Topic 77 - Growth hormone

Question 1

Words to include

Answer 1

• STH (somatotropic hormone)
• GH (Growth Hormone)
• Acidophilic cells
• Adenohypophysis
• Hypothalamic factors
  
  • GRH
  • GIF
• Histotropic hormone
• Glandotropic hormone
  
  • Liver
• Gigantism
• Acromagaly
• Dwarfism
• Protein metabolism
  
  • Amino acids
  • IC protein synthesis
  • Nitrogen balance
• Lipid metabolism
  
  • Adipose tissue
  • Catabolic processes
  • Lipolysis
  • Ketogenic
  • Fatty acids
  • Aceto-acetic acid
  • Beta-OH-butyrate
  • Glucose oxidation (↓)
  • Gluconeogenesis (↑)
• Carbohydrate metabolism
  
  • Antiinsulin-like effect
    
    • Insulin dependent glucose uptake (↓)
    • Plasma glucose
  • Adipose tissue
  • Diabetogenic
    
    • Gluconeogenesis
    • Glucagon production
  • Houssay’s experiment
    
    • Adenohypophysectomy
    • Diabetic dog
  • Pathological hyperglycemia
• Indirect effect
  
  • Somatomedins
  • IGF (Insulin-linke Growth Factor)
  • Insulin receptors
  • Thyroid hormones
    
    • T3 (Triiodothyronine)
    • T4 (Thyroxine)
  • Liver
  • Thyroid gland
  • Somatomedins (sulphating factors)
  • ALP (Anterior Lobe of Pituitary)
• Regulation
  
  • Glucose level
  • Arginine
  • Plasma
  • Plasma hypothalamic factors
  • Endogenous hypothalamic signals

Question 2

Topics to include in the essay

Answer 2

1. Different names of GH
2. Normal growth
3. Location of production of GH
4. The type of hormone GH is
5. Conditions due to abnormal level of GH
6. Effects on the protein metabolism
7. Effects on the lipid metabolism
8. Effects on the carbohydrate metabolism
9. Indirect effects of GH
10. Regulation of GH secretion

Question 3

Name of growth hormone

Answer 3

• Have two different names:
  
  1. STH (Somatotropic Hormone)
  2. GH (Growth Hormone)

Question 4

How is normal growth maintained?

Answer 4

By continuously high levels of GH, and the pulsatile increase and decrease of GH

Question 5

Where is the growth hormone produced

Answer 5

• In the acidophilic cells of the adenohypophysis
  
  • It has both a short and a long duration fluctuation
  • It is synthesized by the effect of GRH (Growth hormone-Releasing Hormone) and GIF (Growth hormone Ihibiting Factor) (hypothalamic factors)

Question 6

Which type of hormone is GH?

Answer 6

• Glandotropic hormone
  
  • Because it stimulates secretion of further hormones in the liver
• GH was previously referred to as a histotropic hormone

Question 7

Conditions due to abnormal level of GH

Answer 7

• Gigantism
  
  • Increased secretion during young age
• Acromegaly
  
  • Increased secretion during adult life
  • Bone growth and the asymmetrical growth of limbs
• Dwarfism
  
  • Decreased secretion during young life (nanosomia)

Question 8

Effects on the protein metabolism

Answer 8

• GH increases the uptake of amino acids in the cells and will by doing so increase the intracellular protein synthesis, this will increase growth
• The production of GH will be directly stimulated by bringing free amino acids into the plasma

Question 9

Effects on the lipid metabolism

Answer 9

• The general effect of GH in the adipose tissue is catabolic by starting the lipolysis
  
  • ​This will again stimulate the glyconeogenesis
• If the concentration of GH is high it will affect the adipose tissue in a ketogenic way, by stimulating the conversion of fatty acids into acetic acid
  
  • ​GH mobilizes energy stores for the later purpose of covering the energy needs of the protein synthesis

Question 10

Effects on the carbohydrate metabolism

Answer 10

• GH will inhibit insulin-facilitated glucose uptake in the adipose tissue
  
  • Increases the plasma glucose level
  • This will again increase glyconeogenesis
• GH stimulate the production of glucagon, too much of GH will lead to pathological hyperglycemia

Question 11

Indirect effect of GH

Answer 11

• Somatomedins / IGF (Insulin-like Growth Factors) are produced by the liver
  
  • Has an influence on the bone, cartilage and the connective tissue
  • IGF will stimulate the bone formation, bone growth and acromegaly in adults
• The IGF cannot effect the insulin receptors, since they cannot reach the concentration needed
• GH exerts its effects through the liver
  
  • In the liver, it stimulates activation of thyroid hormones and synthesis of somatomedins
• ALP = Anterior Lobe of Pituitary

Question 12

Regulatoin of GH secretion

Answer 12

• Low glucose level and decreased level of arginine in the plasma will stimulate the secretion of GH
• The synthesis and release of hormones will be stimulated or inhibited by the plasma hypothalamic factors according to the actual needs
  
  • Adjustments will be done by endogenous hypothalamic signals