Lecture 26

Question 1

Where is the pituitary gland located?

Answer 1

about 1cm in diameter located in the fossa of the sella turcica of the sphenoid bone at base of brain

Question 2

What are the hormones controlled by the anterior lobe of the pituitary?

Answer 2

TSH (thyroid stimulating hormone) and ACTH (adrenocorticotropic hormone)

Question 3

What is the anterior pituitary gland made up of?

Answer 3

• epithelial tissue
• makes up 75% of pituitary
• has two parts
• pars distalis = larger, inferior part
• pars tuberalis = wraps around infundibulum superiorly

Question 4

What is the posterior pituitary made up of?

Answer 4

• derived from neuroectoderm
• mostly composed of supportive glial-type cells called pituicytes
• 2 parts
• Pars nervosa (larger bulbar portion)
• Infundibulum (connecting with the hypothalamus of brain)

Question 5

Where is the Pars Intermedius?

Answer 5

Lies between the anterior and posterior lobes

Question 6

Different groups of neurons
in the hypothalamus can do what 3 things?

Answer 6

• Control secretion
  of anterior pituitary via
  releasing hormones (RH) and
  release inhibiting hormones
  (RIH)
• Synthesize hormones secreted by posterior pituitary
• Directly control secretion of
  cells in the adrenal medulla

Question 7

What do neurosecretory neurons do?

Answer 7

Produce release + release inhibiting hormones into primary capillary plexus

Question 8

What do supra-optic nuclei + paraventricular nuclei do?

Answer 8

Produce ADH and oxytocin

Question 9

How does the Hypothalamic-hypophyseal Portal System work? (movement and production of RH and RIH)

Answer 9

• secreted from hypothalamic neurons in region at base of hypothalamus
• diffuse into 1o capillary network (plexus) which is supplied by superior hypophyseal artery
• Portal veins then carry RH/RIH to 2o capillary network in anterior pituitary
• diffuse out of 2o capillary plexus and stimulate or inhibit secretion of hormone from
  anterior pituitary cells
• Blood then drains into anterior hypophyseal veins to
  enter systemic circulation

Question 10

How does the production of ADH and oxytocin work?

Answer 10

• Neurosecretory cells located in supraoptic (SON) and paraventricular nuclei (PVN) of
  the hypothalamus produce hormones ADH and oxytocin
• ADH and oxytocin packaged into secretory vesicles and transported along axons to
  terminals in posterior pituitary where they are stored.
• Hormones are released by exocytosis when action potentials arrive at terminals and diffuse into capillary plexus of posterior pituitary
  -Supplied by inferior hypophyseal arteries
  -Drained by posterior hypophyseal veins

Question 11

What type of hormone is oxytocin? Where is it made and stored?

Answer 11

• peptide hormone, posterior pituitary
• synthesized mostly in neurons of PVN
• Stored in nerve terminals in posterior pituitary

Question 12

What type of hormone is ADH? Where is it made?

Answer 12

• peptide hormone
• Synthesized mostly in neurons of SON

Question 13

somatotrophs make…

Answer 13

growth hormone

Question 14

thyrotrophs make…

Answer 14

thyroid stimulating hormone (TSH)

Question 15

gonadotrophs make…

Answer 15

follicle stimulating hormone (FSH) and luteinizing hormone (LH)

Question 16

lactotropes make…

Answer 16

prolactin

Question 17

Corticotropes make…

Answer 17

adrenocorticotropic hormone (ACTH)

Question 18

What are somatomedins and how are produced?

Answer 18

• made by liver in response to hGH
• proteins that mediate growth hormone’s effects
• also known as Insulin-like Growth Factors (IGFs)

Question 19

What are the metabolic effects of GH?

Answer 19

• Promotes growth and protein synthesis when nutrition state is favorable
• switches cell metabolism toward use of lipids as an energy source
• GH attenuates (weakens) some of insulins actions

Question 20

GH is regulated by…

Answer 20

GHRH (growth hormone-releasing hormone) and GHIH (somatostatin)