Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
167 Cards in this Set
- Front
- Back
|
What Hormone uses the second messenger system , adenylate cyclase/ cAMP?
|
Most protein hormones and catecholamines
|
|
|
What hormones use the second messenger system, tyrosine kinase ?
|
Insulin and Epidermal growth factor (EGF)
|
|
|
What second messenger system acts as an antagonist system for cAMP?
|
guanylyl cyclase/ cyclic guanosine monophosphate ( cGMP)
|
|
|
What are the three receptor domains for steroids and thyroid hormones?
|
Hormone- binding region
DNA -binding region Amino- terminal region |
|
|
What follows the binding of steroids/thyroid hormones to their receptor?
|
Binding of the hormone to these receptors causes allosteric transformation of the receptor into a form that binds to chromosomal DNA and activates RNA polymerase activity
|
|
|
What is the second messenger for the thyroid hormone?
|
There is none.
The binding of the hormone to the receptor activates RNA polymerase activity and increases transcription of mRNA --> it influences gene expression directly |
|
|
What are the two functional components of the pituitary gland?
|
Anterior lobe, the glandular epithelium
Posterior lobe, the neural secretory tissue |
|
|
Where in the brain is the pituitary located?
|
It is centrally located at the base of the brain, where it lies in a saddle- shaped depression in the sphenoid bone called the sella turcica
|
|
|
What is the embryological origin of the anterior lobe of the pituitary gland?
|
The anterior lobe is derived from an evagination of the ectoderm of the oropharynx toward the brain ( Rathke's pouch)
|
|
|
What is the embryological origin of the posterior lobe of the pituitary gland?
|
The posterior lobe of the pituitary gland is derived from a downgrowth of neuroectoderm of the floor of the 3rd ventricle of the developing brain
|
|
|
What are the three portions of the anterior lobe?
|
Pars distalis
Pars intermedia Pars tuberalis |
|
|
Where is the pars distalis located ?
|
Pars distalis makes up the bulk of the anterior lobe of the pituitary gland and arises from the thickened anterior wall of the pouch
|
|
|
Where is the pars turberalis located?
|
It develops from the thickened lateral walls of the pouch and forms a collar around the infundibulumWb
|
|
|
What are the different portions of the posterior lobe of the pituitary lobe?
|
Pars nervosa
Infundibulum |
|
|
What is the embryological remnant of the posterior wall of Rathke's pouch?
|
Pars intermedia
|
|
|
What are the contents of the Pars nervosa
|
neurosecretory axons and their endings
|
|
|
What is the blood supply for the pars nervosa?
|
Inferior hypophyseal arteries
|
|
|
What areas does the superior hypophyseal arteries supply?
|
Pars tuberalis, median eminence, and infundibulum
|
|
|
What is the arterial supply of the anterior lobe?
|
Most of the anterior lobe of the pituitary gland has no direct arterial supply
|
|
|
Describe the hypophyseal portal system.
|
The internal carotid arteries and posterior communicating artery of the circle of Willis give off the Superior hypophyseal artery -->primary capillary plexus--> hypophyseal portal veins --> secondary capillary plexus
|
|
|
Describe the venous drainage of the pituitary gland.
|
Most of the blood from the pituitary gland drains into the cavernous sinus at the base of the diencephalon and the systemic circulation
|
|
|
What are the trophic hormones of the anterior pituitary lobe?
|
ACTH
TSH FSH LH |
|
|
What is the target area of the ACTH hormone?
|
ACTH maintains structure and stimulates secretion of glucocorticoids and gonadocorticoids by the zona fasciculata and zona reticularis of the adrenal cortex
|
|
|
What is the role of FSH in the testis?
|
Stimulates spermatogenesis in the testis
|
|
|
What is the action of IGF-I on the growth plates and in skeletal muscles?
|
It stimulates the division of progenitor cells located in growth plates and in skeletal muscles
|
|
|
____ stimulates ovarian follicular development and ____ regulates final maturation of ovarian follicle
|
FSH
LH |
|
|
What is the role of LH in the testes
|
It is essential for the maintenance and androgen secretion by the Leydig cells of the testis
|
|
|
______ initiates milk development but ______ stimulates milk ejection from glands
|
Prolactin
Oxytocin |
|
|
Which cells compose about 50% of the pars distalis?
