Endocrine: Intro & Hypothalamus/Pituitary Unit Flashcards by Anthony Carli | Brainscape

Q

Hormones are the product of what tissue?

A

an endocrine gland

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Q

How are hormones transported to their peripheral/distant target cells?

A

the blood stream

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Q

Hormones may exert a trophic effect, meaning it regulates what two things?

A

other gland hormone secretion

growth/integrity of an endocrine gland

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Q

Hormones which act on distant targets are ____crine

A

endocrine

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Q

Hormones which regulate processes in neighboring cells…

A

paracrine

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Q

Hormones that act upon themselves…

A

autocrine

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Q

hormones which regulates its own intracellular activity without being secreted…

A

intracrine

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Q

A hormone which originates int he neuron.

after axonal transport, carried via blood or synaptic transmission

A

neurocrine

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Q

What tissue in the heart can have an endocrine gland effect?

A

epicardial fat

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Q

What are the three broad ways hormones are classified?

A

chemical structure

plasma solubility

signal transduction pathway

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Q

What are the three types of hormones, as based on their chemical structure?

A

Peptides

Amines

Steroids

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Q

Steroid hormones are derived from ________

A

cholesterol

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Q

Amine hormones are derived from _______, and are synthesized where?

A

tyrosine derived

adrenal medullae and thyroid

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Q

What two hormone classes are amine hormones?

A

catecholamines

thyroid hormones

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Q

Peptide hormones are derived from…

A

amino acids

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Q

Most hormones are what type of chemical structure?

A

peptide

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Q

______ hormones are transported in the blood stream as dissolved.

A

Hydrophilic

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Q

__________ hormones are transported via binding proteins in the blood

A

Hydrophobic

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Q

Which hormone types are hydrophilic?

A

peptide hormones and catecholamines

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Q

What two hormone types are hydrophobic?

A

thyroid and steroid based

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Q

Hydrophobic proteins have ___% bound and < ____ % free

A

99% bound

1% free

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Q

These substances…

provide reserve of hormone
keep hormone inactive in blood
involved in hormone turnover

A

Binding proteins

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Q

What 5 factors determine plasma hormone concentration?

A

availability of binding proteins

secretion from gland

inactivation and excretion

peripheral conversion

internalization of hormone/receptor complex

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Q

Inactivation and excretion of hormones occurs in what two organs?

A

kidney and liver

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Q

Hormones are inactivated in the liver via…

A

glucuronidation and sulfate conjugation

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Q

What effect does glucuronidation and sulfate conjucation have on hormone excretion by the kidneys?

A

increases water solubility

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Q

What structural class are the following hormones?

FSH
TSH
LH
hCG
Carb hormones

A

Glycoproteins

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Q

What structural class are the following hormones?

ACTH
AT
Calcitonin
PTH
MSH
Growth Factors
Oxytocin
ADH
GH
Somatostatin
Insulin
Glucagon

A

Peptide Hormones

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Q

What structural class are the following hormones?

Aldosterone
Cortisol
Estradiol
Progesterone
Estrogen
Testosterone
DHEA
Vitamin D

A

Steroids

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Q

What structural class are the following hormones?

epinephrine
NE
DA
T4
T3

A

Amine

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Q

Which signal transduction group of hormones?

enter nucleus where hormone binds to receptor on DNA

A

Group I

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Q

Which signal transduction group of hormones?

Membrane enzyme: Adenylyl Cyclase

Second messenger: cAMP

Kinase: cAMP PK

A

IIA

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Q

Which signal transduction group of hormones?

Membrane enzyme: Guanylyl Cyclase

Second messenger: cGMP

Kinase: cGMP PK

A

IIB

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Q

Which signal transduction group of hormones?

Membrane enzyme: PLC

Second messenger: DAG, IP3

Kinase: PKC, Calmodulin-dep PK

A

IIC

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Q

Which signal transduction group of hormones?

Membrane enzyme: NA

Second messenger: NA

Kinase: Serine or threonine Kinase

A

IID

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Q

The physiological effect of Group I hormones occurs after what?

A

binding to nuclear receptors

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Q

What hormone type?

Precursor: specific gene

Site of Synth: ribosomes, ER, golgi

Storage: granules

A

peptides

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Q

What hormone type?

Precursor: tyroside or iodide

Site of Synth: enzymatic in cytosol or in follicular cell/colloid

Storage: granules or follicular cells

A

amines

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Q

What hormone type?

