Endocrine Control Of Growth And Development Flashcards
What are somatomedians
Insulin like growth hormones - IGF’s
Prod in somatotrophs and cause sec of GH
What are the thyroid hormones
T3 - triiodothyronine
T4 - tetrauidothyroinine
What does calcitonin, vit d and PTH all functionally have in common
They help regulate the calcium balance in the body
What are oestrogens and testosterone important for
Imp for the development of secondary sexual differentiations
Explain GH secretion
In daily bursts not continuous
Initiated by GHRH
Secretion terminated by somatostatin
Where is GHRH and somatostatin produced
The hypothalamus
What is diurnal rhythm
Sleep/wake pattern
Peak sec highest in morning and decreases though the day
What happens if GH is injected to a hypophysectomised animal
Stimulation of bone growth
Stim of protein syn
Stim RBC prod
Anti insulin effect - increase hepatic glucose, promote lipolysis and decreased glucose uptake
What are the effects of GH
Growth by increasing protein syn in tissues it increase num and size of cells
In bone it promotes IGF1 which bone growth at epiphyseal plates before close off
Has metabolic actions
- increase net syn of protein
- decreases glucose uptake
- increase lipolysis
What are the stimulants for GH secretion
Deficiency of energy substrate Hypoglycaemia Exercise and fasting Increases in blood amino acids arg or leu Glucagon Stress Deep sleep
What are the inhabitants of GH
Rapid eye movement sleep Hyperglycaemia Cortisol Free fatty acids GH Hypothyroidism Ageing
What does GH do to carbohydrates
Increases blood glucose
Decreases peripheral insulin sensitivity
Increases hepatic glucose output
What does GH do to proteins
Increase the tissue amino acid uptake
Increase incorporation into proteins
Decrease urea production
What does gh do to lipids
Lipolysis - activates hormone sensitive lipase (ligase stimulated by adrenaline and GH) yield FA’s
What does GH do to IGF’s
Stimulates production of IGF’s
Stimulates growth
Is mitigenic ( stim grow in soft tissues)
What produces IGF-1
The liver
What causes the production of IGF-1
The sce of GH
What does IGF-1 do
Stimulate the bone growth and cell proliferation leading to soft tissue growth
What can sometimes happening dwarfism
That GH is norm,a but IGF-1 hormone subnormal
What happens when there is an adenoma in the anterior pituitary in children and adults
Children - leads to gigantism - excess GH to epiphyseal plates deal - long bone prod
Adult - acromegaly - thickening of bones coarsened facial features and thickend fingers hands and feet
What 3 hormones does the thyroid gland produces
Triiodothyronine
Tetraiodothyronine
Calcitonin
What mech regs t3/t4
Negative feedback loop
How are t3 and t4 ttansported in the blood
Bound to thyroxine- binding globulin plasma protein (TBG)
What is the structure of the thyroid gland
Follicular cells - spheres on the outer layer
Filled with colloid - extracellular storage for th
Tyrosine containing thyroglobulin filed spheres enclosed by follicular cells
What is required for new thyroid hormones and how are they obtained
Iodine and tyrosine and taken up by follicle cells
How are new thyroid hormones prod
Iodine and tyrosine taken up
In colloid iodine attach to tyrosine residue to form MIT and DIT
If DIT+DIT= T4 Or. DIT+ MIT = T3
Sited in colloid until needed
What does t3 and t4 do
Promote accelerate metabolism
Increase carbohydrate fat and protein turnover
Increase oxygen consumption and increased heat production
Imp during Dev if hypothyroidism in child = CRETIN
What is sympathomimetic action
Increases responsiveness to catecholamines adrenaline and noradrenaline by increasing number of adrenal receptors
What is hyperthyroidism
Lead to heat intolerance Nervousness Insomnia Weight loss High nitrogen exertion
What is hypothyroidism
Lead to cold intol
Excess sleep
Muscular fatigue
Weight gain
What is the basal metabolic rate
Amount of energy con husked during a testing individual so energy r reunited to just be in living state (energy for brain activity, pump blood and cellular processes)
What is the primary regulatory hormone of BMR
Thyroid hormone
What is the condition hypothyroidism in adults
Myoxedema
What is goitre
Swell of thyroid gland
Iodine deficiency - red t3/t4 promote excessive TSH secretion a nd growth of thyroid
Graves’ disease - TSI promote thyroid growth
Excess TSH form ant pit
What is when there is no goitre
Hypothyroidism secondary to hypothalamus or ant pit failure (thyroid is not excessively stimulated)
Overactive thyroid TSH suppressed by excessive t3/4
What are testosterones actions
In fetal Dev imp for reproductive organs
During puberty stim bone growth and SECINDARY sexual characteristic
What does estradiol
Oestrogen Stimulates growth of uterus Imp for follicular growth Stim bone growth Delay bone loss during menopause
Where is GH prod
Anterior pituitary
