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What is hyperthyroidism?

When there is an increased rate of secretion from the thyroid gland, so it increases in size (swells)


This causes a decrease in body weight, irritability, and an inability to deal with excess heat


What is the morning after pill?

A high dose of progestogen


What are SERMs?

Selective Estrogen Receptor Modulators


Its conformation is different depending on the binding of DNA/transcription factors


Different conformers will cause pro-oestrogenic / partially oestrogenic / anti-oestrogenic effects


Which type of diabetes mellitus is a type of auto-immune disease?

Type 1 - The antibodies attack the pancreas cells


What is a circadian rhythm?


And what can cause fluctuations from the mean average of a hormone?

A 24hr pattern that is similar day in, day out


Fluctuations can be caused by other hormones that promote or inhibit the hormone in question


What are Cortisol and Aldosterone types of?

Steroid Hormones


What type of cells produce calcitonin in the thyroid gland?

C cells


What are the two types of steroid hormones that are prodcued in the adrenal cortex?

Glucocorticoids (eg, cortisol)


Mineralocorticoids (eg, aldosterone)


What types of thyroid hormones are active?

Unbound only


T3 is the most active (due to more being unbound)


Most of each are bound to thyroid binding globulin or thyroid binding prealbumin


What is the main effect of glucocorticoids?

Increase plasma glucose (indirectly)


What are the effects of a defecit or excess in Growth Hormone

Deficit - Can cause dwarfism and aceelerate aging


Excess - Can cause gigantism and acromegaly


From what are Indoleamines derived from?



Where in the male reproductive system is sperm and hormones produced?

Seminiferous Tubules in the testes


What are the main actions of progesterone?

Produced in the Luteal Phase


Decreases GnRH production


Increases the viscosity in cervical mucous


Increases basal temperature


What is in the periventricular zone of the hypothalamus?

Suprachiamatic neurones - Recieves retinal innervation


Other cells sends input/output to para/sympathetic output neurones in the spinal cord to control the ANS


Neurosecretory cells control the release of regulatory hormones to the pituitary gland


What effect does Thyroid Stimulating Hormone (TSH) have?

Increases the uptake of iodine from blood (pump mechanism)


More Thyroid hormone synthesis via the enzmye iodinase


More thyroglobulin breaks down by lysosomal proteases


What effect does aldosterone have on reabsorption of sodium?

It increases the activity of sodium channels in the tubular membrane


What, with the use of enzymes, does iodinated thyroglobulin release in folicle cells in the thyroid gland?


And how does it become iodinated?

T3 and T4


It becomes iodinated in the folicle cell, which then leaves by exocytosis


What is the main feature that causes a gland to be endocrine?

They are ductless, and so secrete chemicals directly into the blood stream


What receptors do thyroid hormones bind to?


And how do they affect BMR and protein/carbohydrate/fat metabolism

Nuclear receptors --> so effect gene transcription


BMR - They increase the size and number of mitochondria --> causing an increase in ATP production

This causes Na/K ATpase to work more --> releasing more heat


Protein - Altering gene transcription causes more protease synthesis (at high doses) --> and so protein breakdown

Increases protein synthesis (at low doses)


Carbohydrate - Changes in gene transcription will increase the release of insulin (at low doses) or stimulate glycogenolysis (at high doses)


Fat - Changing gene transcription increase the production of lipase, and so increases lipid metabolism


From what are both Cathecholamines (nor/adrenaline) and Thyroid Hormones derived from?



What is the downside of endocrine communication?


But why can this also be a good thing?

Because many receptors are used, and its done in the blood, it is a very slow process (especially if effecting gene transcription)


However this can mean that any effects are maintained for a long period of time


What are the names of the tissues that make up the...

Posterior Pituitary

Anterior Pituitary


Post - Pars Nervosa


Ant - Pars Distalis


What does insulin trigger the liver to do?

