Lec2 - Hypothalamic Pituitary Axis

Question 1

What is the area of the brain directly above the pituitary gland?

Answer 1

Hypothalamus

Question 2

The pituitary gland is connected to the brain via the

Answer 2

Infundibulum

Question 3

Trauma to the head, causing the infundibulum to get snapped can result in?

Answer 3

Endocrine problems, with effects on the ovaries and testes etc.

Question 4

What happens if the pituitary gland becomes enlarged?

Answer 4

It can press on the optic chiasm, causing bilateral hemianopsia

Question 5

The infundibulum contains

Answer 5

The hypothalamico-hypophyseal tract &

the hypothalamico-hypophyseal portal vessels

Question 6

Name the two portions of the pituitary gland

Answer 6

The anterior pituitary gland &

posterior pituitary gland

Question 7

How do the anterior and posterior pituitary glands function in relation to one another?

Answer 7

Independently

Question 8

The posterior pituitary gland is what type of growth from the brain

Answer 8

A “down growth”

Question 9

The posterior pituitary is also known as:

Answer 9

Neurohypophysis

Question 10

Name the hormones stored and secreted from the posterior pituitary gland

Answer 10

Anti-diuretic hormone (ADH)/ Vasopressin

Oxytocin

Question 11

What type of hormones are ADH and oxytocin?

Answer 11

Peptide hormones

Question 12

How many amino acids in ADH and oxytocin?

Answer 12

Nine amino acids

Question 13

How many of the amino acids are identical in ADH and oxytocin?

Answer 13

7

Question 14

What does is the significance of the fact that there are 7 identical amino acids in ADH and oxytocin?

Answer 14

That at high concentrations of each, there can sometimes be cross over of activity e.g. at high concentrations of ADH it has some of the effects of oxytocin

Question 15

Where are the hormones ADH and oxytocin synthesised?

Answer 15

In neurons of the hypothalamus:
Supraoptic nuclei
Paraventricular nucleus of the hypothalamus

Question 16

In what form are ADH and oxytocin synthesised?

Answer 16

They are synthesised as inactive precursor hormones

Question 17

Where are ADH and oxytocin converted into active hormones?

Answer 17

In the posterior pituitary gland

Question 18

The inactive hormones are transported from the supraoptic nuclei and paraventricular nucleus to the pituitary gland via the:

Answer 18

Hypothalamico-neurohypophyseal tract

Question 19

What is secretion of ADH influenced by?

Answer 19

Plasma osmolarity

Question 20

ADH causes stimulation of what receptors?

Answer 20

V2 receptors

Question 21

Stimulation of v2 receptors results in:

Answer 21

translocation of aquaporins to the membrane of the kidney tubule, allowing water reabsorption

Question 22

ADH reabsorbs water in the kidney tubule so

Answer 22

there is less urine output

Question 23

If there is dehydration, what happens to ADH?

Answer 23

ADH is secreted

Question 24

Dehydration can also occur during haemorrhage which leads to a:

Answer 24

reduction in blood pressure

Question 25

At high concentrations ADH causes:

Answer 25

an increase in blood pressure

Question 26

Disorders of ADH secretion lead to:

Answer 26

disorders of fluid balance

Question 27

A reduction in ADH secretion leads to:

Answer 27

an increase in urine volume

Question 28

What is DIABETES INSIPIDUS?

Answer 28

A lack of ADH secretion | resulting in high volume of diluted urine

Question 29

How do you treat DI?

Answer 29

By giving ADH

Question 30

Increased ADH leads to:

Answer 30

Syndrome of Inappropriate ADH (SIA)

Question 31

Syndrome of Inappropriate ADH causes:

Answer 31

very dilute blood and produce very little urine

Question 32

How do you treat SIA?

Answer 32

Removal of the tumour and restrict fluid intake

Question 33

Oxytocin acts via which second messenger?

Answer 33

IP3

Question 34

Oxytocin causes

Answer 34

contraction of the smooth muscle of the uterus and breast

Question 35

Oxytocin is most important during:

Answer 35

parturition and lactation

Question 36

Secretion of oxytocin is stimulated by:

Answer 36

stimulation of the genitals and nipples

Question 37

Stimulation of V1 receptors cause:

Answer 37

Vasoconstriction but this does not happen at physiological concentrations of ADH

Question 38

Oxytocin synthesis increases during

Answer 38

pregnancy

Question 39

An increase in oxytocin synthesis during pregnancy also results in a parallel increase in:

Answer 39

oxytocinase activity

Question 40

During parturition, oxytocin causes contraction of smooth muscle of the uterus to aid:

Answer 40

expulsion of the foetus

Question 41

What is oxytocin responsible for after parturition?

Answer 41

For milk 'let down' / expulsion

Question 42

What is the stimulus for milk let down?

Answer 42

Suckling, but there is a delay between the start of suckling and milk let down

Question 43

Many women start secreting oxytocin when they hear what?

Answer 43

When they hear the baby crying

Question 44

Is oxytocin necessary for the initiation of normal labour?

Answer 44

No

Question 45

Why is administration of oxytocin to induce labour not part of current NICE guidelines?

