ENDOCRINE FUNCTION OF KIDNEY

BY :KHAZI ABDUL JABBAR,GROUP NO.117,UNDER SUPERVISION OF Dr. G.N.Yegorov.

ENDOCRINE SYSTEM

KIDNEY A MIXED ORGAN

HORMONES

THERE ARE THREE TYPES OF HORMONES: steroid

hormones including prostaglandins which function especially in a variety of female functions and the sex hormones all of which are lipids made from cholesterol,

amino acid derivatives (like epinephrine) which are derived from amino acids, especially tyrosine, and

peptide hormones (like insulin) which is the most numerous/diverse group of hormones.

CELLS THAT SECRETES HORMONES:

The juxtaglomerular cells (JG cells or granular cells) are cells in the kidney that synthesize, store, and secrete the enzyme renin. They are specialized smooth in the wall of the afferent arterioles that delivers blood to the glomerulus. In synthesizing renin, they play a critical role in the renin-angiotensin system and thus in renal auto regulation, the self-governance of the kidney.

Extraglomerular mesangial cells(also known asLacis cells,Goormaghtigh cells) are light-staining cells in thekidneyfound outside theglomerulus, near thevascular poleandmacula densa.Lacis cells form thejuxtaglomerularapparatusin combination with two other types of cells: themacula densaof thedistal convoluted tubuleandjuxtaglomerular cellsof theafferent arteriole. This apparatus controlsblood pressure through theRenin Angiotensin Aldosterone system. The specific function of Lacis cells is not well understood, although it has been associated with the secretion oferythropoietin.

RENAL CORPUSCLE:

A – Renal corpuscleB – Proximal tubuleC – Distal convoluted tubuleD – Juxtaglomerular apparatus1. Basement membrane (Basal lamina)2. Bowman's capsule – parietal layer3. Bowman's capsule – visceral layer3a. Pedicels 3b. Podocyte

4. Bowman's space (urinary space)5a. Mesangium – Intraglomerular cell5b. Mesangium – Extraglomerular cell6. Granular cells (Juxtaglomerular cells)7. Macula densa8. Myocytes (smooth muscle)9. Afferent arteriole10. Glomerulus Capillaries11. Efferent arteriole

HORMONES SECRETED BY KIDNEYS:

Secreted hormone From cells Effect

Erythropoietin Extraglomerular mesangial cells

Stimulate erythrocyte production

Calcitriol (1,25-dihydroxyvitamin D3)

Active form of vitamin D3

Increase absorption of calcium and phosphate from gastrointestinaltract

Renin (Primarily) Juxtaglomerular cells Activates the renin-angiotensin system by producing angiotensin I of angiotensinogen

Secreted hormone From cells

Erythropoietin Extraglomerular mesangial cells

Stimulate erythrocyte production

Calcitriol (1,25-dihydroxyvitamin D3

Active form of vitamin D3

Increase absorption of calcium and phosphatefrom gastrointestinal tract

Renin (Primarily) Juxtaglomerular cells Activates the renin-angiotensin system by producing angiotensin I of angiotensinogen

Thrombopoietin stimulates megakaryocytes to produce platelets

Erythropoietin

Erythropoietin

Erythropoietin, or EPO, is a glycoprotein that regulates the transfer of oxygen and nutrients through the bloodstream by increasing red blood cell production in the bone marrow. EPO production is stimulated when blood is lost through a wound or when less oxygen is available, such as higher altitudes. Recombinant EPO can be used as a treatment for those suffering from anemia, a deficiency of red blood cells.

Calcitriol

Calcitriol Calcitriol, also known as vitamin D3, improves the

body's ability to absorb calcium. To produce calcitriol, vitamin D must be introduced into the body, either through a chemical reaction between the skin and sunlight creating calciferol, or dietary vitamin D that has been digested. Vitamin D in the body ends up being converted into calcitriol by the kidneys. Calcitriol travels to the intestines, where it enhances the body's absorption of calcium, improving skeletal health.

Thrombopoietin

Thrombopoietin

Thrombopoietin, or TPO, increases the body's ability to heal itself by stimulating the production of platelets. Thrombopoietin is a cytokine, a protein involved with immune system functioning. TPO that has been secreted into the bloodstream bonds either with platelets or with megakaryocytes, the precursor to platelets. When the body's platelet count is high, excess TPO bonds with the platelets, decreasing production. If the platelet count is low, TPO bonds with megakaryocytes which then mature into platelets.

Rennin

Rennin Rennin is a proteolytic enzyme responsible for

regulating arterial wall size to ensure proper blood pressure. Proteolytic enzymes are capable of breaking down proteins into a more usable form. Renin breaks down the plasma protein angiotensinogen into a peptide containing ten amino acids called angiotensin I. Angiotensin I later gets broken down by a lung-based peptidase known as angiotensin converting enzyme, or ACE. The new eight-amino acid peptide, angiotensin II, increases blood pressure by increasing pulse strength and constricting vein and arterial walls.

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