Endocrine I Flashcards by tcarlso 3

What are the two general population of cells in the hypothalamus?

Neurons and special neurons

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What do “special” neurons in the hypothalamus secrete?

Hypothalamic neurosecretory hormones

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What organ does the hypothalamus regulate?

Pituitary gland

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Where are hypothalamic neurosecretory hormones synthesized? Stored? Terminate?

Made in Hypothalamus
Stored in axon terminals
Terminate in the median eminence

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Where do the hypothalamic neurosecratory transmitters go when released? (3)

Primary capillary plexus
Hypophyseal portal veins
Secondary capillary plexus

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Where do endocrine glands release their product?

ECS and into the bloodstream

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What is the main function of the hypothalmus?

integration of endocrine and autonomic functions

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What is the flow of transmission from the hypothalamus to the target organs?

pituitary gland
Hormones
Target organs

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The releasing or inhibiting hormones / factors pass into what structure?

the parenchyma of the

anterior lobe of the pituitary to influence secretory cells there

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What part of the primary and secondary plexus aids in the uptake of neurotransmitters?

Fenestration

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What is the difference between the anterior and posterior pituitary?

Anterior is glandular

Posterior is neuron

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What are the two general cell populations in the anterior pituitary?

Chromophils

Chromoephobes

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What are the two types of chromophils in the anterior pituitary?

Acidophils

Basophils

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What color do acidophils stain?

Orange-red

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What are somatotropes?

Acidophil

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What are the six hormones released by the pituitary?

Growth Hormone-releasing hormone
Prolactin-releasing hormone
Prolactin inhibitory factor
Corticotropin-releaseing hormone
Thyroid-stimulating hormone releaseing hormone
Gonadotropin-releaseing hormone

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What is the function of Growth Hormone-Releasing Hormone (GHRH) ?

stimulates the secretion of somatotropin (growth hormone, GH)

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What is the function of Prolactin-Releasing Hormone (PRH)?

stimulates the secretion of prolactin

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What is the function of Prolactin-Inhibitory Factor (PIF)?

inhibits the secretion of prolactin

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What is the function of Corticotropin-Releasing Hormone (CRH)?

stimulates the secretion of adrenocorticotropin (ACTH)

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What is the function of Thyroid-Stimulating Hormone-Releasing Hormone (TSH-RH)?

stimulates the secretion of thyroid stimulating hormone (TSH)

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What are the two functions of Gonadotropin-Releasing Hormone (GnRH)?

stimulates the secretion of Luteinizing Hormone (LH)

2. stimulates the secretion of Follicle Stimulating Hormone (FSH)

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Where are the cell bodies of the neurosecratory cells of the hypothalamus housed?

In the supraoptic and paraventricular nuclei

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What is the function of the neurosecratory cells in the hypothalamus?

Synthesize vasopressin (ADH), oxytocin, and neurophysin

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What is the function of neurophysin? What produces it?

Produced by the hypothalamus, and carries ADH + oxytocin

What is the hypothalamohypophyseal tract?

Collection of neurosecratory cells' unmyelinated axons that carries oxytocin and ADH to the Posterior lobe of the pituitary gland into capillaries

What are the two divisions of the pituitary gland?

Adenopophysis (anterior) | Neurohypophysis (posterior)

What is the anterior pituitary covered by? What does it consist of (3)?

1. covered by a fibrous CT capsule | 2. Contain cords of cells, reticular fibers, and fenestrated capillaries

What is the function of the fenestrated endothelial lining of the anterior pituitary?

Permits the diffusion of releasing factors into the gland Permits products pass to capillaries

What are the two types of cells found in the anterior lobe?

Chromophils | Chromophobes

What are the two types of chromophils?

Acidophils | Basophils

What color do acidophils of the anterior pituitary stain?

Orange-red with acidic dyes

What are the two types of acidophils found in the anterior pituitary?

Somatotropes | Lactotropes

What is the function of somatotropes?

Secrete somatotropin (GH) which increases metabolic rates and influences long bone growth

Excessive GH causes what?

Gigantism and acromegaly

What are somatotropes stimulated by? Inhibited?

Stimulated by GHRH | Inhibited by Somatostatin

What is the function of the chromophil lactotropes?

produce prolactin which promotes mammary gland growth during pregnancy & lactation following birth

What are lactotropes stimulated by? Inhibited?

Stimulated by PRH | Inhibited by PIF

What are the three types of basophils (chromophils of the anterior pituitary)? What color do they stain?

Corticotropes Thyrotropes Gonadotropes All stain blue

What is the function of the chromophilic corticoropes?

Secrete ACTH which stimulated the adrenal cortex

Corticotropes are stimulated by what?

CRH

What is the function of the chromophilic thyrotropes?

Secrete TSH (thyrotropin)

What are thyrotropes stimulated by? Inhibited?

Stimulated by TRH | Inhibited by T3 and T4

What is the function of the chromophilic gonadotropes?

Secrete FSH and LH, components of male and female reproduction

Gonadotropes are stimulated by what?

GnRH

What is the infandibulum?

