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Endocrine I and II Cells
Terms in this set (66)
What does the hypothalamous do?
Coordinates endocrine functions and integrates endocrine and autonomic nervous system funcitons
What does the hypothalamous regulate?
1. What are the releasing or inhibiting hormones of the hypothalamous?
2. Where are they transported to and stored in?
3. Where do they go when released from 2?
4. Where do they end their path at?
1. Inhibiting Hormones (Factors)
2. Axon terminals ending in the median eminence
3. Primary capillary plexus (fenstrated capillaries in median eminence) and subsequently drain into hypophyseal portal veins (in infandibulum) and then pass into the secondary capillary plexus (sinusoidal capillaries with fenstrated endothelium located in the anterior lobe of the pituitary)
4. The parenchyma of the anterior lobe of the pituitary
What are the hormones the hypothalamus releases? 6
1. Growth Hormone-releasing hormone (GHRH) stimulating the secretion of somatotropin (Growth hormone, GH)
2. Prolactin Rleasing Hromone (PRH) secretion of prolactin
3. Prolactin Inhibitory Factor (PIF) inhibits the secretion of prolactin
4. Coricotropin-Releasing Hormone (CRH) stimulating the secretion of adrenocorticotropin (ACTH)
5. Thyroid Stimulating Hormone-Releasing Hormone (TSH-RH): stimulates secretion of thyroid stimulating hormone
6. Gonadotropin-Releasing Hormone (GnRH) stimulating secretion of LH and FSH
What do Supraoptic and Paraventricular nuclei of the hypothalamus do?
House the cell bodies of neurosecretory cells that synthesize vasopressin (antidiuretic hormone) and Oxytocin as well as neurophysin ( a carrier protein) that binds to these hormones. The neurosecretory cells give rise to unmyelinated axons which form the hypothalamohypophyseal tract that, carrying ADH and oxytocin with neurophysin, descends to terminate near the capillaries in the posterior lobe of the pituitary gland. There, the axon terminals release hypothalamic hormones (ADH and oxytocin) that pass into the capillaries.
Anterior Pituitary (Adenohypophysis) or Pars Distalis (Pars Anterior):
1. What's it covered in?
2. What type of fibers does it contain?
3. Describe the capillaries it contains
4. Describe the two major subdivisions of cells in the Adenohyphysis
1. Fibrous connective tissue capsule
3. Fenstrated sinusoidal that coencide with the fenstrated endothelial lining allowing releasing factors into the gland and secretory products out.
4. Chromophils (color loving) and Chromophobes (color-hating)
Two divisions of chromophils and what olor they stain
Acidophils: Orange-red with acid dyes (most common type in pars distalis)
Basophils: Stain blue with basic dyes (PAS)
Two types of Acidophils in anterior pituitary
Somatotropes: Stimulated by GHRH, inhibited by somatostatin and secrete somatotropin (GH) increasing cellular metabloic rates and long bone growth.
Lactotropes (Mammotropes): Stimulated by PRH and inhibited by PIF. Produce prolactin which promotes mammary gland growth during pregnancy and lactation following birth.
What do excessive somatotropes cause?
Gigantism in children and acromegaly in adults
3 types of basophils in anterior petuitary
Coricotropes: Stimulated by CRH and secrete ACTH stimulating the adrenal cortex
Thyrotropes: Stimulated by TRH and secretes TSH (thyrotropin). Inhibited by T3 and T4 in the blood
Gonadotropes: Stimulated by GnRH and secretes FSH and LH
Pars intermedia (Zona intermedia):
Contains Rathke's cyts containning colloid (function unknown). Rudimentary in humans
Forms a "sleeve" around the hypophyseal stalk and is very vascular. May release ACTH, FSH and LH
Neurohypophysis (Posterior Pituitary):
2. Pars Nervosa
1. Continuous with median eminence of hypothalamus)
2. Not an endocrine gland, neurosecretory tissue. Recieves unmyelinated hypothalamohypophyseal tract terminals (acontaining ADH and oxytoxcin). Meaning it acts as a storage depot for neurosecretions produced by neurons of the supraoptic and paraventricular nuclei of the hypothalamus.