Precursor: cholesterol

Site of Synth: cytosol, ER, mito

Storage: not stored

A

Steroids

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Q

The peptide chain that is formed after mRNA translation for peptide hormone synthesis is called…

A

preprohormone

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Q

What happens to the preprohormone in the ER?

A

cleaved to prohormone, sent to golgi

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Q

What stimulates the secretion of peptide hormones?

A

increase in cytosolic cAMP and Ca

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Q

What two hormone types may undergo peripheral conversion after release?

A

steroids and amine

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Q

what effect does peripheral conversion confer on a hormone?

A

increased activity several-fold

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Q

Vitamin D3 is converted to 1,25-dihydroxyvitamin D via…

A

hydroxylation in liver and kindey

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Q

testosterone is converted to DHT via…

A

androgens formed in androgen dependent tissues

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Q

Testosterone is converted to estradiol via…

A

brain and testes

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Q

T4 is converted to T3 via

A

most tissues

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Q

This method of hormone secretion:

activated by blood borne substrate

A

A-Humoral

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Q

An example of A-humoral secretion is…

A

PTH regulation of calcium

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Q

Describe the mechanism of PTH regulation of calcium…

A

low calcium triggers PTH release

PTH stimulates release from bones, increases uptake in kidneys and intestines

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Q

This method of hormone secretion:

-extension of CNS that signals gland to secrete hormone

A

B-Neural

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Q

What are three stimuli for B neural hormone secretion?

A

psychic/emotional stress

fight response

altered physiologic states

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Q

SNS stimulation of adrenal medulla leading to NE/epi release is an example of…

A

B neural secretion

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Q

This method of hormone secretion:

hormones A regulates secretion of hormone B, which stimulates secretion of hormone C

A

C-hormonal

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Q

TRH from the hypothalamus stimulates pituitary release of TSH, which stimulates thyroid secretion of T4/T3. This is an example of…

A

C hormonal secretions

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Q

What type of hormone feedback?

most common
hormone action inhibits further secretion
regulated by long loops and short loops
essential for maintaining homeostasis

A

Negative feedback

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Q

Testosterone’s inhibitory action on the anterior pituitary and the hypothalamus are examples of ____ loops in negative feedback

A

long loops

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Q

the anterior pituitary’s inhibition of the hypothalamus in testosterone secretion is an example of the ____ loop in negative feedback

A

short

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Q

Which method of feedback?

least common
hormone stimulates increased secretion
ex: estrogen, oxytocin

A

positive feedback

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Q

In positive feedback, estradiol stimulates ______ to secrete more hormone

A

anterior pituitary

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Q

Hormone action is dependent on…

A

plasma or nuclear receptors

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Q

Hydrophilic hormones like peptides and catecholamines bind where on their target cell?

A

receptor channel on cell membrane

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Q

hydrophobic hormones like steroids and thyroid hormones diffuse through the bilayer and bind where?

A

nuclear receptor

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Q

This is the responsiveness of a target tissue to a hormone.

It is expressed in the dose-response relationship

A

responsiveness

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Q

____ is the minimal hormone concentration to achieve a response.

A

threshold

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Q

_____ is the concentration of hormone that produces 50% of maximum response

A

sensitivity

Q

_____ is the effect of a saturating dose of a hormone

A

maximal response

Q

A decrease in target cells , signal transduction mechanisms, or enzyme activity in the cell would cause…

A

decreased maximal response

Q

a decrease in hormone-receptor affinity and a decrease in receptor number would cause… (down shift)

A

decreased sensitivity (right shift)

Q

This occurs when hormones have a greater overall effect when combined.

A

synergism

Q

This occurs when one hormone cannot exert its full effect without another hormone’s presence.

A

permissiveness

Q

This occurs when one hormone reduces the effect of another hormone

A

antagonism

Q

This happens when a hormone regulates the number or affinity of its own receptor

A

autologous up/down regulation

Q

This occurs when a hormone regulates the number and affinity of another hormone’s receptor…

A

heterologous up/down regulation

Q

Tumors, hyperplasia and autoimmune stimulation typically cause…

A

overproduction

Q

autoimmune destruction, tumor, ischemia, infx, hemorrhage or dietary issues often cause…

A

under production

Q

Anterior or posterior pituitary?

metabolism
growth
reproduction
lactation
stress response

A

anterior

Q

Anterior or posterior pituitary?

water balance
parturition and lactation
BP regulation
Cardiac function
diuresis

A

posterior pituitary

Q

The ________ receives impulses from other parts of the brain, and diverts them to the _________

A

Hypothalamus

pituitary

Q

The function of the hypothalamus-pituitary unit is to coordinate ___________ to maintain __________

A

physiologic response of organs

maintain homeostasis

Q

These neurons originate in the hypothalamus, sending their axons down the infundibular process to terminate in the posterior pituitary…

A

magnocellular neurons

Q

Where do magnocellular neurons release their hormones?

