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GDAN year 2 G&D with some aging > endocrine control of growth > Flashcards

endocrine control of growth Flashcards

1
Q

endocrine glands are …

A

duct less

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2
Q

where do endocrine glands secret

A

into circulation

so hormones travel round the body

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3
Q

long bone

A

growth plate where endochonral growth is taking place
mostly a transient structure in long bones
causes a cartilage prescursor to grow during childhood

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4
Q

growth hormone

A

regulates the amount of growth in long bones

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5
Q

what releases GH

A

anterior pituitary gland

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6
Q

what is anterior pituitary glands under

A

stimulation of growth releasing growth hormone and somatostatic
- forms negative feedback loop

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7
Q

what is released from posterior pituitary gland

A

growth releasing growth hormone and somatostatic

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8
Q

what is the posterior pituitary gland under

A

influence of nerves from hypothalamus

signalling occurs in pulses allows growth hormone to be constant throughout day

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9
Q

gigantism

A

before growth plate closure

  • growth hormone excessive before closing
  • due do anterior pituitary adenoma which is often egentic
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10
Q

where is the pituitary gland found

A

slightly anterior is the optic chaism (optic nerves cross)

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11
Q

pituitary tumour causes

A 
tends to compress optic nerves
loss of peripheral vision
tends to be slow 
patients dont notice at first
- can lose visual acuity and colour
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12
Q

agremegaly

A

after growth plates have clsoed

  • can have earlier onset
  • bone is laid down in an appositional fashion
  • gives lumps/bumps around face and bone
  • pituiriyt tumour has occurred in mid life
  • or the tumour can also be in other tissues, and release the growth hormone (tends to be I. the lung or pancreas)
  • patients can notice the tongue enlarging, and rings becoming small
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13
Q

carney complex

A

melanin patches seen intraorally
due to tumours of melanin producing cells
can have in heart, thyroid gland
condition due to new genetic mutation no family history

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14
Q

what can growth hormone directly infleuce

A

the growth plate and cause proliferation of the progenitor cells
- acts on liver to increase release of insulin like GF

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15
Q

what does IL GF do

A

hypertrophy of cells inside growth plae
- acts on hypothalamus and pituitary gland to reduce secretion of growth hormone
(negative feedback)

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16
Q

what is used as an indicator of GH levels ad why

A

ILGF

more stable than GF istelt

17
Q

what does oestrogen do

A

influences bone growth and interact with GH
maintenance of bone density
can increase GH secretion, therefore indirect effect on bone growth
direct action on growth plate itself

18
Q

what eventually stops bone growth and what does this effect

A

ongoing levels of oestrogen- may cause programmed senescence of the growth plate (biomodal influence)
- delayed pubertal growth spurt may lead to a taller stature, due to the growth plate not being restricted and stop growth early by oestrogen

19
Q

what is the typical androgen

A

testosterone

20
Q

what can androgens do

A

modified by enzymes to act on oestrogen receptors

androgens can act on androgen receptors

21
Q

androgens can be modified by enzymes to act on oestrogen receptors…

A
  • therefore bimodal influence of the growth plate to initially cause lengthening of the bone then following cessation
22
Q

what can androgens do when binding with androgen receptor

A

can cause increase in radial growth of bone

23
Q

what is mandibular sexual dimorphism

A

shape of mandible different between 2 genders
prominnant angle is typically
may be due to interaction of testosterone and oestrogen

24
Q

what is found in the mandible

A

secondary cartilages

25
Q

what occurs at secondary cartialges

A

endochrondral ossification

26
Q

what happens at the condyle

A

ECO
growth around he condyle is where mandibular sexual dimorphism occur
- tester one increases growth
this increases the height and ascending raus
increases sharpness md angle
muscle loading may contribute

27
Q

what does growth hormone also influence and how does it

A

muscle growth

  • GH acts via IGF1 receptors to increase myofibril proliferation
  • muscle growth is usually proportional to body size
  • little evidence that GH promotes hypertrophy beyond the proportional body size
  • paracrine IGF1 has a role in load induced hypertrophy
28
Q

growth hormone performance enhancement

A
  • may have little effect on hypertrophy
  • positive effect on connetive Tissue strength
  • reduce recover time – anticatabolic
  • increase VO2 max (allows more intense anaerobic exercise)
29
Q

what do glucocorticoids do

A

modulate GH

  • increases GH secretion
  • Affect SST (somatostatin) and GHRH, indirect reduction in growth hormone
  • Chronic exposure reduces GH release
30
Q

treatment of children with corticosteroids

A

those with chronic juvenile arthritits
- likely to reduce growth
due to reduction in GH effect at growth plates

31
Q

what do GCC act as

A
  • regulate expression of growth hormone receptors

- outcome related to dose and exposure time to give difference in outcome due to short and long exposures

32
Q

what happens when GCC is present for a long time in adults

A
  • increase risk of osteoporosis, protein loss and raised serum lipids
  • Chronic glucocorticoid mitigated by recombinant GH
  • this can lead to glucose intolerance i.e. diabetic
33
Q

what does GH promote (to do with sugars)

A

release of glucose from fatty acids stores (glycogenesis, glycogenolysis, liposis)
- in responce insulin is release to compensate to restore blood glucose levesl
(lead to insulin resistance?)

34
Q

what happens in a healthy individual

A
  • GH levels fluctuate
  • after carb meal, high level of insulin will then reduce the level of GH
  • will steady out
35
Q

what happens to an inidividual if insulin levels are persistently high

A
  • if insulin levels are persistently high
  • can lead to increase in height
  • insulinopenia reduces childrens growth
  • the growth plate is excessively active, insulin acts as a IGF1 homologue
36
Q

what does thyroid hormone do and how

A

increases linear growth of bones
Directly by
- affecting chondrocytes and osteoblasts in the growth plate
- also stimulates release of GH, which acts on long bone itselt
also drive IGF1 synthesis prepubertal, encouraging growth

37
Q

hypothyroidism

A

reduced levels

reduced adult height

38
Q

pre/post puberty hormone levels

A

1) Before puberty thyroid hormone drives synthetic of insulin like growth factor which then acts on the bones
2) thyroid hormones levels drops, GH levels increase partly due to oestrogen
3) causes increase in insulin like GF levels, which then causes an increase in bone length

Therefore overall Insulin like growth factor may be the overall factor on height

39
Q

what are the headline hormones

A

GH

IGF1

GDAN year 2 G&D with some aging (27 decks)

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