Biochemistry Term: Plasma
Plasma, in the context of biochemistry, refers to the liquid component of blood that remains after blood cells have been removed.
It constitutes approximately 55% of the total volume of blood and is a complex and dynamic fluid containing a diverse array of molecules crucial for maintaining physiological balance within the body. Comprising mostly water (about 90%), plasma also houses various solutes, including ions, proteins, nutrients, hormones, waste products, and gases, playing essential roles in transportation, homeostasis, and immune defense.
One of the primary functions of plasma is to serve as a transport medium for blood cells and other substances. Red blood cells, white blood cells, and platelets are suspended in plasma, allowing them to circulate throughout the body and fulfill their respective roles.
Nutrients, such as glucose, amino acids, and fatty acids, are transported through the plasma to provide energy and building blocks for cellular processes. Additionally, hormones secreted by endocrine glands travel in the plasma to reach target organs, coordinating various physiological activities.
Proteins constitute a significant portion of plasma solutes and play multifaceted roles. Albumin, the most abundant plasma protein, contributes to maintaining osmotic pressure and transporting substances like fatty acids and hormones. Globulins, including antibodies that participate in immune responses, are also present in plasma. Fibrinogen, another plasma protein, is crucial for blood clotting. These proteins collectively contribute to the maintenance of homeostasis and defense mechanisms within the body.
The composition of plasma is continually regulated to ensure the stability of internal environments. Electrolytes, such as sodium, potassium, and calcium ions, help maintain the osmotic balance, pH, and electrical neutrality of plasma.
The liver synthesizes many plasma proteins, and the concentrations of these proteins are closely regulated to ensure proper physiological function. Imbalances in the composition of plasma can have profound effects on health, leading to conditions such as dehydration, electrolyte disturbances, or impaired clotting.
Plasma also plays a vital role in the body's immune defense. Antibodies and other immune system components present in plasma help protect against infections and diseases. Additionally, waste products generated by cellular metabolism, such as urea and creatinine, are transported in the plasma to be excreted by the kidneys.
The continuous exchange of substances between plasma and tissues, facilitated by the cardiovascular system, ensures that cells receive the necessary nutrients and eliminate waste products.
