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Human Development > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

How does the Mullerian duct develop

A

Invagination of the intermediate mesoderm

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2
Q

Describe male sexual characteristic developement

A

Wolffian ducts persist (epididymis, vas deferens and seminal vesicles) - male internal reproductive organs
Male external genitalia

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3
Q

Describe female sexual characteristic developement

A

Mullerian ducts persist (uterine tubes, uterus, cervix and upper 1/3 of the vagina)- female internal reproductive organs

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4
Q

What is N45a1

A

encodes steroidogenic factor 1 - critical regulator of reproduction, upregulates transcription of SOX9 gene

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5
Q

What is dmrt1

A

located at end of 9th chromosome, dose sensitive transcription factor protein that regulates sertoli cells and germ cells (2 copies required for normal sexual development

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6
Q

What is SRY gene

A

adjacent to the centromeric portion of the PAR1 region (close to region of homology so may be duplicated/deleted)
SRY is sufficient to confer testes formation in a female

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7
Q

What is SOX9

A

important for teste formation so males require 2 copes, has capability to bind and regulate itself. Gene on chromosome 17

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8
Q

What is DAX1

A

inhibitor factor. Gene on X chromosome. Represses teste development, dose sensitive. Duplications lead to DSD in XY individuals

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9
Q

What is required for ovary formation

A

requires presence of germ cells and two X chromosomes

Wnt4;ctnnb1 - found on chromosome 1, promotes female sex development and regress male sex development

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10
Q

When does sex differentiation occur

A

8 weeks

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11
Q

How does male sex differentiation occur

A

Male: AMH (prevents Mullerian structures from development), testosterone stabilise Wolffian structures
Testosterone converted into DHT - promotes the development of genital tubercles, labioscrotal folds and urogenital sinus into penis, scrotum and prostate

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12
Q

What happens in the absence of male hormones

A

Wolffian structure regress

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13
Q

What does the genital tubercle become in females

A

Clitoris

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14
Q

What does the urogenital sinus become in females

A

Lower vagina

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15
Q

What do the labioscrotal folds become in females

A

Vuvlar

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16
Q

What is Klinefelter

A

47, XXY
Normal at birth, higher incidence of undescended testes, tall stature, small pea-sized testes, lack of secondary characteristics, gynaecomastia, infertility

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17
Q

What occurs with SRY translocations

A

Present after puberty with short stature, gynaecomastia, small testes, fertility issues
Male gender identity, treated with testosterone

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18
Q

What occurs with 5-alpha reductase deficiency (generates DHT)

A

Internal strctures male, variable appearance of external genitalia at birth, during puberty increased androgen levels lead to virilisation (masculinization) of external genitalia

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19
Q

What hormones at tyrosine derivatives

A

dopamine, adrenaline, thyroxine

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20
Q

How many aa is GnRH

A

10

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21
Q

How many aa is GHRH

A

44

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22
Q

How many aa is prolactin

A

198

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23
Q

What hormone is linked by disulphide bridge

A

Insulin

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24
Q

What are glycoprotein hormones

A

Alpha and beta chains with carbohydrate
Alpha chain - species specific
Beta chain - hormone specific

25
Q

Give examples of glycoprotein hormones

A

LH, FSH, hCG, TSH

26
Q

What happens with pulsatile release of GnRH

A

Release of LH and FSH (vice versa for sustained release)

27
Q

What are steroid hormones made from

A

Cholesterol

28
Q

What does PLC do

A

Breaks down membrane phospholipid

29
Q

What does DAG do

A

Increase PKC

30
Q

What does IP3 do

A

Release Ca2+

31
Q

What does PKC do

A

Increase protein phosphorylation

32
Q

Where is GLUT4 found

A

Adipose and striated muscle tissue

33
Q

Describe insulin binding

A

Ligand binds to alpha chain of the IR ectodomain
Leads to auto phosphorylation of various tyrosine residues within the intracellular TIC domain of the beta chain
Facilitates the recruitment of special adapter protein such as IR, SH2-b, APS and protein phosphatases

34
Q

Describe steroid receptor mechansim

A

Er alpha - oestrogen receptor alpha activates transcription
Er beta - oestrogen receptor beta inhibits transcription
HSP (heat shock protein, prevents interaction with DNA) - dissociated and the activated receptor-ligand complex translocated into the nucleus
Steroid receptor often form dimers
Complex acts as a transcription factor

35
Q

Where are catecholamines stored

A

Secretory granule or vesicle, circualte in free form

36
Q

Where are thyroid hormones stored

A

Formed within thyroglobulin, stored in colloid. Circulate in bound form

37
Q

Where are proteins stored

A

Circulate largely in free form
Stored in secretory granule, released by exocytosis triggered by Ca2+
Contents released and granule recycled

