stimulate GHIH and inhibit GHRH
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What cells are particularly sensitive to GH?
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skeletal muscle cells and chondrocytes
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What do IGF's do
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cause cells to grow and multiply by incresing thier uptake of amino acids
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What is protein sparing?
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not using amino acids so we can use it to build cells
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Where are GH receptors and what do they produce?
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in the liver and they produce and secrete IGF
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Does GH act locally?
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yes
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What type of function tdoes GH have?
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autocrine function or paracrine function
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What type of circulation and release does GH have?
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circadian patter, cyclic release during sleep
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What are the effects of IGF?
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Increased growth rate of skeleton and skeletal muscles in childhood, in adulthood it performs muscle and bone mass maintenence because breakdown=production
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What are the four metabolic effects of IGF?
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-enhance lipolysis in adipose tissue (make energy from fat)\
-decrease glucose uptake by most body cells -stimulates liver cells to elease glucose -decrease ATP production from amino acids |
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What are symptoms of excess GH?
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1. diabetagenic-symptoms of diabetes mellitus
2. ketosis-decrease in blood pH (very dangerous) |
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What is the major difference between the neurohypophysis and adenohypophysis?
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the neurohypophysis does not synthesize its hormones
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What stimulates oxytocin release?
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mechanical stimulation of mammary glands, birthing process
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What is the function of oxytocin?
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stimulates smooth muscle contraction in the wall of the uterus and ejection of milk concentrations during sexual arousal and orgasm
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What are the target tissues of oxytocin?
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uterus and brests
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What causes the release of ADH
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variations in blood volume and blood osmotic pressure:
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What are teh functions of ADH?
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-decreases urine production
-decreases water loss via sweating -increases blood pressure by arteriole constriction |
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What causes negative feedback of ADH?
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low osmotic pressure of the blood or increased blood volume because it inhibits osmoreceptors
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What inhibits secretion of ADH?
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alcohol
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What stimulates secretion of ADH?
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pain, stress, trauma, anxiety, acetycholine, nicotine, morphine
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What do high concentrations of ADH cause?
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vasoconstriction of peripheral blood vessels that helps elevate blood pressure
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What is hormone secretion typically controlled by?
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negative feedback
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What does the thyroid contain?
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large numbers of thyroid molecules
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What do follicle cells produce?
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thyroglobulin
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Thyroglobulin molecules contain what amino acid?
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tyrosine
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How are thyroid hormones synthesized?
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1. iodide trapping (pumped into follicular cell)
2. oxidation of iodide; synthesis of TGB 3. iodination of tyrosine=colloid 4. pinocytosis of colloid 5. digestion of colloid 6. secretion of thyroid hormones (T3 and T4) 7. transport in the blood with use of transport proteins |
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Do T1 and T2 ever go to the blood?
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no
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What are the effects of thyroid hormones on peripheral tissues?
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-elevated rates of oxygen and energy consumption
-increased heart rate and force of contraction: increased blood pressure -increased sensitivity to sympathetic stimulation -maintenance of normal sensitivity of respiratory centers to changes in oxygen and carbon dioxide concentrations -stimulation of RBC formation and enhanced oxygen delivery -enhance actions of catecholamines (E and NE) -accelerate body growth (nervous/skeletal) -essentail for development in fetal and neonatal brain |
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How does the thyroid hormone increase the BMR?
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-increased metabolic rate of CHOs, fats, proteins
-increased ATP synthesis -increased protein synthesis -increased mitochondrial activity -increased heat release |
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What happens when there is too much thyroid hormone?
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-high BMR
-hyperactive ANS -irritable -heat intolerant -CV/heart problems -weight loss |
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What happens when there is not enough thyroid hormone?
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-development/CNS (cretinism)
-low BMR -listless/slow -cold intolerant -obesity |
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What are C cells?
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parafollicular cells
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What do C cells produce?
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calcitonin
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What is the role of calcitonin?
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aids in the regulation of calcium ion concentrations in body fluids by decreasing blood calcium concentration when there are excess calcium ions in the extracellular fluid
-inhibits osteoclasts -accelerates uptake of calcium and phosphates into bone extracellular matrix -stimulates calcium and phosphate excretion by kidneys |
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In what phases of life is calcitonin important?
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-childhood
-pregnancy -starvation |
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In a normal healthy adult, what are the symptoms of too much or too little calcitonin?
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no symptoms!
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What conditions is calcitonin a valuable therapy for?
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Paget disease-disorder in bone modeling
post menopausal osteoporosis |
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What is the primary regulator of calcium ion levels in body fluids?
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parathyroid hormone
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How many parathyroid glands are there altogether?
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four
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What do parathyroid cells produce?
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parathyroid
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What are the two types of cells in the parathyroid gland?
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-parathyroid cells
-oxyphills |
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What are oxyphil cells?
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possibly depleted chief cells that no longer make parathyroid hormone
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What does parathyroid hormone control?
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calcium concentration when the calcium cncentration of the blood falls below normal
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What is the specific action of the parathyroid hormone?
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increased number and activity of osteoclasts
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What is the effect of parathyroid hormone on the kidneys?
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-slows the rate of calcium loss
-increased excretion of HPO4 -promotes formation of calcitrol (active form of vit. D) |
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What is the effect of parathyroid hormone on the GI tract?
