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71 Cards in this Set
- Front
- Back
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most proteins and catecholamines activate what intracellular cascade?
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adenylate cyclase/cAMP
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What hormones activate the tyrosine kinase system?
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insulin and EGF
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Which hormones activate the phosphatidylinositol system?
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oxytocin, GnRH, angiotensin II
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What is an inhibitor second messenger response?
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cGMP
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Where is the adenohypophysis derived?
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from the ectoderm of the oropharynx (Rathkes pouch)
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What forms around the infundibulum?
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pars tuberalis
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What structure is continuous with the median eminence?
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infundibulum of posterior pituitary
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What is the blood supply to the pars tuberalis?
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superior hypophysial arteries which also supplies the median eminence and infundibulum
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Where do the superior hypophyseal arteries arise from?
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internal carotid arteries and posterior communicating arteries of the circle of willis
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The inferior hypophysial arteries primarily supply what? Where do the vessels arise from?
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1) pars nervosa of the posterior pituitary
2) solely from the internal carotids |
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Where might someone have pituitary ischemia if the internal carotids were occluded bilaterally?
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only the pars nervosa because the superior hypophysial arteries receive blood from both the internal carotid arteries and the posterior communicating arteries
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What are the nerves found in the anterior pituitary?
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postsynaptic autonomic fibers that have secretory and vasomotor function
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what are tropic hormones?
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hormones that regulate endocrine distant endocrine glands
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Are GH and PRL tropic hormones?
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no
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How are the cells arranged in the pars distalis of the anterior pituitary?
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cords and nests with interweaving capillaries
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What percentage of the anterior pituitary are chromophobes?
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50%, acidophils 40%
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Somatotropes constitute what percentage of the pars distalis? How are they characterized?
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1) 50%
2) medium-sized, oval cells with round central nuclei |
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How are somatotropes classified based on stain?
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acidophils
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what is ghrelins effect on GH?
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increases release when food is taken in
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How do lactotropes stain?
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acidophilic when they have vesicles and chromophic when vesicle depleted
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What 2 hormones in addition to dopamine effect PRL release?
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TRH and VIP stimulate synthesis and secretion
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How can corticotropes be identified under the microscope?
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medium sized cells with round eccentric nuclei. they have a strong positive reaction with PAS
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A small oval cells with eccentric nuclei stain with both acid and basic dyes and a PAS reagent in the anterior pituitary. What cell type is it?
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gonadotrope
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Large cells with round eccentric nuclei and are basophillic found in the anterior pituitary are?
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thyrotropes
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A cell is identified in the anterior hypothalamus that is large and polygonal with oval centrally located nucleus. What cell is this?
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lactotrope... note that the somatotrope also has a central nucleus but is medium sized and has a prominent nucleoli
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What 2 cell types in the anterior pituitary stain with acid dyes like Orange G but are PAS negative?
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somatotrope and lactotrope
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what does the posterior pituitary consist of?
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infundibulum and pars nervosa
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is the posterior pituitary an endocrine organ?
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no
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Are the axons of the posterior pituitary myelinated?
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no
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Light microscopy reveals intracellular dilations at the distal end of certain cells in the pituitary. What are we looking at?
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herrings bodies at the axon terminals in the posterior pituitary.
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What is inside Herring bodies?
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ADH and oxtocyn
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What effect do low levels of ADH have?
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contraction of smooth muscle on arterioles raising blood pressure
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At high or low doses of ADH does the blood pressure rise?
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low
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besides hypertonicity and low blood volume what factors can stimulate ADH release?
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pain, trauma, emotional stress, nicotine
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What cells in addition to neurosecretory cells are found in the posterior pituitary?
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fibroblasts, mast cells, glial cells called pituicytes
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what is the function of the pituicyte? How are they identified?
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1) they support the capillary network like astrocytes
2) they have round or oval nuclei with pigment vesicles in cytoplasm and have GFAP |
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What cells is glial fibrillary acidic protein found in?
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pituicytes and astrocytes
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Where are the cell bodies that release GHRH found?
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arcuate nucleus
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Where are the cell bodies of neurons that release somatostatin found?
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periventricular, paraventricular and arcuate nucleus
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Where are the cell bodies that release dopamine found?
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arcuate nucleus
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CRH is released from what nuclei?
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arcuate, periventricular, medial paraventricular
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GnRH is released from what nuclei?
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arcuate, ventromedial, doral and paraventricular nuclei
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TRH is released from which nuclei?
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ventromedial, dorsal, paraventricular nuclei
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Where does the pineal gland develop from?
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neuroectoderm of posterior roof of diencephalon
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Where is the pineal gland located?
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posterior wall of 3rd ventricle
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What is the main cell type in the pituitary? How are they characterized?
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1) pinealocytes
2) large deeply infolded nucleus with one or more nucleoli and also have lipid droplets |
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What other cell is dispersed among the pinealocytes?
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interstial (glial) cells... similar to astrocytes
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When is corpora arenacea seen? what else is it called?
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1) begins in childhood and increases with age
2) known as brain sand |
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What is the function of the pineal gland?
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regulates circadian rhythm via information from the retinohypothalamic tract. Melatonin is inhibited in the day by light signals in retina and increased at night
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melatonin has a direct effect to inhibit what hormone?
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GnRH
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What hormones are concentrated in pineal extracts besides melatonin?
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serotonin, NE, dopamine, histamine, somatostatin, TRH
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Tumors that destroy the pituitary at a young age can cause what?
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precocious puberty
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when does the thyroid gland begin to develop? How does it develop?
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4th week from endodermal thickening of the floor of the primitive pharynx. Thyroglossal duct moves inferiorly to neck and from thyroid.
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What is the remnant of the thyroglossal duct?
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pyrimdal lobe of thyroid (40% people)
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melatonin has a direct effect to inhibit what hormone?
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GnRH
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What hormones are concentrated in pineal extracts besides melatonin?
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serotonin, NE, dopamine, histamine, somatostatin, TRH
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Tumors that destroy the pituitary at a young age can cause what?
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precocious puberty
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when does the thyroid gland begin to develop? How does it develop?
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4th week from endodermal thickening of the floor of the primitive pharynx. Thyroglossal duct moves inferiorly to neck and from thyroid.
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What is the remnant of the thyroglossal duct?
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pyrimdal lobe of thyroid (40% people)
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follicular cells are derived from?
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endoderm
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What happens to the thyroid during the 7th week?
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epithelial cells from 4th branchial pouch incorporate into the lateral lobes of the thyroid and form parafollicular cells
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what shape are the cells surrounding the follicles?
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cuboidal
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When stained with H and E how do follicular cells appear?
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basophilic
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What is located at the apical surface of the follicular cell?
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1) colloidal resorption droplets consisting of lysosomes and endocytic vesicles
2) golgi |
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where are the parafollicular (C) cells located?
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in the follicle basal lamina
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What do parafollicular cells secrete?
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calcitonin
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How do C cells appear when stained with H and E?
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pale in small clusters or solitary
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What clinical disease is associated with absent calcitonin?
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none
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When does the fetal thyroid gland become functional?
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week 14
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what congenital condition results with low or absent thyroid hormone?
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cretenism
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what is the microscopic appearance of the thyroid in graves disease?
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transition to columnar epithelium with depleted areas of colloid surrounding the apical surface
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