Topic 76 - Adenohypophysis, the synthesis and release of the ACTH

Question 1

Words to include in the adenohypophysis

Answer 1

• Hypophysis
  
  • Neurohypophysis (posterior lobe)
  • Adenohypophysis (anterior lobe)
• Endocrine gland
• Rathke’s pouch
• Endothermal glandular tissue
• Hypophyseal hormones
  
  • Glandotropic hormones
    
    • TSH (Thyroid Stimulating Hormone)
    • ACTH (Adrenocorticotropic Hormone)
    • FSH (Follicle Stimulating Hormone)
    • LH (Lutenizing hormone)
    • Endocrine gland
  • Histotrophic hormones
    
    • PRL (Prolactin)
    • STH (Growth hormone / somatotropin)

Question 2

Words to include in the synthesis and release of the ACTH

Answer 2

• Adrenocorticotropic hormone / corticotropin
• Glucocorticoid synthesis
• Adrenal cortex
  
  • Zona fasciculata
  • Zona reticularis
• cAMP pathway
• Cholesterol cleaving
• Steroid synthesis
• Direct facilitation of secretion
• Brown area
• Pre-POMC
• POMC
• Signal peptide
• Gamma-MSH
• ACTH
• Beta-LPH
• Alpha-MSH
• CLIP
• Gamma-LPH
• Beta-endorphin
• Beta-MSH
• (met)-enkephalin
• Feedback
  
  • Long feedback
    
    • Negative feedback
  • Ultra-short feedback
    
    • CRF
    • CRF sybthesizing cells

Question 3

General about the adenohypophysis

Answer 3

• The hypophysis is separated into two parts:
  
  1. Neurohypophysis (posterior lobe)
  2. Adenohypophysis (anterior lobe)
• The adenohypophysis is an endocrine gland found in the Rathke’s pouch, it is developed from the entodermal glandular tissue during embryonic life

Question 4

Hypophyseal hormones

Answer 4

• Glandotropic hormones (acts only on endocrine glands)
  
  • TSH (Thyroid stimulating Hormone)
  • ACTH (Adrenocorticotropic Hormone)
  • FSH (Follicle Stimulating Hormone)
  • LH (Luteinizing Hormone)
• Histotrophic hormones
  
  • PRL (Prolactin)
  • STH (Growth Hormone / Somatotropin)

Question 5

ACTH

What does ATCH stand for?

Answer 5

Adrenocortitropic hormone / Corticotropin

Question 6

ACTH

The role of ACTH

Answer 6

• Stimulates glucocorticoid synthesis in the adrenal cortex in the layers:
  
  • Zona fasciculata
  • Zona reticularis
• Stimulation through the enhancement of the activity of cAMP pathway
• ACTH helps to mobilize energy reserves and decrease pain sensation during stress

Question 7

ACTH

Synthesis of ACTH

Answer 7

• ACTH is produced in the brown area (central part) of the adenohypophysis

Question 8

ACTH

Regulation of ACTH

Answer 8

• Regulated by the feedback principle using:
  
  • Long feedback
    
    • Increasing glucocorticoid concentration
    • The glucocorticoid production is stimulated by ACTH, and it will elicit at negative feedback on the ACTH synthesis
  • Ultra-short feedback
    
    • ACTH inhibiting CRF
    • Neural impulses reaching the hypothalamus are integrated by CRF synthesizing cells
    • The release of CRF is pulsatile and its circadian fluctuation determines the synthesis and secretion of ACTH