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increased rate of calcium and magnesium absorption from the GI tract into the blood
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What occurs with hypoparathyroidism?
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-blood calcium deficiency
-results in spontaneous depolarization and tetany |
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What occurs with hyperparathyroidism?
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-excess resorption of bone matrix
-causes: -soft bones that are easily fractured -kidney stones -fatigue, personality changes, lethargy -hardening of arteries by calcium deposit |
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Where is the adrenal gland located?
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above the kidneys
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Are the adrenal glands supplied with blood vessels?
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yes
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What type of hormones do adrenal glands produce?
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metabolic regulation
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Why does the adrenal cortex have a yellow color?
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stored lipids like cholesterol and fattyacids
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How many steroid hormones does the adrenal gland produce?
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two dozen
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What are the steroid hormones produced by the adrenal gland referred to as?
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adreenocortical steroids or corticosterois
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How do corticosteroids exert their effects?
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determining which genes in th enucli of their target cells are transcribed and at what rate
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Are corticosteroids vital?
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YES, you will die unless they are administered
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What are the three distnct regions of the adrenal cortex?
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zona glomerulosa, zona fasciculata, zona reticularis
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What types of hormones does the zona glomerulosa?
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mineralocortioids
*mostly aldosterone |
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What are the targets of aldostreone?
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kidneys
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What does aldosterone do?
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increase renal absorption of Na and water, accelerates urinary loss of potassium
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How is mineralocorticoid secretion controlled?
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activation of th eRAS and inhibited by hormones that oppse that system
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What hormones are excreted by the zona fasciculata?
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glucocorticoids
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What do glucocortiocids affect?
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glucose metabolism, increase rates of glucose and glycogen formation by the liver
-release amino acids from skeletal muscles -lipids from adipose tissues -promote lipid catabolism within peripheral cells |
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What does cortisol reducue?
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inflammation
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What are the targets of glucocorticoids?
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most cells
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What are the primary hormones of glucocorticoids?
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cortisol or cortisone
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How is glucocorticoid secretion regulated?
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stimulated by ACTH
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What hoormones are excreted by the zona reticularis?
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androgens that may be converted to estrogens in the bloodstream
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What hormones does the zona retucularis excrete?
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androgens that are converted to estrogens in the bloodstream
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What are the target cells of most androgens?
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-skin
-bones -other tissues |
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What is the purpose of androgens?
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stimulates pubic hair development in boys and girls
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What regulates excretion of androgens?
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stimulated by ACTH
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What hormones does the adrenal medulla secrete?
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epinephrine and norepinephrine
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What are the target cells of epinephrine and norepinephrine?
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most cells
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What is the effect of epinephrine and norepinephrine?
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-increased cardiac activity
-blood pressure -glycoge breakdown -blood glucose levels |
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How is epinephrine and norepinephrine regulated?
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stimulated by sympathetic preganglionic fib ers during sympathetic activation
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What makes up 99 percent of the pancreas?
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the exocrine pancreas
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What are the ondocrine clusters known as?
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or islets of Langerhans
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What four cells are included in the pancreatic islets?
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-delta cells
-F cells -beta cells -alpha cells |
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What hormone do alpha cells produce?
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glucagon
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How does glucagon work?
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raises blood levels by increasing the rates of glycogen breakdown and glucose release by the liver
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What do beta cells produce?
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insulin
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How does insulin function?
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lowers blood glucose levels by increasing the rate of glucose uptake and utilization by cells, increases glycogen synthesis in skeletal muscles and the liver
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What do delta cells produce?
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peptide hormone that is like growth hormone inhibiting hormone
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How does growth hormone inhibiting hormone work?
|
suppresses the release of glucagon and insulin by other islet cells and slows the rates of food absorpition and enzyme secretion along the digestive tract
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What do F cells produce?
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pancreatic polypeptide
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How does pancreatic polypeptide work?
|
inhibits gallbladder contactions and rgulates the production of some pancreatic enzymes
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What are the primary hormones responsible for regulation of blood glucose leels?
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insulin and glucagon
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What is secreted when the blood glucose levels rise?
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insulin
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What is secreted when the blood glucose levels decline?
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glucagon is secreted
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What are the steps taken when there are rising levels of blood gluose?
|
1. rising levels
2. beta cells secrete insulin 3. increased rate of glucose transport into otarget cells, increased rate of glucose utilization and ATP generation, increased conversion of glucose to glycogen, increased amino acid absorption and protein synthesis, increased triglyceride synthesis in adipose tissue 4. blood glucose levels decrease |
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What are normal blood glucose levels?
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70-110 mg/dL
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What steps are taken when the blood glucose levels are falling?
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1. blood glucose levels fall
2. alpha cells secrete glucagon 3. increased breakdown of glycogen to glucose in liver and skeletal muscle, increased breakdown of fat to fatty acids, increased synthesis and release of glucose 4. blood glucose levels increase |
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Where is the pineal gland located?
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the epithalamus
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What cells does the pineal gland contain?
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neurons, neuroglia, speecial secretory cells (pinealocytes)
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What does the pineal gland secrete?
|
melanocytes
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What affects the rate of melanin production?
|
collaterals from the visual pathways
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What are the three functions of melatonin in humans?
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1. inhibiting reproductive functions
2. protecting against tissue damage by free radicals 3. setting circadin rhythms |
