Plasma: The Liquid Part of Blood

Plasma is the liquid portion of blood, constituting about 55% by volume of blood in a normal person, with the cells forming about 45% by volume of the blood. It is composed of approximately 90% water and 10% dissolved substances, including proteins, salts, nutrients, and wastes. The concentration of these substances in plasma varies depending on the condition of the organism and the portion of the system being examined.

 

Types of Solutes in Plasma

There are six types of solutes present in plasma:

Plasma Proteins: 7 to 9% of the plasma is made up of various types of proteins that are synthesized in the liver. These plasma proteins serve important functions in the body, including:

a) Fibrinogen, which plays a role in the clotting process. Prothrombin, a protein, acts as a catalyst in blood clotting. Plasma without fibrinogen is called serum.

b) Immunoglobulins or antibodies, which are produced by lymphocyte cells in response to antigens and are then passed to plasma and lymph. Immunoglobulins play a critical role in the body's defense against diseases.

c) Maintaining osmotic pressure between the blood stream and surrounding medium, as water does not readily pass through the walls of blood vessels due to the large size of plasma proteins.

Inorganic or Mineral Ions: Salts make up about 0.9% of human plasma, with sodium chloride and bicarbonates comprising over two-thirds of this amount. Trace amounts of calcium, magnesium, copper, potassium, zinc, and other metabolic ions are also present. Shifts in the concentration of these ions can cause significant disturbances in the body.

Organic Nutrients: Plasma also contains organic nutrients such as glucose, fats, phospholipids, amino acids, and lactic acids.

Metabolites and Wastes: Amino acids, glucose, vitamins, lipids, urea, and uric acids are among the metabolic waste products present in plasma.

Hormones: Plasma serves as a carrier for various hormones that are transported throughout the body.

Dissolved Gases: Carbon dioxide (CO₂), oxygen (O₂), and nitrogen (N₂) are also present in plasma.

Defining Circulatory System

The circulatory system, also known as the cardiovascular system, is responsible for the transport of blood, oxygen, and nutrients throughout the body. It consists of three main components: the heart, blood vessels, and blood.

Heart

The heart is a muscular organ that acts as a pump, constantly circulating blood throughout the body. It has four chambers: two atria and two ventricles. The atria receive oxygenated blood from the lungs or gills and deoxygenated blood from the body, while the ventricles pump the blood out to the body or to the lungs or gills for oxygenation. The heart contracts and relaxes in a coordinated manner to ensure that blood is pumped efficiently to all parts of the body.

Blood vessels

Blood vessels are tubular structures that transport blood throughout the body. They include arteries, veins, and capillaries. Arteries carry oxygenated blood away from the heart to the rest of the body, while veins carry deoxygenated blood back to the heart. Capillaries are the smallest and thinnest blood vessels, and they connect arteries and veins. Capillaries allow for the exchange of oxygen, nutrients, and waste products between the blood and the body's tissues.

Blood

Blood is a specialized fluid that carries oxygen, nutrients, hormones, and waste products throughout the body. It consists of red blood cells, white blood cells, and plasma. Red blood cells contain hemoglobin, a protein that binds with oxygen, and carry oxygen from the lungs or gills to the body's tissues. White blood cells are part of the immune system and help fight off infections and diseases. Plasma is a yellowish fluid that carries nutrients, hormones, and waste products in the bloodstream.

The circulatory system not only transports oxygen, nutrients, and hormones, but also plays a role in the body's immune system. It transports white blood cells to various parts of the body to fight off infections and diseases, helping to maintain overall health and well-being.

The circulatory system is a complex network of the heart, blood vessels, and blood that is responsible for the transport of blood, oxygen, and nutrients throughout the body. It plays a crucial role in maintaining the proper functioning of all body tissues and organs, as well as supporting the immune system.