Convert glucose to glycogen (glycogenosis)


Convert sugars to fats


Explain how the uterine wall contracts during birth

The posteriour pituitary releases oxytocin --> which causes uterine contraction


This causes prostaglandins to be produced, which positively feedbacks to make more contractions


The contractions increase the cervical stretch --> which positively feedbacks on oxytocin production, and uterine contraction


Explain how progesterone-only contraceptives (POC) work

Cervical mucus becomes thick and sticky


Endometrium changes to make implantation less likely


Weak negative feedback inhibition of LH


Must be taken continuously


Insulin and glucagon can be described as "_____________+ hormones, due to the fact that they give opposite effects to each other



How do progesterone receptors work?

It binds to nuclear receptors, changing gene transcription


There are two isoform of the receptor, PR-A and PR-B

PR-B mediates the stimulatory effects of progesterone


In the testes, what cells produce hormones such as testosterone?


And what cells are sperm formed>

Leydig Cells (Intersitial)


Sertoli Cells


What are the 3 layers of the uterine wall?

Myometrium - Outer, muscular layer


Endometrium - Thin, inner layer


Perimetrium - Meets the abdominal cavity


What is the hypothalamic-pituitary axis?

The hypothalamus secretes many hormones to control homeostatic functions --> with only little amount of homrone needed to have a large effect on the pituitary


The pituitary gland then acts as an "output organ", initiating the response --> this occurs due to the hypothalamus indirectly controlling it


This is a one-way process


Why does the menopause occur?

There are few primoridal folicles remaining


More LH/FSH (gonadotrophins) are released due to a loss of negative feedback loops



What is the main precursor for androgens?

Cholesterol (as a steroid hormone)




What type of receptors will steroid hormones usually bind to?

And why?

Also what effect will this have?

Intracellular receptors --> Effecting gene transcription


This is because steroid hormones are lipophillic and so can pass through membranes easily


What are the two main steroid hormones that are secreted from the adrenal cortex?

Aldosterone and Cortisol


How does oestrogen receptors work?

Oestrogen binds to the recptors, causing a conformational change (due to the dissociation of heat shock proteins)


The receptor undergoes dimerization, increasing the affinity for DNA --> allowing the oestrogen-receptor complex to bind to specific DNA sites (Oestrogen response/recognition elements)


What are the precursors for Thyroxine (T4) and Triiodothyronine (T3)?

T4 = DIT + DIT


T3 = DIT + MIT


DIT = Di-iodotyrosine

MIT = Mono-iodotyrosine


What is the role of colloid in the thyroid glands follicle?


And what happens if its over or under active?

It is where thyroglobulin is stored


Over - There are low colloid levels, so a reduced production of TSH


Under - There are high colloid levels, so there is an increased production of TSH


Outline the hormonal control of Ovarian function?

The hypothalamus secretes GnRH, causing the anterior pituitary to secrete FSH and LH


LH stimulates Theca cells to secrete androgens, which produces Oestrogen --> which negatively feedbacks on the hypothalamus (GnRH) and the pituitary (LH)


FSH stimulates Granulosa cells to secrete Inhibit, which negatively feedbacks on FSH only


Explain the order of oogenesis

Primary folicles in the ovary become matured by FSH, causing the intermediate cells to produce oestrogen


Ovulation then occurs when there is a surge of LH, then the corpus leutem is formed (which secretes progesterone if a sperm is present)


How does insulin cause an increase in glucose uptake?

Insulin binds to RTKs (receptor tyrosine-kinases) on the membranes of cells


This causes the cell to express more glucose transporters at the cell surface --> causing more glucose to be uptaken


How are glucocorticoids (cortisol) secreted?

The hypothalamus releases Corticotrophin Releasing Hormine (CRH)


This stimulates the pituitary to release Adreno Cortico Trophic Hormone (ACTH) --> causing the adrenal cortex to secrete Cortisol


This forms a negative feedback loop --> reducing the stimulation of the hypothalamus


How does combined oral contraception (COCs) work?

Oestrogen suppreses ovulation by inhibiting the release of LH/FSH (natural negative feedback loop)


Progesterones thicken the cervical mucus, and thins the endometrium


What does insulin decrease from the plasma?


