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Healthy Body > Endocrine System > Flashcards

Endocrine System Flashcards

1
Q

Example of amine hormones

A

Catecholamines: adrenaline, noradrenaline

Thyroid hormones: thyroxine, triiodothyronine

Melatonin (regulating sleep)

All derived from amino acids, eg tyrosine and tryptophan

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2
Q

Describe adrenal catecholamine synthesis pathway

A

Tyrosine –> L-DOPA (tyrosine hydroxylase)

L-DOPA–> dopamine (dopa decarboxylase)

Dopamine–> noradrenaline (dopamine- beta- hydroxylase)

Noradrenaline –> adrenaline ( phenylethanolamine N-methyl transferase)

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3
Q

Describe thyroid hormone synthesis pathway

A

Tyrosine -> mono iodotyrosine MIT -> di iodotyrosine DIT

DIT + DIT –> thyroxine T4

DIT + MIT –> triiodothyronine T3

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4
Q

3 examples of steroid hormones?

A

Adrenal hormones: cortisol, aldosterone.

Sex hormones: testosterone, estradiol (esterogen)

Vitamin D

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5
Q

Structure of steroid, what is it made from

A

Made from cholesterol

TETRA planar ring structure

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6
Q

3 Example of peptide hormones

A

Short AA chain: ADH, oxytocin
Polypeptide: insulin, prolactin,PTH, calcitonin, ANP,IGF1/2 (small proteins)
GROWTH HORMONES

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7
Q

Describe Peptide hormones synthesis

A

Product of genes in the cell nucleus, DNA-mRNA-polypeptide-protein
Transcription in nucleus, translation in cyto (pre hormone to prohormone)

to Golgi app to secretory vesicles (prohormone to hormone)

Storage (hormone)

and readily secreted by exocytosis. (Pro hormone and hormone)
Fusion with the membrane to blood stream

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8
Q

Types of hormone receptors

And the specificity

A

Cells only respond upon the presence of receptor for that hormone

Cells surface R
Intracellularly R (hormones)
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9
Q

Examples of cell surface R and type of hormone?

A

Adrenaline and GPCR (7 transmembrane protein R)

Insulin and RTK (pi-ed)

Stimulate intracellular signalling cascade

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10
Q

Example of intracellular R and type of hormone?

A

Cytosolic R and corticosteroid hormone

Activate gene transcription

In blood, the hormone binds to carrier proteins because not hydrophilic.
Steroid are Structurally able to cross lipid bilayer due to lipophilicity
Bind to cytosolic R -R-hormone complex- transfer to nucleus -bind to specific sequence of DNA- regulate gene transcription

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11
Q

Describe the pattern of hormone release

A

Circadian rhythm

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12
Q

4 types of endocrine disorders and an example for each

A

Hypo-secretion : type 1 diabetes

Hyper -secretion: pancreatic endocrine tumour

Hypo-responsive: insulin resistant type 2 diabetes (lack of functioning R)

Hyper -responsive: hyperthyroidism thyrotropin TSH R constitutive activation

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13
Q

What are the three major chemical class of hormones?

A

Amino acids/amines
Peptides and proteins
Steroid

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14
Q

Where is PTH made?

A

Chief cells of the parathyroid gland (x4) on thyroid gland

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15
Q

What are the effects of PTH

A

Increase plasma conc of Ca

Stimulate VitD synthesis

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16
Q

Which receptor does Ca act on parathyroid gland? (Short term regulation)

A

G protein coupled calcium sensing receptor (CaSR)

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17
Q

A fall in plasma Ca causes…

A

A rise in PTH secretion

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18
Q

What would happen if the plasma Ca level is too low?

A

The CaSR on parathyroid gland would not be activated. Secretion of PTH is stimulated. Inverse relationship

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19
Q

Where does VitD act on to inhibit PTH Secretion?

A

Act directly on the PTG to decrease preproPTH mRNA

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20
Q

What is PTH derived from?

A

PreproPTH, and proPTH

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21
Q

What’s the main effect of PTH? And effect on kidney?

A

INCREASE PLASMA CA2+

In kidney, it stimulates Ca reabsorption in distal tubule

Inhibits PO4^3- reabsorption in proximal tubule (Ca x Pi = constant)

Increase activity of 1 alpha hydroxylase and decreases 24- hydroxylase-> increase synthesis of VitD3

22
Q

What are the roles of
Osteoblasts
Osteoclasts

A

Bone building cells- laying down new bones and pack Ca into bones

Bone resorption (digestion) site, recycle/restore Ca into plasma

23
Q

2 Effects of PTH on bone?

A

1 stimulates rapid efflux of Ca from freely exchangeable calcium pool (osteocytes), inhibit osteoblasts laying new bones

2 slowly stimulates activity or osteoclasts to inveease bone resorption (Ca and Pi release)

24
Q

Why is effect of PTH on GI tract indirect?

A

Because GI tract has no parathyroid gland receptor, so can only be affected by indirectly increase VitD production

25
Q

What’s the effect of VitD on GI tract?