|
Somatotrophes
|
|
|
What are the three regulatory hormones of GH?
|
Ghrelin
Growth hormone- releasing hormone Somatostatin |
|
|
How does ghrelin work?
|
It is a potent stimulator of GH secretion and appears to coordinate food intake with GH secretion
|
|
|
Describe the cell of a somatotroph.
|
Medium sized, oval cell with round centrally located nuclei with the presence of eosinophilic vesicles
|
|
|
What is the relationship between prolactin and thyrotropin releasing hormone
|
Thyrotropin releasing hormone and vasoactive inhibitory peptide (VIP) are known to stimulate synthesis and secretion of prolactin
|
|
|
During the storage phase of a mammotrope it stains _____ but during the secretory phase it stains ___
|
acidophilic
chromatophobe |
|
|
describe a mammotrope cell
|
large, polygonal cell with oval nuclei
|
|
|
How is prolactin regulated?
|
The secretion of prolactin is under inhibitory control of dopamine and TRH and VIP are known to stimulate its release
|
|
|
Describe a corticotrope cell
|
It is medium-sized polygonal with round and eccentric nuclei
|
|
|
What is the precursor molecule to ACTH?
|
proopiomelanocortin (POMC)
|
|
|
What are the components to POMC?
|
ACTH
beta-lipotropic hormone melanocyte -stimulating hormone beta-endorphin enkephalin |
|
|
Describe the cells of gonadotrophes
|
these are small oval cells with round and eccentric nuclei
|
|
|
Describe the thyrotrope cells
|
Large, polygonal cells with round and eccentric nuclei that are basophilic and stain with PAS
|
|
|
what is found in the pars intermedia.
|
Small cystic cavities that represent the residual lumen of Rathke's pouch , basophils and chromophobes
|
|
|
Where are the cell bodies for the pars nervosa located?
|
The cell bodies are found in the supraoptic nuclei and paraventricular nuclei of the hypothalamus
|
|
|
Where do the axons of the hypothalamohypohyseal tract terminate.
|
They end in close proximity to the fenestrated capillary network of the pars nervosa
|
|
|
What is neurophysin?
|
A protein that binds to the hormone by noncovalent bonds
|
|
|
What are Herring bodies?
|
These are dilations of the axon terminals that are filled with accumulations of neurosecretory vesicles, smooth ER, mitochondria, few microtubules
|
|
|
How are ADH and oxytocin made?
|
Oxytocin and ADH are synthesized as part of a large molecule that includes the hormone and its neurophysin
|
|
|
What are the effects of ADH on blood vessels
|
In large nonphysiologic doses, it can increase the BP by promoting the contraction of smooth muscle in small arteries and arterioles
|
|
|
What is the effect of ADH on the kidney?
|
The effect of ADH on the kidney is to insert water channels (aquaporins) into cells of the DCT and collecting ducts --> increasing the permeability to water
|
|
|
Where is AQP 2 inserted?
|
in the apical domain
|
|
|
Where is AQP-3 inserted?
|
in the basolateral domain
|
|
|
What mutation is responsible for the nephrogenic diabetes insipidus?
|
mutation of the V2 receptor;
ADH acts thorough this receptor on the basolateral domain of the cells |
|
|
What physiologic conditions trigger ADH release
|
An increase in plasma osmolality or a decrease in blood volume stimulates ADH release
|
|
|
What receptors can trigger ADH release
|
1. the cell bodies of the hypothalamus secretory neurons may serve as osmoreceptors
2. The carotid bodies --> decrease in blood volume 3. The JG apparutus --> plasma osmalilty |
|
|
Oxytocin promotes smooth muscle contraction of the ____ and the _____ cells of the breast.
|
uterus
myoepithelial |
|
|
When does oxytocin promote smooth muscle contraction of the uterus?
|
Orgasm,
menstruation parturition |
|
|
What is the neurohormonal reflex that triggers oxytocin release in the uterus
|
In the uterus, the neurohormonal reflex is initiated by distention of the vagina and cervix
|
|
|
What is the neurohormonal reflex that triggers oxytocin release in the breast
|
The reflex is initiated by breastfeeding
|
|
|
What feelings of the pituicyte are similiar to the astroglia?
