I. Overview of growth hormone
①Structure: A protein containing a single chain of 191 amino acid residues, connected by two disulfide bonds.
②Secretion: Secreted by anterior pituitary eosinophils
③Molecular weight: 22125D
Second, the secretion of growth hormone
①Characteristic: pulsatile secretion, age-related, with the largest pulse amplitude and the largest amount of secretion in the middle of puberty
②Frequency: secreted about once every 3-5 hours, 6-8 times a day for 24 hours
③peak: secretion peaks one hour after sleep, and the secretion volume is more than half of the total amount of the day.
④Regulation: The hypothalamus secretes two neurohormones
III. Stimulating factors of growth hormone secretion
Deep sleep, exercise, stress state, hypoglycemia, drugs: insulin (induces hypoglycemia), colistin, arginine, etc.
IV. Inhibitory factors of growth hormone secretion
Fast eye movement sleep, psychological factors, central nervous system tumor, birth injury, hypothyroidism, drugs: glucocorticoids, etc.
V. Physiological role of growth hormone
1.Promote growth and regulate bone metabolism
(1) Stimulate the differentiation and proliferation of epiphyseal chondrocytes, thus promoting bone growth and increasing bone length.
(2) It can directly stimulate the metabolism of osteoblasts and play an important role in maintaining bone mineral content and bone density.
(3) Cooperate with sex hormones and calcitonin to intervene in bone remodeling.
2.Regulate substance metabolism
(1) Promote protein synthesis and correct negative nitrogen balance.
(2) Regulate lipid metabolism, reduce body fat reserves, increase serum fatty acid content, reduce serum cholesterol and low-density lipoprotein levels.
(3) Decreases cellular sensitivity to insulin, reduces glucose utilization by peripheral tissues, and raises blood glucose.
(4) It has important effects on water and mineral metabolism. It can make intracellular potassium salt and phosphate retention, and also promote renal tubular sodium reabsorption, causing water and sodium retention.
3.Other effects
(1) Increase the immunity of the body, stimulate immunoglobulin synthesis, and promote the proliferation of macrophages and lymphocytes.
(2) Accelerate wound healing, stimulate the synthesis of collagen by fibroblasts in burn wounds and surgical incisions.
(3) Promote myocardial protein synthesis, increase myocardial contractility and reduce myocardial oxygen consumption.
(4) GH has anti-aging, promote brain function effect; promote sperm formation, ovulation, etc.