Hypothalamus-Pituitary

Question 1

How is the pituitary formed?

Answer 1

Rathke’s pouch of the oral cavity becomes anterior pituitary and neuroectoderm of the bottom floor of the third ventricle forms the posterior pituitary.

Question 2

What are the hormones of the posterior pituitary?

Answer 2

oxytocin and vasopressin

Question 3

What is the link between the hypothalamus and anterior pituitary?

Answer 3

1. neurons from the hypothalamus release hypophysiotropic hormones
2. hormones travel through the median eminence in portal veins and reach the capillary system
3. production of anterior pituitary hormone
4. retrograde of blood flow = -ve feedback on the hypothalamus

Question 4

What are the different types of hypothalamus neurons?

Answer 4

1. magnicellular neurons (posterior pituitary)
2. parvicellular neurons (releasing factors into anterior pituitary)
3. hypothalamic neurons

Question 5

What are the important hormones from anterior pituitary?

Answer 5

CRH, TRH, AVP

Question 6

Where are sends the signals from the hypothalamus?

Answer 6

• pituitary glands
• cerebral cortex
• motor/premotor neurons of brain and spinal cord
• sympathetic and parasympathetic neurons

Question 7

What are the hypothalamic nuclei producing mainly oxytocin and AVP?

Answer 7

supraoptic and paraventricular

Question 8

what are the cell types present in the anterior pituitary?

Answer 8

• gonadotroph => LH, FSH
• corticotroph => ACTH, b-lipotropin
• thyrotroph => TSH
• somatotroph => GH
• lactotroph => PRL

Question 9

what cells are bright red when reacting with an acidic dye?

Answer 9

acidophils:

• lactotrophs
• somatotrophs

Question 10

what are the hormones that act on Gi-alpha?

Answer 10

somatostatin (GH) and dopamine

Question 11

What is the role of the pineal gland and how is it regulated?

Answer 11

the pineal gland is responsible for the production of melatonin. it is regulated by the light received by photoreceptors of the retina. the signal goes to the SCN (clock). norepinephrine is released and binds to B-adrenergic receptors of pineal gland.

Question 12

where are situated melatonin receptors?

Answer 12

almost everywhere in the body

Question 13

Which hormones are made of two glycoprotein chains and what do they have in common?

Answer 13

TSH, FSH, LH

alpha chain

Question 14

In which life stage GH production is the most elevated?

Answer 14

fetus + adolescent

Question 15

What is the epiphyseal plate?

Answer 15

region of the bone between epiphysis and diaphysis where GH and IGF-1 acts and trigger proliferation and differentiation of bone cells = calcification

Question 16

What are the differences between IGF-I and IGF-II?

Answer 16

IGF-I is GH dependent and in the liver, whereas IGF-II is not dependent on GH and is important in fetal development

Question 17

TRUE OR FALSE

High [IGF-I] results in more growth.

Answer 17

FALSE

bc target cells produce proteases that beaks IGF_BP from IGF-1 apart

Question 18

TRUE OR FALSE

IGFs remain constant even if GH levels fluctuate.

Answer 18

TRUE

Question 19

What regulates the secretion of GH?

Answer 19

GHRH and somatostatin (inhibitory factor) from the hypothalamus

Question 20

What two hormones are responsible for the initiation and maintenance of milk secretion?

Answer 20

PRL and cortisol

Question 21

Which form of PRL is the most active?

Answer 21

monomeric

Question 22

What is the effect of dopamine on PRL?

Answer 22

negative => + dopamine = - PRL

PRL has a -ve feedback on dopamine

Question 23

What are the mechanisms of PRL receptors?

Answer 23

1. ligand-dependent dimerization = ligand needs to bind for dimerization and phosphorylation of JAK2 and STAT
2. lingand-independent dimerization

Question 24

On which cells PRL acts?

Answer 24

alveolar epithelial cells of

Question 25

On which cells oxytocin acts?

Answer 25

contraction of myoepithelial cells to eject milk from the alveoli

Question 26

What are the hormones responsible for alveolar growth?

Answer 26

Progesterone, estrogen, adrenal steroids, PRL

Question 27

What are the functions or PRL?

Answer 27

- milk production - acts on gonadotrophs (presence of receptors) = amenorrhea - immunomodulation => B + T lymphocytes and macrophages - stimulates mitosis

Question 28

What is the precursor of ACTH?

Answer 28

large peptide hormone POMC

Question 29

Explain the molecular pathway of tanning.

Answer 29

1. UV damage stimulates keratinocytes to produce MSH (melanocyte stimulating hormone) 2. melanocytes produce melanin 3. melanin back to keratinocytes to reduce UV damage.

Question 30

How does ACTH act on adrenal glands?

Answer 30

1. binds to receptor 2. activates Gsa 3. mobilization of cholesterol into mitochondria 4. conversion of cholesterol to pregnenolone

Question 31

How's ACTH regulated?

Answer 31

by hypothalamic hormone CRH peak around early morning then it decreases CRH

Question 32

Draw the feedback mechanism of TSH

Answer 32

GO

Question 33

What are the roles of FSH in males and females?

Answer 33

``` ♂ = stimulation of spermatogenesis + production of sex hormone binding globulin ♀ = dev ovarian follicles + estradiol production both = secretion of inhibin = FSH -ve feedback ```

Question 34

What are the roles of LH in males and females?

Answer 34

``` ♂ = Leydig cells testosterone production ♀ = ovulation, luteinisation, sterodiogeneis in follicles ```

Question 35

Go see slide 84

Answer 35

GO

Question 36

What is the difference btw gigantism and acromegaly?

Answer 36

both hypersecretion of GH gigantism = high GH during growth phase acromegaly = high GH after growth in adults

Question 37

What are the symptoms of adenomas?

Answer 37

droopy eyes, double vision, altered facial sensations, visual field defects

Question 38

Melatonin is made from what?

Answer 38

tryptophan

Question 39

What are hCS-A,B,V and L?

Answer 39

human chorionic somatotropin secreted by the placenta to induce changes in the mother's body supporting pregnancy

Question 40

True or False | somatostatin inhibits GH synthesis

Answer 40

FALSE | it inhibits GH secretion