|
They are irregular in shape with many branches, have specific intermediate filaments assembled from glial fibrillary acidic proteins (GFAP)
|
|
|
Where is the hypothalamus located in the brain
|
The hypothalamus located in the middle of the base of the brain and it encapsulates the ventral portion of the third portion.
|
|
|
Where is the pineal gland located?
|
It is located at the posterior wall of the third ventricle near the center of the brain
|
|
|
What is the embryological origin of the pineal gland?
|
It develops from neuroectoderm of the posterior portion of the roof of the diencephalon and remains attached to the brain by a short stalk
|
|
|
What are the two types of cells in the pineal gland?
|
Pinealocytes
Interstitial (glial) cells |
|
|
The ______ of ADH leads to diabetes insipidus
|
absence
|
|
|
What are the symptoms of diabetes insipidus?
|
polyuria
hypotonic urine |
|
|
What is the difference between nephrogenic and hypothalamic diabetes insipidus?
|
Hypothalamic DI has an absence of ADH where nephrogenic DI has a normal to high level of ADH but lack of renal response to ADH
|
|
|
How do you treat hypothalamic DI
|
Hypothalamic DI is usually treated by administration of analogs of ADH (desmopressin)
|
|
|
How do you treat nephrogenic DI
|
the treatment of the nephrogenic type of disease is aimed at reducing the volume of urine output
|
|
|
What is the function of somatostatin?
|
Inhibits secretion of GH by somatotropes and inhibits insulin secretion by beta cells of pancreatic islets
|
|
|
What is the treatment of SIADH ?
|
treat underlying cause and impose fluid restrictions
|
|
|
Light ____ melatonin production whereas dark _____ melatonin
|
inhibits
releases |
|
|
What is brain sand?
|
Calcified concretions present in the pineal gland. They are derived from precipitation of calcium phosphates and carbonates that are released into the cytoplasm when the pineal secretions are exocytosed
|
|
|
How does the pineal gland obatin info about the light and dark cycles.
|
It obtains info about light and dark cycles from the retina via the retinohypothalamic tract
|
|
|
What is the retinohypothalamic tract?
|
The retinohypothalamic tract connects in the suprachiasmatic nucleus with sympathetic neural tracts traveling into the pineal gland
|
|
|
What is the function of melatonin?
|
It regulates body rhythms and day/night cycles
Inhibits secretion of GnRH |
|
|
Destruction to what endocrine results in precocious puberty?
|
The pineal gland
|
|
|
What is the functional unit of the thyroid gland?
|
Thyroid follicles
|
|
|
When does the thyroid begin to develop?
|
The thyroid gland begins to develop during the 4th week
|
|
|
What is the embryological origin of the thyroid?
|
The thyroid starts to develop from a primordium originating as an endodermal thickening of the floor of the primitive pharynx
|
|
|
describe the embryological migration of the thyroid.
|
The primordium of the thyroid grows caudally and forms a ductlike invagination known as the thyroglossal duct. The thyroglossal duct descends through the tissue of the neck to its final destination in front of the trachea, where it divides into two lobes
|
|
|
What is the embryological remnant of the pyramidal lobe of the thyroid?
|
The pyramidal lobe is found in about 40% of people- it is the remaining thyroglossal duct that has not atropied
|
|
|
What is the embryological origin of the parafollicular cells?
|
The ultimobranchial body cells.
|
|
|
Describe the embryological migration of the parafollicular cells.
|
During week 7, the ultimobranchial body cells ( epithelial cells lining the invagination of the fourth branchial pouches start their migration and become incorporated into the lateral lobes of the thyroid
|
|
|
During development when do the follicles fill with colloid?
|
by week 14
|
|
|
when do follicles form within the thyroid?
|
by ninth week
|
|
|
What cells are responsible for production of the thyroid hormones T3 and T4?
|
Follicular cells
|
|
|
What cells are responsible for calcitonin?
|
the parafollicular cells
|
|
|
How does calcitonin lower calcium levels?
|
Calcitonin lowers blood calcium levels by suppressing the resorptive action of osteoclasts and promotes calcium deposition in bones by increasing the rate of osteoid calcification
|
|
|
What is an example of a calcitonin secreting tumor?
