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139 Cards in this Set
- Front
- Back
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What are the 3 classes of Hormones?
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-Steroids
- Small Peptides, polypeptides, and proteins - Amino Acids and Arachidonic (polyunsaturated fatty acid) acids and there derivatives |
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What mechanism is injured if regulation of hormonal secretion is hindered?
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Feedback Mechanism
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What are the two types of hormonal receptors?
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Cell Surface - Transmembrane Receptor detect hormone at surface and sends a second messenger inside to elicit a physiologic effect.
Intracellular Receptors- Steroid hormone attaches to a carrier protein and the bound steroid/protein goes to nucleus; eliciting it to synthesize mRNA |
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What is the adenohypophysis?
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Anterior lobe of the Pituitary Gland
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What is the Neurohypophysis?
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Posterior lobe of the Pituitary Gland
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Where does the pituitary gland lie?
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In the Sella Turcica of the Sphenoid bone
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What is the adenohypophysis developed from?
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Rathke's Pouch
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What is Rathke's pouch?
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Evagination of the ectoderm of the oropharynx toward the brain
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What is the Neruohypophysis developed from?
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Downgrowth of neuroectoderm of the floor of the 3rd ventricle
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Where are the pars distalis, pars intermedia, and pars tuberalis located?
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In andenohypophysis
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Where are the Pars Nervosa and the Infundibulum located?
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Neruohypophysis
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What does the Pars nervosa contain?
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within the Neruohypophysis; and contains axons and their endings
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What does the Infudibulum contain?
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Within the Neruohypophysis; and contains axons forming the Hypothalamo-Hypophyseal tracts
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What provides a route for hormones of the Anterior Pituitary to flow to the hypothalamus? And what does this provide?
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Hypothalamo-Hypophyseal Portal System; provides direct feedback to brain
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What are tropic hormones?
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Regulate the activity of other endocrine glands in the body
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What are the 4 Tropic hormones secreted by the ant pituitary?
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-'F'SH => Follicle-Stimulating
-'L'H => Luteninizing -'A'CTH => Adrenocorticotropic -'T'SH => Thyroid-Stimulating FLAT -> mnemonic |
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What are two hormones that act directly on target organs; which the anterior pituitary secretes?
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-GH => Growth Hormone
-PRL => Prolactin |
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How are the cells arranged in the Pars Distalis?
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In cords and nests; seperated by fenstrated capillaries
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What are the three staining cells of the pars distalis?
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Acidophils (40%)
Basophils (10%) Chromophobes (50%) |
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What are cells of the pars distalis called that have no relation to hormone secreting activity?
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Chromophones
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What are the 5 functional cells of the Ant Pituitary?
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-Somatotrophs (50%)
-Lactotrophs (20%) -Corticotrophs (20%) -Gonadotrophs (10%) -Thyrotrophs (5%) |
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What cell of the anterior pituitary secretes Growth Hormone?
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Somatotrophs (GH Cells)
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What are acidophilis (Eosinophilic) vesicles; found in the cytoplasm of the anterior pituitary gland?
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Somatotrophs
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What hormones regulate the release of growth hormone?
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- GH RH => Growth Hormone Releasing Hormone
- Somato Statin => Inhibits release of GH - Ghrelin (from stomach) => stimulates release of GH |
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What can pituitary adenomas cause?
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Can cause hormonally active tumors; Tumors that originate from somatotrophs -> stimulates excess release of GH
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What does Somatotrophic tumors cause in adults/kids?
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Kids - Acromegaly
Adults- Gigantism |
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What are other names of Lactotrophs?
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PRL Cells
Mammotrophs |
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What does Lactotrophs secrete?
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Prolactin
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What is the significant when staining Lactotrophs?
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Cells full - Stain acidophilically
After hormones released - Colorless (aka chromophobes) |
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What inhibits the release of prolactin from lactotrophs?
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Dopamine
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What produces Dopamine?
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Hypothalamus
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When would lactotrophs undergo hypertrophy and hyperplasia? What else increases in size concurrently?
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-During pregnancy and lactation
-Also an increase in the size of the pituitary |
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Whats does Corticotrophs secrete?
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a precursor molecule of ACTH (adrenocorticotropic)
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How does cortiocotrophs stain?
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Basophilic; strong PAS +
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What regulates Cortiocotrophs?