38
Q

Which hormones are hydrophilic

A

Catecholamines and peptide hormones, do not associate with plasma protein

39
Q

Where are steroid hormones stored

A

Formed from cholesterol, multi enzyme biosynthesis
Circulate mainly in bound form
Not stored
Biosynthesis involves mitochondria and smooth ER

40
Q

Describe anterior lobe of the pituitary

A

Pars distalis, pars tuberalis - endocrine cells

41
Q

What hormones are produced in the anterior pituitary and from what cells

A 
Corticotroph - ACTH
Gonadotroph - FHS, LH
Lactotroph - Prolactin 
Somatotroph - GH
Thyrotroph - TSH
Melanocyte stimulating hormone
42
Q

Describe posterior lobe of the pituitary

A

Pars nervosa, infundibulum (pituitary stalk) - neurocrine cells

43
Q

List the hypothalamic hormones

A 
Corticotropin releasing hormone
Gonadotropin releasing hormone
Prolactin releasing hormone - TRH
Prolactin inhibitory factor - dopamine
Growth hormone releasing hormone
GH release inhibiting hormone (somatostatin)
Thyrotropin releasing hormone
44
Q

Describe hormone production in males

A

Hypothalamus (GnRH) ->Anterior pituitary (FSH and LH)
FSH -> sertoli cells facilitate spermatogenesis ->production of inhibin to inhibit secretion of LH and FSH
LH ->leydig cells (increased production of testosterone)-> negative feedback to anterior pituitary and hypothalamus
LH and FSH stimulate spermatogenesis and testosterone secretion by the testes

45
Q

What does prolactin do

A

Increased secretion during pregnancy and lactation
Release controlled by hypothalamic hormones
In pregnancy promotes additional breast development
Post-partum stimulates milk production

46
Q

What releases and what inhibits prolactin

A

Prolactin inhibitory factor - dopamine

Prolactin releasing factor - TRH

47
Q

Describe posterior pituitary hormones

A

Synthesised with neruophysin as precursor in cell bodies in supraoptic nucleus and paraventricular nucleus of hypothalamus
Associated with neurophysin I (OXY) or neurophysin II (AVP)

48
Q

Describe oxytocin’s mechanism of action

A

Suckling -> nipple mechanoreceptors -> hypothalamus -> posterior pituitary í oxytocin -> stimulation of myoepithelial cells -> milk ejection

49
Q

How does AVP maintain blood pressure

A

Fluid balance - increased water re-absorption

Blood vessels - vasoconstriction

50
Q

What does hyperprolactinaemia cause

A

Galactorrhoea - milk secretion from breast
Gynaecomastia - excess breast growth n males
Infertility - males and females

51
Q

What is the treatment for hyperprolactinaemia

A

D2 agonists (cabergoline, bromocriptine)

52
Q

How is infertility treated

A

Often caused by hyperprolactinaemia

Prolactin causes milk production and suppresses menstrual cycle

53
Q

Describe GH synthesis and release

A

Partly acts by GH receptor and partly by synthesis of IGF in the liver
Release controlled by hypothalamic hormones (GHRH, somatostatin)
GH and IGF induce negative feedback

54
Q

What are the actions of growth hormone

A 
Growth of long bones until fusion of epiphyses
Increase in size of viscera
Anti-insulin effects
Metabolic effects related to growth
Anabolic for protein
Catabolic for fats and carbohydrates
55
Q

What factors stimulate GH secretionn

A

Physiological: exercise, stress, sleep, postprandial glucose decline
Pharmacological: drug induced hypoglycaemia, aa infusions, small peptide hormones, monoaminergic stimuli

56
Q

What happens with GH hypersecretion

A

Gigantism before fusion of epiphyses

Acromegaly (typically enlargement of hands and feet) after fusion of epiphyses - greatly enhanced basal levels

57
Q

What is the treatment of GH hypersecretion

A 
Trans-shpenoidal surgery
Bromocriptine/carbegoline - D2 agonists
Octreotide - long acting somatostatin 
Lanreotide - analogues SSTR2 agonists
Pasireotide - SSTR5 agonist
58
Q

What happens with GH hyposecretion

A

Short stature before fusion of epiphyses

Adult growth hormone deficiency after fusion of epiphyses

59
Q

What is the treatment for GH hyposecretion

A

Treatment with recombinant hGH (somatropin) or recombinant HIGF-1 (mecasermin)

Human Development (9 decks)

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