1. What are they?
2. What does nervous stimulation cause?
3. What are the two things they can contain?
4. They contain pituicytes, what are these?
1. Accumulations of neurosecretory granules in the axons and axon terminals of the hypothalamophyophyseal tract
2. Granules to release their contents near the fenestrated capillary plexus.
3. Vasopressin (ADH): Targeting distal tubules and collecting ducts of the kidney for water reabsorption to lower urine volume.
Oxytocin: Targing uterin myometrium and myoepithelial cells of mammary gland to stimulate smooth muscle contraction of uterus and mammary gland.
4. Glia-like, local cells taht cover and support axons and their terminals
Common, benign tumors of anterior pitutary affecting the secretory activity of other cells in the anterior pituitary and may compress and wear down surrounding neural tissue and bone.
Reduction of ADH causing insufficient water resorption by the kidney and polyurea (excess urination) and dehydration. May be caused by damage to hypothalamus or pars nervosa.
Arterial supply of Pituitary
Internal carotid including branches superior hypophyseal arteries that supply pars tuberalis and infundibulum and inferior hypophyseal areris supplying posterior lobe.
What is the blood supply to the anterior lobe of the pituitary?
There isn't its own blood vessel.
Venous Drainage of the pituitary
Primary capillary plexus (of median eminence) empties into hypophyseal portal veins (in infundibulum) to secondary capillary plexus (in anterior pituitary
Thyroid Gland: Capsule
1. What is it derived from?
2. What type of tissue?
3. What does it give rise to?
4. What does #3 carry with it?
5. Where are parathyroid glands?
1. Deep cervical fascia
2. Dense irregular collagenous connective tissue
3. Trabeculae partitioning the gland into lobules.
4. blood vessels, lymphatic vessels adn nerve fibers. Thyroid is a very vascular gland.
5. within the capsule covering the posterior part/surface of thyroid gland
What 3 hormones to the thyroid gland produce? What do they do?
T3 (triiodothyronine), T4 (tetraiodothronine) and calcitonin. T3 and T4 regulate cell and tissue metabolism and heat production and calcitonin regulates blood calcium levels
1. What are they?
2. What are they surrounded by?
3. What do they store
4. How does this differ from other endocrine glands?
6. Parafolicular cells
1. Basic structural and functional unit fo the thyroid. They are spherical and verying in diameter
2. Basal lamina, reticular fibers (anchor follicles to surrounding connective tissue) and then a fenstrated capillary plexus
3. Glandular secretrory product extracellularly in follicular lumen.
4. Other endocrine glands store their secretory product in the parenchyma (cellular part) of gland
5. Thyroglobulin (glycoprotein) stains pink
6. Islands of cells wedgeed in spaces between follicle cells. Don't come in contact with colloid
Thyroid Follicular epithelium:
1. nucleus shape
2. Cytoplasm acidophilic or basophilic
3. Site of glycosylation and packaging of secretory product.
4. What do the vesicles contain?
1. round to ovid
Parafollicular cells in thyroid:
1. Cytoplasm color?
2. what are they derived from?
3. What do their secretory granules contain?
1. Much lighter pink than follicular endothelium
2. Neural crest
3. Calcitonin; lowers blood calcium levels to normal by inhibiting bone breakdown by osteoclasts and promotes calcium dpeosition in bones.
What hormones are formed by colloid in the lumin of thyroid gland
T3 and T4
How are T3 and T4 Synthesized
- Follicular cells synthesize throglobulin (a glycoprotein containing tyrosine residues) and release it into the follicular lumen.
- Iodide from blood is pumped into the follicular cells and is oxidized on the apical (microvillar) membrane facing the colloid into its active form of iodine and remains in follical lumen. This iodine iodinates the tyrosine residues of each thyroglobulin molecule to form monoiodotyrosine (MIT) and diiodotyrosine (DIT) which undergo coupling reactions to form Triiodinated tyrosine and Tetraiodinated tyrosine.