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CRH (Corticotropin-Releaseing Hormone) of Hypothalamus
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What does gonadotrophs secrete?
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FSH (Follicle Stimulating Hormone)
LH (Luteninizing Hormone) via FSH, and LH Cells |
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What is the function of LH cells?
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sitimulates ovulation and synthesis of androgen in males
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How does Gonadotrophs stain?
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Basophilic and PAS+
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What regulates Gonadotrophs?
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GnRH via Hypothalamus
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What does Thyrotrophs secrete?
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TSH
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How does thyrotrophs stain?
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Basophilic and PAS +
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What regulates Thyrotrophs?
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TRH via Hypothalamus
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What characterizes the Pars Intermedia?
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Cystic Cavities and Colloid Filled Follicles
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What is the function of Pars intermedia in humans?
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Unclear
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What does the Pars Tuberalis extend along?
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The infudibulum
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What does the Pars Tuberalis contain?
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Highly vascular; Veins of Hypothalamo-Hypophysial System
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What is the Neurohypopthysis an extension of?
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The CNS
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What part of the pituitary gland is endocrine and what part is a storage site?
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Anterior - Endocrine
Posterior - Storage Site |
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What does the neurohypopthysis store?
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Neurosecretion of the neurons of the supraoptic and paraventricular nuclei OF the hypothalamus
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What are the specialized Gilal cells of the posterior pituitary?
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Pituicytes
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What are Pituicytes associated with?
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Fenstrated capillaries
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What is the function of pituicyes?
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Supporting role similar to astrocytes
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What is the contents of the Para Nervosa?
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non-myelinated axons and their nerve endings
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Where are the cell bodies of the non-myelinated axons and nerve endings; which are contained in the Para Nervosa?
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Supraoptic and Paraventricular
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What are 2 unique factors about the non-myelinated axons and nerve endings that are contained within the Pars Nervosa?
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-End close to the fenstrated capillary network
-Contain secretory vesicles in all parts of the cells; for example -> within the cell body, the axon, and the axon terminal |
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What are secretory vesicles called when they form dilatations of the axon terminal within the Pars Nervosa?
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Herring Bodies
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What does Herring Bodies Contain?
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Oxytocin or ADH (vasopressin)
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What does Oxytocin do?
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Promotes smooth muscle contraction of the uterus and myoepithelial cells of breast
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What does ADH do?
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- ADH => Antidiuretic
Facilitates resorption of water from DCT and collecting tubule of kidney by acting on ADH regulated water channels (APQ-2) |
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What does the absence or reduced production of ADH cause?
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Diabetes Insipidus
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What does absence or reduced production of ADH cause?
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Diabetes Insipidus
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How does Diabetes Insipidus present?
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Large volumes of diluted urine; counteracts by making patient very thirsty
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Damage to what can cause injury to ADH production?
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Damage to hypothalamus or damage to the posterior pituitary (ie. tumor or head injury)
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Generally; what dose the hypothalamus regulate the activity of?
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The pituitary activity
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What are the 3 main functions of the hypothalamus?
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-Coordinate most of the endocrine functions in body
-One of the major controlling center of autonomomic nervous system -Forms part of the feedback loop between the pituitary and target organs |
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Generally; what does the Pineal Gland regulate?
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Daily body rhythm
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What does the pineal gland develop from?
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Neuroectoderm; remains attached to brain
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What are the 2 cell types of the Pineal Gland?
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Pinealocytes and Interstitial cells (Gilal)
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What are Glial cells?
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Connective tissue of the nervous system
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What are the chief cells of the Pineal Gland? what are their arrangement?
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Pinealocytes; clumps or cords
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What characteristic can be used when attempting to identify tissue of the pineal gland?
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Brain Sand (corpora arenacea)=> calcified concretions (hard solid mass)
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What is the function of the Pineal Gland?
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A photosensitive organ; time keeper and regulator of the day/night cycle (Circadian Rhythm); role in adjusting to the sudden changes in day length (ie. Jet Lag); also SAD (Seasonal affective disorder)
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How does the Pineal Gland receive information about light/dark?
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via Retina; via the Retinohypothalamic Track; which connects the suprachiasatic nucleus with sympathetic neural tracts travelling into the pineal gland
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What do light impulses inhibit?
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Production of melatonin
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When is Melatonin levels high?
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At night
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What does the Thyroid Gland develop from?
