Module 6: Endocrine

Question 1

What are the 4 hormone classes and they are all water soluble except for which one?

Answer 1

1. Peptide hormones
2. Derivatives of phenylalanine
3. Derivatives of arachidonic acid
4. Steroid hormones

Steroid hormones are lipid soluble

Question 2

1. What are the 3 steps of peptide hormone biosynthesis?
2. What is the precursor for all steroid hormones?
3. What are the 4 types of steroid hormones?

Answer 2

1. Pre-prohormone, prohormone and parent hormone
2. Cholesterol
3. Corticoids
   Progestins
   Androgens
   Oestrogens

Question 3

1. What is the difference between an exocrine gland and an endocrine gland?
2. What are the 5 ways hormones can communicate?

Answer 3

1. Exocrine: secrete into a duct
   Endocrine secrete directly into blood vessels
2. Endocrine, intracrine, paracrine, autocrine and juxtacrine

Question 4

1. What are the 3 glands under the direct control of the hypothalamus and pituitary?
2. What are the 3 types of effects that a hormone can have on another substance? Briefly explain them…

Answer 4

1. Thyroids, gonads and adrenal cortex
2. Permissive effect: strengthens effect
   Synergistic effect: both hormones needed together
   Antagonistic effect: opposite effects of two different hormones

Question 5

Steroid hormones
What are the following secreted by:
1. Cortisol and aldosterone
2. Oestrogen and pregesterone
3. Oestrogen and progesterone
4. Testosterone

Answer 5

1. Adrenal cortex
2. Ovaries
3. Placenta
4. Testes

Question 6

Steroids

1. What two things make all steroid hormones?
2. Which enzyme helps this?
3. How do steroid hormones circulate after being released?
4. What converts cholesterol into pregnenalone? What kind of step is this?
5. Are steroid hormones stored and what does this mean?

Answer 6

1. Pregnenolone and progesterone
2. 3 beta HSD
3. Bound to protein
4. Desmolase- limiting step
5. Not stored (synthesised as required), therefore slower time for action

Question 7

Hormone signalling methods:

1. Which 3 ways do water soluble hormones signal?
2. Which 2 ways do lipid soluble hormones signal?

Answer 7

1. Cell membrane receptors, G-protein coupled receptors and tyrosine kinase coupled receptors
2. Intracellular cytoplasmic or nuclear receptors

Question 8

1. The hypothalamus controls which 2 systems?
2. What does the hypothalamus contain that has different releasing factors?
3. What does the hypothalamus sit on top of?

Answer 8

1. Autonomic nervous system and endocrine system
2. Nuclei
3. Pituitary gland

Question 9

Pituitary gland:

1. What are the two areas called and what are alternative names for it?
2. What does each part secrete?
3. What can be said about their embryological origins?
4. Does the gland lie inside or outside the blood brain barrier?

Answer 9

1. Anterior = adenohypophysis
Posterior = neurohypophysis
2. Anterior: secretes classic hormones
Posterior: secretes neurohormones
3. Both have separate embryological origin
4. Outside the BBB

Question 10

Posterior pituitary

1. What is its other name?
2. What is it an extension of?
3. What is composed of?
4. How is connected to the hypothalamus?

Answer 10

1. Neurohypophysis
2. Hypothalamus
3. Axons of hypothalmic neurons
4. Pituitary stalk

Question 11

Anterior pituitary

1. What is its other name?
2. What is another name for the system its a part of?
3. What distinguishing thing does it contain?

Answer 11

1. Adenohypophysis
2. Hypothalamo-hypophyseal system
3. Blood vessels

Question 12

Hypothalmic factors/hormones

1. Where are the two places these travel to? One of these destinations is via a structure, what is it?
2. Which part is responsible for storing the hormones and which one acts on specific cells?
3. These hormones can be what 2 things in terms of behaviour?

