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157 Cards in this Set
- Front
- Back
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What is the role of calcium in extracellular fluid vs. intracellular fluid? |
Extracellular - bone mineral, bone coagulation, membrane excitability
Intracellular - neuronal activation, hormone secretion, muscle contraction |
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How does the body respond if you don't eat enough calcium?
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There is an exchangeable pool of calcium in the bone that can be released into the extracellular fluid.
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How does absorption of calcium change with age?
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60% is absorbed by infants but only 30% is absorbed by adults (but high protein diet can increase absorption)
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How does calcium turnover per year change with age?
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In infants, 100% of calcium is turned over within a year but only 18% in adults
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What stimulates and inhibits osteoblasts?
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Stimulate: PTH, Vitamin D, Il-1, T3, T4, hGH, IGF-1, PGE2, TNF, estrogens
Inhibit: glucocorticoids |
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What stimulates and inhibits osteoclasts?
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Stimulates: PTH, Vitamin D, IL-6, IL-11
Inhibits: Calcitonin, Estrogens, TGF-beta, IFNa, PGE2 |
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When is PTH released?
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when plasma calcium levels are low (high calcium suppress PTH secretion)
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How does PTH increase calcium plasma levels?
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1. Increase bone resorption
2. Increase kidney reabsorption of calcium 3. Production of calcitrol leads to increase intestinal absorption of calcium |
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How does Vitamin D lead to the increased absorption of calcium in the intestines?
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1. Produces calbindin which binds to calcium to transport it
2. Acts on the Calcium ATPAse pump |
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What does Vitamin D do in the bone?
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Stimulate osteoblasts to mobilize calcium
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What does Vitamin D do in the kidney?
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Facilitate Calcium reabsorption
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How are PTH and Vitamin D related?
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PTH converts inactive Vitamin D to active calcitrol in the kidney (calcitrol will negative feedback to PTH)
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Where is calcitonin produced?
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c-cells in thyroid gland
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When is calcitonin secreted?
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when plasma calcium levels are high
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What does calcitonin do?
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"PTH Antagonist"
1. Inhibit osteoclasts 2. Increase Calcium excretion at kidneys |
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What are the 3 ways that osteoporosis is treated? |
1. Bisposphonates
2. Selective Estrogen Receptor modulators 3. Parathyroid hormone |
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As a therapeutic agent, what is the difference between calcium carbonate and calcium citrate?
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Calcium Carbonate - cheapest, most absorbed with food, needs acidic environment
Calcium Citrate - equally absorbed with and without food, absorbed with reduced stomach acid |
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How much calcium do you need over the day?
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25 mmol (1000 mg/day)
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Do diuretics increase or decrease calcium excretion?
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Thiazide diuretics decrease calcium excretion but loop diuretics increase calcium excretion
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Where is oral vitamin D stored in the body?
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Fat and muscle
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How do bisphosphonates help treat osteoporosis?
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They are taken up by osteoclasts and cause apoptosis. This decreases bone resorption.
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To get bone formation, how should you administer teriparatide (PTH)?
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Intermittent low-doses leads to net effect of bone formation (frequent high doses will lead to bone resorption)
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How do selective estrogen receptor modulators work?
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They anatognize receptors in breast and uterus and stimualte receptor in bone and lipid metabolism.
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What are the two type of neurons in the hypothalamus?
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1. Release trophic hormones to blood in median eminence. Blood then goes to anterior pituitary gland.
2. Neurons that produce ADH and oxytocin and secrete it directly into posterior pituitary gland. |
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In the growth hormone axis, what two hormones does the hypothalamus release?
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Somatostatin - inhibits GH secretion, released at constant level
GHRH - stimulates GH secretion, released in pulses |
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What is the half life of GH?
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6-20 minutes (that is why most if bound to binding protein)
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Describe the GH receptor
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- Membrane bound
- Cytokine Receptor - Activates JAK2 |
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What external factors increase GH secretion?
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1. Fasting
2. Hypoglycemia 3. Exercise 4. High protein diet 5. Glucagon 6. Being asleep 7. L-dopa, estrogen, androgens, a-adrenergic agonists |
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What does GH do?