Answer 45

Because oxytocin causes the uterus to contract but if the cervix hasn't dilated, then the baby has nowhere to go and this can cause damage to the baby

Question 46

The anterior pituitary gland is what type of growth from the palate?

Answer 46

An upgrowth

Question 47

Name the hormones stored and secreted from the anterior pituitary gland:

Answer 47

``` Adrenocorticotrophic hormone (ACTH) Growth hormone (GH) Thyroid stimulating hormone (TSH) Follicle stimulating hormone (FSH) Luteinising hormone (LH) Prolactin (PRL) ```

Question 48

Prolactin is involved in

Answer 48

milk synthesis

Question 49

Oxytocin is involved in

Answer 49

milk expression

Question 50

Thyroid stimulating hormone is synthesised by:

Answer 50

thyrotrophe cells

Question 51

Adrenocorticotrophic hormone is synthesised by:

Answer 51

corticotrophe cells

Question 52

Follicle stimulating hormone (FSH) is synthesised by:

Answer 52

gonadotrophe cells

Question 53

Tumours of the pituitary gland can cause:

Answer 53

excess secretion of one or all of the hormones secreted by the pituitary gland

Question 54

``` The hypothalamus secretes: Thyrotrophin Releasing Hormone (TRH) Corticotrophin Releasing Hormone (CRH) Gonadotrophin Releasing hormone (GnRH) Growth Hormone Releasing Hormone (GHRH) ```

Answer 54

``` to stimulate secretion of: Thyroid stimulating hormone (TSH) Adrenocorticotrophin hormone (ACTH) Follicle Stimulating Hormone (FSH) Growth Hormone (GH) ```

Question 55

The releasing hormones are released by the hypothalamus into the:

Answer 55

hypothalamico-adenohypophyseal portal vessels which carry them into the anterior pituitary gland

Question 56

Do the releasing hormones enter the systemic circulation?

Answer 56

No

Question 57

The signs are

Answer 57

what the doctor can see

Question 58

The symptoms are

Answer 58

what the patient reports

Question 59

What biochemical tests should be done?

Answer 59

``` TSH & FT4 Cortisol LH and FSH PRL Testosterone/ ask about periods ```

Question 60

Why do we measure FSH?

Answer 60

To see whether the problem is in the pituitary or in the ovary

Question 61

How do we learn about the female sex hormones in a patient?

Answer 61

By asking a woman about her periods

Question 62

How can we tell about testosterone levels in a man?

Answer 62

By looking at him

Question 63

When do we experience the highest levels of cortisol?

Answer 63

In the morning, just after getting out of bed

Question 64

What are the next steps in investigation after biochemical tests?

Answer 64

Imaging e.g. MRI of pituitary | Visual field tests e.g. bitemporal hemianopia means there is compression of the optic chasm

Question 65

How many amino acids in prolactin?

Answer 65

199 amino acids

Question 66

Where is prolactin synthesised?

Answer 66

Lactotrophe cells of the anterior pituitary gland

Question 67

The secretion of prolactin is under what kind of control?

Answer 67

Hypothalamic control by means of Prolactin Release Inhibiting Factor aka DOPAMINE

Question 68

DOPAMINE

Answer 68

inhibits prolactin release

Question 69

Thyrotrophin releasing hormone

Answer 69

stimulates prolactin release

Question 70

Anti-psychotic medications are

Answer 70

dopamine antagonists

Question 71

Therefore anti-psychotic medications e.g. haloperidol

Answer 71

induce prolactin secretion

Question 72

Prolactin secretion is stimulated by:

Answer 72

Mild stress Nipple stimulation Coitus

Question 73

Prolactin inhibits

Answer 73

fertility - it is harder to get pregnant whilst breastfeeding

Question 74

What is the primary role of prolactin is to

Answer 74

promote lactation and the development of breast tissue

Question 75

Hyperprolactinaemia

Answer 75

is the most common cause of infertility

Question 76

A tumour of the pituitary gland which secretes prolactin is called

Answer 76

A prolactinoma

Question 77

What happens to prolactin production as we age?

Answer 77

It increases

Question 78

Where is growth hormone synthesised?

Answer 78

Somatotrophe cells of the anterior pituitary gland

Question 79

Secretion of growth hormone is controlled by?

Answer 79

Hypothalamic control via the growth hormone releasing hormone

Question 80

Growth hormone inhibiting hormone is also known as

Answer 80

Somatotrophin

Question 81

What has more control in the release of GH - GHRH or GHIH?

Answer 81

Growth hormone releasing hormone GHRH

Question 82

Secretion of growth hormone is stimulated by

Answer 82

decreased carbohydrates and fatty acids and increased amino acids

Question 83

In some tissues, GH acts via

Answer 83

second messengers

Question 84

Where are these second messengers produced?

Answer 84

In the liver

Question 85

What are the second messengers produced in the liver called?

Answer 85

Insulin-growth-factor 1 | Insulin-growth-factor 2

Question 86

What is the function of these second messengers?

Answer 86

to promote growth

Question 87

What is the primary effect of GH?

Answer 87

to promote linear growth of adolescence by increasing protein synthesis and collagen deposition

Question 88

Growth hormone is also involved in

Answer 88

tissue turnover and repair

Question 89

Foetal growth is relatively independent of GH - True or False?

Answer 89

True