Module 6: Endocrine Flashcards
What are the 4 hormone classes and they are all water soluble except for which one?
- Peptide hormones
- Derivatives of phenylalanine
- Derivatives of arachidonic acid
- Steroid hormones
Steroid hormones are lipid soluble
- What are the 3 steps of peptide hormone biosynthesis?
- What is the precursor for all steroid hormones?
- What are the 4 types of steroid hormones?
- Pre-prohormone, prohormone and parent hormone
- Cholesterol
- Corticoids
Progestins
Androgens
Oestrogens
- What is the difference between an exocrine gland and an endocrine gland?
- What are the 5 ways hormones can communicate?
- Exocrine: secrete into a duct
Endocrine secrete directly into blood vessels - Endocrine, intracrine, paracrine, autocrine and juxtacrine
- What are the 3 glands under the direct control of the hypothalamus and pituitary?
- What are the 3 types of effects that a hormone can have on another substance? Briefly explain them…
- Thyroids, gonads and adrenal cortex
- Permissive effect: strengthens effect
Synergistic effect: both hormones needed together
Antagonistic effect: opposite effects of two different hormones
Steroid hormones What are the following secreted by: 1. Cortisol and aldosterone 2. Oestrogen and pregesterone 3. Oestrogen and progesterone 4. Testosterone
- Adrenal cortex
- Ovaries
- Placenta
- Testes
Steroids
- What two things make all steroid hormones?
- Which enzyme helps this?
- How do steroid hormones circulate after being released?
- What converts cholesterol into pregnenalone? What kind of step is this?
- Are steroid hormones stored and what does this mean?
- Pregnenolone and progesterone
- 3 beta HSD
- Bound to protein
- Desmolase- limiting step
- Not stored (synthesised as required), therefore slower time for action
Hormone signalling methods:
- Which 3 ways do water soluble hormones signal?
- Which 2 ways do lipid soluble hormones signal?
- Cell membrane receptors, G-protein coupled receptors and tyrosine kinase coupled receptors
- Intracellular cytoplasmic or nuclear receptors
- The hypothalamus controls which 2 systems?
- What does the hypothalamus contain that has different releasing factors?
- What does the hypothalamus sit on top of?
- Autonomic nervous system and endocrine system
- Nuclei
- Pituitary gland
Pituitary gland:
- What are the two areas called and what are alternative names for it?
- What does each part secrete?
- What can be said about their embryological origins?
- Does the gland lie inside or outside the blood brain barrier?
1. Anterior = adenohypophysis Posterior = neurohypophysis 2. Anterior: secretes classic hormones Posterior: secretes neurohormones 3. Both have separate embryological origin 4. Outside the BBB
Posterior pituitary
- What is its other name?
- What is it an extension of?
- What is composed of?
- How is connected to the hypothalamus?
- Neurohypophysis
- Hypothalamus
- Axons of hypothalmic neurons
- Pituitary stalk
Anterior pituitary
- What is its other name?
- What is another name for the system its a part of?
- What distinguishing thing does it contain?
- Adenohypophysis
- Hypothalamo-hypophyseal system
- Blood vessels
Hypothalmic factors/hormones
- Where are the two places these travel to? One of these destinations is via a structure, what is it?
- Which part is responsible for storing the hormones and which one acts on specific cells?
- These hormones can be what 2 things in terms of behaviour?
- Anterior pituitary - via median eminence
Posterior pituitary - Anterior pituitary: acts on specific cells once here
Posterior pituitary: stored - Stimulating or inhibitory
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
- TRH: thryotrophin releasing hormone
- GnRH: gonadotropin releasing hormone
- CRH: corticotrophin releasing hormone
- GHRH: growth hormone releasing hormone
- S: somatostatin
- PRH: prolactin-releasing hormone
- PIH: prolactin inhibiting hormone
- D: dopamine
What is the effect of the following:
- TRH
- GnRH
- CRH
- GHRH
- S
- PRH
- PIH
- TRH - stimulates TSH
- GnRH - stimulates LH and FSH
- CRH - Stimulates ACTH
- GHRH - stimulates GH
- S - INHIBITS GH
- PRH - stimulates prolactin
- PIH - INHIBITS PROLACTIN
Hypothalmic factors that travel to posterior pituitary
- What two things travel to the posterior pituitary?
- One of these had an alternative name. What is it?
- Which 2 hypothalmic nuclei are they made in?
- What bodies are they stored in?
1. Vasopressin Oxytocin 2. Vasopressin = ADH 3. Supraoptic and paraventricular 4. Herring bodies
ADH = anti-diuretic hormone (posterior pituitary)
- What does it promote?
- What is the main stimulus for it?
- What is this stimulus sensed by in the hypothalamus?