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1. Decrease muscle insulin sensitivity (leads to increased glucose in blood)
2. Stimulate protein synthesis 3. Increase lipolysis 4. Increase Na+ retention 5. Increase growth at epiphysial plates 6. Increase IGF-1 7. Increase hepatic glucose output |
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What does IGF-1 do?
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1. Stimulate protein synthesis
2. Effects at epiphyseal plate 3. Inhibit lipolysis 4. Insulin-like activity |
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How do GH and IGF-1 make bone grow?
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1. GH cause production of IGF-1 mRNA in pre-chondrocytes
2. This leads to early chondrocytes 3. IGF-1 causes clonal expansion and maturation |
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What decreases GH secretion?
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1. REM sleep
2. Glucose 3. Cortisol 4. Free fatty acids 5. Medroxyprogesterone 6 Growth Hormone |
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In the TSH axis, what does the hypohalamus release?
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TRH (tonic/consistent release)
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Which thyroid hormone is primarily released from the thyroid? Which thyroid hormone is the active version?
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Mainly released = T4
Active hormone = T3 |
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Which amino acid forms the backbone of thyroid hormone?
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Tyroxine
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How is thyroid hormone made?
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1. Thyroid follicle cells take Iodide from blood using ATP.
2. Thyroid follicle cells produce thyroglobulin 3. Thyroglobulin bound to I move to colloid where it is stored. 4. Re-enter cell where T3 and T4 cleaved off and sent to blood |
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What binding proteins bind to thyroid hormone?
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Albumin, Transthyretin, and T Binding Globulin
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What is the half life of thyroid hormone?
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6 - 7 days
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What increases the production of T Binding Globulin?
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1. Estrogen and pregnancy
2. Methadone and heroin 3. Tranquilizers |
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What decreases the production of T Binding Globulin?
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1. Anticancer drugs
2. Androgens 3. Glucocorticoids |
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How does thyroid hormone increase basal metabolic rate?
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1. Increase Na/K ATPase
2. Increase O2 consumption 3. Heat generation/sweating 4. Increase respiration 5. Increase cardiovascular function 6. Weight loss |
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How does thyroid hormone relate to growth?
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1. Required for fetal/neonatal skeleton
2. Involved in pubertal growth spurt 3. Permissive for GH |
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How does thyroid hormone relate to reproduction?
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1 Required for milk production
2. Normal menstrual cycles and fertility |
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What is the half life of TSH?
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60 minutes
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What inhibits the thyroid hormone axis?
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Stress, somatostatin, dopamine, and glucocorticoids
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What happens to the thyroid hormone axis when there is not enough iodine (hypothyroidism)?
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Low thyroid hormone --> increased TRH and TSH, thyroid gland enlargement (goiter)
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What is cretinism?
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congenital hypothyroidism
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What is the pathology of Graves Disease?
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Hyperthyroidism because body produces antibodies that stimulate TSH-R at thyroid gland
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What pituitary hormone stimulates Leydig cells?
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LH
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What pituitary hormone stimulates Sertoli cells?
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FSH
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In the androgen axis, what does the hypothalamus secrete?
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GnRH in pulses
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What do the Leydig cells produce?
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Testosterone
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What do the Sertoli cells produce?
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1. Inhibin (negative feeback to FSH)
2. Androgen binding proteins 3. Spermatogenesis |
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Why can't the testis turn progesterone into glucocorticoids?
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Testis don't have 11- or 21-hydroxylase
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Does the pregnenolone in the testis mostly form DHEA or androstenedione?
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DHEA
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When do you get a surge in testosterone in males?
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1. Fetal
2. Neonatal 3. Puberty |
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What does 5a-Reductase do?
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It converts testosterone to dihydrotestosterone in peripheral tissues
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What is the role of testosterone in the male?
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1. Wolffian stimulation
2. Sexual differentiation 3. Spermatogenesis 4. Gonadotrophin Regulation 5. Muscle Mass Sex Drive |
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What is the role of DHT in males?
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1. External virilization
2. Sexual maturation at puberty |
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True of False: DHT forms a more stable connection with the androgen receptor than testosterone.