A

1 stimulates absorption of Ca and Pi

Effect is delayed >24hr and INDIRECT

26
Q

What’s the negative feedback regulation of plasma calcium

A

When Cp of Ca is low, G protein coupled CaSR senses low conc. parathyroid gland produces PTH.
PTH affects Kinney, bones, GI tract.
Restore Cp of Ca towards normal
Inhibition signal sent to parathyroid gland switch off PTH production

27
Q

What’s the extra cellular Ca2+ function?

A

NM CSA

Nerve function
Muscle contraction

Coagulation
Skeletal mineralisation
Activation of most cells types (signalling pathways) eg heart–> fibrillation

28
Q

What type of hormone a parathyroid hormone?

A

Peptide hormone : a single chain of polypeptide

29
Q

What’s the precursor of PTH?

A

Pre-proPTH, proPTH

30
Q

What’s the short term and long term regulation of PTH secretion?

A

Short term : a falls on Cp Ca2+ causes a rise in OTH secretion

Long term : 1a,25 dihydroxyvitaminD3 acts directly on the PTG to decrease pre-proPTH mRNA

31
Q

What’s the vitamin D binding protein called?

ONLY FREE FRACTION IS ACTIVE

A

Transcalciferin

32
Q

What’s 1a,25 dihydroxyvitamin D3?

Is it a steroid?

A

Active metabolite of VitD

A secosteroid - have steroid ring structure, lipophilic- get inside cells, nuclear R- change gene transcription.

33
Q

Where and how is 1a,25 OH2 vitD3 produced?

A

In kidney by 1a-hydroxylation of 25 (OH) VitD3

34
Q

Vitamins D3 is also called?

A

Cholecalciferol

35
Q

Describe the metabolism of 1a,25 (OH)2 vitD3

A

Skin- 7-dehydrocholesterol –> vitamin D3 (sunlight)

Liver- vitamin D3–> 25 hydroxyvitamin D3 (25 hydroxylase)

Kidney- 25 hydroxyvitamin D3–> 1a,25 (1a hydroxylase)

Blood - to target tissue, organ (SI)

36
Q

What are somatomedins?

A

Small proteins produced by the liver in response to GH
Insulin like growth factor
4 produced, somatomedin C most important
Long half life (20h) camp are to GH (

37
Q

What are the effect of growth hormone? Somatotropin

A 
SPF-C
Increase cell size, number, differentiation 
Stimulate protein synthesis
Stimulate fat utilisation 
Alter carbohydrate metabolism
38
Q

Growth hormone is a what hormone

A

Polypeptide hormone

39
Q

What receptor does peptide hormone act on?

A

Receptor tyrosine kinase RTK

40
Q

What are the effect of Gh?

A

Stimulate somatomedins IGF-1, IGF-2 production in liver.
IGF: growth E, increase cell size no differentiation
Increase protein synthesis
Bone growth

metabolic E, fat break down, increase Blood glucose

41
Q

What stimulate GH release

A

GHRH by ventromedial hypothalamus
Reduction in glucose AA and FFA
Exercise
Hypoglycaemia

42
Q

What factors affect GH release

A

GHRH, GHIH by ventromedial hypothalamus
Sleep, exercise, stress
Age

43
Q

What are the conditions associated with GH deficit?

A

Dwarfism - anterior pituitary dysfunction
-hereditary somatomedin deficit

Accelerated aging- loss of GH after puberty
- decreased protein synthesis

44
Q

Conditions for excess GH?

A

Gigantism - early life pituitary tumour

Acromegaly - Tumor after adolescence

45
Q

What are the anterior pituitary hormones?

A 
Trophic hormones: 
Follicle stimulating hormone 
Adrenocorticotrophic hormone 
Thyroid stimulating hormone
Luteinizing hormone (reproduction)
Primary hormones:
GH, prolactin
46
Q

Describe the condition of acromegaly?

A

Tumour of pituitary after aldolescene

  • EX GH
  • middle age
  • premature death
  • slow onset miss diagnose
  • abnormal growth of feet and hands
47
Q

Describe the synthesis of TH (t3/t4) from tyrosine

A

T+ I= MIT +I= DIT
DIT+DIT=T4 = thyroxine 90%
MIT + DIT = t3 = tri iodo thyronine 10%

48
Q

Describe thyroid hormone synthesis

A
  • ACTIVELY ACCUMULATE iodine (I2 pump bw blood vessel n cell) and Iodine tyrosine, form t3,t4
  • IODINATED THYROGLOBULIN enters lumen by EXOCYTOSIS
  • stored enters FOLLICLE CELLS by ENDOCYTOSIS
  • LYSOSOMAl DIGESTION help release
  • 90% bound to PP
  • 10% target tissue and E
49
Q

T3/t4 which produce most cellular effect?

A

T3

T4 is a prohormone produce t3

50
Q

Describe the role of thyroid hormone in hoemostaric regulation

A
  1. Energy metabolism (mito R)
  2. Carbs, lipid, protein metabolism (nucleus R via TRE)
  3. Growth
  4. Body temp
  5. Reg nervous, CV, reproduction, skeletal sys
51
Q

Where is calcitonin produced

A

Parafollicular C cells in thyroid gland

Healthy Body (9 decks)

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