Hormones

Question 1

What are hormones?

Answer 1

Chemical messengers secreted from glands, and bind to target receptors to elicit an activator or inhibitory response within the target cell, carried by the circulatory system

Question 2

How are peptide hormones synthesised?

Answer 2

Synthesised as pro-hormones requiring further processing (cleavage) to activate.

Question 3

How do peptide hormones enter the cell?

Answer 3

Polar Peptide hormones are impermeable to the phospholipid bilayer therefore bind to receptors to transduce a secondary messenger system

Question 4

How are peptide hormones stored?

Answer 4

In secretory vesicles

Question 5

What type of secretion are peptide hormones?

Answer 5

Regulatory secretion

Question 6

Why are steroid hormones membrane permeable?

Answer 6

Proteins contain a sterol group, thus can dissolve in phospholipid bilayer and diffuse into the cell

Question 7

How are steroid hormones stored?

Answer 7

Released immediately

Question 8

What is the term used to describe the secretion of steroid hormones?

Answer 8

Constitutive secretion

Question 9

Which types of intracellular receptors to steroid bind to?

Answer 9

Type 1: Cytoplasmic (intracellular receptor)

Type 2: Nuclear

Question 10

Which pituitary gland is continuous with the hypothalamus?

Answer 10

Posterior pituitary gland

Question 11

How is the anterior pituitary gland anatomically distinct in comparison the posterior pituitary gland?

Answer 11

The anterior pituitary gland is distinct and not continuous with the hypothalamus; there is no presence of neural tissue

Question 12

How is the pituitary suspended from the inferior side of the brain?

Answer 12

By the pituitary stalk

Question 13

What is another term for the pituitary stalk?

Answer 13

Infundibulum

Question 14

Where does the pituitary gland reside?

Answer 14

Sella turcica of the sphenoid bone

Question 15

What is a supra-sella tumour?

Answer 15

Pituitary tumour above the sell-turcica (fossa)

Question 16

What is another term for the anterior pituitary?

Answer 16

Adenohypophysis

Question 17

Where is Rathke’s pouch?

Answer 17

Anterior pituitary gland, composed of glandular epithelium

Question 18

Which region of the anterior pituitary gland secretes majority of hormones?

Answer 18

Pars distalis

Question 19

Which epithelial layer separates the pars anterior from the posterior lobe?

Answer 19

Pars intermedia

Question 20

What is the term for the portal circulation in the hypothalamus and pituitary gland?

Answer 20

Hypophyseal portal circulation

Question 21

What is the neurohypothysis?

Answer 21

Posterior pituitary gland

Question 22

Which hormones are secreted from the posterior pituitary gland?

Answer 22

Oxytocin and ADH

Question 23

Which nuclei secrete oxytocin and ADH within the posterior pituitary gland?

Answer 23

Supraoptic

Paraventricular nuclei

Question 24

Which neurones secrete hypothalamic hormones into the primary capillary plexus?

Answer 24

Parvocellular hypothalamic neurones

Question 25

Where are hypothalamic hormones secreted into?

Answer 25

Primary capillary plexus

Question 26

Which circulation is linked to the primary capillary plexus?

Answer 26

The portal hypophyseal circulation

Question 27

Where do the parvocellular neurones terminate (site of primary plexus)?

Answer 27

Median eminence

Question 28

Which hormones are released from the hypothalamus?

Answer 28

Hypothalamic releasing/inhibitory factors

Question 29

How are the hypothalamic releasing/inhibitory factors transported to the anterior pituitary?

Answer 29

The portal hypophyseal circulation | Primary capillary plexus to the secondary capillary plexus

Question 30

Where is the median eminence located?

Answer 30

Infundibulum

Question 31

What type of cells comprise the anterior pituitary gland?

Answer 31

Endocrine cells

Question 32

What are the 5 classes of endocrine cells?

Answer 32

``` Lactotrophs Somatotrophs Gonadtrophs Thyrotrophs Corticotrophs ```

Question 33

Which plexus releases hypothalamic inhibitory/releasing factors into the anterior pituitary gland?

Answer 33

Secondary capillary plexus

Question 34

Which releasing hormone stimulates the release of TSH?

Answer 34

Thyrotropin-releasing hormone (TRH)

Question 35

What effect does TRH have on anterior pituitary?

Answer 35

Stimulates the release of thyroid-stimulating-hormone

Question 36

Which endocrine cell do TRH act on?

Answer 36

Thyrotrophs

Question 37

Which hormone is secreted by somatotrophs?

Answer 37

Growth hormone

Question 38

Which hormone is secreted by lactotrophs?

Answer 38

Prolactin

Question 39

Which hormone is secreted by thyrotrophs?

Answer 39

Thyroid-stimulating hormone

Question 40

Which hormones are secreted by gonadotrophs?

Answer 40

``` Lutenising hormone (LH) Follicle-stimulating hormone ```

Question 41

Which hormone is secreted by corticotrophs?

Answer 41

Adrenocorticotrophic hormone (ACTH)

Question 42

What is the target organ of growth hormone?

Answer 42

General body tissue, particularly the liver

Question 43

What is the target organ of prolactin?

Answer 43

Mammary gland

Question 44

What is the target organ of TSH?

Answer 44

Thyroid gland

Question 45

What is the target organ of LH?

