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Endocrine > Hypothalamus, Anterior, and Posterior Pituitary_Parthasarathi > Flashcards

Hypothalamus, Anterior, and Posterior Pituitary_Parthasarathi Flashcards

1
Q

where is the pituitary gland located?

A

sella turcica

at base of brain in a bony pocket

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2
Q

what is the stalk of tissue that connects the pituitary to the bottom of the brain? what other structures accompany in this area

A

infundibulum

nerves and special vv (long portal vv) are contained in the infundibulum

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3
Q

what two things make up the anterior pituitary

A

pars distalis and pars tuberalis

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4
Q

what two things make up the posterior pituitary

A

pars nervosa (neural lobe) and pars intermedia

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5
Q

in general, what does the hypothalamus produce? what is the function of the hypothalamus?

A

many regulatory functions, control over many endocrine glands and their hormones - various nuclei, clusters of nerve cell bodies, synthesize “hypothalamic releasing hormones” and ADH and oxytocin

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6
Q

what is the bottom portion of the hypothalamus called? what is located here?

A

median eminence
here are located the axon terminals of neurons containing the hypothalamic releasing hormones that regulate the anterior pituitary

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7
Q

describe how the hypothalamic releasing hormones reach the anterior pituitary and how they control shit there

A

via the portal system
the hormones are secreted into the capillary system in the hypothalamus from the nerve axon terminals there. Hormones flow down the long portal vein to the anterior pituitary where they reach another capillary bed. Cells of the anterior pituitary sense the high conc of these releasing hormones and respond

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8
Q

which hormones are released from the posterior pituitary? what is the mechanism of release?

A

ADH and Oxytocin
the nerve cell bodies of the hypothalamus have axons that travel all the way down the infundibulum and terminate on the capillary bed located in the posterior pituitary - (i.e. NOT a portal system) release of hormones into this capillary bed and then general distribution in systemic circulation

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9
Q

what kind of tissue do we consider the posterior pituitary to be?

A

a neural secretory tissue - neurohypophysis

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10
Q

what kind of tissue/strucure is the anterior pituitary? (general) what cell type is contained

A

glandular epithelial tissue

it is a secretory organ, so epithelial cells

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11
Q

where do ADH and oxytocin originate?

A

the posterior pit hormones originate in the hypothalamus (where they are synthesized)

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12
Q

since the hypothalamic releasing hormones are secreted directly into the blood stream (the portal system) why is there not a larger systemic effect from these?

A

it is a concentration dependent process - the highest concentration is locally, i.e. at the anterior pituitary, thus only the ant pit responds - by secreting its hormones that it has synthesized
(he made a point about this in class, it is a straight forward concept I know)

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13
Q

what are the names of the two nuclei that produce ADH and oxytocin for release from the posterior pituitary?

A

the paraventricular nucleus and the supraoptic nucleus

both located in the hypothalamus

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14
Q

what can the posterior lobe of the pituitary be considered an extension of?

A

a neural extension of the hypothalamus

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15
Q

what is the function of oxytocin, released by the post pit?

A

stimulates contraction of smooth muscles in pregnant uterus and myoepithelial cells in mammary gland

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16
Q

what is the function of myoepithelial cells of the mammary gland?

A

the milk “letdown” - basically they contract to help push milk out - they are distinct from the milk producing cells

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17
Q

what is the function of of ADH/vasopressin? what are the 2 specific mechanisms?

A

regulates body retention of water

1) increase water channels in the walls of kidney of tubules - inc water retention
2) smooth muscle contraction of walls of blood vessels - “pressor effect”

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18
Q

what is the stimulus for the release of oxytocin or ADH from the post pit? what is it analogous to?

A

secreted when action potentials reach nerve terminals; analogous to neurotransmitter release

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19
Q

what is the structure of ADH and OT? what is key about this?

