Hypothalamus, Anterior, and Posterior Pituitary_Parthasarathi

Question 1

where is the pituitary gland located?

Answer 1

sella turcica

at base of brain in a bony pocket

Question 2

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

Answer 2

infundibulum

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

Question 3

what two things make up the anterior pituitary

Answer 3

pars distalis and pars tuberalis

Question 4

what two things make up the posterior pituitary

Answer 4

pars nervosa (neural lobe) and pars intermedia

Question 5

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

Answer 5

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

Question 6

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

Answer 6

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

Question 7

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

Answer 7

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

Question 8

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

Answer 8

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

Question 9

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

Answer 9

a neural secretory tissue - neurohypophysis

Question 10

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

Answer 10

glandular epithelial tissue

it is a secretory organ, so epithelial cells

Question 11

where do ADH and oxytocin originate?

Answer 11

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

Question 12

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?

Answer 12

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)

Question 13

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

Answer 13

the paraventricular nucleus and the supraoptic nucleus

both located in the hypothalamus

Question 14

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

Answer 14

a neural extension of the hypothalamus

Question 15

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

Answer 15

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

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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”

Question 18

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

Answer 18

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

Question 19

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

Answer 19

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

Question 20

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

Answer 20

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

Question 21

what are the 2 main stimuli for ADH secretion?

Answer 21

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

Question 22

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

Answer 22

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

Question 23

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

Answer 23

there will be a dec in ADH secretion

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

Question 24

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

Answer 24

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

Question 25

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

Answer 25

GH, PRL, ACTH, FSH, LH, TSH

Question 26

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

Answer 26

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

Question 27

how are all the hypothalamic regulating hormones stored?

Answer 27

in granules, released upon stimulus into the portal system

Question 28

what is the precursor for ACTH and MSH?

Answer 28

POMC - pro-opiomelanocortin

Question 29

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

Answer 29

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)

Question 30

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

Answer 30

diurnal - happens daily, certain time of day

Question 31

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

Answer 31

basophils and acidophils

Question 32

what 4 hormones do basophils produce?

Answer 32

FSH, LH, ACTH, FSH | "B-FLAT"

Question 33

What 2 hormones do acidophils produce?

Answer 33

GH, PRL | "GPA"

Question 34

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

Answer 34

acidophils | $$

Question 35

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

Answer 35

TSH, FSH, LH

Question 36

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

Answer 36

dimers of alpha and beta subunits

Question 37

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

Answer 37

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)

Question 38

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

Answer 38

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

Question 39

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

Answer 39

augments release of ACTH

Question 40

what hormone does TRH affect and how

Answer 40

augments release of TSH

Question 41

what hormone does GnRH affect and how

Answer 41

augments release of the gonadotropins LH and FSH

Question 42

what hormone does GHRH affect and how

Answer 42

augments the release of GH

Question 43

what hormone does Somatostatin affect and how?

Answer 43

it inhibits the release of GH

Question 44

what hormone does Dopamine affect and how

Answer 44

it inhibits the release of Prolactin

Question 45

something about long, short and ultra short feedback loops

Answer 45

just know how they work

Question 46

what 3 things affect the release of oxytocin

Answer 46

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