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True
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Why is GnRH agonist a possible form of male contraception?
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Because GnRH only works if it is given in pulses. When you give continuous agonist, you have a shutdown of the axis.
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Why will an injection of testosterone decrease sperm production?
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It will feedback an inhibit axis.
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Which cells in the developing follicle primarily produce estrogen?
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Granulosa Cells
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In the menses cycle, what day does ovulation normally occur?
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Day 14
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How can you cause multiple ovulations?
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Give high doses of FSH
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What does the corpus luteum produce?
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Progesterone and Estrogen
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What drives the proliferation of granulosa cells?
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Estrogen and FSH
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What hormone leads to the development of the corpus luteum?
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LH
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When is the LH surge?
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Right before ovulation, when FSH starts to decrease
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What hormone stimulates the thecal cells?
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LH
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What hormone stimulates the granulosa cells?
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FSH
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What do the thecal cells produce?
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Androstenedione (which then goes to the granulosa cells to be converted to estradiol)
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When do you have the highest levels of progesterone?
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Luteal Phase
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What is the main form of estrogen in females who are not pregnant?
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Estradiol
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What causes the endometrium to grow?
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Estrogen
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What causes the endometrium to be shed?
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Decrease in progesterone and estrogen and increase in prostaglandin
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What hormone causes the body temperature to rise during ovulation?
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Progesterone
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During the early and mid follicular phase, what feedback is provided by estrogen?
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Positive feedback to granulosa cells
Negative feedback to LH, FSH, and GnRH |
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What is the feedback system during the late follicular and ovulation phases?
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Estrogen provides POSITIVE feedback to GnRH
Inhibin provides negative feedback to FSH Progesterone from granulosa cells provide positive feedback to LH and GnRH |
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What is the feedback system during the luteal phase?
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Estrogen, Progesterone and Inhibin provide negative feedback to GnRH, LH, and FSH
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What produces HCG? What does HCG do?
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The blastocyst produces it. HCG maintains corpus luteum in pregnancy.
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In pregnancy, what does estrogen do?
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1. Stimulates growth of myometrium
2. Mammary gland development 3. Fetal Development |
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In pregnancy, what does progesterone do?
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1. Inhibits spontaneous uterine contractions
2 Mammary gland development 3. Inhibits new follicular development |
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In pregnancy, what does human placental lactogen do?
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1. Prepare mammary gland for lactation
2. Reduce maternal utilization of glucose |
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In pregnancy, what does relaxin do?`
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1. Soften cervix for delivery
2. Loosens connective tissue between pelvic bones |
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In pregnancy, when does the corpus luteum regress?
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6-8 weeks (when placenta is developed enough to make estrogen and progesterone)
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What is the main form of estrogen during pregnancy?
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Estriol
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How is estriol made during pregnancy?
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1. Cholesterol from mom passes to placenta
2. Cholesterol is converted to progesterone in placenta 3. Progesterone is converted to DHEAS in fetal adrenal cortex 4. DHEAS is converted to 16a-DHEAS in fetal liver 5. 16a-DHEAS is converted to estriol in placenta |
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What precedes uterine contractions before birth?
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1. increase estrogen and oxytocin receptors
2. Increase in placental CRH 3. Increase in fetal cortisol 4. Increase prostaglandins 5. Decrease progesterone |
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Which hormones help develop the mammary gland?
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progesterone and estrogen
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What hormone drives the production of milk? What hormone drives the secretion of milk?
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Production = prolactin
Secretion = oxytocin |
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What prevents lactation during pregnancy?
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Estrogen and Progesterone inhibit prolactin
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What hormone from the hypothalamus inhibits prolactin?
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Dopamine
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What do the three zones of the adrenal cortex produce?
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Z. glomerulosa - aldosterone
Z. fasiculata - Cortisol Z. reticularis - DHEA |
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In the adrenal axis, what hormones does the hypothalamus release?
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Corticotropin Releasing Hormone (CRH) and Vasopressin (AVP) in PULSES
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What effects does ACTH have in the adrenal gland?
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1. Stimulate adrenal growth (hyperplasia and hypertrophy)
2. Cortisol secretion 3. Androgen secretion |
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What do CRH and AVP stimulate in the pituitary gland?