1. What stimulates the production of T3 and T4?
2. Site of thyroglobuin synthesis in thyroid gland?
3. Site of thyroglobulin glycosylation in thyroid gland?
4. What transport method does iodide enter the follicular cells via
5. What membrane bound enzyme oxydizes iodide.
6. WHat is needed to oxidize iodide?
7. What catalyzes iodination of thyroglobulins tyrosine residues
8. Is thyroglobulin a hormone?
1. TSH in anterior pituitary and TSH binds to TSH receptors on basal lamina of thyroid follicualr cells.
3. Golgi and rER
4. Active trasport via sodum/iodide symporters
5. Thyroid peroxidase
7. Thyroid peroxidase
8. No, inactive storage form of thyroid hormone
What stimulates the release of T3 and T4?
How are T3 and T4 released?
- Follicular cells uptake colloid (thyroglobulin) from follicular lumin
- Proteases cleave iodinated tyrosine residues from thyroglobulin creating Triiodothyronine (T3) from triiodinated tyrosine when released from thyroglobulin and Tetraiodothyronine (T4) from tetraiodinated tyrosine. Also cleaved are tyrosine residues from MITs and DITs
- Thyroid horomones are relased from basal aspect of follicular cells into the extracellular space where they then pass into the fenstrated capillary network which drains into the general circulation as inactive hormones. They are then delivered to tissues and organs where they become activated.
1. Which enzyme splits the iodinated tyrosine from MIT and DIT
2. What is the difference in production of T3 and T4
3. What breaks down the iodinated tyrosine residues from thyroglobulin?
1. Iodotyrosine dehalogenase
2. T4 is produced only by thyroid follicular cells where T3 is mostly produced via conversion from T4 by the kidney, liver and heart.
3. Proteases found in endosomes
What does T3 and T4 do to:
1. Cellular metabolism
2. Growth rate
3. Mental acivity
4. Endocrine gland functions
5. Carbohydrate metabolism
6. Formation of phopholipids and triglycerides
7. Formation of fatty acids
8. Body weight
9. Heart rate
What do very high levels of T3 and T4 create?
muscle tremors, fatigue, impotence in men and abnormal menstrual bleeding in women.
What is thyroglobulin broken down into?
Amino acids and carbohydrates by lysosomal proteases
What percent of parathyroid gland is fat in adults?
What casues exophthalmos?
Hyperthyroidism. Exophthalmos is bulging of the eyes due to increase of fibrous deposition in extraocular muscles.
Where on thyroid are paratyroid gland?
In thyroid capsule on the dorsal side of the thyroid
The parachyma of parathyroid contains epithelial cells arranged in what two ways?
What three types of cells make up this parenchyma?
1. Cords and clusters
2. Chief Cells, Oxyphil cells and intermediate cells
Chief cells in the parathyroid:
1. What dye do they like?
2. What hormone is in their secretory granules?
3. What makes the Preproparathyroid hormone and what happens to it from there?
2. Parathyroid hormone (PTH)
3. rER, it splits as it's carried to the lumen of the rER forming proparthyroid hormone and a polypeptide. When it enters the golgi, it's split again to from parathyroid hormone and a polypeptide. Golgi encloses it in secretory granule and takes it out via exocytosis.
2. What dye?
3. Size compared to chief cells?
1. Unknown, maybe dorment chief cells
2. Eosin (Acidophil)
Intermediate cell in parathyroid.
What does PTH do?
Increases blood calcium level and decreses serum phosphate
What stimulates PTH release? What inhibits?
Low levels of serum calcium. High levels of serum calcium.
What does PTH do to osteoblasts?
Binds to osteoblast receptors causing osteoblasts to release osteoclast stimulating factors
What doe PTH do in the kidney?
prevents calcium loss in the urine and promotes phosphate loss in th urine
What does PTH do in the GI?
Regulates formation of vitamin D in kidney and, hence controls the rate of calcium absorption from GI since vitamin D facilitates calcium absorption from the GI.
What happens in complete removal of parathyroid glands?
Tetany. Drops blood calcium level causing tetanic contraction of muscles including the laryngeal and respiratory muscles resulting in death.
What happens in hyperparathyroidism?
