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84 Cards in this Set
- Front
- Back
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What is the endocrine system responsible for generically?
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Maintain homeostasis and coordinating body growth and development
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What are the three methods of intercellular endocrine communication?
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i. Endocrine control - hormone is distributed through circulatory system
ii. Paracrine control - hormones are discharged into surrounding CT spaces where they act upon adjacent cells or nearby target cells iii. Autocrine control - cells express receptors for hormones that they secrete |
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What is one of the master endocrine organs and why is it considered to be this?
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Hypothalamus, because it coordinates most of the functions of the endocrine glands
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What is the response time of:
Nervous? Endocrine? |
1. fast
2. slow, diffuse, long lasting |
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What are the three types of endocrine secretions?
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SAP
Steroid derivatives e.g progesterone, testosterone Amino acid derivatives, thyroxine, epinephrine, melatonin Peptide hormones, insulin, glucagon |
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What are the components of the endocrine system?
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Glands, scattered masses of endocrine tissues in other tissues (islets of langerhans), isolated cells (cells of the diffuse neuroendocrine system)
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Where does the pituitary gland lie in the brain, what is suspend by and from, and what are its two functional components?
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1. lies in the sella turcica
2. suspended by a stalk (infundibulum) from the hypothalmaus 3. Anterior pituitary (Adenohypophysis) & Posterior pituitary (Neurohypophysis) |
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What is another name for the pituitary gland?
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Hypophysis
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What is the adenohypophysis derived from?
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Oral ectoderm from the roof of the primitive mouth that migrated towards the brain forming a structure called Rathke's Pouch
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What is neurohypophysis derived from?
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Neuroectoderm from the floor of the diencephalon
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What is a rathke's cyst?
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Remnant of Rathke's pouch, it is colloid-filled cysts in the pars intermedia (in the anterior pituitary)
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What is the blood supply of the pituitary?
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Hypothalamo-hypophyseal portal circulation
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What a supplies the infundibulum?
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Superior hypophyseal arteries from the internal carotid artery
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What a. supplies the Neurohypophysis?
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Inferior hypophyseal a. from the internal carotid
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What do fenestrated capillaries come from in the pituitary and what do these arteries allow?
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Come from superior hypophyseal aa, and they allow secretions from nuclei in the hypothalamus
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What forms the hypophyseal portal veins, and what do these veins do?
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Formed by fenestrated capillaries rejoining. Deliver hypothalamic secretions directly to the cells in the pars distalis
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What do the hypophyseal portal veins give rise to and what does this allow?
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A second fenestrated capillary plexus, that allows hormones secreted from the anterior pituitary to enter the general circulation and be distributed throughout the body
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What does the adenohypophysis regulate, what are the cells separated by, how is hormone release controlled, what are the three regions?
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Regulate: thyroid, adrenal cortex, gonads... Separated by fenestrated capillaries...Release controlled by Hormones from hypothalamus that are delivered by hypothalamo-hypophseal portal system... Pars distalis, pars intermedia, pars tuberalis
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What is the glandular portion of the pituitary?
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Adenohypophysis (anterior pituitary)
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What is the largest component of the anterior pituitary, what are its 3 components, what are the 3 types of endocrine cells
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Pars distalis...components: cords of endocrine cells, CT - fibroblasts & reticular cells, large-bore fenestrated capillaries... Chromophobes, Chromophils - acidophils and basophils
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How do chromophobes stain and what are they thought to be?
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Clear/poorly stained due to few or no secretory granules
Thought to be degranulated chormophils or undifferentiated progenitor cells |
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What are chromophils? How do they stain, and what are the two types of chromophils?
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i. Hormone secreting cells
ii. Stain intensely due to abundant cytoplasmic granules iii. Acidophils, basophils |
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Where are acidophils located, what do they secrete, what color do they stain, and what are the two types?
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i. pars distalis
ii. simple peptide hormones iii. stain orange red with eosin iv. Somatotrophs and mammotrophs |
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What do somatotrophs secreted, what are they stimulated by and hinhibited by?