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Endodermal lining of the floor of the primitive pharynx
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What forms the Thyroglossal Duct?
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As the thyroid is developing (via the endodermal lining of the floor of the primitive pharynx); it grows caudally (like a tail) and forms this duct-like invagination
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When does the thyroid divide into its lobes?
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When it reaches its final destination in front of the trachea
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What is the Pyramidal Lobe?
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During migration of the developing thyroid gland; the duct undergoes atrophy; leaving this embroyonic remnant
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In what week of development of the thyoid gland do you find follicular cells?
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Week 9
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What gives rise to the Parafollicular "C" Cells of the thyroid? When?
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By week 7;
epithelial cells from invaginatino of the 4th brachial pouches migrate to the thyroid-called 'ultimobranchial bodies' ultimobrachial bodies give rise to parafollicular C Cells |
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What is the structural unit of the thyroid?
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Thyroid Follicle
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How is a Thyroid Follicle described?
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Cyst-like compartment; lined by simple cuboidal or low columnar epithelium
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What does the Thyroid Follicle contain?
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Colloid (gel-like substance)
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What hormones are secreted from the thyroid follicle?
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T3 and T4
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What hormones are secreted from the Parafollicular (C Cells)?
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Calcitonin
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What are the steps of thyroid synthesis?
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1. Uptake of AA; synthesis and secretion of Thyroglobulin
2. Uptake of Iodine; oxidation to iodine and released into colloid 3. Iodination of thyroglobulin in colloid; forming MIT and DIT 4. Formation of T3 and T4; via oxidative coupling reactions 5. Resorption of colloid via receptor mediated endocytosis 6. Release of T4 and T3 from cell into circulation |
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What role does T3 and T4 play in normal fetal growth?
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Crosses plancental barrier; critical for early stages of brain development
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What occurs if there is a deficiency of T3/T4 during fetal growth?
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Irreversible damage to CNS; ie. reduced number of neurons, defected myelination, & mental retardation
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How does Calcitonin inhibit bone resorption?
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decreases Ca levels
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How are the Parathyroids positioned?
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On posterior surface of thyroid; 2 superior and 2 inferior
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Where do the inferior parathyroids and thymus develop from?
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3rd Branchial Pouch
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Where does the Superior Parathyroids develop from?
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4th Branchial Pouch
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What do the chief cells of the parathyroids secrete?
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Principal (Chief cells) Cells secrete PTH
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What is the function of PTH?
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Regulates Ca and Phosphate level in blood;
-stimulates bone resorption -Decreases Ca excretion by kidneys -Increases intestinal absorption of Ca Reciprocal effects with Calacitonin |
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What dose C Cells Secrete?
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Calacitonin
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What is the function of calacitonin?
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decreases Ca levels; hindering bone growth; reciprocal effects with PTH
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What is the time lag of PTH and Calcitonin?
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PTH- peak levels after several hours; a slow and long term effect
Calcitonin- Rapidly lowers serum Ca levels; peak effect in about 1hr; rapid |
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Where does the cortex of the adrenal gland develop from?
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Mesenchyme
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Where does the medulla of the adrenal gland develop from?
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Neural crest cells that migrate into the developing gland
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What are the three zones of the Adrenal Cortex?
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Zona Glomerulosa (outer; about 15%)
Zona Fasciulata (middle; largest; about 80%) Zona Reticularis (Inner; about 5-7%) |
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How are the cells arranged in the Zona Glomerulosa of the adrenal cortex?
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closely packed ovoid clusters and curved columns; continuous with the cellular cords of the Zona Fasiculata; fenestrated capillaries in b/w cords
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What organelle are abundant in the zona glomerulosa cells?
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Abundant sER
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What is Mineralocorticoids?
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A cortiocosteriod; that is involved with maintaining the salt balance in the body
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What mineralocoriocoid is secreted by the zona glomerulosa of the cortex of the adrenal?
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Aldosterone
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What is the function of Aldosterone?
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Acts on DCT to stimulate resorption of Na and H2o and excretion of potassum.
increasing BV and increasing BP |
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What does the renin-angiotensin-aldosterone system send feedback information to?
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Zona Glomerulosa cells of the adrenal cortex
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What does the JGA secrete in response to low BP or low Na levels.
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Renin
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What is the function of Renin?
