QS Study

A hormone is a chemical substance that is secreted into the internal body fluid by one cell or group of cells and exerts a physiological control effect on other cells of the body.

It is vital for every movement of life, as well as the processes of digestion, metabolism, growth, reproduction, and mood control.

Hormones act on the kidney

  • Aldosterone: Stimulus – dec in blood volume, inc in plasma (K⁺); Action on kidney – inc in Na⁺ reabsorption, inc in K⁺ secretion, inc in H⁺ secretion.
  • ADH: Stimulus – inc plasma osmolarity and dec in blood volume; Action on kidney – inc in H2O permeability (late distal tubule and collection duct principal cells).
  • Parathormone (PTH): Stimulus: dec in plasma; Action on kidney: dec phosphate reabsorption, inc Ca²⁺ reabsorption, stimulates 1α-hydroxylase.
  • Growth hormone (GH): Stimulus – dec in blood volume; Action on kidney – inc in Na⁺-H⁺ exchange and HCO₃⁻ reabsorption
  • ANF (Atrial natriuretic factor): Stimulus – inc in atrial pressure; Action on kidney – inc GFR, dec in Na⁺ reabsorption.

Fig: Hormones acts on Kidney and Breast

Hormone acts on breast – The breast is an inhomogeneous anatomic structure composed of layers of different types of tissue, among which predominate two types: adipose tissue and glandular tissue.

  • Estrogen – The growth is mainly that of the ducts lengthening and branching and is carried out in synergism with the anterior pituitary hormones, prolactin, and somatotropin.
  • Progesterone – instead, causes duct and ductule cells to multiply, leading to ductule development and duct enlargement or widening.
  • Prolactin – contributes to the increased growth and differentiation of the alveoli
  • Oxytocin, – stimulates cell division along the duct wall
  • Growth hormone – Growth hormone may have an indirect effect of lactogenesis by increasing the secretion of IGFs.
  • Thyroid hormone – This indicates the essential synergism between prolactin and the glucocorticoids to induce lactogenesis.