Endocrine Physiology 3 Flashcards
Which immunoglobulin affects growth
IgF-1
Growth Hormone becomes significant from?
10 Months
What produces spikes in GH secretion
Androgens and Oestrogens
What terminates growth
Androgens and Oestrogens causing epiphysis of long bones to fuse
Growth Hormone is what type of hormone
Peptide released from Ant Pituitary aka Somatotropin
Growth hormone requires what kind of action of thyroid hormones and insulin before stimulations growth
Permissive
Growth Hormone acts on what type of receptor
Tyrosine Kinase Receptors
What is mediated indirectly by IgF-I in growth
growth of long bones
IgF-1 is also known as
Somatomedian C
What mediates action of GH
Somatomedin c aka IGF-1
IGF-I is secreted by
Liver
IGF-I exhibits neg feedback on GH release
via inhibiting GHRH and stimulating GHIH (somatostatin).
Hyperglycaemic properties of GH dominate the what action of IGF-I
hypoglycaemic action of IGF-I
What is the site of bone growth
epiphyseal plate
Growth hormone does what to gluconeogenesis by liver
Increases
Growth does what to adipocytes
more sensitive to lipolytic stimuli.
What does GH to blood glucose
increases
What does GH do to amino acid uptake and protein synthesis
Increases amino acid uptake and protein synthesis in almost all cells = anabolic effect
What does cortisol do to protein catabolism
stimulates
Growth hormone does what to glucose stores
Mobilises them to increase BG
GH does what to insulin
inhibits action of insulin
Where is GH present
Pituitary Glands
Highest rate of GH Secretion
teenage years during first 2 hours of sleep (deep delta sleep) 20x in children
What 5 factors increase GHRH Secretion
Action or Potential decrease in energy supply to cells Increased Amino Acids in Plasma Stress and Illness Delta Sleep Oestrogen and Tesoterstone
What happens in Exercise and Cold to Growth Hormone
Increased Demand
Growth Hormones does what to amino acid transport
Promote
Oestrogen and Testosterone do what to IGF Mediated Neg Feedback
Decrease
Stimuli that increase GHIH
- Glucose
- FFA
- Ageing
- Cortisol
How does Giantism happen?
Excess GH due to Pit Tumour before Epiphyseal Plates of Long bones Close
How does Acromegaly happen
Excess GH due to pit tumour after epiphyseal plates seal.
No longitudinal growth/no increase in height
Growth Hormone needs what inhibited to help growth
Igf-1 Inhibition
Thyroid Hormone synthesises which hormones
T3 Triiodothyronine
T4 Thyroxine
Thyroid Hormones which cell types
Clear Cells
Follicular Cells
Which cells secrete calcitonin
Clear Cells in Thyroid Gland which regulate Ca2+
Thyroglobulin is rich in
Tyrosine Residues
Thyroglobulin and Enzymes are secreted from follicular cells into
Colloid
What hormones related to thyroid are derived from diet
Tyrosine
Iodide
How does Iodide enter follicular cells
From Plasma via Na+/I Transporter (Symport) then transported into colloid via pendrin transporter
Addition of one iodine to tyrosine makes
Monoiodotyrosine
Addition of second iodine to tyrosine makes
Diiodotyrosine
Monoiodotyrosine + Diiodotyrosine makes
T3
Diiodotyrosine and Diiodotyrosine makes
Tetraiodothyronine or T4
Thyroid Hormone synthesis is catalysed by
Thyroid Peroxidase
T3 and T4 in lipids are
soluble and circulate in plasma
When not stimulated thyroid hormones stored in
colloid
What percentage of T3 and T4 circulates in plasma bound to plasma protein
99.8%
Thyroxine Binding Globulin has what kind of affinity for T4
high with long half life
T4 half life in plasma
6 days
T3 half life in plasma
1 day
0.2% of total plasma TH is
physiologically active and exerts inhibitor affect on TSH and TRH
Most TH circulates in form of protein bound
T4
50x more total free bound T4 in plasma than
T3
90% of TH binding to TH receptors inside cells is
T3 due to higher affinity making it more physiologically active
Somatostatin does what to TSH
Inhibits
Glucocorticoid does what to TSH
inhibits TSH and converts T4 to T3
T4 is converted to
T3 in target tissue
Thyroid hormone does what to metabolic rate
Raises
Thyroid hormone does what to hepatic gluconeogenesis
increase
Thyroid hormone does what to proteolysis and lipolysis
net increase
TH is what to epinephrine, b receptors
Permissive