|
Medullary carcinoma of the thyroid
|
|
|
What is the prinicpal component of Colloid?
|
A large iodinated glycoprotein called thyroglobulin containing about 120 tyrosine glands
|
|
|
What is the storage form of the thyroid hormones?
|
Thyroglobulin
|
|
|
What is the mechanism for transporting iodide from the blood to inside the follicular cells?
|
Iodide is actively transported from the blood into their cytoplasm using ATPase- dependent sodium/iodide symporters (NIS)
|
|
|
What is the mechanism for transporting iodide from inside the follicular cells to inside the colloid?
|
Iodide ions are transported to the lumen of the follicle by iodide/chloride transporter called pendrin
|
|
|
Where is iodide converted to iodine?
|
After it is transported immediately transported to the colloid, iodide id oxidized to iodine. This catalyzed by membrane-bound thyroid peroxidase (TPO)
|
|
|
how are diiodotyrosine residues formed?
|
When two iodine molecules are added to a tyrosine residue; this is catalyzed by thyroid peroxidase
|
|
|
What are the two pathways for resorption of colloid by the follicular cells?
|
Lysosomal and transepithelial pathways
|
|
|
What does the presence of goiter indicate, hyper- or hypothyroidism?
|
It can be found with both
|
|
|
What autoimmunoglobins cause Hashimoto's thyroiditis?
|
Autoimmune thyroiditis is characterized by the presence of abnormal antibodies against thryoglobulin, TPO, and the TSH
|
|
|
What is the changes to the dermis with myxedema?
|
Myxedema is caused by an accumulation of large amounts of hyaluronan in the ECM of the connective tissue of the dermis
|
|
|
What is the role of autoantibodies in Graves disease?
|
Graves' disease have abnormal immunoglobulins (IgG that bind to the TSH receptors on the follicular cells and stimulate adenylate cyclase activity.
|
|
|
What is the level of TSH in Grave's disease
|
TSH is usually normal.
|
|
|
What are the mircoscopic features of the thyroid in Graves's disease?
|
Microscopic features include the presence of columnar follicular cells lining the thyroid follicles
|
|
|
What is the major pathway for colloid resorption in normal conditions?
|
Lysosomal
|
|
|
Which pathway uses the apical surface protein megalin to introduce thyroglobulin into the cell?
|
the transepithelial pathway
|
|
|
Why do patients with Graves' disease have detectable amounts of circulating thyroglobulin with portions of megalin receptor?
|
The transepithelial pathway allows intact thyroglobulin to be transported from the apical to the basolateral surface of the follicular cells.
In pathologic conditions of high TSH or TSH- like stimulation, megalin expression is increased and large amounts of thyroglobulin follow this pathway |
|
|
Where is most T3 produced?
|
Most T3 is produced through conversion from T4 by organs such as the kidney, liver, and heart
|
|
|
In the lysosomal pathway, what is the ratio of T4: T3?
|
In the lysosomal pathway, the T4:T3 ratio is 20:1
|
|
|
What are the effects of thyroid deficiency in pregnancy?
|
There is irrreversible damage to the CNS, causing reduced numbers of neurons, defective myelination, and mental retardation
|
|
|
How is thyroid hormone recycled back to the thyroid
|
Once uncoupled from the thyroglobulin, DIT and MIT molecules are further deiodinated within the cytoplasm of the follicular cells to release the amino acid tyrosine and iodide, for recycling
|
|
|
What is the reason for stunted body growth with intrauterine thyroid deficiency?
|
Thyroid hormones also stimulate gene expression for GH in the somatotropes
|
|
|
Where are the parathyroid glands located?
|
On the posterior of the lateral lobes of the thyroid gland.
|
|
|
What is the blood supply of the parathyroid glands?
|
THe blood supply is from the inferior thyroid artery or from the anastomoses between the superior and inferior thyroid artery
|
|
|
What is the embryological origin of the inferior parathyroid glands?
|
From the 3rd branchial pouch and the thymus. The inferior parathyroid separate from the thymus and come to lie below the superior parathyroid glands
|
|
|
What is the embryological origin of the superior parathyroid glands?
|
From the 4th branchial pouch
|
|
|
When do the principal cells differentiate?
|
During embryological development and are functionally acitve i regulating fetal calcium metabolism
|
|
|
What cells are responsible for regulating the synthesis, storage, and secretion of PTH?
|
Principal cells
|
|
|
What is the histological difference between principal and oxyphil cells?
|
The principal cells are slightly acidophilic small, polygonal cells with a central located nucleus.