Stalk of the pituitary gland

What is the posterior pituitary?

a neural secretory tissue that functions as a storage depot for neurosecretions produced by neurons of the supraoptic and paraventricular nuclei of the hypothalamus

What are the two chemicals that the posterior pituitary contains?

ADH and oxytocin

What are Herring bodies?

accumulations of neurosecretory granules in the axons | and axon terminals of the hypothalamohypophyseal tract

What specialization do the capillaries near the anterior pituitary have that helps them release hormones into the blood?

Fenestrations

What do herring bodies contain?

Granules of ADH or Oxytocin

What is the function of ADH?

targets the distal tubules and collecting ducts of the kidney to lower urine volume

What is the function of oxytocin?

targets the uterine myometrium, and myoepithelial cells of mammary gland to stimulate smooth muscle contraction of uterus

What are pituicytes? Where are they found?

Glia-like, local cells that cover and support axons and their terminals of the posterior pituitary

What are pituitary adenomes?

Benign tumors of the anterior pituitary that may affect the secretory activity of other cells in the anterior pit

What causes Diabetes insipidous?

Damage to the hypothalamus or the pars nervosa, causing a reduction in ADH

What is the capsule that surrounds the thyroid gland derived from? What type of tissues comprises it?

Derived from deep cervical fascia, and consists of dense irregular collagenous connective tissue

What is the function of the capsule of the thyroid?

Has trabeculae and septa that parition the glands into lobules and provide vessels and nerves

What is the function of the thyroid gland (3)?

Synthesize T3, T4, and calcitonin

What are the functions of T3 and T4?

regulate cell and tissue metabolism | and heat production

What is the function of calcitonin?

Reduces [Ca]

What is the basic structural unit of the thyroid?

The follicle

What cellular structure are follicles of the thyroid surrounded by? What is it composed of?

Basal lamina composed of reticular fibers

What specialization do the capillaries that surround lobules of the thyroid gland have?

Fenestrations

What is the function of thyroid follicles?

d. store glandular secretory product in follicular lumen (extracellularly)

Where are the secretory products of endocrine cells usually stored?

In the cells themselves

What are the three variation of the follicular epithelium of the thyroid follicles, and what does each mean in terms of the activity?

Simple squamous = low Simple cuboidal = nl Simple collumnar = very active

What are the parafollicular cells? What are they derived from? Where are they found?

1. Derived from neural crest cells 2. Wedged between follicles in the BL 3. Contain calcitonin

What is calcitonin?

Peptide hormone stored by parafollicular cells that acts to lower blood [Ca]

What is the mechanism by which calcitonin exerts its effects?

Inhibits osteoclasts | Promoted [Ca] deposition (osteoid calcification)

What is contained within the follicular lumen?

Colloid (thryoglobulin = T3, T4)

What synthesizes thyroglobulin? Where is it stored?

Follicular cells, stored in follicular lumen

What happens to the iodine taken in through the diet? Where does it go?

Reduced to iodide and transported into follicular cells , where it is bound to Y residues

What secretes TSH? Where does it go?

Thyrptropes of the Anterior pituitary, to the blood stream to thyroid

What is the site of Throglobulin synthesis? What process does it undergo on its way to the follicular lumen?

1. rER 2. Golgi 3. Vesicles 4. Lumen Glycosylation

What type of transporter is used in pumping iodide into the follicular cells?

Na/K ATPase

What oxidzes iodide? Where is this found?

Thyroid peroxidase, bound to the membrane on the follicular APICAL cell membrane, facing the colloid

What is needed for the proper functioning of thyroid peroxidase?

Hydrogen peroxide

What does the reaction of thyroglobulin and iodine produce?

MIT and DIT

True or false: thyroglobulin is a hormone?

False-only a storage vessel for MITs and DITs

How are MITs and DITs converted to T3 and T4?

uncoupling rxn when they are near each other on thyroglobulin

How thyroid hormone released?

1. MITs and DITs taken up by follicular cells 2. Cleavage from thyroglobulin 3. Release of T3 and T4 to ECM to capillaries

What happens to the MITs and DITs that are cleaved off of the thyroglobulin molecule?

Recycled

What is the cell/structure that releases TSH?

Thyrotropes from the Anterior pituitary

Where does TSH bind to?

Receptors on the basal membrane of follicular cells

How does endocytosis of thyroglobulin occur? What happens once inside the follicular cells that allows for digestion?

Filopodia forma at the luminal surface and engulfs Combines with endosomes that have proteases

Where is the only place T4 is made? Where else can T3 be made?

T4 = thyroid T4 can be cleaved in the kidney, liver, and heart to make T3

What effect does T3 and T4 have on cellular metabolism, growth rate, and mental activity?

Increase

What effect does T3 and T4 have on phospholipid formation?

Decreases

What effect does T3 and T4 have on triglyceride formation?

Decrease

What effect does T3 and T4 have on cholesterol?

Increaes

What effect does T3 and T4 have on FA synthesis?

Increase

What effect does T3 and T4 have on body weight?

Decreases

What effect does T3 and T4 have on Heart rate?

Increases