Hormones of the Posterior Pituitary Gland

Question 1

Hormones of the
Posterior Pituitary Gland
• Small oligopeptides (____amino acid residues)
• Synthesized in the ____within the hypothalamus
• Transported along axons to the nerve terminals within the posterior pituitary gland
• Stored in____

Answer 1

9

nerve cell bodies

secretory vesicles

Question 2

1. Structure:
   • These hormones are small____ made up of only 9 amino acids. Their short structure allows them to act quickly in the body.
2. Synthesis:
   • Both ADH and oxytocin are synthesized in the nerve cell bodies located in the_____. Specifically, ADH is primarily produced in the_____, while oxytocin is mainly produced in the_____ of the hypothalamus.
3. Transport:
   • Once synthesized, these hormones are transported along axons (nerve fibers) to the posterior pituitary gland. This movement happens via specialized structures called______.
4. Storage:
   • In the posterior pituitary, ADH and oxytocin are stored in ____within the nerve terminals. They remain there until specific signals from the body trigger their release into the bloodstream.

Answer 2

oligopeptides

hypothalamus; supraoptic nucleus; paraventricular nucleus

neurosecretory granules

secretory vesicles

Question 3

• originates primarily in the _____of the hypothalamus.
• causes ejection of milk from the breast when stimulated by suckling.

Answer 3

OXYTOCIN

paraventricular nuclei

Question 4

OXYTOCIN
ACTIONS (2)

Answer 4

• Contraction of myoepithelial cells in the breast
• Contraction of the uterus

Question 5

OXYTOCIN
REGULATION
•______
• is the major stimulus for oxytocin secretion.
• The sight or sound of the infant may stimulate the hypothalamic neurons to secrete oxytocin, even in the absence of suckling.

•______ and ______
• increases the secretion of oxytocin.

Answer 5

Suckling

Dilation of the cervix and orgasm

Question 6

OXYTOCIN
CLINICAL SIGNIFICANCE
• Excess or deficiency pathologic conditions are rare and are limited to case reports
• Clinical demand for measurement is extremely rare

• Half-life of_____
• rapid degradation by_____

Answer 6

3-5 minutes

oxytocinase

Question 7

ANTIDIURETIC HORMONE
• A.k.a.

Answer 7

Arginine Vasopressin (AVP)

Question 8

ANTIDIURETIC HORMONE
• A.k.a. Arginine Vasopressin (AVP)
• Synthesized within the______ of the hypothalamus
• Maintain______ homeostasis by regulating water balance

Answer 8

paraventricular nuclei

osmotic homeostasis

Question 9

ADH/ AVP

• Primary stimulus:

Answer 9

Hyperosmolar plasma

Question 10

REGULATION
Factors that Increase ADH Secretion

Answer 10

Serum osmolarity
Volume contraction
Pain
Nausea (powerful stimulant)
Hypoglycemia
Nicotine, opiates, antineoplastic drugs

Question 11

Factors that Decrease ADH Secretion

Answer 11

Low Serum osmolarity
Ethanol
a -Agonists
ANP

Question 12

ANTIDIURETIC HORMONE

• Concentration of dissolved particles (Sodium, Glucose, BUN)

Answer 12

PLASMA OSMOLALITY

Question 13

• ADH
• Stimulated =
• Suppressed =

Answer 13

> 295 mOsm/kg

<284 mOsm/kg

Question 14

ADH

_______
• within the hypothalamus

_______
• stimulate ADH

Answer 14

Thirst receptors

Osmoreceptors

Question 15

ANTIDIURETIC HORMONE
PLASMA OSMOLALITY

Answer 15

2(Na+) + (Glucose/18) + (BUN/2.8)

Question 16

ANTIDIURETIC HORMONE
INTRAVASCULAR VOLUME
• Detected by______

Answer 16

baroreceptors

Question 17

ADH
INTRAVASCULAR VOLUME

•___________ - right atrium and pulmonary venous system
•___________ - carotid sinus and aortic arch

Answer 17

Low-pressure volume receptors

High-pressure arterial receptors

Question 18

ANTIDIURETIC HORMONE
REGULATION
• Secretion is much more sensitive to changes in______ than to changes in_____

Answer 18

osmolality

intravascular volume

Question 19

• deficiency of ADH caused by failure of the hypothalamus to produce the hormone

Answer 19

• Central/Neurogenic

Question 20

• pituitary tumor, traumatic injury, autoimmune, idiopathic

Answer 20

• Central/Neurogenic

Question 21

• failure of the kidney to respond to ADH

Answer 21

• Nephrogenic

Question 22

• renal failure, drugs, congenital defects in the receptors in the DCT

Answer 22

• Nephrogenic

Question 23

DIABETES INSIPIDUS
• Laboratory Tests

Answer 23

• Water Deprivation Test

• Response to either endogenous or exogenous AVP/ADH

Question 24

• Preferred diagnostic test fir DI

Answer 24

Water Deprivation Test

Question 25

PROBLEM

DM vs DI

Answer 25

DM - Insulin deficiency
DI - ADH deficiency

Question 26

Decreased SG

Answer 26

Decreased production or Function of ADH

Diabetes insipidus

Question 27

Increased SG

Answer 27

Decreased insulin or Decreased function
of insulin

Increased glucose

Diabetes mellitus

Question 28

WATER DEPRIVATION TESTS
Parameter

Normal

ADH Level

Plasma Osmolality after water deprivation

Urine Osmolality after water deprivation

Answer 28

↑

↓

↑

Question 29

WATER DEPRIVATION TESTS
Parameter

DI

ADH Level

Plasma Osmolality after water deprivation

Urine Osmolality after water deprivation

Answer 29

↓

↑

↓

Question 30

ANTIDIURETIC HORMONE
DIABETES INSIPIDUS
EXOGENOUS ADH ADMINISTRATION

Normal

Plasma Osmolality after
ADH administration

Urine Osmolality after
ADH administration

Answer 30

N/↓

↑

Question 31

ANTIDIURETIC HORMONE
DIABETES INSIPIDUS
EXOGENOUS ADH ADMINISTRATION

Neurogenic DI

Plasma Osmolality after
ADH administration

Urine Osmolality after
ADH administration

Answer 31

N/↓

↑

Question 32

ANTIDIURETIC HORMONE
DIABETES INSIPIDUS
EXOGENOUS ADH ADMINISTRATION

Nephrongenic DI

Plasma Osmolality after
ADH administration

Urine Osmolality after
ADH administration

Answer 32

↑

↓

Question 33

• characterized by hypersecretion of ADH resulting to excess water reabsorption, dilutional effect on plasma components and hypoosmolality

Answer 33

SYNDROME OF INAPPROPRIATE ADH (SIADH)