A

capillary bed

Q

Where do parvicellular neurons originate and terminate?

A

originate: hypothalamus
terminate: median eminence

Q

Parvicellular neurons link the hypothalamus with the…

A

anterior pituitary

Q

Parvicellular neurons secrete ______ hormones

A

releasing hormones

Q

Releasing hormones from parvicellular neurons are transported to the anterior pituitary by…

A

hypothalamo-hypophyseal portal vessels

Q

This type of hormone regulates the secretion of tropic hormones from the anterior pituitary

A

releasing hormones

Q

what type of neurons are located primarily in the paraventricular nuclei and the supraoptic nuclei?

A

magnocellular neurons

Q

GHRH acts on what cell types to increases synthesis of GH?

A

Somatotrophs

Q

Somatotrophs (GH releasing cells) account for ___% of pituitary cell population

A

45%

Q

TRH acts on what cell types to increase synthesis of TSH?

A

thyrotrophs

Q

Thyrotrophs (TSH releasing cells) account for ___% of pituitary cell population

A

3-5%

Q

Somatostatin decreases synthesis of what two hormones?

A

GH and TSH

Q

TRH acts on what cell types to increase synthesis of prolactin?

A

mammotrophs

Q

Mammotrophs account for what percent of pituitary cell population?

A

10-15%

Q

GnRH increases synthesis of what two hormones?

A

LH and FSH

Q

GnRH stimulates what cell types to increase synthesis of FSH?

A

Gonadotrophs

Q

Gonadotrophs make up ___% of pituitary cell population

A

15%

Q

This hormone:

acts on many tissues
stimulates growth via IGF production in liver
Works on energy metabolism

A

GH

Q

This hormone:

acts on thyroid gland
Stimulates growth of thyroid gland
Stimulates secretion of T3, T4

A

TSH

Q

This hormone:

acts on the mammary glands
stimulates breast development
stimulates milk production

A

prolactin

Q

This hormone:

acts on the gonads
stimulates ovulation and estrogen synth in females
stimulates testosterone secretion from leydig cells in males

A

LH

Q

This hormone:

acts on the gonads
development of follicle in females
initiates spermatogenesis in males

A

FSH

Q

CRH stimulates what cell type to release ACTH?

A

corticotrophs

Q

Corticotrophs account for ___% of pituitary cell population

A

15%

Q

PRH stimulates what cell type to synthesize prolactin?

A

lactotrophs

Q

Dopamine inhibits the synthesis of what hormone?

A

prolactin

Q

This hormone:

targets adrenal glands
stimulates adrenal gland growth
stimulates synthesis of corticosteroids

A

ACTH

Q

This hormone:

acts on mammary glands
stimulates breast development and milk production

A

prolactin

Q

these two hormones are synthesized in hypothalamic neuronal cell bodies of magnocellular neurons

A

ADH and oxytocin

Q

ADH and oxytocin are synthesized in the ____ fashion as _____

A

peptide fashion

preprohormones

Q

Describe the half-life of ADH and oxytocin

A

8 minutes

Q

The cys residues of ADH and oxytocin are capable of forming…

A

disulfide bridges

Q

What classification of hormones have the following features?

transported in axons
secreted at nerve terminals
released to fenestrated pituitary capillaries via action potentials

A

neuropeptides

Q

ADH and oxytocin are co-secreted with…

A

neurophysins

Q

These carrier proteins prevent diffusion of hormones out of posterior pituitary axons…

A

neurophysins

Q

NPI is tied to…

A

oxytocin

Q

NPII is tied to…

A

ADH

Q

During intraaxonal transport, the precursor hormone is cleaved to what three substances…

A

ADH/oxytocin
NP
terminal glycoprotein

Q

NP arranges into tetramers that can bind how many ADH?

A

5 ADH

Q

_____ are found in the anterior hypothalamus outside the BBB, and have direct contact with systemic circulation

A

osmoreceptors

Q

what 2 things signal osmoreceptors to stimulate AVP(ADH) release?