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Converts angiotensinogen in the blood to angiotensin-1
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What happens to angiotensin-1 in the renin-angiotensin-aldosterone system?
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converted to angiotenson II in lung via ACE
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What is the function of Angiotensin II?
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acts on Zona Glomerulosa which secretes aldosterone
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What type of inhibitor can be used to treat chronic hypertension?
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ACE inhibitors
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How can you describe Zona Fasciculata?
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Large polyhedral cells in long; straight cords; separated by capillaries
cells; highly developled sER and mitochondria with tubular cristae |
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What is numerous in the Zona Fasciculata?
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Lipid Droplets;extensive sER cytoplasm is acidophilic
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What is the principal secretion of the zona fasciculata? what is secreted in small amounts?
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Glucocorticoids (involved in metabolism of fat)
and small amounts of Gonadocorticoids Androgens |
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What does Glucoccorticoids have a role in?
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Gluconeogenesis and glycogenesis
and .. they Depress the inflammatory and immune responces; (inhibit wound healing) |
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What is the action of Hydrocortisone (a glucocorticoid)?
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acts on various cells to increase metabolic availability of glucose and fatty acids
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How does Glucocorticoids inhibit wound healing?
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By suppressing IL-1 and IL-2 and destruction of lymphocytes in LN
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What regulates the secretion of the Zona Fasciculata of the adrenal gland?
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ACTH; Adrenocotricotropic, via the pituitary gland (stimulates adrenal gland)
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What feedback control; controls the production and secretion of glucocorticoids and steriods of the the Zona Fascinulata?
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CRH-ACTH System
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What is ACTH necessary for?
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Cell growth and maintenance; stimulates steroid synthesis; increased BF through the adrenal gland
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What does circulating glucocorticoids act on?
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-May act directly on pituitary gland
-Mostly; exert feedback control on neruons of the arcuate nucleus of the hypothalamus |
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What effect does glucocorticoids have on the nucleus of the hypothatlamus?
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Release of CRH into hypothalamo-hypophysial portal circulation
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How is the Zona Reticularis part of the cortex of the adrenal gland described?
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Cells arranged in -<>- cords
Separated by fenstrated capillaries Few Lipid droplets |
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What does the Zona Reticularis part of the cortex of the adrenal gland produce?
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Weak androgens;
ie DHEA (Dehydroepiandeosterone) and glucocorticoids |
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After Hypophysectomy; what happens to Zona Reticularis and what must be given?
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Zona Renticularis atrophies
ACTH must be taken in to maintain the structure and function of the Zona Fasciculata |
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What is the medulla of the adrenal made up of?
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Large pale staining epithelioid cells - Chromaffin cells
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What are Chromaffin Cells?
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Epitheliod cells of the adrenal medulla; they are modified neurons without axonal processes
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What inhibits axonal growth in chromaffin cells?
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Glucocorticoids; via adrenal cortex
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What passes directly to the chromaffin cells of the medulla?
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Numerous myelinated, presynaptic sympathetic nerve fibers
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What action does the neurotransmitters (Ach) signal to the chromaffin cells via the numerous myelinated; presynathetic nerve fibers elicit?
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causes cells to secrete catecholamines storied in the vesicles
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What are chromaffin cells "equal" to?
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Post synaptic neruons
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What are the two cells of the medulla of the adrenal medulla?
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Chromaffin Cells and
Ganglion Cells |
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How are Chromaffin Cells arranged?
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in ovoid clusters and short interconnecting cords with capillaries in between them
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What does the large, dense core vesicles of the Chromaffin cells secrete?
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Norepinephrine
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What does the smaller; less dense vesicles of the Chromaffin Cells secrete?
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Epinephrine
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What are the two effects the Glucocorticoids from the adrenal cortex have on the Medulla?
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1. Control over morphology of chromaffin cells
=> prevent formation of neural processes 2. Induce conversion of nor-epinephrine to epinephrine (via methylation) |
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What is the function of the catecholamines?
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Fight or Flight response; both epinephrine and nor-epinephrine release glucose into blood stream; via Glycogenolysis; also mobilises free fatty acids from adipose tissue
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What are the actions of Catecholamines?
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-Rise in BP
-Dilation of Coronary Vessels -Vasodilation of BV or skeletal muscle -Vasoconstriction of vessels of skin and gut -Increase in heart rate and cardiac output -Increase in rate and depth of breathing |