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POMC which is converted to ACTH
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What are the metabolic effects of glucocorticoids?
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1. Convert amino acids to glucose
2. Increase amino acids in blood 3. Maintain glucose for brain 4. Increase fatty acids in plasma for energy |
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What are the permissive effects of glucocorticoids?
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Increase cardiovascular responses to catecholamines during stress
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What are the immunosuppressive effects of glucocorticoids?
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Decrease inflammation
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What are the behavioral effects of glucocorticoids?
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Alter cognitive function
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During pregnancy, how do you treat congenital adrenal hyperplasia?
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Give mom synthetic glucocorticoids to suppress virilization
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What is the half life of cortisol?
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60-90 minutes
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What part of the brain controls the cortisol rhythm?
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Suprachiasmatic nucleus in the hypothalamus
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What does 11-beta-HSD do?
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Causes interchange between cortisol and cortisone (less active)
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What are the steps that lead to the release of Aldosterone?
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1. Decrease in ECF volume and renal artery pressure
2. Renin is released 3. Renin converts Angiotensinogen to Angiotensin I 4. ACE converts angiotensin I to Angiotensin II 5. Angiotensin II causes release of Aldosterone |
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What are the effects of aldosterone?
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Decrease sodium excretion --> increase ECF and blood pressure
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What is the pathology of Conn's Syndrome?
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Excess aldosterone --> hypertension and hypernatremia/hypokalemia
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What is the pathology of Cushing's Syndrome?
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Excess cortisol --> excess glucose, protein shortage, unusual fat distrubtion, poor wound healing
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What is the pathology of Addison's disease?
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Deficit of Aldosterone and cortisol
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How is total body water distributed to ICF and ECF?
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2/3 = Intracellular
1/3 = Extracellular |
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How does TBW change with age and gender?
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TBW decreases with age. Women have lower TBW than men.
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What is an effective osmole?
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Substance (Sodium/Chloride) when added to body makes water leave cells.
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What is tonicity?
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Concentration of osmoles. Use concentration of Na as estimate.
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True or False: The osmolarity of ECF and ICF are always equalized.
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True
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What is the equation for osmolarity?
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# of particles in compartment / volume of compartment
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If a patient has hyponatremia (low plasma sodium), what happens to his ICF volume?
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Increases
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If a patient has hypernatremia (high plasma sodium) what happens to his ICF volume?
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decreases
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Does plasma or interstitial fluid have higher osmolarity?
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Plasma because more proteins, namely albumin
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How frequently would a family practitioner be expected to see patients with a thyroid nodule?
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In the U.S., 4-7 percent of adult population.
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What is the major concern when identifying a palpable thyroid nodule?
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Possibility of cancer
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What do you do to diagnose a patient with a thyroid nodule?
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1. Measure serum TSH
2. Fine-needle aspiration with ultrasonography 3. Check serum calcitonin if family history of cancer |
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What diagnoses do you expect for a thyroid nodule?
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From most common to least common:
colloid nodules, cysts, thyroiditis, benign follicular neoplasms, thyroid carcinoma |
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When is L-thyroxine given?
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It is given to treat hypothyroidism or for thyroid cancer (suppresses TSH which is growth factor for cancer cells)
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In an endocrine axis, what is the difference between a primary, secondary, and tertiary defect?
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Tertiary = hypothalamus
Secondary = pituitary Primary = target organ |
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What is the order in which pituitary hormones are usually lost?
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GH, FSH+LH, TSH, ACTH, Prolactin ("Go Find The Adenoma, Please")
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What is the Triple Bolus Test and when it is used?
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Used when you suspect hypofunction of pituitary
1. IV Insulin --> hypoglycemia to stimulate cortisol and GH 2. TRH to stimulate TSH and prolactin 3. GnRH to stimulate LH and FSH |
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What inhibits prolactin?
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Dopamine
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What does prolactin inhibit?
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GnRH and Testosterone
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How does hyperfunction of the thyroid present?
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1. Heat intolerance
2. Weight loss 3. Tachycardia 4. Tremor 5. Anxiety 6. Lid Lag 7. Soft and moist skin |
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How do you assess the cause of thyrotoxicosis?