- What is the other stimulus and what is it sensed by?
- What are 2 inhibitors of ADH release?
- Water conservation by the kidney
- Increased osmotic pressure
- Osmoreceptors
- Volume depletion sensed by baroreceptors
- Alcohol and alpha blockers
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…
- Breast
Uterus - Milk ejection reflex and uterine smooth muscle contraction
- Suckling, nipple receptors, oxytocin released from posterior pituitary, myoepithelial cells contract, milk moves and is ejected
Anterior pituitary: What type of cells secrete the following hormones? 1. ACTH 2. TSH 3. LH and FSH 4. GH 5. Prolactin
- ACTH = corticotroph
- TSH = thyrotroph
- LH and FSH = gonadotroph
- GH = somatotroph
- Prolactin = lactotroph
Anterior pituitary: What is the target of the following hormones? 1. ACTH 2. TSH 3. LH and FSH 4. GH 5. Prolactin
- ACTH: adrenal cortex
- TSH: thyroid gland
- LH and FSH: ovaries and testes
- GH: most tissues
- Prolactin: breasts and gonads
ACTH
- What is it derived from?
- What is it stimulated by?
- What cell is it secreted from?
- Where does it act?
- What does this cause the release of?
- When do the levels increase, and what does this eventually cause?
- POMC gene
- CRH
- Corticotroph
- Adrenal cortex
- Glucocorticoid/cortisol release
- Early before awakening, causing cortisol awakening response
Cortisol Complete the following sentences that describe the functions of cortisol: 1. Regulation of..... 2. Potent... 3. During fasting... 4. Metabolic adaptation...
- Regulation of carbohydrate, protein and to a lesser extent, fat
- Potent anti-inflammatory and immunosuppressive effects
- During fasting, maintains plasma glucose levels
- Metabolic adaptation in response to stressful stimuli
Melanocyte stimulating hormone
- What does it decrease?
- What does it increase?
- What stimulates it release?
- What inhibits its release?
- Which two conditions is it increased in?
- Decreases appetite
- Skin pigmentation
- CRH
- Dopamine
- Cushing’s and Addison’s disease
TSH - thyroid stimulating hormone
- What cells does it increase?
- What hormone secretion does it increase?
- What kind of secretion is it during the day?
- Thyroid follicular cells
- Thyroid hormone
- Pulsatile
Gonadotrophins: FSH and LH
- What 3 things are these involved in?
- In males these are involved in what?
- In females these are involved in which 2 things?
- Control of sexual differentiation, steroid hormone synthesis and gametogenesis
- Spermatogenesis
- Oestrogen biosynthesis and regulate hormones involved in the menstrual cycle
Prolactin
- What stimulates its secretion?
- What 2 things inhibit it?
- What is its function?
- PRH
- PIH/dopamine
- Initiate and maintain milk secretion
Growth hormone (GH)
- What cell type is it released from?
- What 2 things control it?
- What 2 things does it stimulate post-natally?
- What 2 things does it help maintain?
- Somatotrophs
- GHRH and GHIH
- Somatic growth and development
- Lean body and bone mass
What are the 4 ways in which homeostasis is regulated to control hormone secretion?
- Negative and positive feedback in axes
- Inhibitory feedback
- Precursor to active form
- Bound hormone is inactive
- Which one is most common in biological systems: positive feedback or negative feedback?
- What is a brief definition of positive and negative feedback?
- What does an inhibitory hormone do?
- Negative feedback
- Positive feedback: response from signal stimulates more signal
Negative feedback: response from signal decreases signal from its generator - Prevents release of hormone until it itself is suppressed
Glucocorticoids (eg. Cortisol)
- What is its main function?
- What type of reactions happen in the liver?
- What type of reactions happen in the muscles and fat cells?
- What is the overall result?
- Where would the primary, secondary and tertiary defects be?
- Prepares body for stress
- Anabolic
- Catabolic
- Increase in blood sugar levels
- Primary = end organ/target gland
Secondary = trophic hormone (anterior pituitary)
Tertiary = releasing hormone (hypothalamus)
HPA axis disorders
- Cushings disease is increased ACTH due to what?
- Cushing’s syndrome is increased ACTH due to what?
- Pituitary defect
2. Non pituitary defect
Dynamic endocrine testing
- What kind of tests do you do if hormone levels are low?
- What kind of tests do you do if hormone levels are high?
- What does the synacthen test do?
- What kind of imaging can you do to confirm?
- Stimulation tests
- Suppression tests
- Stimulation test
- MRI
Thyroid gland
- Where is the thyroid?
- What is its vascularity like?
- It contains a large store of which two things?
- Which two iodine rich hormones does it secrete and what are the acronyms for both?
