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?
What type of cells produce calcitonin in the thyroid gland?
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?
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...
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)
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?
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?
- Amino Acids
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?
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?
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