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i. somatotropin (growth hormone)
ii. Somatotropin releasing hormone (GHRH) iii. Inhibited by somatostatin (GHIH) |
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What do mammotrophs secrete, what are they stimulated and inhibited by?
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i. prolactin
ii. prolactin releasing hormone iii. prolatin inhibitory factor (dopamine) |
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What color do basophils stain, and what are the 3 types?
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i. Stain blue with hematoxylin
ii. Thyrotrophs, gonadotrophs, Corticotrophs |
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What hormones are secreted by basophils?
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BFLAT
Follicle stimulating hormone Leuteinizing hormone Adrenocorticotropic hormone (ACTH; corticotropin) Thyroid stimulating hormone (TSH; thyrotropin) |
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What do thyrotrophs secrete, and what are they inhibited and stimulated by?
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i. Thyroid stimulating hormone (thyrotropin)
ii. inhibited by feedback iii. Stimulated by thyrotropin - releasing hormone |
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What do gonadotrophs secrete, what are the stimulated and inhibited by?
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i. secrete follicle stimulating hormone and leutinizing hormone
ii. stimulated by gonadotropin- releasing hormone iii. inhibited by various ovary/testicular hormones |
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What do corticotrophs secrete, what are the stimulated and inhibited by?
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i. Secrete adrenocorticotropic hormone (corticotropin)
ii. Stimulated by corticotropin releasing hormone iii. no listed inhibitions |
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What are rathke's cysts a remnant of and what are they?
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Remnant of Rathke's pouch, small colloid-filled cysts
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Where is the pars intermedia located?
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Between pars distalis & pars nervosa; poorly developed in humans
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What does the pars tuberalis wrap around, and what is it similar to?
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wraps around the infundibular stalk, similar to the pars distalis
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What portion of the pituitary is the neurohypophysis (posterior pituitary) What are it s 2 regions, what does it contain many of and where are their bodies located?
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i. neural portion of the pituitary
ii. Infundibular stalk and Pars Nervosa iii. Abundant axons whose cell bodies are located mainly in the supraoptic and paraventricular nuclei of thehypothalamus |
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What are the three structural components of the neurohypophysis (posterior pituitary)?
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i. hypothalamic axons
ii. fenestrated capillary plexus iii. Pituicytes - highly branched glial cells whos processes support the unmyelinated aaxons |
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What does the Neurohypophysis secrete and how does the secretion occur?
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i. secretes oxytocin and vasopressin
ii. hormones are produced in nuclei of hypothalamus but released from axon terminals in pars nervosa. Hormone collects in herring bodies then released into fenestrated capillaries and leave pituitary via inferior hypophyseal veins |
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What is a herring body?
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Dilated portion of axon terminals that collects hormones
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What can a pituitary adenoma cause, what does this lead to?
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i. Excess of GH secretion
ii. Gigantism if tumor occurs during childhood when epiphyseal plates are active Acromegaly in adults after epiphysial plates close. b/c cartilage and membranous bone continue growing |
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What can insufficient GH production lead to?
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Dwarfism
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What is cushings disease?
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i. Adenoma of corticotrophic basophils
ii. Excess secretion of ACTH leading to increased production of cortisol by the adrenal cortex. Cortisol causes fat deposition, osteoporosis, muscle wasting |
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What is diabetes insipidus?
Caused by, leading to, and how do you get it? |
i. Absent or reduced production of vasopressin
ii. Inadequate water resorption by kidneys iii. exhibit extreme thirst and excessive production of diluted urine iv. Results from head injuries, tumors or lesions that damage the hypothalamus |
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What is the pineal gland, morphologically, and what does it contain?
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i. small cone shaped organ attached to the posterior aspect of the 3rd ventricle
ii. Radiopaque, midline marker for radiologists |
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What cell types are there in the pineal gland 2?
What do the nuclei look like, and what are their functions |
i. Pinealocytes (95%), large light nuclei, secrete melatonin
ii. Glial cells - supporting netweork, dark elongated nuclei |
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What is the shape of the thyroid gland? and other general features 4...
