Term
| What are the 2 main parts of the pituitary gland? |
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Definition
1. Pars Distalis (anterior lobe)
2. Pars nervosa (posterior lobe) |
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Term
| Why are there 2 pieces to the pituitary gland? |
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Definition
| Embryologically, a piece of ectoderm (Rathkhe's pouch) pinches off and migrates next to the invagination from the diencephalon. So they pituitary has 2 distinct embryological origins |
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Term
| Describe staining differences in the AP and PP |
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Definition
AP - Much heavier cell density, hormone producing area of the pituitary, stains much darker then the PP
PP - much lower cell density, mostly nerve terminals whose cell bodies are housed in the hypothalmus, so does not stain well |
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Term
| What are the different cell types that are present in the pars distalis? |
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Definition
1. Basophils
2. Chromophobe
3. Acidophils |
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Term
| What hormones are made by acidophils in the pars distalis? By the basophils? |
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Definition
Acidophils - Prolactin, growth hormone
Basophils - Thyroid stimulating hormone, adreno cortico trohpic hormone (ACTH), follicle stimulating hormone, and leutinizing hormone |
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Term
| What hormones are released by the pars nervosa? |
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Definition
1. ADH (Vasopressin)
2. Oxytocin |
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Term
| What hormones are secreted by the cells of the pars intermedia? |
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Definition
ACTH and MSH (melanocyte stimiulating hormone)
Note: Mostly basophils in the intermedia |
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Term
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Definition
| Axon terminals where granules full of packaged hormones get released in the posterior pituitary |
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Term
| Describe the embryologic origin of the thyroid gland |
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Definition
1. Thyroid comes from an invagination of the endoderm near the base of the tongue
2. Parathyroid glands come from ectodermally derived cells |
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Term
| What end of the gland produces the hormones? |
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Definition
| The follicles produce the hormones (the precursors exist in the colloid, and the follicular cells release the hormones when they are made) |
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Term
| Explain the production process of T3 and T4 |
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Definition
1. Thyroglobulin is made in the golgi complex loaded with Tyrosine
2. Granules full of it react with iodo peroxidase, and iodine oxidizes tyrosine to produce hormone precursors
3. Thyroglobulin is exocytosed into the colloid where it is modified (iodinated Thyroglobulin)
4. When you want to make hormones the cell endocytozes the thyroglobulin and it goes through the digestive pathway to the lysosome, producing T3 and T4 which can enter the bloodstream |
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Term
| What enzyme catalyzes the iodonation of thyroglobulin? |
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Definition
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Term
| What are the two cell types in the parathyroid and what are their functions? |
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Definition
1. Chief cells - Secrete PTH
2. Oxyphil cells - Support for chief cells |
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Term
| Explain how PTH regulates Calcium levels |
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Definition
1. Low Ca stimulates release of PTH
2. PTH causes osteoclasts to reabsorb bone Ca, stops kidney from secreting Calcium, and increases GI absorption of Ca to return levels to normal
Note: High Ca levels causes inhibition of PTH and the opposite occurs |
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