Answer 12

1. Anterior pituitary - via median eminence
   Posterior pituitary
2. Anterior pituitary: acts on specific cells once here
   Posterior pituitary: stored
3. Stimulating or inhibitory

Question 13

Hypothalmic factors that travel to anterior pituitary
Give the full name for the following acronyms:
1. TRH
2. GnRH
3. CRH
4. GHRH
5. S
6. PRH
7. PIH
8. D

Answer 13

1. TRH: thryotrophin releasing hormone
2. GnRH: gonadotropin releasing hormone
3. CRH: corticotrophin releasing hormone
4. GHRH: growth hormone releasing hormone
5. S: somatostatin
6. PRH: prolactin-releasing hormone
7. PIH: prolactin inhibiting hormone
8. D: dopamine

Question 14

What is the effect of the following:

1. TRH
2. GnRH
3. CRH
4. GHRH
5. S
6. PRH
7. PIH

Answer 14

1. TRH - stimulates TSH
2. GnRH - stimulates LH and FSH
3. CRH - Stimulates ACTH
4. GHRH - stimulates GH
5. S - INHIBITS GH
6. PRH - stimulates prolactin
7. PIH - INHIBITS PROLACTIN

Question 15

Hypothalmic factors that travel to posterior pituitary

1. What two things travel to the posterior pituitary?
2. One of these had an alternative name. What is it?
3. Which 2 hypothalmic nuclei are they made in?
4. What bodies are they stored in?

Answer 15

1. Vasopressin
Oxytocin
2. Vasopressin = ADH
3. Supraoptic and paraventricular
4. Herring bodies

Question 16

ADH = anti-diuretic hormone (posterior pituitary)

1. What does it promote?
2. What is the main stimulus for it?
3. What is this stimulus sensed by in the hypothalamus?
4. What is the other stimulus and what is it sensed by?
5. What are 2 inhibitors of ADH release?

Answer 16

1. Water conservation by the kidney
2. Increased osmotic pressure
3. Osmoreceptors
4. Volume depletion sensed by baroreceptors
5. Alcohol and alpha blockers

Question 17

Oxytocin (posterior pituitary)
1. It has 2 major targets:
The myoepithelial cells of the _________
The smooth muscle cells of the ____________
2. What are the 2 main functions?
3. Explain the milk let-down reflex briefly…

Answer 17

1. Breast
   Uterus
2. Milk ejection reflex and uterine smooth muscle contraction
3. Suckling, nipple receptors, oxytocin released from posterior pituitary, myoepithelial cells contract, milk moves and is ejected

Question 18

Anterior pituitary:
What type of cells secrete the following hormones?
1. ACTH
2. TSH
3. LH and FSH
4. GH
5. Prolactin

Answer 18

1. ACTH = corticotroph
2. TSH = thyrotroph
3. LH and FSH = gonadotroph
4. GH = somatotroph
5. Prolactin = lactotroph

Question 19

Anterior pituitary:
What is the target of the following hormones?
1. ACTH
2. TSH
3. LH and FSH
4. GH
5. Prolactin

Answer 19

1. ACTH: adrenal cortex
2. TSH: thyroid gland
3. LH and FSH: ovaries and testes
4. GH: most tissues
5. Prolactin: breasts and gonads

Question 20

ACTH

1. What is it derived from?
2. What is it stimulated by?
3. What cell is it secreted from?
4. Where does it act?
5. What does this cause the release of?
6. When do the levels increase, and what does this eventually cause?

Answer 20

1. POMC gene
2. CRH
3. Corticotroph
4. Adrenal cortex
5. Glucocorticoid/cortisol release
6. Early before awakening, causing cortisol awakening response

Question 21

Cortisol
Complete the following sentences that describe the functions of cortisol:
1. Regulation of.....
2. Potent...
3. During fasting...
4. Metabolic adaptation...

Answer 21

1. Regulation of carbohydrate, protein and to a lesser extent, fat
2. Potent anti-inflammatory and immunosuppressive effects
3. During fasting, maintains plasma glucose levels
4. Metabolic adaptation in response to stressful stimuli

Question 22

Melanocyte stimulating hormone

1. What does it decrease?
2. What does it increase?
3. What stimulates it release?
4. What inhibits its release?
5. Which two conditions is it increased in?

Answer 22

1. Decreases appetite
2. Skin pigmentation
3. CRH
4. Dopamine
5. Cushing’s and Addison’s disease

Question 23

TSH - thyroid stimulating hormone

1. What cells does it increase?
2. What hormone secretion does it increase?
3. What kind of secretion is it during the day?

