THE KIDNEY'S ROLE IN HOMEOSTASIS

The kidney's role in homeostasis

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THE KIDNEY'S ROLE IN HOMEOSTASIS by Mind Map: THE KIDNEY'S ROLE IN HOMEOSTASIS

1. Electrolyte Balance

1.1. Filtration of electrolytes like Sodium, Potassium, Calcium, Phosphate, Magnesium and Chloride occurs in the glomerulus of the kidneys

1.1.1. The needed electrolytes are reabsorbed through the peritubular capillaries going back to the circulation

1.1.2. Any excess electrolytes are secreted in the renal tubules and excreted as urine

2. Maintenance of Normal Red Blood Cell Count

2.1. In response to hypoxia due to low RBC, Erythropoietin-Producing Oxygen Sensing Cells detect low oxygen

2.1.1. Production of Erythropoietin by the kidneys occurs

2.1.1.1. Stem cells in the red bone marrow are stimulated by Erthropoietin to produce Erythrocytes through the process of Erythropoiesis

2.1.1.1.1. Increased RBC Count

3. Blood Pressure Control

3.1. Renin are produced by the kidneys in response to low blood pressure, low blood volume, low serum sodium levels and high serum potassium levels

3.1.1. Renin converts Angiotensinogen which is formed by the liver to Angiotensin I

3.1.1.1. Angiotensin-Converting Enzyme metabolizes Angiotensin I into Angiotensin II

3.1.1.1.1. Causes blood vessels to constrict

3.1.1.1.2. Causes the production of Aldosterone by the adrenal cortex of the adrenal gland

4. Fluid Balance

4.1. Fluid Overload

4.1.1. Causes the atrium to stretch

4.1.1.1. In response Atrial Natriuretic peptide (ANP) is released from cardiac atrial cells

4.1.1.1.1. ANP inhibits secretion of aldosterone by the adrenal cortex of the adrenal gland, reduces renin production by the kidneys and decreases Antidiuretic Hormone (ADH) from Posterior Pituitary Gland

4.2. Decreased serum sodium and body fluids

4.2.1. Aldosterone is secreted from the adrenal cortex of the adrenal gland

4.2.1.1. More Sodium and water reabsorption

4.3. Fall in plasma osmolality

4.3.1. In response, antidiuretic Hormone (ADH) secretion by the posterior pituitary gland is decreased

4.3.1.1. ADH receptors found in the collecting ducts of the renal tubules receive less ADH

4.3.1.1.1. More secretion and excretion of sodium and water in the form of urine

5. Acid-Base Balance

5.1. Fall in Plasma pH (less than7.35) / Acidosis

5.1.1. There is an increase in Hydrogen Ion concentration in the body fluids

5.1.1.1. In response, excess Hydrogen are secreted in the distal tubules and collecting tubules, so more Hydrogen is excreted in the form of urine

5.1.1.1.1. More bicarbonate are reabsorbed by the peritubular capillaries into the plasma fluid

5.2. Rise in plasma pH (more than 7.45) / Alkalosis

5.2.1. There is a decrease in Hydrogen Ion concentration in the body fluids

5.2.1.1. In response, Hydrogen secretion by the distal tubules and collecting tubules decreases and more are reabsorbed

5.2.1.1.1. Bicarbonate reabsorption decreases and excretion increases, so plasma bicarbonate level is decreased

6. Waste Excretion in Urine

6.1. Excess electrolytes like sodium, potassium, calcium, magnesium, chloride, phosphates and bicarbonate; urea and creatinine; and drug metabolites are excreted by the kidneys in the form of urine