EX 2; Endocrinology Flashcards by Tala Ebrahimian

What is the main route of communication in the endocrine system

chemical signals (hormones) released into blood

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What are two factors affecting onset and duration of signal effects

the response can be delayed; time for the blood to travel

the duration is prolonged; some hormones stay in blood

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This part of the endocrine system releases hormones directly into the blood of ECF

endocrine glands

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The endocrine glands for an organ system without what

physical links; hormone connection

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What are the three steps in hormone travel

release
in the blood
reaching the target

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The specificity of target cells is due to what

receptors on the target cells

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This is any organ or tissue that secretes something; ducts (exocrine)

gland

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Most hormones are made of this structure

peptides

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True or False

Only very small peptides are hormones

False; thy can vary in size, from small to very larg

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These are sugar residues attached to backbone, helping to protect the hormone from degradation, and to enhance specificity

glycosylations

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Some peptide hormones function as neurotransmitters, what is the main difference between them

where it is released; the blood or a synapse

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This is the first thing synthesized in peptide hormone synthesis it comes off of ribosomes

preprohormone

contains lots of aa’s and gets folded

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This step in peptide hormone synthesis is to the RER, then off to golgi, then to secretary vesicles

prohormone

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Cleavage of he pro-part (aa’s) of a pro-hormone, leads to this, that is stored in vesicles

hormones

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What two things are released from the vesicles

pro fragments and hormones

the pro-hormone is cleaved to the pro fragments and hormone in the secretory vesicles

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What three things are important in the packaging and storing of peptide hormones

allows a cell to store until its needed
helps regulate cell itself
prevents degradation

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What are some of the glandular source of lipid hormones (steroids)

gonads
outer adrenal cortex
placenta
some brain cells

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All steroids are derived from what by a series of enzymatic reactions

cholesterol

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Some cholesterol needed for the membrane is produced via which method

de novo synthesis

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Most cholesterol is derived from what

low density lipoproteins; LDL is up-taken by a cell via LDL receptor to an endosome where it is broken down to a cholesterol ester

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This type of cell stores cholesterol esters; looks like an adipocyte

steridogenic cells

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These determines which stereoid is produced

enzymes

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Steroid hormone synthesis is typical stimulated by what

peptide hormones from other glands

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This frees cholesterol from stores

cholesterol esterases; PKA phosphorylates cholesterol esterases to free cholesterol

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This protein facilitates intracellular transport of cholesterol (to mitochondria)

steroid acute regulatory protein (StAR)

Steroids are not stored why?

they are lipid soluble; they will diffuse out of the membrane to intracellular fluid

What three things regulate steroids

enzymes regulate peptide hormone stimulating steroidogenesis increases cell division of steroid producing cells

Most steroid biosynthesis enzymatic reactions are what

uni-directional

What are the five different molecules along the steroid biosynthesis pathway

cholesterol --> progestagens --> corticosteroids or androgens --> estrogens

Amine hormones are all derived from which amino acid

tyrosine

What are the two hormones that are synthesized in the thyroid

thriiodothyronine (T3) | thyroxine (T4)

Thyroid hormones are steroid-like with respect to what two things

solubility and receptors

Catecholamines are synthesized in which two areas

adrenal gland | hypothalamus

What are three examples of catecholamines

norepinephrine epinephrine dopamine

catecholamines are common what

neurotransmitters

Catecholamines are similar to what in respect to solubility and receptors

peptide-like

What is the 4t class of hormones

eicosanoids

Lipids are derived from what

arachindonic acid

Most hormones are secreted in which way

in short burst; timing based on upstream signals

Secretion of GH and cortisol is what type of pattern

circadian | GH secretion high when sleeping and cortisol is high during the day

What are the three factors that hormone secretion may be controlled by

plasma concentration of a nutrient neuronal control hormone control

This type of hormone dissolves in the blood

hydrophilic hormones

This type of protein requires a carrier protein

lipophilic hormones

The use of these will affect hormone availability

carriers; only free hormones can react, therefore it must be released by the carrier protein

