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Baz Y2 Semester 1 > Week 5 Endocrinology Intro > Flashcards

Week 5 Endocrinology Intro Flashcards

1
Q

What is the difference between and endocrine and exocrine gland?

A

Endocrine glands:

  • Do not have ducts, products are secreted directly into blood:
    e.g. pituitary, thyroid, adrenal, parathyroid glands, gonads (testis & ovaries)

Exocrine glands:

  • Products secreted via ducts to epithelial surfaces inside or outside the body:
    e.g. sweat, salivary, mucus, mammary gastric, prostate glands, liver bile duct

Some glands, e.g. pancreas, do both:
Endocrine:
insulin, glucagon, somatostatin & pancreatic polypeptide
Exocrine:
digestive enzymes secreted via pancreatic duct to the small intestine

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2
Q

What are the two types of endocrine signalling?

A

‘Classical’ endocrine signalling:
hormone carried by blood
to receptors on ‘target’ cells

Intracrine signalling:
inactive prohormone enters a cell
activated intracellularly
(e.g. sex steroids)

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3
Q

A hormone which is an example of classical endocrine signalling?

A

Thyroxine

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4
Q

A hormone which is an example of intracrine signalling?

A

Testosterone/ Oestrogen

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5
Q

What are the two subtypes of endrocrine signalling where hormones diffuse straight through fluid in tissues rather than the blood?

A

Paracrine (local) signalling:
hormone diffuses through tissue fluids …
to receptors on ‘target’ cells

Autocrine (local) signalling:
hormone diffuses through tissue fluids …
to receptors on the same cell

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6
Q

Difference between peptide, steroid and amine hormones?

A

Peptide hormones are peptides and are water soluable

Amine hormones bind to plasma proteins

Steroid protiens also bind to plasma proteins but contain a cholesterol backbone and can pass through the lipid membrane of a cell

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7
Q

Give an example of a steroid hormone?

A

Testosterone and Oestrogen

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8
Q

Give two examples of amine hormones

A

Adrenaline and thyroxine

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9
Q

Give an example of a peptide hormone

A

Adrenocorticotropic hormone (ACTH)

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10
Q

What is the diffuse endrocrine system?

A

Anything that has something to do with hormones that isn’t either the HP axis or the classic endocrine organs which interact with the HP axis

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11
Q

Signalling hormones or End Organ hormones - which has a shorter half life?

A

‘Signalling’ hormones:
short half-life - only a few mins
‘End-organ’ hormones:
long-lived - hours to days

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12
Q

Where are hormones broken down?

A

Broken down int he liver and kidneys

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13
Q

How does metabolism affect hormone levels?

A

The rate at which hormones are broken down is dependent on metabolism

If metabolism is increased then hormones go down and they are broken down faster

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14
Q

What is the main interface between the central nervous system and the endocrine system?

A

Hypothalamus

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15
Q

What is the difference in the way that the anterior and posterior pituitrary recieve signals?

A

The anterior pituriary recieves signals via hormones in the portal system from the hypothalamus

The posterior has a direct neural connection with the thalamus

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16
Q

Complete this statement about the anterior pituitrary cells and corresponding hypothalamic releasing hormones

CRH: Corticotropin-releasing hormone
GNRH: Gonadotrophin releasing hormone
TRH: Thyrotropin-releasing hormone
DA: Dopamine
GHRH: Growth hormone-releasing hormone

A
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17
Q

Complete this statement about the anterior pituitrary cells and corresponding hypothalamic releasing hormones

A

CRH: Corticotropin-releasing hormone
GNRH: Gonadotrophin releasing hormone
TRH: Thyrotropin-releasing hormone
DA: Dopamine
GHRH: Growth hormone-releasing hormone

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18
Q

Complete this statement about which anterior pituitary hormones are released by which cells

A

ACTH: Adrenocorticotropic hormone
TSH: Thyroid stimulating hormone
FSH&LH: Follicle stimulating hormone & Luteinising hormone
GH (somatotrophin): Growth hormone
PRL: Prolactin

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19
Q

Complete this statement about which anterior pituitary hormones are released by which cells

ACTH: Adrenocorticotropic hormone
TSH: Thyroid stimulating hormone
FSH&LH: Follicle stimulating hormone & Luteinising hormone
GH (somatotrophin): Growth hormone
PRL: Prolactin

A
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20
Q

What two hormones are made in the posterior pituitary?

A

Oxytocin and Vasopressin

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21
Q

Fill in the target organs and corresponding physiological or hormonal resonse

A
22
Q

Describe the general levels of aterior pituitary hormone and target gland hormone you would see with a hormone producing tumour in the target gland

A
23
Q

Describe the general levels of aterior pituitary hormone and target gland hormone you would see with a hormone producing tumour in the anterior pituitary

A
24
Q

Describe the general levels of aterior pituitary hormone and target gland hormone you would see with target gland failure

A
25
Q

Describe the general levels of aterior pituitary hormone and target gland hormone you would see with anterior pituitary failure

A
26
Q

Which is these statements applies to Hypothalamic hormones, Pituitary hormones or Target tissue hormones:

Hormones rarely measured in plasma (measure by petrosal sinus sampling)

Hormones often measured in plasma for
diagnosis

Hormones measured in plasma for diagnosis
AND to monitor hormone reduction or replacement

A

Hormones rarely measured in plasma (measure by petrosal sinus sampling) - Hypothalamic hormones

Hormones often measured in plasma for diagnosis - pituitary hormones

Hormones measured in plasma for diagnosis AND to monitor hormone reduction or replacement - target tissue hormones

27
Q

What are steroid hormones made from?

