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28 Cards in this Set

  • Front
  • Back
hyper- or hypo- thyroidism?

- Irritability
• Anxiety
• Heat intolerance
• Insomnia
• Eye tearing
• Dyspnea
• Heart palpitations
• Increased appetite, but weight loss
• Diarrhea
• Increased defecation
• Sweating
• Hair loss
• Amenorrhea
• Muscle fatigue
• Tremors
Hyperthyroidism
hyper- or hypo- thyroidism?

• Memory loss
• Depression
• Cold intolerance
• Hoarseness
• Periorbital edema
• Peripheral edema
• Chest pain
• Decreased appetite, but weight gain
• Constipation
• Dry skin
• Coarse hair
• Menorrhagia
• Muscle fatigue
Hypothyroidism
What is the active form of thyroid hormone?
T3
TSH is released from the _______________
anterior pituitary
What cleaves T4 to active T3?
D1 & D2
(type 1 & 2 deiodonase)
So, T4 is preferentially released from the thryroid gland. Explain the steps that occur for it to produce a thyroid hormone response
T4 converted to T3 via D2

T3 enters cell via TH Receptor

T3 interacts with retinoid X receptor (RXR)

Binds to thyroid-hormone responsive gene

Changes in critical proteins, thus, inducing a response
D1 converts T4 --> T3 in what tissues?
Liver

Kidney

Thyroid
D2 converts T4 --> T3 in what tissues?
Skeletal Muscle

Cardiac Muscle

Hypothalamus

Pituitary
What hormone produces these effects?

• normal growth and metabolism
• overall oxygen utilization
• basal metabolic rate
• carbohydrate metabolism
• protein metabolism
• lipid metabolism
• thermogenesis
Thyroid hormone
What form of Ca++ is biologically active?
Ionized Ca++
Name the hormone:

Binding of Ca++ to its receptor:
- inhibits cAMP
- stimulates PLC

**unique situation in which an increase in [Ca] does NOT lead to exocytosis**
PTH
PTH is secreted in response to (2)
Absolute [Ca]

Rate of fall of [Ca]

(When [Ca] is getting low, PTH is released)
PTH release:

increases/decreases bone resorption

increases/decreases loss of calcium in urine

increases/decreases absorption of calcium in intestines
increases bone resorption

decreases loss of calcium in urine

increases absorption of calcium in intestine
How does low-dose PTH increase bone formation?
↑ β-catenin which is needed for bone formation
KNOW THIS TABLE
This hormone has an indirect effect on the formation of Vit. D:

Promotes absorption of Ca++ and phosphate in intestines
PTH
How does PTH affect both osteoclasts and osteoblasts to ultimately increase bone resorption?
(+) osteoblast
production of M-CSF
and RANK ligand to
promote production
and activity of osteoclasts

(-) osteoblast
production of OPG,
which blocks the
interaction of RANK
ligand and its receptor
How does PTH increase intestinal absorption of Ca++ and Phosphorus?
↑ 1α hydroxylase activity In PT cells

↑ synthesis of 1,25 (OH)2-Vit. D
This hormone increases the reabsorption of Ca++ in the distal tubule and increases Ca++ ATPase and Ca+/Na+ exchanger activity on the basolateral membrane

(Net result is increased serum Ca++)
PTH
Ca2+ in the lacunae is in equilibrium with plasma Ca2+ but, under the action of
_______, Ca2+ is taken up by the osteocytes, transported to the surface osteoblasts which pump the Ca2+ into the
extracellular fluid, thus raising plasma Ca2+ concentrations.
PTH
What is the primary mediator of hypercalcemia associated with malignacy?
Parathyroid Hormone Related Protein
(PTHrP)

**Binds to same receptor as PTH – elicits the same response as PTH**
This hormone:

↓ bone resoprtion; ↓ plasma Ca++
Calcitonin
This hormone:

↑ intestinal Ca++ absorption; ↑ bone resorption; ↑ plasma Ca++; (-) PTH
Vit. D
Growth hormone, IGF-1, Insulin, Sex steroids (estrogens/androgens) all _____ bone formation
increase bone formation
Thyroid hormones, cytokines (IL-1) and Gluccocorticoids all _____ bone resorption
increase bone resorption
High Yield!!
Reduced estrogen has what effect on osteoblasts?
Basically, it inhibits their formation by ↓preosteoblasts

It also ↑osteoclasts
This is probably important