endocrine control of growth and disorders of growth Flashcards

1
Q

What hormones are associated with growth

A

Growth hormone - (GHRH and GHIH )
IGF-1
Thyroid hormones (T3,T4)
Insulin
Sex steroids
Cortisol

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2
Q

What is another name for growth hormone inhibiting hormone

A

Somatostatin

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3
Q

What hormones are mainly influencing growth from 8-10 months

A

Thyroid hormones and insulin

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4
Q

What age does growth hormone take over the influence of growth

A

10 months

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5
Q

What causes growth during puberty

A

Androgens and oestrogens causing spikes in GH which causes increased IGF-1 which causes increased growth

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6
Q

what hormones terminate growth

A

Androgens and oestrogens by causing the fusing of the epiphyses of the long bone

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7
Q

What system of the body do thyroid hormones play a important part in developing in utero

A

nervous system

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8
Q

What is congenital hypothyroidism

A

Babies are born of normal size but are unable to produce Thyroid hormones

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9
Q

What is the relation between iodine and thyroid hormones

A

iodine is essential in the production of thyroid hormone

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10
Q

What is the relationship between thyroid hormone and growth hormones

A

Thyroid hormones have a permissive effect on GH

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11
Q

What are the features of congenital hypothyroidism

A

retain infantile proportions

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12
Q

What are the features of children who are deficient in growth hormone

A

proportionally normal but small

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13
Q

What is another name for growth hormone

A

somatotropin - released from somatotroph cells

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14
Q

What is the function of growth hormone

A

It is a trophic hormone so causes release of IGF-1

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15
Q

What controls the release of growth hormones

A

GHIH - somatostatin - growth hormone inhibiting hormone

GHRH - growth hormone releasing hormone

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16
Q

What is the role of growth hormone in adult life

A

It is essential in maintenance and repair of tissue §

17
Q

What is the effect of GH on it’s target tissues

A

Increase in cell size (hypertrophy)
Increase in number of cells (hyperplasia)

18
Q

What is the indirect effect of GH

A

Growth of long bones through the hormone IGF-1

19
Q

What does IGF-1 stand for

A

Insulin-like growth factor-1

20
Q

What controls the release of growth hormone

A

Negative feedback loop of IGF-1

21
Q

What are the direct effects of growth hormone

A

Increases gluconeogenesis
Inhibits effect of insulin
makes adipocytes more sensitive to being broken down
Increases amino acid uptake and protein synthesis in nearly all cells

22
Q

Why is growth hormone said to be diabetogenic

A

It has anti-insulin effect

23
Q

When during a persons day cycle is the majority of growth hormone secreted

A

The first 2 hours of sleep

24
Q

Why is IGF-1 relatively constant throughout the day

A

Binds tightly to carrier protein which protects it from being broken down

25
Q

What stimuli cause increased secretion of GHRH and therefore more GH

A

Actual or potential decreases in energy supply to cells
Increased amino acids in the plasma
physical stress or illness
Delta sleep (first 2 hours)
Oestrogen and testosterone

26
Q

What causes increased GHIH and therefore decreased GH

A

Glucose - GH is hyperglycaemic so increased glucose inhibits it
FFA - free fatty acids are produced by GH so in abundance, they inhibit GH
Ageing
Cortisol

27
Q

What usually causes hypersecretion of GH

A

Endocrine tumors

28
Q

What does hypersecretion of GH cause

A

Gigantism
Acromegaly

29
Q

What causes gigantism

A

Excess GH due to a pituitary tumour before epiphyseal plates of long bone fuse - therefore excessive growth

30
Q

What causes acromegaly

A

Excess GH due to a pituitary tumour after the epiphyseal plates of long bone fuse - no increase in height but there can be growth in other areas such as hands and feet

31
Q

What is adult feet growing a sign of

A

Acromegaly

32
Q

What is the treatment for gigantism or acromegaly

A

Removal of pituitary tumour somatostatin analogues

33
Q
A