Answer 23

1. Thyroid follicular cells
2. Thyroid hormone
3. Pulsatile

Question 24

Gonadotrophins: FSH and LH

1. What 3 things are these involved in?
2. In males these are involved in what?
3. In females these are involved in which 2 things?

Answer 24

1. Control of sexual differentiation, steroid hormone synthesis and gametogenesis
2. Spermatogenesis
3. Oestrogen biosynthesis and regulate hormones involved in the menstrual cycle

Question 25

Prolactin 1. What stimulates its secretion? 2. What 2 things inhibit it? 3. What is its function?

Answer 25

1. PRH 2. PIH/dopamine 3. Initiate and maintain milk secretion

Question 26

Growth hormone (GH) 1. What cell type is it released from? 2. What 2 things control it? 3. What 2 things does it stimulate post-natally? 4. What 2 things does it help maintain?

Answer 26

1. Somatotrophs 2. GHRH and GHIH 3. Somatic growth and development 4. Lean body and bone mass

Question 27

What are the 4 ways in which homeostasis is regulated to control hormone secretion?

Answer 27

1. Negative and positive feedback in axes 2. Inhibitory feedback 3. Precursor to active form 4. Bound hormone is inactive

Question 28

1. Which one is most common in biological systems: positive feedback or negative feedback? 2. What is a brief definition of positive and negative feedback? 3. What does an inhibitory hormone do?

Answer 28

1. Negative feedback 2. Positive feedback: response from signal stimulates more signal Negative feedback: response from signal decreases signal from its generator 3. Prevents release of hormone until it itself is suppressed

Question 29

Glucocorticoids (eg. Cortisol) 1. What is its main function? 2. What type of reactions happen in the liver? 3. What type of reactions happen in the muscles and fat cells? 4. What is the overall result? 5. Where would the primary, secondary and tertiary defects be?

Answer 29

1. Prepares body for stress 2. Anabolic 3. Catabolic 4. Increase in blood sugar levels 5. Primary = end organ/target gland Secondary = trophic hormone (anterior pituitary) Tertiary = releasing hormone (hypothalamus)

Question 30

HPA axis disorders 1. Cushings disease is increased ACTH due to what? 2. Cushing's syndrome is increased ACTH due to what?

Answer 30

1. Pituitary defect | 2. Non pituitary defect

Question 31

Dynamic endocrine testing 1. What kind of tests do you do if hormone levels are low? 2. What kind of tests do you do if hormone levels are high? 3. What does the synacthen test do? 4. What kind of imaging can you do to confirm?

Answer 31

1. Stimulation tests 2. Suppression tests 3. Stimulation test 4. MRI

Question 32

Thyroid gland 1. Where is the thyroid? 2. What is its vascularity like? 3. It contains a large store of which two things? 4. Which two iodine rich hormones does it secrete and what are the acronyms for both? 5. What are the two types of cell in a thyroid gland and what do each produce?

Answer 32

1. On each side of trachea 2. Highly vascularised 3. Thyroid hormones and iodine 4. Tri-iodo-thyronine = T3 Thyroxine = T4 5. Follicular cells make thyroid hormone Parafollicular cells make calcitonin

Question 33

Thyroid 1. What 4 hormones does it make? 2. What is the difference between T3 and T4?

Answer 33

``` 1. Tri-iodo-thyronine = T3 = active Reverse T3 = inactive Thyroxine = T4 Calcitonin 2. T3 is the active form T4 acts as the plasma reserve ```

Question 34

Thyroid hormones 1. What do thyroid hormones stimulate in most tissues? 2. What 2 things does this lead to? 3. What 2 types of metabolism do thyroid hormones do? 4. What role do these hormones play in growth? 5. What role do these hormones play in cardiovascular system? 6. What role do these hormones play in the CNS?

Answer 34

1. Metabolic activities 2. Increase in metabolic rate and increase in body heat production 3. Lipid metabolism and carbohydrate metabolism 4. Normal growth in children 5. Increase heart rate and vasodilation 6. Alterations in mental state

Question 35

Thyroid | 1. What 4 sites of action does T3 have?

Answer 35

1. Cell membrane, mitochondria, nucleus and neonatal cells

Question 36

HPT axis 1. What does the hypothalamus release? 2. What does the anterior pituitary release? 3. Where does it go? Stimulating what cells? 4. What is released? 5. What two points does high T3 feed back into? 6. What 4 things stimulate the hypothalamus? 7. What stimulates the pituitary gland? 8. What 4 things inhibits the pituitary gland?

Answer 36

1. TRH 2. TSH 3. Thyroid gland, stimulating thyroid follicular cells 4. T3 and T4 5. Hypothalamus and anterior pituitary 6. Cold, stress, low blood levels of T3 and T4, and low metabolic rate 7. Estrogens 8. Cytokines, somatostatin, dopamine and glucocorticoids

Question 37