The oxyphil cells are more rounded, and larger than the principal cells and have a distinctly cytoplasm |
|
|
What are the consequences of total parathyroid removal?
|
Death will ensue because muscles, including the laryngeal and other respiratory muscles, go into tetanic contraction as the blood calcium falls
|
|
|
What are the effects of elevated PTH on calcium and phosphate?
|
It causes calcium levels to increase and the phosphate levels to decrease
|
|
|
What are the effects of PTH on osteoclasts?
|
The bone-resorbing osteoclasts do not have PTH receptors. They are activated indirectly through PTH activation of osteoblasts.
|
|
|
How does PTH indirectly activate osteoclasts?
|
Osteoblasts are activated by PTH which increases local RANK production and decreases osteoprotegrin (OPG) secretion
|
|
|
What is osteoprotegrin?
|
It is a decoy receptor for RANKL, the lack of available ligand affects the RANK-RANKL signaling pathway and acts as a potent inhibitor of osteoclast formation. It is mainly produced by osteoblasts
|
|
|
What is the action of PTH on the kidney?
|
1. kidney excretion of calcium is decreased by stimulating tubular reabsorption
2. urinary phosphate secretion is increased 3. 1alpha hydroxylase is stimulated to convert more 25-OH vitamin D3 to active 1,25 (OH)2 vitamin D3 |
|
|
Where is calcium reabsorbed in the kidney?
|
Distal tubule
|
|
|
Where is phosphate reabsorbed in the kidney?
|
Proximal tubule
|
|
|
How does PTH affect the absorption of calcium in the intestine?
|
intestinal absorption of calcium is increased
|
|
|
What are the two distinct regions of the adrenal gland
|
The cortex and the medulla
|
|
|
What is the steroid secreting portion of the adrenal gland?
|
the cortex
|
|
|
What is the catecholamine secreting portion of the adrenal gland?
|
the medulla
|
|
|
Describe the dual supply of the medulla.
|
1. Capsular capillaries feed into the fenestrated cortical Sinusoidal Capillaries with then feed the fenestrated medullary sinusoidal capillaries
2. medullary arterioles feed into the medullary capillary sinusoids |
|
|
Describe the venous drainage from the cortical and medullary sinusoids.
|
From the cortical and medullary sinusoids drain into the venules which drain into the adrenomedullary collecting veins that join to form the central adrenomedullary vein
|
|
|
Where does the left central adrenomedullary vein drain into?
|
Left renal vein
|
|
|
Where does the right central adrenomedullary vein drain into?
|
IVC
|
|
|
What is the importance of the central adrenomedullary vein and venules having longitudinal smooth muscle in the tunica media?
|
Synchronous contraction of longitudinal smooth muscles cells cause the adrenal gland to contract , enhancing the efflux of hormones from the adrenal medulla
|
|
|
Where are the mineralocorticoids secreted?
|
the parenchymal cells of the zona glomerulosa
|
|
|
What cells in the adrenal medulla are responsible for the secretion of catecholamines?
|
Chromaffin cells
|
|
|
What is the embryological origin of the adrenocortical cells?
|
The cortical cells originate from mesodermal mesenchyme
|
|
|
What is the embyrological origin of the medulla cells?
|
The medulla originates from neural crest cell.
|
|
|
Where does the adrenal gland form embryological?
|
The develops between the root of the dorsal mesentery of the primitive gut and the developing urogenital ridges
|
|
|
Where are glucocorticoids made?
|
Parenchymal cells of the zona fasciculata and to a lesser extent of the zona reticularis
|
|
|
What is the innervation of the medulla?
|
Presynaptic sympathetic nerves
|
|
|
What is the result when the chromaffin are stimulated by nerve impulses?
|
They release their secretory products. They are considered the equivalent of postsynaptic neurons
|
|
|
If chromaffin cells act like postsynaptic neurons, why don't they have axons?
