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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
Give examples of glycoprotein hormones
LH, FSH, hCG, TSH
26
What happens with pulsatile release of GnRH
Release of LH and FSH (vice versa for sustained release)
27
What are steroid hormones made from
Cholesterol
28
What does PLC do
Breaks down membrane phospholipid
29
What does DAG do
Increase PKC
30
What does IP3 do
Release Ca2+
31
What does PKC do
Increase protein phosphorylation
32
Where is GLUT4 found
Adipose and striated muscle tissue
33
Describe insulin binding
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
Describe steroid receptor mechansim
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
Where are catecholamines stored
Secretory granule or vesicle, circualte in free form
36
Where are thyroid hormones stored
Formed within thyroglobulin, stored in colloid. Circulate in bound form
37
Where are proteins stored
Circulate largely in free form Stored in secretory granule, released by exocytosis triggered by Ca2+ Contents released and granule recycled
38
Which hormones are hydrophilic
Catecholamines and peptide hormones, do not associate with plasma protein
39
Where are steroid hormones stored
Formed from cholesterol, multi enzyme biosynthesis Circulate mainly in bound form Not stored Biosynthesis involves mitochondria and smooth ER
40
Describe anterior lobe of the pituitary
Pars distalis, pars tuberalis - endocrine cells
41
What hormones are produced in the anterior pituitary and from what cells
``` Corticotroph - ACTH Gonadotroph - FHS, LH Lactotroph - Prolactin Somatotroph - GH Thyrotroph - TSH Melanocyte stimulating hormone ```
42
Describe posterior lobe of the pituitary
Pars nervosa, infundibulum (pituitary stalk) - neurocrine cells
43
List the hypothalamic hormones
``` 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
Describe hormone production in males
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
What does prolactin do
Increased secretion during pregnancy and lactation Release controlled by hypothalamic hormones In pregnancy promotes additional breast development Post-partum stimulates milk production
46
What releases and what inhibits prolactin
Prolactin inhibitory factor - dopamine | Prolactin releasing factor - TRH
47
Describe posterior pituitary hormones
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
Describe oxytocin's mechanism of action
Suckling -> nipple mechanoreceptors -> hypothalamus -> posterior pituitary í oxytocin -> stimulation of myoepithelial cells -> milk ejection
49
How does AVP maintain blood pressure
Fluid balance - increased water re-absorption | Blood vessels - vasoconstriction
50
What does hyperprolactinaemia cause
Galactorrhoea - milk secretion from breast Gynaecomastia - excess breast growth n males Infertility - males and females
51
What is the treatment for hyperprolactinaemia
D2 agonists (cabergoline, bromocriptine)
52
How is infertility treated
Often caused by hyperprolactinaemia | Prolactin causes milk production and suppresses menstrual cycle
53
Describe GH synthesis and release
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
What are the actions of growth hormone
``` 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
What factors stimulate GH secretionn
Physiological: exercise, stress, sleep, postprandial glucose decline Pharmacological: drug induced hypoglycaemia, aa infusions, small peptide hormones, monoaminergic stimuli
56
What happens with GH hypersecretion
Gigantism before fusion of epiphyses | Acromegaly (typically enlargement of hands and feet) after fusion of epiphyses - greatly enhanced basal levels
57
What is the treatment of GH hypersecretion
``` Trans-shpenoidal surgery Bromocriptine/carbegoline - D2 agonists Octreotide - long acting somatostatin Lanreotide - analogues SSTR2 agonists Pasireotide - SSTR5 agonist ```
58
What happens with GH hyposecretion
Short stature before fusion of epiphyses | Adult growth hormone deficiency after fusion of epiphyses
59
What is the treatment for GH hyposecretion
Treatment with recombinant hGH (somatropin) or recombinant HIGF-1 (mecasermin)

Human Development (9 decks)

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