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Give iodine (RAI) and see if gland incorporates it.
Yes = gland is overactive (hyperthyroid) No = gland is leaking thyroid hormone (thyroiditis or ingesting thyroid hormone) |
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How does hypofunction of the thyroid present?
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1. Fatigue
2. Weight gain despite reduced food 3. Bradycardia 4. Constipation 5. Dry skin 6. Menorrhagia (heavy periods) 7. Myxedema |
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How do you treat hyperthyroidism?
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1. Thionamide drugs to block production of T4 and T3
2.Beta blocker to reduce SNS 3. Radioactive iodine to kill thyroid cells |
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What supplements should a mother take during pregnancy and/or lactation?
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Iron and Folate
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True or False: Lactation increases a mother's weight.
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False
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What are the benefits of human milk?
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1. Immunological Properties
2. Mother-Child bonding 3. Nutritional (iron, low protein, easily digested fat) 4. Low allergenicity |
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Why is cow's milk a poor choice for infants?
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1.Increased protein --> increased oslute
2. Deficient in iron, zinc and Vitamin C 3. May cause GI blood loss 4. No essential fatty acids |
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True or False: Lactation increases the risk of breast cancer.
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False, it decreases it
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True or False: Testosterone is not needed to inhibit the mullerian system (internal female genitalia)
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True, all you need is the mullerian inhibiting factor produced by the testis
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Describe the androgen receptor.
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Androgen receptor are proteins within the cytoplasm. When they bind with the androgen they then enter the nucleus.
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What is the FISH technique?
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1. Take cells in metaphase
2. Denature chromosomes 3. Expose fluorscently labeled probe for specific gene 4. Probe will bind to gene during renaturation and indicate chromosomal location of gene |
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Why do individuals with AIS have high LH levels?
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Negative feedback to LH is dependent on funcitonal complex of testosterone and the androgen receptor
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What enzyme is needed to convert testosterone to estradiol?
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Aromatase
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What is the main risk of birth control pills? What increases this risk?
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Main risk = thromboembolic disease
Age and smoking increase this risk |
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How do oral contraceptives work?
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Estrogen sensitizes hypothalamus and pituitary to progestin. Progestin inhibits FSH and LH thereby preventing ovulation.
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What drugs may decrease the effectiveness of oral contraceptives?
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1. Anticonvulsants
2. Antibiotics 3. Sedatives |
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What prevents glucocorticoids from activating the mineralocorticoid receptor?
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11-beta-HSD2 is an enzymatic barrier by converting cortisol to cortisone.
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What effect does hypovolemia have on the renal plasma flow and filtration fraction?
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RPF decreases but FF increases because of Ang II effect on efferent arteriole.
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What are the three causes of excess loss of Na in urine?
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1. Diuretics
2. Osmotic diuresis (NA get swept along with glucose) 3. Renal tubular disease |
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In hypovolemia, what is the volume, sodium concentration, and osmolarity of urine?
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Volume - low
Na Concentration - low Osmolarity - high (from urea) |
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What disease states cause reduced Na excretion?
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1. Renal failure
2. Heart failure 3. Cirrhosis 4. Nephrotic Syndrome |
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What stimulates ADH release?
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1. Increase in ECF osmolarity (hypernatremia)
2. Hypovolemia 3. Heart Failure 4. Cirrhosis |
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What is the effect of ADH? |
Water resorption in cortical and medullary collecting duct
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What is the pathology of diabetes insipidus?
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Lack of ADH effect either ecause of low levels or because kidney does not respond to it.
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How is sodium permeability and membrane excitability related to ECF K+ levels?
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Increase ECF K+ --> Decrease Na permeability and membrane excitability
Decrease ECF K+ --> Increase NA permeability and membrane excitability |
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What happens to the intracellular K+ concentration when insulin increases? |
K+ concentration increases in cell
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How does aldosterone cause potassium excretion? |
1. Adds sodium channels to kidney
2. Sodium reabsorbed. 3. Negative charge from Cl left in lumen 4. Potassium secretion into lumen from adjacent cells |