Metabolism and excretion of hormones does what to the signal

inactivates it

Which two organs are important in the metabolism and excretion of hormones

liver and kidney

True or False | Some hormone degradation occurs in the blood

True

These hormones and water soluble and can be activated by proteolytic degradation

catecholmines and peptides

These hormones are protected via attachment of carrier proteins from degradation

steroids

Circulating concentrations are a function of what

synthesis va removal or clearance

Receptors for hydrophilic hormones are where

on the cell surface or in plasma membrane

Receptor activation triggers what

a signal transduction pathway; activates the 2nd messenger system

This response involves ions; opening the ion channels in plasma membrane or cell itself; rapid response

ionotropic responses

This response is more delayed and involves metabolism within the cell; transport around the cell via secretory vesicles

metabotropic responses

A response involving ions and phosphorylation is what type of response

rapid response

A response involving the alteration of protein translation/transcription mechanism is what type of response

delayed response

Receptors for lipophilic hormones are located where

intracellular and/or nuclear

These two things form a DNA-binding protein that regulates transcription

receptor + ligand

Where is the location of the hypothalamus and pituitary gland

hypothalamus is on the floor of the diencephalon | pituitary gland lies just below the hypothalamus in the sella turcica

What are the three components of the pituitary gland

anterior = adenohypophysis posterior = neurohypophysis infundibulum connecting the two structures

This part of the pituitary gland is derived from oral ectoderm; not neural

anteriorhypophysis

This part of the pituitary gland is from the neural area; hypothalamus

neurohypophysis; posterior

The hormones are synthesized where

in the neuronal cell bodies in the supraoptic and paraventicular nuclei

hormones are released in response to what

an action potential; axon terminals are in the posterior pituitary; the hormones are released into capillaries of the systemic circulation

This hormone from the posterior pituitary has actions on the smooth muscle

oxytocin; labor

This hormone from the posterior pituitary has actions in the kidney and blood

vasopressin (ADH)

This is NOT an extension of the hypothalamus, but it is regulated by hormones secreted by hypothalamic neurons

adenohypophysis

This secretes hypophysiotropic (or releasing) hormones; stimulates ant. pituitary

hypothalamic neurons

Axon terminals lie where

in the median eminence

Hypothalamic hormones are transported in the in the blood within what

the portal vessels to the anterior pituitary

This is composed of 5 different cell types that produce 6 primary hormones in response to different hypophysiotropic hormones

anterior pituitary

Hypophysiotropic or releasing hormones are typically named for what

the pituitary hormones they regulate; both stimulatory and inhibitory

Hypophysiotropic hormones all do what

regulate the release of hormones from the anterior pituitary

What are 6 of the 8 hormones the anterior pituitary secretes

``` FSH LH GH thyrotropin prolactin ACTH ```

This is a precursor polypeptide synthesized in corticotrophs

pro-opiomenalocortin (POMC)

POMC is cleaved to yield multiple peptides with varied actions and target tissues like what

ACTH ɣ-MSH (melanocyte) β-LPH (lipotropic)

True or False | hypophysiotropic hormones are often found elsewhere in the nervous system

True

True or False | Hypophysiotropic hormones are all peptides

False; they are not all peptides

The hypo-thalmo-pituitary portion of the endocrine stem is often referred to as what

neuroendocrine system

The hypothalamus + pituitary + target = what

an axis

The complexicity of the neuroendocrine system provides what two thins

multiple control sites, and permits and amplification of the initial signal

The release of the hypophysiotropic horses is controlled by what

neural signals; both stimulatory and inhibitory inputs | involving specific neural pathways

Release of hypophysiotropic hormones is also controlled by feedback mechanisms like what

loop feedbacks

This system is self-regulation by product/hormone of the ultimate target tissue

long-loop negative feedback

This system occurs when the hormone from the 2nd gland in the axis affects the action of the 1st land

short-loop negative feedback

Feedback mechanisms return hormone concentrations to what

normal; i.e maintain homeostasis