A

loss of intracellular water

increased plasma sodium/chloride

Q

osmoreceptors stimulate what type of neurons directly to release AVP?

A

magnocellular neurons

Q

does AVP release occur before or after the stimulation of thirst?

A

before

Q

a __% change in osmolarity above threshold will produce an increase in AVP release, meaning the system is very sensitive

A

1% change

Q

AVP targets what receptor on the kindeys?

A

V2 receptor

Q

AVP secretion results in what three things

A

increased plasma volume
decreased osmolarity
low urine output

Q

What 4 homeostatic adjustments are made with increased plasma osmolarity

A

AVP secretion, water reabsorption, decreased urine output and stimulation of thirst

Q

AVP is released due to increases in blood osmolarity. What else can trigger AVP release?

A

decrease in blood volume/pressure

Q

Baroreceptors decrease their rate of firing when BP decreases. This has what two effects?

A

increased AVP

thirst center stimulation

Q

decreased blood pressure is perceived by the macula densa, resulting in RAAS activation. ATII has what effect on osmoreceptors?

A

sensitization leading to enhanced AVP release

Q

What receptor does AVP act upon to induce vasoconstriction?

A

V1

Q

is the BP mediated AVP system more or less sensitive than the osmolarity system?

A

less

Q

During childbirth (parturition), what two factors stimulate the release of OT?

A

cervical distension

uterus contraction

Q

In the lactating breast, OT stimulates what?

A

milk ejection

Q

In the pregnant uterus, OT induces what action?

A

smooth muscle contractions

Q

signals reaching the PVN and SON provide a ______ feedback of OT

A

positive

Q

Suckling of the nipple in the lactating breast stimulates secretion of ___

A

OT

Q

receptors in the nipple generate what type of impulses that reach the hypothalamus?

A

afferent

Q

OT stimulates milk ejection by causing the contraction of what cells lining milk ducts?

A

myoepithelial cells

Q

continued suckling has what effect via what feedback mechanism?

A

OT synthesis via positive feedback

Q

is sucking required for milk secretion?

A

no

Q

What three stimuli other than suckling can stimulate milk secretion?

A

sight, smell, sound of infant

Q

OT has what effect on the uterus during suckling?

A

promote uterine regression

Q

Receptors in the cervix generate what type of impulse that reach the hypothalamus?

A

afferent

Q

cholinergic synapses within the PVN and SON stimulate the production of what two substances in the posterior pituitary?

A

OT and NP-I

Q

The uterus is more sensitive to OT due to…

A

increased OTR density

Q

By what magnitude is OTR amplified in the pregnant uterus?

A

200x

Q

Increased OTR density is mediated by what three factors?

A

OT, progesterone, gap junction formation

Q

oxytocin has what other two effects outside of milk ejection and uterine contraction?

A

cardiovascular and cardiometabolic effects

Q

What axis for OT resides in the heart?

A

OT-natriuretic peptide-nitric oxide axis

Q

OT causes _____ release from cardiomyocytes.

A

ANP and BNP

Q

ANP stimulates the release of _____ from vascular endothelium

A

nitric oxide

Q

OT is ___x more abundant in the atria than the ventricles

A

3-4x

Q

ANP is found in both atria and ventricles, but mostly in atria. BNP, however, is found mainly in…

A

ventricles

Q

In plasma, OT binds to OTRs present in what three tissue types?

A

vasculature

kindey

cardiac

Q

In the peripheral arterioles, OT induces _______ which decreases pressure and resistance.

A

NO dependent vasodilation

Q

The NO dependent vasodilation mediated by OT, is enhanced by the presence of _____

A

estrogen

Q

In cardiac muscle, OT binds to OTR resuling in synthesis and release of what two substances…

A

ANP and NO

Q

OT mediated release of ANP and NO have what effects on heart?

A

negative inotropic and chronotropic

Q

ANP induces ____ of peripheral arterioles after binding the NPR-A receptor

A

vasodilation

Q

At physiologic conditions, OT stimulates what two processes via renal OTR

A

diuresis and natriuresis

Q

increased plasma OT and reduction in hypothalamic CRF leads to decreased production of what hormone?

A

cortisol

Q

increased ANP in the plasma has what 5 effects?

A

arteriolar dilation
diuresis, natriuresis, kaliuresis
decreased plasma volume

Q

Studies have shown that OT increased peripheral glucose uptake by GLUT4 independent of…

A

insulin receptors

Q

OT can induce bradycardia, negative inotropy and _____ glucose uptake

A

increased