endocrine control of growth and disorders of growth Flashcards
What hormones are associated with growth
Growth hormone - (GHRH and GHIH )
IGF-1
Thyroid hormones (T3,T4)
Insulin
Sex steroids
Cortisol
What is another name for growth hormone inhibiting hormone
Somatostatin
What hormones are mainly influencing growth from 8-10 months
Thyroid hormones and insulin
What age does growth hormone take over the influence of growth
10 months
What causes growth during puberty
Androgens and oestrogens causing spikes in GH which causes increased IGF-1 which causes increased growth
what hormones terminate growth
Androgens and oestrogens by causing the fusing of the epiphyses of the long bone
What system of the body do thyroid hormones play a important part in developing in utero
nervous system
What is congenital hypothyroidism
Babies are born of normal size but are unable to produce Thyroid hormones
What is the relation between iodine and thyroid hormones
iodine is essential in the production of thyroid hormone
What is the relationship between thyroid hormone and growth hormones
Thyroid hormones have a permissive effect on GH
What are the features of congenital hypothyroidism
retain infantile proportions
What are the features of children who are deficient in growth hormone
proportionally normal but small
What is another name for growth hormone
somatotropin - released from somatotroph cells
What is the function of growth hormone
It is a trophic hormone so causes release of IGF-1
What controls the release of growth hormones
GHIH - somatostatin - growth hormone inhibiting hormone
GHRH - growth hormone releasing hormone
What is the role of growth hormone in adult life
It is essential in maintenance and repair of tissue §
What is the effect of GH on it’s target tissues
Increase in cell size (hypertrophy)
Increase in number of cells (hyperplasia)
What is the indirect effect of GH
Growth of long bones through the hormone IGF-1
What does IGF-1 stand for
Insulin-like growth factor-1
What controls the release of growth hormone
Negative feedback loop of IGF-1
What are the direct effects of growth hormone
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
Why is growth hormone said to be diabetogenic
It has anti-insulin effect
When during a persons day cycle is the majority of growth hormone secreted
The first 2 hours of sleep
Why is IGF-1 relatively constant throughout the day
Binds tightly to carrier protein which protects it from being broken down
What stimuli cause increased secretion of GHRH and therefore more GH
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
What causes increased GHIH and therefore decreased GH
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
What usually causes hypersecretion of GH
Endocrine tumors
What does hypersecretion of GH cause
Gigantism
Acromegaly
What causes gigantism
Excess GH due to a pituitary tumour before epiphyseal plates of long bone fuse - therefore excessive growth
What causes acromegaly
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
What is adult feet growing a sign of
Acromegaly
What is the treatment for gigantism or acromegaly
Removal of pituitary tumour somatostatin analogues
