Growth hormone/insulin-like growth factor-I system and connective tissues: basic aspects and clinical implications

Healing is the physiological process by which the body restores the integrity and function of damaged tissues following injury. It involves a coordinated interplay of cellular proliferation, extracellular matrix remodeling, and growth factor signaling. The extent and nature of the tissue damage determine whether healing occurs by resolution, regeneration, or replacement.ResolutionResolution represents the most complete form of healing, occurring when the injury is minimal and tissue...

Hematopoietic growth factors are molecules that regulate the differentiation rate of hematopoietic stem cells (HSCs). Erythropoietin (EPO), primarily produced by the kidneys, plays a crucial role in erythrocyte production. When oxygen levels in the blood are low, EPO is released into the bloodstream, reaching the bone marrow, where it stimulates HSCs to differentiate and mature into erythrocytes, which are vital for oxygen transport.
Thrombopoietin (TPO), mainly released by the liver,...

The small, pea-sized pituitary gland is located at the base of the brain. It is crucial in regulating various bodily functions, from growth to reproduction. The gland is divided into the anterior lobe and the posterior lobe. The secretory cell clusters in the pars distalis of the anterior pituitary lobe are controlled by hypothalamic regulators and synthesize six primary hormones.
The most abundantly secreted hormone from the anterior lobe is the growth hormone, which controls overall growth by...

Insulin action is mediated through a receptor tyrosine kinase, akin to the IGF-1 receptor. The number of receptors per cell varies significantly, from 40 on erythrocytes to 300,000 on adipocytes and hepatocytes. The insulin receptor consists of linked α/β subunit dimers, forming a heterotetramer glycoprotein with two extracellular α subunits and two β subunits spanning the membrane. The α subunits inhibit the inherent tyrosine kinase activity of the β subunits, but this inhibition is released...

Insulin is released by beta cells of the pancreas when blood glucose levels are high. It facilitates glucose absorption and utilization in insulin-dependent cells with insulin receptors on their plasma membranes. Insulin promotes glucose uptake by increasing the number of glucose transport proteins in the cell membrane, allowing glucose to enter the cell. As a result, glucose utilization and ATP production are enhanced.
In addition to accelerating glucose uptake and utilization, insulin has...

Hypertrophy is the increase in the size of individual cells, resulting in the enlargement of a tissue or organ. Unlike hyperplasia, which involves an increase in cell number, hypertrophy is characterized by an increase in cell volume. This process often occurs in response to higher functional demand or hormonal stimulation, leading to the production of more structural proteins and organelles, thereby enhancing the cells' work capacity.There are two primary types of hypertrophy: physiological...