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1. Butterfly shaped gland lying adjacent to cricoid cartilage, anterior/lateral to larynx
2. Two lateral lobes connected by a narrow isthmus anterior to the trachea 3. Covered by a thin capsule that sends septa into the gland, dividing it into lobules 4. Lobules are composed almost entirely of round colloid - filled follicles |
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What are thyroid follicles? and what cell type do they contain?
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i. Spherical cyst-like compartments that comprise the parenchyma of the gland
ii. Follicular cells- simple cuboidal epithelium |
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What do follicular cells synthesize and how is the hormone released?
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i. Synthesize thyroglobulin
ii. Thyroglobulin is released into follicle lumen, the thyroglobulin is then iodinated by enzymes located in apical plasma membrane and stored as a colloid. When stimulated by TSH follicular cells endocytose colloid and enzymes reduce thyroglobulin to Thyroid hormone which are then released into capillaries |
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What are the two types of thyroid hormone and what effect does the hormone have?
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I. T3 - triiodothyronine, T4- Thyroxine
ii. Increase metabolism |
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Where are parafollicular cells located? how do they stain, what do they produce?
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i. periphery of the follicle but within the basement membrane
ii. Large cells with pale staining nucleus iii. Contain calcitonin |
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What triggers calcitonin secretion and what does calcitonin do?
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i. elevated blood calcium levels
ii. Decreases blood calcium by inhibiting osteoclasts |
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What can cause hypothyroidism (3), and what are symptoms
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1. Iodine deficiency, 2. Autoimmune disease (Hashimoto's thyroiditis) 3. Secondary to pituitary or hypothalamic disease. Symptoms: fatigue, muscular sluggishness, slow heart rate, decreased cardiac output and blood volume, mental lethargy
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What is hyperthyroidism caused by (2) and what are symptoms
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Hyperplasia of follicles and high production of thyroid hormone OR Grave's disease (autoimmune) antibodies produced that bind TSH receptors and cause synthesis of thyroid hormones to increase. Symptoms include excitability, weight loss, tachycardia, eye protrusions
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What are general features of the parathyroid glands? 2
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1. four small, ovoid glands located on the posterior surface of the thyroid gland
2. Thin connective tissue capsule sends septa into the gland dividing it into lobules |
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What are the 2 types of cells in the parathyroid gland?
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1. chief cells - most numerous
2. Oxyphil cells |
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What do chief cells secrete, and what does the secretion do?
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Secrete parathyroid hormone which increases blood calcium levels by stimulating bone resorption, Ca resorption in kidneys, calcium uptake in intestinal cells
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What do Oxyphil cells look like compared to chief cells and what is their function?
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Are larger, occur in clumps, acidophilic
Function is not well understood |
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What does hyperparathyroidism cause and lead to?
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Causes excessive PTH secretion (usu. a benign tumor) Causes increased blood calcium, bone weakness/fractures, kidney stones
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What is hypoparathyroidism what are its symptoms?
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Deficiency in PTH secretion. Decreased blood calcium, dense bones, muscle cramps and tremors
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Where are adrenal glands located, what does it consist of?
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Located at the superior pole of each kidney
Consists of an outer cortex and inner medulla |
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What is a adrenal trabeculae?
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A thick connective tissue capsule that sends septa into the gland
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What is the adrenal cortex derived from and produce?
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Derived from mesoderm and produces corticosteroids
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What is the adrenal medulla derived from and what does it produce?
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Derived from neural crest cells and produces catecholamines
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Does the adrenal gland have a rich blood supply?
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Yes
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What are the 2 blood supply routes of the adrenal glands?
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i. Direct route - branches of capsular arteries form medullary arteries and bypass the cortex to directly supply the medulla
ii. Indirect route - arteries penetrate capsule and form a subcapsular plexus which form capillaries and sinusoids that irrigate all cortical regions first in route to the medulla |
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What type of cells compose the adrenal cortex and what are the three ones?
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i. composed of cuboidal cells arranged in cords usually 2 cells wide, running radially with capillaries
ii. Zona Glomerulosa, Fasciculata, Reticularis |
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Where is the Zona glomerulosa, how are cells arranged, size and stain, what do they sythesize?