And what does Glucagon increase from the plasma?

Insulin decreases....

- Glucose

- Amino Acids

- FFA's


Glucagon increases....

- Glucose

- Ketones


Which chain of insulin is biologically active?



How is insulin secreted?


Also what type of drug can increase the amount of insulin that is released?

Glucose moves into the cell --> Glucose-6-phosphate

This glucose is used to make lots of ATP, closing K+ channels

This causes depolarization --> leading to Ca2+ channels opening

The influx of calcium causes insulin to leave by exocytosis


Sulfonylureas can cause the closure of the K+ channels


What is the difference between primary and secondary glands?

Primary = Main purpose is to make hormones


Secondary = Makes hormones as a 'side job'


What are the 3 phases of the menopause?

Perimenopause - Fluctuation of hormone levels


Menopause - Oestrogen levels drop


Postmenopause - Oestrogen levels drop even further


What is hypothyroidmism?

Where there is a low level of T4, but high levels of TSH


This causes an increase in body weight, fatigue, and the inability to deal with the cold


What is mean by "pulsatile GnRH release"

Stimulation of the hypothalamus causes GnRH release around every 60-90 mins from the pituitary


What causes difference in growth hormone secretion?

Released due to Growth Hormone-Releasing Hormone (GHRH)


Release is decreased due Growth Hormone-Inhibiting Hormone (GHIH/Somatostatin)


Factors such as Exercise, Stress and Sleep can have an impact


What do Delta-cells produce and release?



This suppresses GI motility, insulin and glucagon


Outline the hormonal control of the testes

The hypothalamus secretes Gonadotrophin-Releasing Factor (GnRH) --> causing stimulation of the anterior pituitary to secrete FSH and LH


LH stimulates Leydig cells to produce testosterone, this has a negative feedback on LH and secretion of GnRH


FSH stimulates Sertoli cells to stimulate spermatogenesis and Inhibin, this has a negative feedback on FSH only


For protein and peptide hormones, what is released from the cell by exocytosis?

A prohormone or hormone


Explain the stages of the uterine cycle

Menses - This is when menstruation occurs (degredation of endometrium


Proliferative - The endometrium is restored, with a surge of Oestrogen


Secretory - There is a peak of progestrone and inhibin due to the enlargement of endometrial glands


Explain what Growth Hormones are/do (eg, somatotrophin)

Growth hormones are a type of polypeptide/protein hormones that act at RTK's


Increase cell size

Stimulate Protein synthesis --> via increases in translation/transcription and AA uptake

Stimulate Fat utilization

Increases blood glucose


What is the effect of adrenaline/nor-adrenaline that is secreted from the adrenal medulla?

They have effects on metabolism

Only little amounts of adrenaline is needed to have alarge effects (opposite for noradrenaline)


What type of receptor does insulin bind to?

Tyrosine-Kinase Receptors


Leading to autophosphorylation --> and intracellular effects


Describe the pathway that causes T3 and T4 to be secreted

Tryrotropin Releasing Hormone (TRH) is released from the hypothalamus


This stimulates Thyroid Stimulating Hormone (TSH) to be released from the anterior pituitary --> causing an increase of iodine uptake


This causes more T3 and T4 to be synthesised --> T4 then acts as a prohormone for T3


The production of T3 and T4 stimulates somatostatin to be released from the hypothalamus --> which inhibits TSH


The production of T3 and T4 also directly inhibits TRH and TSH


What are the 3 major chemical classes of hormones?

Amino Acids/Amines






What are IGFs / Somatomedians?

Insulin Growth Factors are small proteins that are produced in the liver as a result of growth hormones


These have a long half-life, allowing for the repsonse to occur for a long time (unlike GH)


What is released from the adrenal medulla?


And how is it secreted?



Secreted via the sympathetic NS (autonomic), and so Acetylcholine is used in preganglionic fibres --> the hormone then reaches the target organ via the drug