endocrine control of growth

Question 1

endocrine glands are …

Answer 1

duct less

Question 2

where do endocrine glands secret

Answer 2

into circulation

so hormones travel round the body

Question 3

long bone

Answer 3

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

Question 4

growth hormone

Answer 4

regulates the amount of growth in long bones

Question 5

what releases GH

Answer 5

anterior pituitary gland

Question 6

what is anterior pituitary glands under

Answer 6

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

Question 7

what is released from posterior pituitary gland

Answer 7

growth releasing growth hormone and somatostatic

Question 8

what is the posterior pituitary gland under

Answer 8

influence of nerves from hypothalamus

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

Question 9

gigantism

Answer 9

before growth plate closure

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

Question 10

where is the pituitary gland found

Answer 10

slightly anterior is the optic chaism (optic nerves cross)

Question 11

pituitary tumour causes

Answer 11

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

Question 12

agremegaly

Answer 12

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

Question 13

carney complex

Answer 13

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

Question 14

what can growth hormone directly infleuce

Answer 14

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

Question 15

what does IL GF do

Answer 15

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

Question 16

what is used as an indicator of GH levels ad why

Answer 16

ILGF

more stable than GF istelt

Question 17

what does oestrogen do

Answer 17

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

Question 18

what eventually stops bone growth and what does this effect

Answer 18

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

Question 19

what is the typical androgen

Answer 19

testosterone

Question 20

what can androgens do

Answer 20

modified by enzymes to act on oestrogen receptors

androgens can act on androgen receptors

Question 21

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

Answer 21

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

Question 22

what can androgens do when binding with androgen receptor

Answer 22

can cause increase in radial growth of bone

Question 23

what is mandibular sexual dimorphism

Answer 23

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

Question 24

what is found in the mandible

Answer 24

secondary cartilages

Question 25

what occurs at secondary cartialges

Answer 25

endochrondral ossification

Question 26

what happens at the condyle

Answer 26

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

Question 27

what does growth hormone also influence and how does it

Answer 27

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

Question 28

growth hormone performance enhancement

Answer 28

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

Question 29

what do glucocorticoids do

Answer 29

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

Question 30

treatment of children with corticosteroids

Answer 30

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

Question 31

what do GCC act as

Answer 31

- regulate expression of growth hormone receptors | - outcome related to dose and exposure time to give difference in outcome due to short and long exposures

Question 32

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

Answer 32

- 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

Question 33

what does GH promote (to do with sugars)

Answer 33

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?)

Question 34

what happens in a healthy individual

Answer 34

- GH levels fluctuate - after carb meal, high level of insulin will then reduce the level of GH - will steady out

Question 35

what happens to an inidividual if insulin levels are persistently high

Answer 35

- 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

Question 36

what does thyroid hormone do and how

Answer 36

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

Question 37

hypothyroidism

Answer 37

reduced levels | reduced adult height

Question 38

pre/post puberty hormone levels

Answer 38

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

Question 39

what are the headline hormones

Answer 39

GH | IGF1