|
Axonal growth is inhibited by the glucocorticoids that are made in the cortex
|
|
|
What is the function of the ganglion cells in the adrenal medulla?
|
The axons of the ganglion cells extend peripherally to the parenchyma of the adrenal cortex to modulate its secretory activity and innervate blood vessels, and extend to the splanchnic nerves innverating the abdominal organs
|
|
|
What is the function of the chromogranins?
|
Epinephrine and Norepinephrine are bound to the heavy weight chromogranin proteins that help to add density to vesicle contents
|
|
|
How do newly made catecholamines enter into vesicles?
|
The catecholamines are made in the cytosol and are transported into the vesicles through the action of a mgnesium- activated ATPase
|
|
|
What is the effect of glucocorticoids on the medulla?
|
They induce the enzyme that catalyzes the methylation of norepinephrine to make epinephrine
|
|
|
Why would we expect pheochromocytoma to also arise outside of the medulla?
|
Chromaffin cells are also found in paravertebral and pervertebral sympathetic ganglia
|
|
|
What is the main catecholamine that pheochromocytomas secrete?
|
Norepinephrine
|
|
|
The stimulation of which receptors results in an increase in heart rate and contractility?
|
beta adrenergic receptors
|
|
|
Stimulation of which receptors stimulate glycogenesis, glycogenlysis, and intestinal relaxation?
|
Alpha adrenergic receptors
|
|
|
What is the rule of 10s with pheochromocytomas?
|
10% are extraadrenal
10% reside outside the abdomen 10% occurs in children 10% are multiple or bilateral 10% are not associated with hypertension 10% are malignant 10% are familial 10% recur after surgical removal 10% are found incidentally |
|
|
What are the three zones of the adrenal cortex
|
zona glomerulosa
zona fasciculata zona reticularis |
|
|
What is the most predominant zone in the adrenal cortex?
|
zona fasciculata - it makes up 80%
|
|
|
What is the difference between the organization of the zona glomerulosa and the zona fasciculata?
|
The cells of the zona glomerulosa are arranged in closely packed ovoid clusters and curved columns.Its cells are small and columnar
The cells of the zona fasciculata are arranged in long straight cords that are separated by sinusoidal capillaries. The cells are large and polyhedral |
|
|
What is the function of aldosterone?
|
Aldosterone acts on the distal tubules of the nephron, the gastric mucosa, and the salivary/sweat glands to stimulate resorption of sodium at these sites and secretion of K
|
|
|
What stimulates the release of aldosterone?
|
Angiotensin II stimulates the cells of the zona glomerulosa to secrete aldosterone
|
|
|
What is the action of glucocorticoids on the liver?
|
Glucocorticoids stimulate conversion of amino acids to glucose, stimulate the polymerization of glucose to glycogen, and promote the uptake of amino acids and fatty acids
|
|
|
What is the action of glucocorticoids on adipose tissue?
|
Glucocorticoids stimulate the breakdown of lipids to glycerol and free fatty acids
|
|
|
How do glucocorticoids depress the inflammatory response?
|
It depresses the inflammatory response by suppressing IL-1 and IL2 production by lymphocytes and macrophages
|
|
|
What is the principal secretion of the cells in the zona reticularis?
|
Weak androgens, DHEA
|
|
|
What is the origin of the fetal cortex?
|
Mesodermal cells from between the root of mesentery and the developing gonad zone penetrate the underlying mesenchyme
|
|
|
What is the embryological permanent cortex?
|
It arises from the secondary mesodermal cell migration that surrounds the primary cell mass
|
|
|
Where is the fetal adrenal medulla?
|
The fetal adrenal lacks a definite medulla - the chromaffin cells remain in small, scattered cell clusters during fetal life
|
|
|
What is the fetal placental unit?
|
The fetal adrenal gland interacts with the placenta to function as a steroid secreting organ because it lacks certain enzymes necessary for steroid synthesis. The placenta lacks certain enzymes needed for steroid synthesis that are present in the fetal adrenal gland.
|
|
|
When do the chromaffin cells form the medulla?
|
Within the first postnatal month
|
|
|
When does the fetal cortex disappear?
|
At birth, the fetal cortex undergoes a rapid involution that reduces the gland with the first postnatal month to about a quater of its previous size
|