- What are the two types of cell in a thyroid gland and what do each produce?
- On each side of trachea
- Highly vascularised
- Thyroid hormones and iodine
- Tri-iodo-thyronine = T3
Thyroxine = T4 - Follicular cells make thyroid hormone
Parafollicular cells make calcitonin
Thyroid
- What 4 hormones does it make?
- What is the difference between T3 and T4?
1. Tri-iodo-thyronine = T3 = active Reverse T3 = inactive Thyroxine = T4 Calcitonin 2. T3 is the active form T4 acts as the plasma reserve
Thyroid hormones
- What do thyroid hormones stimulate in most tissues?
- What 2 things does this lead to?
- What 2 types of metabolism do thyroid hormones do?
- What role do these hormones play in growth?
- What role do these hormones play in cardiovascular system?
- What role do these hormones play in the CNS?
- Metabolic activities
- Increase in metabolic rate and increase in body heat production
- Lipid metabolism and carbohydrate metabolism
- Normal growth in children
- Increase heart rate and vasodilation
- Alterations in mental state
Thyroid
1. What 4 sites of action does T3 have?
- Cell membrane, mitochondria, nucleus and neonatal cells
HPT axis
- What does the hypothalamus release?
- What does the anterior pituitary release?
- Where does it go? Stimulating what cells?
- What is released?
- What two points does high T3 feed back into?
- What 4 things stimulate the hypothalamus?
- What stimulates the pituitary gland?
- What 4 things inhibits the pituitary gland?
- TRH
- TSH
- Thyroid gland, stimulating thyroid follicular cells
- T3 and T4
- Hypothalamus and anterior pituitary
- Cold, stress, low blood levels of T3 and T4, and low metabolic rate
- Estrogens
- Cytokines, somatostatin, dopamine and glucocorticoids
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
- Done by follicular cells, against electrochemical gradient
- Thyroglobulin (TGB) synthesised in vesicles, exocytosis, colloid
These vesicles express thyroperoxidase (TPO), as soon as membrane fuses, it’s released - 2 iodides, oxidation by TPO, iodine, binds to tyrosine
- Iodination of tyrosine residues to T1 then T2 by TPO
- Coupling/conjugation of T1 and T2 to T3 and T4
- Pinocytosis and lysosomal digestion of TGB- so follicular cells can release thyroid hormones (T3 and T4)
- T3 and T4 secreted into blood, transported mainly by thyroxine binding globulin
- Give some examples of symptoms in hyperthyroidism…
- Give some examples of symptoms in hypothyroidism…
- Give an example of hyperthyroidism
- Tachycardia, warm moist skin, increased appetite, weight loss, anxiety and tremor + goitre
- Bradycardia, dry thin hair and skin, fatigue and depression + goitre
- Graves’ disease
HPG axis basic:
- What does the hypothalamus release?
- What 2 things does the anterior pituitary release?
- What 5 things can influence GnRH secretion?
- What is the pulsatile secretion of GnRH like prepuberty, at puberty and in later life?
- GnRH
- LH and FSH
- Stress, exercise and diet, testosterone, progesterone and estradiol
- Prepuberty = infrequent
Puberty = sharp increase
Later life = no clear secretion
Gonadotrophins
- What type of hormone are LH and FSH?
- What are the 3 main functions of gonadotrophs?
- Males: What enzyme does LH activate in testosterone synthesis?
- Males: FSH stimulates the maturation of what in the Sertoli cells?
- Females: what 3 things do LH and FSH do?
- Glycoprotein hormones
- Control of sexual differentiation, steroid hormone synthesis and gametogenesis
- Desmolase
- Spermatozoa
- Estrogen biosynthesis, regulate menstrual hormones and stimulate follicle development
HPG axis in males
- What testes cells does LH act on?
- What does this produce?
- What two things can this inhibit?
- What testes cells does FSH act on? What else synergistically acts on these cells?
- What do these cells produce?
- What two things combine to finally give spermatogenesis?
- When sufficient spermatogenesis has been achieved, which cells produce what that will inhibit further FSH release?
- Leydig cells
- Testosterone
- Hypothalamus and anterior pituitary
- Sertoli cells along with testosterone
- ABP = androgen binding protein
- Testosterone and ABP
- Sertoli cells release inhibin
HPG axis in females
- What does the hypothalamus produce?
- What two things does the anterior pituitary produce?
- Both of these act where?
- What is released at this place that can inhibit FSH release?
- What process happens next, what does it lead to, and what does it end in if there is no fertilisation?
- What other thing is released at that place? This has a positive and a negative effect on what part of the process?
- GnRH
- LH and FSH
- Ovaries
- Inhibin
- Ovulation - progesterone - menstruation
- Estrogens - on the hypothalamus