Session 8 - HPA, Growth Hormone And Pituitary Disorders

Question 1

What is the relationship between the hypothalamus and the posterior pituitary gland?

Answer 1

Axons from hypothalamus passes down the infundibulum and terminates in posterior pituitary

Question 2

What is the relationship between the anterior pituitary and the hypothalamus?

Answer 2

Hypothalamus releases tropic hormones into hypophyseal portal system supplying anterior pituitary to control its hormonal secretions

Question 3

What are the 8 hormones produced by the hypothalamus?

Answer 3

Oxytocin 
Antidiuretic hormone
Thyrotropin releasing hormone
Corticotropin releasing hormone
Gonadotropin releasing hormone
Growth hormone releasing hormone
Growth hormone inhibiting hormone

Question 4

What is the 2 roles of oxytocin?

Answer 4

Milk let-down reflex

Uterus contractions during birth

Question 5

What is the role of antidiuretic hormone?

Answer 5

Regulation of body water volume

Question 6

What is the role of thyrotropin releasing hormone?

Answer 6

Stimulate release of thyroid stimulating hormone from anterior pituitary, which stimulates thyroid gland to secrete T3&4 and increase metabolic rate

Question 7

What is the role of prolactin release-inhibiting hormone?

Answer 7

Inhibit release of prolactin from anterior pituitary, inhibit breast growth and milk secretion

Question 8

What is the role of corticotropin releasing hormone?

Answer 8

Stimulate release of adrenocorticotropic hormone from anterior pituitary, stimulates adrenal gland to secrete cortisol and increase stress response and metabolic actions

Question 9

What is the role of gonadotropin releasing hormone?

Answer 9

Stimulate release of follicle-stimulating hormone and luteinizing hormone which stimulates ovaries and testes to secrete sex hormones and gamete production respectively

Question 10

What is the role of growth hormone releasing hormone?

Answer 10

Stimulate release of growth hormone to increase growth

Question 11

What is the role of growth hormone inhibiting hormone?

Answer 11

Inhibit release of growth hormone, inhibit growth

Question 12

What are the 6 hormones produced by anterior pituitary?

Answer 12

Thyroid stimulating hormone
Adrenocorticotropic hormone
Luteinizing hormone
Follicle stimulating hormone
Prolactin
Growth hormone

Question 13

What is the role of thyroid stimulating hormone?

Answer 13

Secretion of thyroid hormone from thyroid gland

Question 14

What is the role of adrenocorticotropic hormone?

Answer 14

Secretion of hormones from adrenal cortex

Question 15

What is the role of luteinizing hormone?

Answer 15

Ovulation and secretion of sex hormones

Question 16

What is the role of follicle stimulating hormone?

Answer 16

Development of eggs and sperm

Question 17

What is the role of prolactin?

Answer 17

Mammary gland development and milk secretion

Question 18

What is the role of growth hormone?

Answer 18

Growth and energy metabolism, stimulates insulin-like growth factors

Question 19

What are 2 ways that growth hormone secretion is regulated?

Answer 19

Long loop and short loop negative feedback

Question 20

What is the long loop negative feedback to regulate growth hormone secretion?

Answer 20

Insulin-like growth factors

inhibit release of growth hormone releasing hormone
stimulates release of somatostatin / growth hormone inhibiting hormone
Inhibit release of growth hormone

Question 21

What is the short loop negative feedback to regulate growth hormone secretion?

Answer 21

Growth hormone stimulates somatostatin release

Question 22

What are the 2 ways growth hormones exert effects on cells?

Answer 22

Directly through growth hormone receptors

Indirectly through insulin-like growth factor-I

Question 23

How does growth hormone exert its effects directly?

Answer 23

Growth hormone binds to growth hormone receptors (cytokines receptors) coupled to Janus Kinases (JAKs) which phosphorylate target proteins, altering their functions, and also results in signalling cascades that activate transcription factors to increase production of IGFs

Question 24

How does growth hormone exert its effects on cells indirectly?

Answer 24

Produce insulin-like growth factors which circulate in blood bound to specific binding proteins which modulate their availability to activate IGF receptors (tyrosine kinase) to cause hypertrophy, hyperplasia, increased protein synthesis and lipolysis

Question 25

What is the most common cause of pituitary malfunction?

Answer 25

Benign tumor / adenoma

Question 26

How do pituitary tumors cause problems?

Answer 26

Puts physical pressure on other local structure or secrete substances

Question 27

What are 5 problems that a non functioning tumor can cause?

Answer 27

``` Inadequate production of hormones Headache Visual problems Nausea Vomiting ```

Question 28

What is a problem that a hypersecreting tumor can cause?

Answer 28

Systemic effects of over secreted hormone

Question 29

What are the 3 steps of investigating a suspected pituitary tumor?

Answer 29

MRI scan to see anatomy, size and location Assessment of visual field defects Assessment of endocrine function to determine excess or deficiency through biopsy or blood test

Question 30

What are 4 possible causes of hypopituitarism?

Answer 30

Adenoma Radiation Head injury Inflammatory disease

Question 31

What happens during hypopituitarism?

Answer 31

Progressive loss of anterior pituitary function with GH and LH first to be affected

Question 32

What is panhypopituitarism?

Answer 32

Deficiency of all anterior pituitary hormones

Question 33

What are symptoms of growth hormone deficiency?

Answer 33

Decreased tolerance to exercise Decreased muscle strength Increased body fat Reduced sense of well being

Question 34

What is the common cause of GH deficiency in adults and children?

Answer 34

Pituitary adenoma in adults | Idiopathic but maybe gene mutations and autoimmmune condition in children

Question 35

What are 4 symptoms of gonadotropin deficiency?

Answer 35

Decreased libido Infertility Oligomenorrhea Impotence

Question 36

What are 4 causes of ADH deficiency?

Answer 36

Hypothalamic tumor Pituitary tumor extended up into hypothalamus Cranial radiotherapy Infections

Question 37

What are 3 symptoms of ADH deficiency?

Answer 37

Polyuria Polydipsia Dehydration

Question 38

What are 3 main conditions caused by hyperpituitarism?

Answer 38

Prolactin excess Growth hormone excess ACTH excess

Question 39

What is the normal function of prolactin?

Answer 39

Initiate and maintain lactation

Question 40

What is prolactin inhibited by?

Answer 40

Dopamine

Question 41

What are 5 symptoms of hyperprolactinanemia?

Answer 41

``` Galactorrhea - unexplained milk production Gynecomastia - hard breast Hypogonadism - lower sexual activity Amenorrhea - ceased menstruation Erectile dysfunction ```

Question 42

What is the common cause of hyperprolactinaemia?

Answer 42

Prolactinoma

Question 43

How to treat hyperprolactinaemia?

Answer 43

Dopamine receptor agonists like cabergoline

Question 44

What are 8 symptoms of growth hormone excess?

Answer 44

``` Broad nose Coarse facial features Thick lips Prominent supraorbital ridge Enlargement of hands and feet Excessive sweating Deeper voice Gigantism (if in childhood) ```

Question 45

What are 3 treatment options for acromegaly?

Answer 45

Surgery to remove adenoma Radiation Drug therapy

Question 46

What are 3 drugs to treat acromegaly?

Answer 46

Dopamine receptor agonists to reduce GH Somatostatin to limit GH secretion GH receptor antagonist - Pegvisomant

Question 47

What does ACTH excess cause?

Answer 47

Cushing’s syndrome