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PA10309 > Endocrine > Flashcards

Endocrine Flashcards

1
Q

What is hyperthyroidism?

A

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

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2
Q

What is the morning after pill?

A

A high dose of progestogen

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3
Q

What are SERMs?

A

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

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4
Q

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

A

Type 1 - The antibodies attack the pancreas cells

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5
Q

What is a circadian rhythm?

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

A

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

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6
Q

What are Cortisol and Aldosterone types of?

A

Steroid Hormones

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7
Q

What type of cells produce calcitonin in the thyroid gland?

A

C cells

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8
Q

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

A

Glucocorticoids (eg, cortisol)

Mineralocorticoids (eg, aldosterone)

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9
Q

What types of thyroid hormones are active?

A

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

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10
Q

What is the main effect of glucocorticoids?

A

Increase plasma glucose (indirectly)

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11
Q

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

A

Deficit - Can cause dwarfism and aceelerate aging

Excess - Can cause gigantism and acromegaly

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12
Q

From what are Indoleamines derived from?

A

Tryptophan

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13
Q

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

A

Seminiferous Tubules in the testes

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14
Q

What are the main actions of progesterone?

A

Produced in the Luteal Phase

Decreases GnRH production

Increases the viscosity in cervical mucous

Increases basal temperature

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15
Q

What is in the periventricular zone of the hypothalamus?

A

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

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16
Q

What effect does Thyroid Stimulating Hormone (TSH) have?

A

Increases the uptake of iodine from blood (pump mechanism)

More Thyroid hormone synthesis via the enzmye iodinase

More thyroglobulin breaks down by lysosomal proteases

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17
Q

What effect does aldosterone have on reabsorption of sodium?

A

It increases the activity of sodium channels in the tubular membrane

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18
Q

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

And how does it become iodinated?

A

T3 and T4

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

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19
Q

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

A

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

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20
Q

What receptors do thyroid hormones bind to?

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

A

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

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21
Q

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

A

Tyrosine

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22
Q

What is the downside of endocrine communication?

But why can this also be a good thing?

A

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

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23
Q

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

Posterior Pituitary

Anterior Pituitary

A

Post - Pars Nervosa

Ant - Pars Distalis

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24
Q

What does insulin trigger the liver to do?

A

Convert glucose to glycogen (glycogenosis)

Convert sugars to fats

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25
Q

Explain how the uterine wall contracts during birth

A

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

26
Q

Explain how progesterone-only contraceptives (POC) work

A

Cervical mucus becomes thick and sticky

Endometrium changes to make implantation less likely

Weak negative feedback inhibition of LH

Must be taken continuously

27
Q

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

A

Counter-regulatory

28
Q

How do progesterone receptors work?

A

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

29
Q

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

And what cells are sperm formed>

A

Leydig Cells (Intersitial)

Sertoli Cells

30
Q

What are the 3 layers of the uterine wall?

A

Myometrium - Outer, muscular layer

Endometrium - Thin, inner layer

Perimetrium - Meets the abdominal cavity

31
Q

What is the hypothalamic-pituitary axis?

A

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

32
Q

Why does the menopause occur?

A

There are few primoridal folicles remaining

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

33
Q

What is the main precursor for androgens?

A

Cholesterol (as a steroid hormone)

34
Q

What type of receptors will steroid hormones usually bind to?

And why?

Also what effect will this have?

A

Intracellular receptors –> Effecting gene transcription

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

35
Q

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

A

Aldosterone and Cortisol

36
Q

How does oestrogen receptors work?

A

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)

37
Q

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

A

T4 = DIT + DIT

T3 = DIT + MIT

DIT = Di-iodotyrosine

MIT = Mono-iodotyrosine

38
Q

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

And what happens if its over or under active?

A

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

39
Q

Outline the hormonal control of Ovarian function?

A

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

40
Q

Explain the order of oogenesis

A

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)

41
Q

How does insulin cause an increase in glucose uptake?

A

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

42
Q

How are glucocorticoids (cortisol) secreted?

A

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

43
Q

How does combined oral contraception (COCs) work?

A

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

Progesterones thicken the cervical mucus, and thins the endometrium

44
Q

What does insulin decrease from the plasma?

And what does Glucagon increase from the plasma?

A

Insulin decreases….

  • Glucose
  • Amino Acids
  • FFA’s

Glucagon increases….

  • Glucose
  • Ketones
45
Q

Which chain of insulin is biologically active?

A

B-Chain

46
Q

How is insulin secreted?

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

A

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

47
Q

What is the difference between primary and secondary glands?

A

Primary = Main purpose is to make hormones

Secondary = Makes hormones as a ‘side job’

48
Q

What are the 3 phases of the menopause?

A

Perimenopause - Fluctuation of hormone levels

Menopause - Oestrogen levels drop

Postmenopause - Oestrogen levels drop even further

49
Q

What is hypothyroidmism?

A

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

50
Q

What is mean by “pulsatile GnRH release”

A

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

51
Q

What causes difference in growth hormone secretion?

A

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

52
Q

What do Delta-cells produce and release?

A

Somatostatin

This suppresses GI motility, insulin and glucagon

53
Q

Outline the hormonal control of the testes

A

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

54
Q

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

A

A prohormone or hormone

55
Q

Explain the stages of the uterine cycle

A

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

56
Q

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

A

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

57
Q

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

A

They have effects on metabolism

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

58
Q

What type of receptor does insulin bind to?

A

Tyrosine-Kinase Receptors

Leading to autophosphorylation –> and intracellular effects

59
Q

Describe the pathway that causes T3 and T4 to be secreted

A

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

60
Q

What are the 3 major chemical classes of hormones?

A

Amino Acids/Amines

Peptides/Proteins

Steroids

61
Q

What are IGFs / Somatomedians?

A

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)

62
Q

What is released from the adrenal medulla?

And how is it secreted?

A

Adrenaline/nor-adrenaline

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

PA10309 (9 decks)

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