``` Thyroid formation, storage and release Explain the following steps for thyroid synthesis: 1. Iodide trapping 2. Pendrin channel iodide apical membrane 3. TPO: oxidation iodide iodine 4. TPO: iodination to T1 and T2 5. TPO: T3 and T4 6. Pinocytosis and lysosomal digestion 7. Secretion by TBG ```

Answer 37

1. Done by follicular cells, against electrochemical gradient 2. Thyroglobulin (TGB) synthesised in vesicles, exocytosis, colloid These vesicles express thyroperoxidase (TPO), as soon as membrane fuses, it's released 3. 2 iodides, oxidation by TPO, iodine, binds to tyrosine 4. Iodination of tyrosine residues to T1 then T2 by TPO 5. Coupling/conjugation of T1 and T2 to T3 and T4 6. Pinocytosis and lysosomal digestion of TGB- so follicular cells can release thyroid hormones (T3 and T4) 7. T3 and T4 secreted into blood, transported mainly by thyroxine binding globulin

Question 38

1. Give some examples of symptoms in hyperthyroidism... 2. Give some examples of symptoms in hypothyroidism... 3. Give an example of hyperthyroidism

Answer 38

1. Tachycardia, warm moist skin, increased appetite, weight loss, anxiety and tremor + goitre 2. Bradycardia, dry thin hair and skin, fatigue and depression + goitre 3. Graves' disease

Question 39

HPG axis basic: 1. What does the hypothalamus release? 2. What 2 things does the anterior pituitary release? 3. What 5 things can influence GnRH secretion? 4. What is the pulsatile secretion of GnRH like prepuberty, at puberty and in later life?

Answer 39

1. GnRH 2. LH and FSH 3. Stress, exercise and diet, testosterone, progesterone and estradiol 4. Prepuberty = infrequent Puberty = sharp increase Later life = no clear secretion

Question 40

Gonadotrophins 1. What type of hormone are LH and FSH? 2. What are the 3 main functions of gonadotrophs? 3. Males: What enzyme does LH activate in testosterone synthesis? 4. Males: FSH stimulates the maturation of what in the Sertoli cells? 5. Females: what 3 things do LH and FSH do?

Answer 40

1. Glycoprotein hormones 2. Control of sexual differentiation, steroid hormone synthesis and gametogenesis 3. Desmolase 4. Spermatozoa 5. Estrogen biosynthesis, regulate menstrual hormones and stimulate follicle development

Question 41

HPG axis in males 1. What testes cells does LH act on? 2. What does this produce? 3. What two things can this inhibit? 4. What testes cells does FSH act on? What else synergistically acts on these cells? 5. What do these cells produce? 6. What two things combine to finally give spermatogenesis? 6. When sufficient spermatogenesis has been achieved, which cells produce what that will inhibit further FSH release?

Answer 41

1. Leydig cells 2. Testosterone 3. Hypothalamus and anterior pituitary 4. Sertoli cells along with testosterone 5. ABP = androgen binding protein 6. Testosterone and ABP 7. Sertoli cells release inhibin

Question 42

HPG axis in females 1. What does the hypothalamus produce? 2. What two things does the anterior pituitary produce? 3. Both of these act where? 4. What is released at this place that can inhibit FSH release? 5. What process happens next, what does it lead to, and what does it end in if there is no fertilisation? 6. What other thing is released at that place? This has a positive and a negative effect on what part of the process?

Answer 42

1. GnRH 2. LH and FSH 3. Ovaries 4. Inhibin 5. Ovulation - progesterone - menstruation 6. Estrogens - on the hypothalamus