Urinary System

Nephron Physiology: filtration, reabsorption, secretion, and excretion

The major functions of the following electrolytes:

Reabsorption is the absorption of molecules, ions, and water that are necessary for the body to maintain homeostasis from the glomerular filtrate back into the blood.

Secretion is the transfer of hydrogen ions, creatinine, drugs, and urea from the blood into the collecting duct, and is primarily made of water.

Filtration is the transfer of soluble components, like water and waste, from the blood into the glomerulus.

The nephron is the functional unit of the kidney because the nephron filters the plasma, reabsorbs critical molecules, and excretes the rest

Calcium

Phosphate

Chloride

Hyponatremia

Potassium

Hypernatremia

Sodium

the major cation of the extracellular fluid. It is responsible for one-half of the osmotic pressure gradient that exists between the interior of cells and their surrounding environment.

the major intracellular cation. It helps establish the resting membrane potential in neurons and muscle fibers after membrane depolarization and action potentials.

the predominant extracellular anion. Chloride a major contributor to the osmotic pressure gradient between the ICF and ECF, and its role is to maintain proper hydration. Chloride functions to balance cations in the ECF, maintaining the electrical neutrality of this fluid.

a normal constituent of nucleic acids; hence, blood levels of phosphate will increase whenever nucleic acids are broken down.

provides hardness to the bone and serves as a mineral reserve for calcium and salts for the rest of the tissues. Calcium ions, Ca2+, are necessary for muscle contraction, enzyme activity, and blood coagulation. Also it helps to stabilize cell membranes and is essential for the release of neurotransmitters from neurons and of hormones from endocrine glands.

hypokalemia

alkalemia

hyperkalemia

alkalosis

hypocalcemia

acidemia

hypercalcemia

acidosis

the blood is too acidic and there is too little bicarbonate.

Cause: too many ketones in the body from diarrhea, too much exercise or too much aspirin

low blood pH

the opposite of metabolic acidosis.

too much bicarbonate can be caused by excessive vomiting, extensive use of diuretics or laxatives and over secretion of aldosterone.

occurs when the serum pH is higher than normal (7.45 or higher)

lower-than-normal levels of sodium in the blood

abnormal increase of blood sodium.

abnormally decreased blood levels of potassium

higher-than-normal blood potassium levels

abnormally low blood levels of calcium

abnormally increased blood levels of calcium

The role of the renin-angiotensin-aldosterone system, ADH, and ANP in the regulation of blood volume and pressure

ADH

ANP

renin-angiotensin-aldosterone system

system involved in the regulation of systemic blood pressure, renal blood flow and glomerular filtration rate

ADH a hormone released from the posterior pituitary gland that causes an increase in blood pressure. ADH vasoconstricts our blood vessels, which causes increased blood pressure. It also increases water absorption from the distal tubule and collecting ducts.

a cardiac hormone which gene and receptors are widely present in the body. It's function is to lower blood pressure and to control electrolyte homeostasis.

Angiotensin

Renin

ACE

Aldosterone

protein whose presence in the blood is to promote aldosterone secretion and raises blood pressure.

a hormone that increases the absorption of water from the distal convoluted tubule and collecting duct of the kidney's nephrons.

an enzyme located mainly in the lungs that converts angiotensin I into angiotensin II.

angiotensin II a vasoconstrictive hormone increases systemic blood pressure, renal perfusion pressure and the glomerular filtration rate.

It also constricts blood vessels all over the body to increase systemic blood pressure. Also works in the kidneys to maintain blood pressure in the glomerulus so that the glomerular filtration rate stays normal even in the face of low blood pressure.

an enzyme released by the juxtaglomerular cells of the kidneys in response to low blood pressure, causing the transformation of angiotensinogen to angiotensin I.