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i. Immediately below the capsule
ii. Arranged in round clumps (gomeruli) iii. Small, fairly dark staining iv. Synthesize mineralocorticoids (aldosterone and deoxycorticosterone) |
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What are the two mineral corticoids, what is their function, and what is it stimulated by?
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i. aldosterone, deoxycorticosterone
ii. control salt and water balance by increasing sodium resorption in the kidney iii. stimulated by ACTH from pars distalis and angiotensin II |
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Which layer of the Adrenal cortex is thickest, how are cells arranged, how is the cytoplasm, and what does it produce?
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Zona Fasciculata
ii. Cuboidal cells in long radial cords bordered by fenestrated capillaries iii. Light foam cytoplasm b/c of lipid droplets iv. Produces glucocorticoid |
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What are the 2 glucocorticoids? What is their function and what are they stimulated by?
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i. Cortisol and corticosterone
ii. control carbohydrate, fat and protein metabolism; stimulate carbohydrate synthesis in the liver. suppress immune response iii. Stimulated by ACTH from Pars Distalis |
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Where is the zona reticularis, how are cells arranged, what do cells look like, and what do they synthesize?
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i. Innermost layer (next to cortex)
ii. Irregular cords, anastomosing network by many capillaries iii. Small, acidophilic cells, few lipid droplets iv. Synthesize small amounts of glucocorticoids and weak androgens |
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What does adrenal medulla consist of? and what do theses cell secrete?
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i. Anastomosing cords of chromaffin cells
ii. secrete the catecholamines (Epinephrine and norepinephrine) |
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What is a chromaffin cell?
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modified postganglionic sympathetic neurons that has lost its axons and dendrites
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What secretes catecholamines and what are the two types of catecholamines?
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Secreted by chromaffin cells they are epinephrine and norepinephrine
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Which cells produce norepinephrine and which cells convert norepinephrine to epinephrine?
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Cells receiving direct blood supply from medullary artery produce norepinephrine, and cells receiving indirect blood supply with glucocorticoids convert norepinephrine
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What is the adrenal medulla innervated by?
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cholinergic preganglionic sympathetic nerve fibers
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What are general features of pancreatic islets of langerhans? 4
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i. small nests of endocrine cells scattered in pancrease
ii. round clusters of pale-staining cells surrounded by intensely staining pancreatic acini iii. Profusely invested with a network of fenestrated capillaries iv. Hard to distinguish between principal cells with H&E |
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What are the 5 major types of islet cells?
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Alpha, Beta, Delta, G and PP cells
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Which cell secretes glucagon? insulin? somatostatin? pancreating polypeptide? gastrin?
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Glucagon - alpha cells
Insulin - Beta cells Somatostatin - Delta cells Pancreatic polypeptide - PP cell Gastrin - G cells |
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What is the fxn of glucagon, insulin?
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Glucagon acts on hepatocytes (low blood sugar). Glycogen -> glucose
Insulin - high blood glucose, enhances glucose uptake, glycogen (hepatocytes) and triglyceride (adipocytes) synthesis |
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When is somatostatin released? What does PP do? What does Gastrin do?
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Somatostatin - increased blood glucose and amino acids
PP - inhibits pancreatic exocrine secretions Gastrin - stimulates production of HCL by the stomach and gastric motility |
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Where are beta and alpha cells located in pancreatic islets?
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Beta - center
Alpha - periphery |
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What can cause diabetes mellitus?
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Decreased insulin production or defective insulin receptors
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What is Type I diabetes and what is it characterized by? symptoms, who does it affect
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Insulin dependent; juvenile onset
Affect persons <20 y/o Loss of beta cells (autoimmune) Symptoms are thirst hunger and urination |
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What is Type II diabetes, what is it characterized by,
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Non-insulin dependent; adult onset. Affects ppl >40 y/o, starting to occur in younger population mb due to obesity
Insulin levels may be normal but cells are unresponsive |
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Which type of diabetes is more common?
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Type II 90%
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