L70-Hypothalamic Pituitary Relationship

Question 1

Where is the hypothalamus located?

Answer 1

below thalamus between the lamina terminals and mammillary bodies, forming the floor of 3rd ventricle

Question 2

What does the hypothalamus secrete?

Answer 2

Hypothalamic releasing hormones

Question 3

What is the median eminence?

Answer 3

Floor of hypothalamus that acts as convergence point for axons

Question 4

What are the hypothalamic nuclei?

Answer 4

PVN: paraventricular Nucleus
POA: Preoptic Nucleus
ARC: Arcuate Nucleus
SCN: Suprachiasmatic Nucleus
SON: Supraoptic nucleus

Question 5

Which nucleus secretes GnRH?

Answer 5

POA: preoptic nucleus

Question 6

What nucleus secretes CRH?

Answer 6

PVN: paraventricular/Parvocellular

Question 7

What nucelus secretes TRH?

Answer 7

PVN: paraventricular

Question 8

What nucleus secrete GHRH?

Answer 8

Arcuate Nucleus

Question 9

What nucleus secretes soatostatin?

Answer 9

PeVN : periventricular

Question 10

What nucleus secretes Dopamin?

Answer 10

Arcuate nucleus

Question 11

Which peptide hormones use the cAMP second messenger pathway?

Answer 11

CRH, GHRH, Somatostatin

Question 12

Which peptide hormones use the IP3/DAG/PKC pathway?

Answer 12

TRH, GnRH,

Question 13

How is GnRH released?

Answer 13

Pulsatile manner and acts through GPCRs

Question 14

What is Kallman Syndrome?

Answer 14

Genetic disease where GnRH neurons fail to enter CNS
Leads to reproductive failure and anosmia
Can be X linked (Kal1) or Autosomal (Kal2)
GnRH neurons are arrested at the cribiform plate in X linked Kallman Syndrome

Question 15

Describe the sequence of events in which GnRH activate gonadotrophs

Answer 15

GnRH released from hypophyseal portal system -> bind to GnRH receptor (GPCR) -> activate PLC -> form IP3 and DAG -> mobilize intracellular calcium and activate PKC-> increased LH/FSH release and synthesis

Question 16

How does GnRH pulse frequency determine LH or FSH transcription?

Answer 16

High GnRH pulse frequency-> LH(Beta) transcription

Low GnRH Pulse Frequency-> FSH (beta) transcription

Question 17

Which hormones share the same alpha subunit?

Answer 17

FSH-B, LH-B, TSH-B, hCG-B

Question 18

What is the pituitary blood supply?

Answer 18

Superior hypophyseal artery give rise to capillary plexus in anterior pituitary -> primary capillary plexus in median eminence-> hypophyseal portal veins -> secondary capillary pelxus in pars distalis

Inferior hypophysial artery supplies posterior pituitary

Question 19

What are the 2 major pathways between the hypothalamus and pituitary?

Answer 19

Tuberoinfundibular System: neurons sending axonal projections to median eminence with hormones targeting anterior pituitary

Neurohypophysial Tract: Neurons whose axons terminate in posterior pituitary

Question 20

What makes up the anterior pituitary?

Answer 20

Pars Distalis (90%)
Pars Tuberalis
Pars Intermedia

Question 21

What makes up the Posterior Pituitary

Answer 21

Pars Nervosa

Infundibulum

Question 22

How is the tissue between anterior and posteiror pituitaries different?

Answer 22

Anterior pituitary is glandular tissue from embryonic foregut

Posterior pituitary is neural tissue from neuroectoderm

Question 23

What neurons have their axons terminate in the neurohypophysis of the posterior pituitary

Answer 23

Magnocellular Neurons

Question 24

What is the blood supply of the posterior pituitary?

Answer 24

Inferior hypophysial artery

Question 25

What are the major hormones released from the posterior pituitary

Answer 25

AVP and Oxytocin

Question 26

What are Herring Bodies?

Answer 26

Dilations of unmyelinated axons near the terminals found in the neural tissue in the posterior pituitary; This is where hormones are released and are close to fenestrated capillaries

Question 27

What are pituicytes?

Answer 27

glial like cells of the posterior pituitary

Question 28

What cell types are found in the anterior pituitary and how do they stain?

Answer 28

Acidophils(lght): somatotrophs, lactotrophs Basophils(dark): Corticotrophs, Gonadotrophs, Thyrotrophs Chromophobes(clear): Paracrine actions

Question 29

What do the acidophils secrete?

Answer 29

Somatotrophs: GH Lactotrophs: Prolactin (lactation)

Question 30

What do the basophils secrete?

Answer 30

Corticotrophs: ACTH (stress) Gonadotrophs: FSH, LH Thyrotrophs: TSH

Question 31

How are the anterior pituitary hormone cell types regionally distributed?

Answer 31

TSH centrally and anterior ACTH centrally and middle and posterior GH/PRL: anterior to posterior on the sides