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By the end of this section, you will be able to:
  • List the role of the six most important electrolytes in the body
  • Name the disorders associated with abnormally high and low levels of the six electrolytes
  • Identify the predominant extracellular anion
  • Describe the role of aldosterone on the level of water in the body

The body contains a large variety of ions, or electrolytes, which perform a variety of functions. Some ions assist in the transmission of electrical impulses along cell membranes in neurons and muscles. Other ions help to stabilize protein structures in enzymes. Still others aid in releasing hormones from endocrine glands. All of the ions in plasma contribute to the osmotic balance that controls the movement of water between cells and their environment.

Electrolytes in living systems include sodium, potassium, chloride, bicarbonate, calcium, phosphate, magnesium, copper, zinc, iron, manganese, molybdenum, copper, and chromium. In terms of body functioning, six electrolytes are most important: sodium, potassium, chloride, bicarbonate, calcium, and phosphate.

Roles of electrolytes

These six ions aid in nerve excitability, endocrine secretion, membrane permeability, buffering body fluids, and controlling the movement of fluids between compartments. These ions enter the body through the digestive tract. More than 90 percent of the calcium and phosphate that enters the body is incorporated into bones and teeth, with bone serving as a mineral reserve for these ions. In the event that calcium and phosphate are needed for other functions, bone tissue can be broken down to supply the blood and other tissues with these minerals. Phosphate is a normal constituent of nucleic acids; hence, blood levels of phosphate will increase whenever nucleic acids are broken down.

Excretion of ions occurs mainly through the kidneys, with lesser amounts lost in sweat and in feces. Excessive sweating may cause a significant loss, especially of sodium and chloride. Severe vomiting or diarrhea will cause a loss of chloride and bicarbonate ions. Adjustments in respiratory and renal functions allow the body to regulate the levels of these ions in the ECF.

[link] lists the reference values for blood plasma, cerebrospinal fluid (CSF), and urine for the six ions addressed in this section. In a clinical setting, sodium, potassium, and chloride are typically analyzed in a routine urine sample. In contrast, calcium and phosphate analysis requires a collection of urine across a 24-hour period, because the output of these ions can vary considerably over the course of a day. Urine values reflect the rates of excretion of these ions. Bicarbonate is the one ion that is not normally excreted in urine; instead, it is conserved by the kidneys for use in the body’s buffering systems.

Electrolyte and Ion Reference Values
Name Chemical symbol Plasma CSF Urine
Sodium Na + 136.00–146.00 (mM) 138.00–150.00 (mM) 40.00–220.00 (mM)
Potassium K + 3.50–5.00 (mM) 0.35–3.5 (mM) 25.00–125.00 (mM)
Chloride Cl - 98.00–107.00 (mM) 118.00–132.00 (mM) 110.00–250.00 (mM)
Bicarbonate HCO 3 - 22.00–29.00 (mM) ------ ------
Calcium Ca ++ 2.15–2.55 (mmol/day) ------ Up to 7.49 (mmol/day)
Phosphate HPO 4 2 0.81–1.45 (mmol/day) ------ 12.90–42.00 (mmol/day)

Questions & Answers

what is metabolism
fred Reply
Chemical reaction that takes in place in the cell of a living organism that includes anabolism and Catobolism.
metabolic chemical reaction is of two types, anabolism and catabolism. The break down of larger molecules into smaller molecules is called catabolism.
Metabolism is the chemical reaction that includes anabolism and catabolism
Anabolism is the chemical reaction that combines all the smaller quantities to make large
Catabolism is the chemical process that breaks larger quantities into small
what's abdominal police?
hydrochloric acid is the stomach police
its the stomach omentum
description of the ears
Nana Reply
which component of mucus allows it to maintain local level of hydration
Loriann Reply
can the teeth be classify under bones?
Ojaga Reply
Bony prominents
What is the largest muscle in the lower leg
Gwen Reply
what's a nervous system
Dante Reply
Is a the group of neurons and glial cells that work together to receive, integrate and responds appropriately to stimulus in the periphery, spinal cord and brain.
study about internal structure, outer structure and their functions
Navdeep Reply
circulatory system on blood pressure
Lakhu Reply
What is ELISA
(enzyme linked immunosorbent assay) is a test that uses antibodies and color change to identify a substance.
what's defense mechanism?
psychological strategies that are unconsciously used to protect a person from anxiety arising from unacceptable thoughts or feelings.
difference between apocrine sweat glands and merocrine sweat glands
Binkheir Reply
I believe the apocrine sweat gland uses a sac under the hair follicle and the merocrine sweat gland releases directly on to the surface of the skin
normal blood volume in our body
pankaj Reply
Normal blood volume in adults is 6 litres
4.7 to 5ltr.. normal for adult
what are the advantages of the concave shape of red blood cells?
Amy Reply
This structure is VERY flexible. It can allow these cells to get into the most tiny places in our bodies. a VERY good design! The advantage of red blood cells' biconcave shape is that the surface area is increased to allow more haemoglobin to be stored in the cell.
They can stack so that they can move to capillaries
what is the difference between phagocytosis and Pinosis
action of gluteus medius and minimus
Green Reply
Lateral rotation of the hip joint
Briefly explain location of ecg on a patient
Prince Reply
it is a machine that gives a graphical representation of heart beat
Briefly explain location of ecg leads on a patient?
in ecg we use electrical leads over the chest ,ancle and wrist
what is the anatomical and function difference between paravertebral and prevertebral ganglia ?
Rada Reply

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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