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41 Cards in this Set
- Front
- Back
Where is pituitary gland located?
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the bottom of the hypothalamus at the base of the brain
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How does the pituitary attach to the hypothalamus?
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infindulum
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The hypophyseal bud gives rise to _____________; whereas the neurohypophyseal bud gives rise to the _______________.
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anterior ; posterior
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What are the secretions of the posterior pituitary known as?
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neuropeptides
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What are the three parts of the anterior pituitary?
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pars distalis, pars intermedia, pars tuberalis
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Explain the anatomy of the Hypothalamohypophysial portal system
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A system of veins that originate in the hypothalamus and pass through the pituitary gland and into its anterior lobe, where they branch into a capillary bed and convey releasing factors to the anterior lobe
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What does this hypothalamas hormone do? Growth Releasing Hormone (GHRH)
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Increased growth hormone secretion
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What does this hypothalamas hormone do? Growth Inhibiting Hormone (GHIH) aka Somatostatin
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Inhibits growth hormone secretion
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What does this hypothalamas hormone do? Thyrotropin Releasing Hormone (TRH)
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Increased thyroid stimulating hormone secretion
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What does this hypothalamas hormone do? Corticotropin Releasing Hormone (CRH)
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Increased adenocorticotropic hormone secretion
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What does this hypothalamas hormone do? Gonadotropin Releasing Hormone (GRH)
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Increased secretion of luteinizing hormone and follicle stimulating hormone
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What does this hypothalamas hormone do? Prolactin Releasing Hormone (PRH)
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Increased prolactin secretion
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What does this hypothalamas hormone do? Prolactin Inhibiting Hormone (PIH)
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Decreased prolactin secretion
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What are the actions of ADH (aka vasopressin)?
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Antidiuretic
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How is the secretion and release of ADH controlled?
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If the concentration of electrolytes increases or if the concentration of water decreases, then ADH secretion is stimulated
If BP decreases, then ADH secretion is stimulated |
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What are the actions of OT (Oxytocin aka Bonding Hormone)?
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Let down milk for breastfeeding, uterine contraction after childbirth
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What are the functions of growth hormone?
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1) Stimulates uptake of amino acids; protein synthesis
2) Stimulates breakdown of fats 3) Promotes bone and cartilage growth 4) Regulates blood levels of nutrients after a meal and during periods of fasting |
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Explain the direct effect of growth hormone.
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GH binds to receptors on cells and causes changes within the cells. Adipose
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Explain the indirect effect of growth hormone.
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causes liver and skeletal muscle to produce somatomedins; e.g., insulin-like growth factors
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Describe the following disorders which result from abnormal secretion of growth hormone: Pituitary dwarf
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due to an isolated deficiency of GH
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Describe the following disorders which result from abnormal secretion of growth hormone: Giantism
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over-production of growth hormone before puberty/epiphyseal plate closure
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Describe the following disorders which result from abnormal secretion of growth hormone: Acromegaly
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excess growth hormone (GH) after epiphyseal plate closure at puberty
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Adrenocorticotropic hormone (ACTH) corticotrophin
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Increased glucocorticoid hormone secretion
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Glygogenesis:
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Glucose → Glycogen
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Glycogenolysis
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Glycogen → Glucose
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Glycolysis
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Glucose → Pyruvic acid
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Lipogenesis
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Sythesis of fatty acids from metabolic products
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Lipolysis
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Breakdown of fatty acids through β oxidation. Acetyl group enters Kreb's Cycle
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Protein synthesis
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Amino acids linked together to make protein
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Gluconeogenesis
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Amino acids deaminated, ketone groups enter metabolic pathway
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How is thyroid hormone transported in the blood?
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Transported in blood bound to thyroxine-binding globulin from the liver.
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Explain the relationship between T3 and T4
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33-40% of T4converted to T3in cells: T3 more potent
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What is the mechanism of action of thyroxin (thyroid hormone)?
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Bind with intracellular receptor molecules and initiate new protein synthesis
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Explain the regulation of the secretion of T3/T4 hormone
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1) Stress and hypothermia cause TRH to be released
2) TRH causes anterior pituitary secret TSH 3) TSH causes increased synthesis of T3/T4 |
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Cretinism
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Caused by maternal iodine deficiency or congenital errors in thyroid hormone synthesis; results in mental
retardation and a short, grotesque appearance |
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Myxedema
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hypothyroidism (hair loss, constipation, weight gain, dry skin, low heart rate, low BP)
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Grave’s disease
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Characterized by goiter and exophthalmos; apparently an autoimmune disease; most patients have long-acting
thyroid stimulator, a TSH-like immune globulin, in their plasma |
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Simple goiter
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dietary iodine intake is very low and there is too little
iodine to synthesize T3 and T4 |
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What are the actions of Calcitonin CT?
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Primary target tissue: bone. Decreases osteoclast activity, lengthens life span of osteoblasts.
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How is Calcitonin regulated?
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Produced by parafollicular cells
• Secretion triggered by high Ca2+ concentration in blood; acts to decrease Ca2+concentration |
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Any pathologic conditions related to faulty secretion of Calcitonin?
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No (Osteoporosis?)
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