A

Cholesterol

28
Q

What is the key concept for how steroids are made?

A

Cholesterol side groups are cleaved or modified.

The hydrophobic 6 carbon side chain is removed making steroid hormones more water soluble than cholesterol

29
Q

What are the 6 main endogenous steroid hormone’s we have to know about

A

Aldosterone
Cortisol
Androstenedione
Progesterone
Testosterone
Oestrogen

30
Q

Out of these 6 steroid hormones which ones are adrenal and which are gonadal:

Aldosterone
Testosterone
Androstenedione
Progesterone
Cortisol
Oestrogen

A

Adrenal:

Aldosterone
Cortisol
Androstenedione

Gonadal:

Progesterone
Testosterone
Oestrogen

31
Q

What is an axample of a mineralocorticoid?

A

Aldosterone

Regulates sodium/potassium

32
Q

What is an example of a glucocortcoid?

A

Cortisol

glucose synthesis
protein & lipid metabolism
inflammation, immune response

33
Q

What is an example of an adrenal androgen?

A

Androstenedione

Fetal steroids & growth

34
Q

What is the group of enzymes involved in the cleaving or modifying cholesterol side groups during steroidgenesis?

A

cytochrome P450s

Clue P45 is what you get when you leave a job, so cholesterol gets this when it leaves being cholesterol

35
Q

What does cholesterol side chain cleavage enzyme do?

A

P450scc converts cholesterol into pregnenolone which is the first step in steroidgenesis

36
Q

What type of enzyme is involved in interconverting steroid from active to inactive form?

A

Steroid dehydrogenases/reductases

They come in pairs and convert steroid form active forms to inactive forms

37
Q

What is the purpose of inactivating hormones or binding the active ones to plasma proteins?

A

It saves them for the target tissues.

Bound + inactive hormones are transported in the plasma hormones are re-activated in target tissues

38
Q

Adosterone has a classical genomic steroid mechanism but also has a non-genomic mechanism mimicing that of a peptide or amine hormone.

What are these functions?

A

Kindneys:

Slow action (>30 mins-48hr)
Aldosterone-regulated synthesis of kidney epithelial sodium channel (ENaC) subunits

Rapid signalling (< 1 min)
Aldosterone-mediated vasoconstriction of vascular smooth muscle & endothelial cells

39
Q

What are the two structures of the adrenal glands?

A

Cortex: 80-90% of normal gland
Make steroid hormones:
Mineralocorticoids
Glucocorticoids
adrenal androgens

Medulla: 10-20% of normal gland
Make catecholamines:
adrenaline (epinephrine)
noradrenaline (norepinephrine)

40
Q

What part of the adrenal gland is involved in the hypothalamic-pituitary-adrenal (HPA) axis

A

Adrenal cortex, specifically the zona fasciculata and zona reticularis as it is cortisol and androstenedione that is released in response to ACTH

41
Q

The adrenal cortex can be subdivided into what?

What do each of these parts make?

A

zona glomerulosa (ZG) - mineralocorticoids

zona fasciculata (ZF) - glucocorticoids

zona reticularis (ZR) - adrenal androgens

42
Q

In a diurnal circadian rythym when is ACTH highest and when is Cortisol highest?

A

Diurnal CRH release regulates ACTH release:
high in the early morning (04.00-08.00)
lower later in the day

ACTH regulates cortisol synthesis:
High on waking (06.00-10.00)
lower later in the day (with ‘stress’ activity spikes)
lowest in the middle of the night

43
Q

Metabolically how does the action of cortisol oppose that of insulin?

A

Generally speaking it opposes the action of insulin

Anabolic:
Increased gluconeogenesis & liver glucose output
Catabolic:
Inhibition of glucose uptake by peripheral muscle & fat tissue
Immune system suppression
Increased muscle protein breakdown
Increased fat breakdown
Increased bone resorption
Increased appetite & central fat deposition

44
Q

How is androstenedione converted in oestrogen and testosterone?

A

Intracrine conversion to testosterone & oestradiol in peripheral tissues

45
Q

What are the main roles of Dehydroepiandrosterone (this is whats is actually made in the ZR and androstenedione is an intermediary to the final androgens)

A

Regulates secondary sexual characteristics:

  • Facial & body hair, pelvic build, upper body musculature, body fat composition, etc.

Prenatal DHEA production:

  • Role in maintaining oestrogenic environment
  • Role in foetal development??

Postnatal DHEA production:

  • Role in initiation of puberty (adrenarche)??
  • Main source of androgens & post-menopausal oestrogen in females
  • Role in longevity; elixir of life??
46
Q

In the gonadal hormone feeback loop what is the extra hormone that inhibits the hypothalamus and pituitary ?

A

Inhibin

47
Q

What is desmopressin?

A

A synthetic vassopressin

48
Q

What is urine osmolality?

A

The concentration of chemicals in urine.

49
Q

What another name for anti-diuretic hormone?

A

Vasopressin

49
Q
A

Baz Y2 Semester 1 (17 decks)

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