Answer 45

Testes

Question 46

What is the target organ of FSH?

Answer 46

Ovaries

Question 47

What is the target organ of ACTH?

Answer 47

Adrenal cortex

Question 48

Which hormone inhibits the secretion of growth hormone?

Answer 48

Somatostatin

Question 49

Which hormone stimulates the release of growth hormone?

Answer 49

Growth hormone relating hormone (GnRH)

Question 50

Which hormone stimulates the release of TSH?

Answer 50

Thyrotropin-releasing hormone

Question 51

Which hormone stimulates the release of ACTH?

Answer 51

Corticotrophin-releasing hormone

Question 52

Which hormone stimulates the release of LH & FSH?

Answer 52

gonadotrophin-releasing hormone

Question 53

What typical condition arises due to a pituitary tumour?

Answer 53

Bitemporal hemianopia

Question 54

Why does bitemporal hemianopia occur?

Answer 54

Adenoma engulfs the entirety of the sella turcica, the superior optic chasm is compressed (region where decussation occurs) Fibres from optic retinae are therefore compressed, thus no sensory stimulation from the lateral fields to primary visual cortex

Question 55

Which nerve bundle is compressed due to an adenoma?

Answer 55

Optic chiasm

Question 56

Describe the neuroendocrine reflex arc for prolactin:

Answer 56

Mechanical stimulation of the nipple touch and sensory receptors, activating afferent pathways. Action potentials traverse along the axons, through the ascending sensory pathways Afferent signals integrated in the hypothalamus, and inhibit dopamine release from dopaminergic parvocellular neurones Reduced concentration of dopamine in the hypothalamic-pituitary portal system, results in reduction of inhibition of anterior pituitary lactotrophs Increased plasma prolactin increases milk secretion in the mammary glands

Question 57

Which hormone inhibits the release of prolactin?

Answer 57

Dopamine

Question 58

What is released upon growth hormone receptor activation of the liver?

Answer 58

IGF-1 (Somatomedin)

Question 59

What is IGF-1?

Answer 59

Mediator of growth hormone stimulated somatic growth, binding to target receptors

Question 60

How do pituitary gigantism occur?

Answer 60

Refers to growth hormone excess that occurs before epiphyseal growth plate fusion. Patient has elevated levels of serum growth hormone an IGF

Question 61

Which hormones are elevated in pituitary gigantism?

Answer 61

Growth hormone and IGF

Question 62

What is acromegaly?

Answer 62

Excessive concentrations of growth hormone, elevated levels of igf-1 Epiphyseal growth plates have fused

Question 63

What are the clinical features for acromegaly?

Answer 63

``` Coarsening of facial features Macroglossia Prominent nose Proganthism Sweatiness Frequent headache Bitemporal hemianopia Obstructive sleep apnoea ```

Question 64

What is obstructive sleep apnoea?

Answer 64

Osseous and soft tissue changes surrounding the upper airway results in narrowing and subsequent collapse during sleep, disruption to sleep patterns

Question 65

What test can be used to diagnostically confirm an adenoma?

Answer 65

MRI scans

Question 66

How does an oral glucose tolerance test diagnose with an adenoma?

Answer 66

OGTT reduces GH plasma concentrations, patients with acromegaly do not respond

Question 67

How can a blood test be used for diagnostics of adenoma?

Answer 67

Growth hormone and IGF-1 measurements

Question 68

Where are the posterior pituitary hormones stored?

Answer 68

Neurosecretory vesicles (Herring bodies)

Question 69

Which tissues present in the hypothalamus?

Answer 69

Neural tissue

Question 70

Which magnocellular hypothalamic neurones secrete AVP?

Answer 70

Supraoptic

Question 71

Which nuclei secrete oxytocin?

Answer 71

Paraventricular nuclei

Question 72

Which region of the posterior pituitary contain Herring bodies?

Answer 72

Pars nervosa

Question 73

What stimulates the release of AVP or oxytocin?

Answer 73

Excitation of hypothalamic magnocellular neurones

Question 74

Which neurosecretory cells secrete ADH?

Answer 74

Neurosecretory cells 2 (Supraoptic)

Question 75

What is the effect of ADH?

Answer 75

Increases the permeability of the distal convoluted tubule and collecting duct to water

Question 76

Which receptors does ADH bind to?

Answer 76

Specific V2 G protein-coupled receptors of the cell surface membrane

Question 77

What intracellular effect does ADH have?

Answer 77

Triggers adenylate cyclase activity to form cyclic-AMP, secondary messenger enables protein kinase A to active aquaporin-2 and 3 genes

Question 78

Which water channels are synthesised upon ADH activation?

Answer 78

Aquaporins

Question 79

Which side does aquaporins-2 insert itself in?

Answer 79

Tubular lumen

Question 80

What effect does oxytocin have?

Answer 80

Stimulates uterine contractions, and dilation of cervix Milk ejection

Question 81

When are oxytocin receptors in the uterus synthesised at the highest rate?

Answer 81

During pregnancy within the uterus, the smooth muscles become more sensitive

Question 82

What feedback loop does oxytocin exhibit?

Answer 82

Positive feedback mechanism

Question 83

How is the positive feedback loop of oxytocin initiated?

Answer 83

Cervical stretching

Question 84

Which hypothalamic nuclei releases oxytocin?

Answer 84

Paraventricular nuclei