Hypercalcemia hence urinary tract stones and calcification of lungs, myocardium, stomah and blood vessels
What is the pancrease covered by?
A capsule that gives rise to septa carying blood vessels, lymphatic vessels, nerves and gland ducts
Does the pancrease put out endocrine or exocrine glands?
Both, exocrine producing digestive enzyme and endocrine producing hormones.
What part of the pancrease is the endocrine portion?
Islets of Langerhans
5 types of cells in the islets of langerhans
1. Alpha cells: Glucagon
2. Beta cells: Insulin
3. Delta cells: Somatostatin (reduces smooth muscle contraction of digestive tract and gallbladder)
4. G cells: Gastrin (stimulates synthesis of HCl by parietal cells in stomach mucosa)
5. PP cells (F cells): Pancreatic polypeptide (inhibiting pancreatic exocrine secretions)
2 different causes of diabetes
1. Beta cells don't produce insulin
2. Defective insulin receptors on target cells
Type I diabetes:
1. Polydipsia (excessive thirst)
2. Polyphagia (excessive eating)
3. Polyuria (excessive urination)
How to tell the difference between the spleen's red pulp/white pulp and pancreas?
White pulp is surrounded by a dark circle called corona and light stained center. Islets of langerhans has pale islets without dark circle around the outside. Also, there is connective tissue trebeculae in spleen but no ducts as in pancreas.
What color do alpha cells and beta cells stain
Alpha cells stain pink and beta cells stain blue
What are the suprarenal (adrenal) glands covered by?
Capsule with trabeculae that carry blood and nerve into gland
2 regions of the parenchyma of the adrenal glands and what do these produce?
Cortex; 90% of region producing corticosteroids
Medulla: associated with sympathetic nervous system and produces catecholamines (epinepherine and norepinepherine)
3 zones of the cortex of the adrenal gland?
1. Zona glomulosa (outer zone) (glomularis means ball of yarn)
2. Zona Fasciculata (intermediate zone)
3. Zona reticularis (inner zone)
Zona glomerulosa of adrenal gland:
1. Type of cell and arrangement
2. Cytoplasm acidophilic or basophillic?
3. What hormone do they synthesize?
1. Columnar cells in cords and clusters
2. Acidophilic with lots of sER and lipid droplets
3. Mineralocoricois hormones, mainly aldosterone targeting distal convoluted tubule of the kidney to stimulate water balance and absorption of sodium and excretion of potassium
Zona fasciculata of adrenal gland
1. type of cells?
2. What do they synthesize?
3. Cushings Syndrome (Hyperadrenocoricism)
1. Spongiocytes (lipid droplet vacuoles impart a foamy appearance): in radial columns with sinusoidal capillaries and medullary artery running between
2. Glucocoricoid hormones hydrocortisol (cortisol) and corticosterone that both function in control of car bohydrate, fat and protein metabolism
3. Results from small tumors of basophils in anterior pituitary gland producing excess ACTH overstimulating the adrenal cortex enlarging the cortex and producing excess cortisol. Causes obesity primarily in face, neck and trunk and impotency in males and amenorrhea in females.
Zona reticularis in adrenal cortex
1. Acidophilic or basophilic?
2. What do cells form?
What do cells synthesize?
1. Intensely acidophilic
2. Anastomsing cords
3. Weak androgens dehydroepiandrosterone and androstenedione
What is the suprarenal medulla derived from?
neural crest cells, modified sympathetic ganglion
2 major type of cells in suprarenal medulla
Chromaffin cells and Sympathetic ganglion cells
Chromaffin cells in adrenal medulla
1. What does it synthesize?
2. Where does it recieve axon termianals from?
3. What is it the equivalent of?
1. Catecholamines Epinephrine and Norepinephrine creating fight or flight
2. preganglionic sympathetic neurons of splanchnic nerves that rease Ach.
3. Postganglionic sympathetic cells with no dendrites or axons
Sympathetic Ganglion cells in adrenal medulla
1. What part of adrenal medulla is it in?
2. Where do they send their axons?
1. In connective tissue of medulla
2. Cortex where they modulate corical activity and innervate blood vessels
How do identify the medulla of the adrenal gland
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