Mind map

Growth Hormone

Yousaf Alabrash English

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Growth Hormone

site of origin
- Pituitary gland
  - anatomy
    - anterior lobe
      - paras anterior
        acidophils
        somatotropes
        secrete GH
        lactotropes
        secrete prolactin
        basophils
        gonadotrophes
        FSH and LH
        cotricotrophes
        ACTH
        thyrotropes
        TSH
        chromophopes
      - paras intermediate
        colloid filled cysts
        secrete MSH
      - paras distalis
        portal venules system
        at medial eminence
    - posterior lobe
      - paras nervosa
        infundibulum
        medial emenince
    - infundiblum
      - connection with
        hypothalamus
release of GH
- physiology of hormone release
  - hypothalamic-hypophyseal tract
    - 1-hypothalamic nucleus secrete hormones
      - supraoptic--oxytocin
      - paraventricular -- ADH
        2-released into the axons
        3-stored in paras nervosa to be released when needed
  - hypophyseal portal system
    - 1-neuroendocrine cells in the hypothalamus secrete hormones
      - releasing hormones
      - inhibiting hormones
        2-released into the axons
        3-at he medial eminence, they get released into the portal venules to be carried to the anterior pituitary to stimulate or inhibit its hormonal releases
    - factors that regulate GH secretion
      - pattern of release: pulsatile
actions on the organs level
- metabolic actions
  - CHO
    - hyperglycemic effect
      - muscles+adipocytes
        -- glucose utilization
        because of decreased sensitivity to insulin due to ++fatty acids level
        GH
      - liver-++ gluconeogenesis
  - LIPID
    - increase lipid catabolism
      - adipocytyes
        stimulate Hormone sensitive lipase to breakdown the fats
        ++oxidation of fatty acids
      - liver
        stimulate ketogenesis (because of excess acetyl Coa)
        inhibit lipogenesis
  - PROTEIN
    - INCREASE protein anabolism
      - muscles
        ++ aminoacids transport across membranes
        ++ RNA translation into proteins by ribosomes
        ++ DNA transcription into RNA to make proteins
        DECREASE PROTEIN cataqbolism (protein sparing)
- growth
  - go to liver and generate IGF-1
    - growth of bone
      - width
        stimulate osteoblasts
        increase bone desposition on the surface
        increase in bone thickness
      - length
        increase the metabolism of chondrocytes
        increase the secretion of cartilage in the epiphyseal cartilage
        increase the conversion of this cartilage into bone
- actions in the cell-- 3 signal transduction pathways
  - JAK/STAT pathway
    - MAPK and PI3K/PKB pathways
pathologies and their treatment
- GH excess
  - before epiphyseal closure
    - gigantism
      - increase in length to 8-9 feet
        all tissue of the body growth rapidly
        hypopituitarism
  - after epiphyseal closure
    - acromegaly
      - increase in bone thickness
        growth in soft tissue (heart-kidney)
  - main cause: GH secreting tumor
  - treatment
    - main line is surgery-2nd line: radiation
      - 3rd line: pharmacological
        Somatostatin analog
        octreoline
        Dopamine agonists
        bromocreptine
        GH receptor antagonists
        pigvisomant
- GH deficiency
  - main cause: hypopituitarism
  - child
    - pituitary dwarfism
      - patient becomes very short-sexual functions might be imparied
  - adult
    - generalized symptoms
      - decrease muscle mass - obesity -lack of energy - accelerated aging
  - treatment
    - depends on the cause
      - GH is deficient
        recombinent hGH
        Saizen
      - IGF-1 is deficient
        rIGF-1
        Mecasermin
      - Hypothalamic damage
        Synthesitic GHRH
        Sermorelin