Posterior Pituitary Hormones

Question 1

What are the divisions of the pituitary gland/hypophysis?

Answer 1

Anterior pituitary/Adenohypophysis
Posterior pituitary/Neurohypophysis

Question 2

Embryological origin of anterior pituitary

Answer 2

Pharyngeal epithelium

Question 3

Embryological origin of posterior pituitary

Answer 3

Neural tissue

Question 4

Key hormones secreted from anterior pituitary

Answer 4

Growth Hormone (GH)
Adrenocorticotropic hormone/Corticotropic (ACTH)
Thyroid Simulating Hormone (TSH)
Leuteinizing Hormone (LH)
Follicle Stimulating Hormone (FSH)
Prolactin (PRL)

Question 5

Key hormones secreted from posterior pituitary

Answer 5

Vasopressin/ADH
Oxytocin

Question 6

Which nuclei supply the posterior pituitary?

Answer 6

Paraventricular nucleus
Supraoptic nucleus

Question 7

Chemical structure of oxytocin and vasopressin

Answer 7

Both contain 9 amino acids

Two amino acids vary between oxytocin and vasopressin

Question 8

Where is oxytocin synthesized?

Answer 8

Paraventricular nucleus

Question 9

Where is vasopressin synthesized?

Answer 9

Supraoptic nucleus

Question 10

How are the hormones transported to the posterior pituitary gland?

Answer 10

Through the hypothalamo-hypophysial tract

Question 11

How are the posterior pituitary hormones transported around the body?

Answer 11

In combination with carrier protein neurophysin

Question 12

What is the purpose of vasopressin?

Answer 12

Maintains blood pressure
Maintains serum osmolarity

Question 13

What are the vasopressin receptors?

Answer 13

V_1A
V_1B
V₂

Question 14

Binding of ADH to V_1A receptors have the effects of …

Answer 14

Increasing blood pressure
Platelet aggregation

Question 15

V_1A receptors
Pathway to raising blood pressure

Answer 15

Question 16

V_1A receptors
Pathway to causing platelet aggregation

Answer 16

Question 17

What effect does V_1B receptors have on the body?

Answer 17

Maintaining blood pressure

Question 18

Pathway for V_1B to maintaining BP

Answer 18

Question 19

What effect does V₂ have on the body?

Answer 19

Regulation of water reabsorption

Question 20

Pathway for V₂ to affect water reabsorption

Answer 20

ADH binds to V₂ receptors
Causes phosphorylation of aquaporins
Aquaporins enable water reabsorption

Question 21

Pathway for increasing ADH secretion

Answer 21

Question 22

How is the effect of ADH reduced?

Answer 22

Cortisol inhibits ADH release from pituitary
ANP inhibits ADH effect on renal collecting ducts

Question 23

What type of receptor are oxytocin receptors?

Answer 23

G protein-coupled receptors

Question 24

What are the target tissues for oxytocin binding?

Answer 24

Breast
Brain

Question 25

How does oxytocin affect the target tissue?

Answer 25

Mitogen-activated protein (MAP) kinase is activated Signaling cascade causes altered gene expression

Question 26

Describe oxytocin sensitivity in third trimester

Answer 26

Estradiol levels increase causing more oxytocin receptor sensitivity in preparation for labour

Question 27

Describe response to oxytocin in first stage of labour

Answer 27

Question 28

What is the synthetic form of oxytocin?

Answer 28

Pitocin

Question 29

Purpose of pitocin

Answer 29

Initiate stronger contraction to hasten delivery Used during postpartum hemorrhage to slow excess bleeding

Question 30

Why does oxytocin secretion continue after delivery?

Answer 30

Enables continued uterine contraction in postpartum period to help uterus reach pre-pregnancy size

Question 31

Pathway of oxytocin affecting breast milk secretion

Answer 31

Question 32

What regions of the central nervous system can oxytocin affect?

Answer 32

Hypothalamus Amygdala Basal Ganglia

Question 33

How does oxytocin affect the hypothalamus?

Answer 33

Reduces stress by CRH-ACTH-Cortisol Axis Promotes nurturing and bonding behaviors

Question 34

How does oxytocin affect the amygdala?

Answer 34

Reduces activity in the amygdala (Reduces fear, anxiety, and aggression)

Question 35

How does oxytocin affect the basal ganglia?

Answer 35

Stimulates the ventral striatum which processes motivation and reward ## Footnote Ventral striatum is activated by feelings of love, anticipation, and interpersonal social rewards

Question 36

What other behavioural effects may oxytocin have?

Answer 36

Maternal-fetal bonding Motivation and reward Group decision-making and teamwork Negative memories Behavioral release (reduces pain associated with stress) Sexual stimulation and orgasm