Magnesium functions – the role of magnesium in human body

Magnesium is the fourth most common cation in the human body and the second most abundant intracellular cation in the human body. The human body contains approximately 24g (1000mmole) of magnesium and it is involved in many intracellular processes and is very essential for life. Metabolic irregularity or disturbance is associated with various abnormalities. The main sources of magnesium are vegetables, soybeans, nuts, whole grain cereals, eggs, and seafood. The minimum daily dietary magnesium intake to maintain magnesium balance in a normal person is about 240mg per day.

Magnesium functions – Co-factor and agitator of many enzymes

Magnesium plays an important role in the functions of more than 300 enzymes, Na⁺. K⁺ ATPase, hexokinase, choline esterase. It actively participates in many metabolic activities in the body. Magnesium helps to metabolize proteins, lipids, carbohydrates, and nucleic acid. Magnesium is also vital in regulating the cellular distribution of sodium and potassium through involvement in Na⁺, K⁺ ATPase.

Magnesium functions -Maintains irritability of the cells

Magnesium acts as an inhibitor to the central nervous system, neuromuscular and cardiac muscles. For neuromuscular irritability magnesium and calcium are synergic and for cardiac muscles they are the antagonist.

Magnesium functions – Maintains homeostasis of cells

Magnesium is an essential cofactor in correlative enzymes of DNA, cell cycle and apoptosis. In plasma, magnesium is important for maintaining DNA structure and veracity of DNA replication and activating DNA repairing including nucleotide excision repair, base excision repair, miss match repair, and microtubule assembly. 

The Primary Functions of Thyroid Hormone

The primary functions of the thyroid hormone basically include:

Heat Production

Increases oxygen consumption and BMK of targeted tissues, especially in liver, cardiac muscles and kidney

Protein Metabolism

Promote the synthesis of proteins and enzymes

Carbohydrate Metabolism

Elevates the glucose level in the blood

Fat Metabolism

Promotes oxidization of fatty acids and strengthen the effects of catecholamine and glycogen of lypolysis.

Effects on growth and development

Essential for mental and physical development in human, especially for the development of brain and bone tissues

Effects on CNS

Increases the effectiveness of permissive antigen and increase the excitability of CNS

Effects of Cardiovascular System

Increases heart rate, cardiac contractility, cardiac output and vasodilatation  

Physiological Dead Space

The airway and its functions

The main goals of the respiration are to provide oxygen to the tissues and to remove carbon dioxide. To achieve these goals, respiration can be divided into four major functions. They

1. Pulmonary Ventilation. Means the inflow and out flow of air between the atmosphere and the lung alveoli.
2. Diffusion, of oxygen and carbon dioxide between the alveoli and the blood
3. Transport of oxygen and carbon dioxide in the blood and body fluids to and from the body’s tissue cell
4. Regulation of ventilation and other focets of respiration

The upper airway consists of the nose, mouth, pharynx, and larynx. The larynx opens into the trachea, which in turn branches into two bronchi, enter into both lungs. The airway beyond larynx can be divided into two zones

Conducting zone

Extends from the top of the trachea to the beginning of the respiratory bronchioles

Functions

Provide low resistance pathway for air flow

Defends against microbes, toxic chemicals, and other foreign matters

Respiratory Zone

Extend from the respiratory bronchioles to the alveoli and is the region where gases exchange with blood. The inner surface of the airway down to the end of the respiratory bronchioles contains cilia, glands and epithelial cells, secrets mucus which keep the lungs clear of particulate matter and bacteria that enters body with dust particles. Another protective mechanism against infection is provided by the macrophages that exist in the airway and alveoli, these macrophages engulf and destroy inhaled particles and bacteria that have reached alveoli.

Reference 

Guyton, A & Hall, J. (2006).Text book of Medical Physiology.11^th Edition. Elsevier Saunders 

Basics of electrocardiogram (ECG)

The electrocardiogram (ECG or EKG) is primarily a tool for evaluating the electrical events within the heart. The action potentials of cardiac muscle cells can be viewed as batteries that cause charge to move throughout the body fluids. These moving charges currents, in other words – are caused by all the action potentials occurring simultaneously in many individual myocardial cells and can be detected by recording electrodes at the surface of the skin.

In a typical ECG , the first deflection is called the P wave. It corresponds to current flows during atrial depolarization. It generates about 0.2 mv and lasts for 0.1s

The second deflection, the QRS complex, occurs approximately 0.15s later. It is the result of ventricular depolarization. It is a complex deflection because the paths taken by the wave of depolarization through the thick ventricular walls differ from instant to instant, and the current generated in the body fluids change direction accordingly.

The S-T interval represents the time during which the entire ventricular muscle is depolarized.

The final deflection, the T wave , is the result of ventricular repolarization. Atrial repolarization is usually not evident on the ECG because it occurs at the same time as the QRS complex.A typical ECG makes use of multiple combinations of recording locations on the limbs and the chest (called ECG leads).

It is not a direct record of the changes in membrane potential across individual cardiac muscle cells. Instead it is a measure of the currents generated in the extracellular fluid