A

nonapeptides, contain S-S bridge
similar structures - so overlapping activities
both cause contraction of shit

20
Q

what is a key point about the regulation of oxytocin secretion? what is this called?

A

it operates via a positive feedback mechanism
“explosive response”
as the uterus contracts, it causes more release of oxytocin

21
Q

what are the 2 main stimuli for ADH secretion?

A

decrease ECF (plasma) volume
inc osmolarity
both related to the same thing, one is not separate from the other necessarily

22
Q

describe the sequence of events upon dehydration or lack of water intake in an individual and the resulting ADH secretion

A

dehydration –> dec ECF and inc Osm –> release of ADH –> inc water permeability of kidney DCT and CD –> dec water excretion, thus more water retention

23
Q

recall - what happens to ADH secretion upon removal of stimulus (water ingestion, thus dec osm)

A

there will be a dec in ADH secretion

note the sensible relationship of the stimuli and subsequent release (or not) of hormones

24
Q

how are Osm and volume (BP) related in the regulation of ADH secretion?

A

just know that they both factor in concurrently to the plasma ADH levels

25
Q

what are the 6 hormones released from the anterior lobe of the pit?

A

GH, PRL, ACTH, FSH, LH, TSH

26
Q

what structural category do all the regulating hormones fall in? what is the one exception?

A

all of the releasing hormones are peptide hormones
Dopamine - is not
$$

27
Q

how are all the hypothalamic regulating hormones stored?

A

in granules, released upon stimulus into the portal system

28
Q

what is the precursor for ACTH and MSH?

A

POMC - pro-opiomelanocortin

29
Q

what does excess ACTH cause (functionally)? why? what is this disease called?

A

Addison’s disease
excess ACTH causes hyperpigmentation
the structure of MSH (melanocyte stimulating hormone) lies within the ACTH molecule
(Both MSH and ACTH come from the POMC precursor)

30
Q

what is the term we use to describe the release pattern of MSH?

A

diurnal - happens daily, certain time of day

31
Q

what are the two main cell types located in the ant pit? the cells responsible for synthesis of the hormones

A

basophils and acidophils

32
Q

what 4 hormones do basophils produce?

A

FSH, LH, ACTH, FSH

“B-FLAT”

33
Q

What 2 hormones do acidophils produce?

A

GH, PRL

“GPA”

34
Q

what cell type, acidophils or basophils, occupy the bulk of the ant pit?

A

acidophils

$$

35
Q

he says all the regulating hormones are peptide hormones, but some are listed as glycoproteins. which 3 hormones are listed as glycoproteins?

A

TSH, FSH, LH

36
Q

what is the structure of the 3 glycoprotein hormones, TSH, FSH, LH?

A

dimers of alpha and beta subunits

37
Q

for the glycoprotein hormones TSH, FSH, LH, which of the alpha or beta subunit determines the biological activity? why is this important?

A

beta subunit determines biological activity
practial message: assays need to measure the beta subunit to determine what hormone you are dealing with
(the alpha subunits of all 3 are very similar)

38
Q

which hormones of the pituitary are listed as proteins? where are they produced?

A

GH, PRL
produced in acidophils
again, recall that acidophils make up the bulk of the anterior pituitary

39
Q

what hormone does CRH (corticotropin releasing hormone) affect and how?

A

augments release of ACTH

40
Q

what hormone does TRH affect and how

A

augments release of TSH

41
Q

what hormone does GnRH affect and how

A

augments release of the gonadotropins LH and FSH

42
Q

what hormone does GHRH affect and how

A

augments the release of GH

43
Q

what hormone does Somatostatin affect and how?

A

it inhibits the release of GH

44
Q

what hormone does Dopamine affect and how

A

it inhibits the release of Prolactin

45
Q

something about long, short and ultra short feedback loops

A

just know how they work

46
Q

what 3 things affect the release of oxytocin

A

emotional input (the pavlov dog shit - conditioned response), sucking stimulus, and sensory input

Endocrine (6 decks)

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