BlogNEETBody Fluids and Circulation – Definition, Brief Note, Types

Body Fluids and Circulation – Definition, Brief Note, Types

Vertebrates circulate blood, a fluid connective tissue, throughout their bodies to transport essential substances to cells and waste substances away from them. Lymph (tissue fluid) is another fluid that is used for the transport of certain substances. A fluid matrix, plasma, and formed elements make up blood. The formed elements are red blood cells (RBCs, erythrocytes), white blood cells (WBCs, leucocytes), and platelets (thrombocytes). Human blood is classified into A, B, AB, and O systems based on the presence or absence of two surface antigens, A and B, on RBCs. Another blood grouping method is based on the presence or absence of another antigen on the surface of RBCs known as the Rhesus factor (Rh). Tissue fluid is a fluid derived from blood that fills the spaces between cells in tissues. Except for the protein content and the formed elements, this fluid is known as lymph is nearly identical to blood.

    Fill Out the Form for Expert Academic Guidance!


    Live ClassesBooksTest SeriesSelf Learning

    Verify OTP Code (required)

    I agree to the terms and conditions and privacy policy.


    Our bodies are made up of cells. Cells require nutrients and oxygen to survive, as well as waste removal. Hormones must also be transported from the endocrine glands that secrete them to their target cells. This work of transporting nutrients, gases, wastes, and other substances from one part of our body to another is done by blood (body fluids) and is referred to as circulation. Any fluid produced by a living organism is referred to as body fluids.

    A brief outline of the topic

    You’ve learned that all living cells require nutrients, oxygen, and other essential substances. Furthermore, waste or harmful substances produced must be removed on a continuous basis in order for tissues to function properly. It is therefore critical to have efficient mechanisms for moving these substances into and out of cells. Different animal groups have evolved different modes of transportation. Simple organisms, such as sponges and coelenterates, circulate water from their surroundings through their body cavities, allowing cells to exchange these substances. More complex organisms transport such materials within their bodies using special fluids. Most higher organisms, including humans, use blood as their primary body fluid for this purpose. Lymph, another body fluid, also aids in the transport of certain substances.

    Video Lesson – Molecular Orbital Theory

    A brief note

    Body fluids and circulation classification

    In humans, the body fluids can be classified into two major types according to the location

    1. Extracellular fluid – This is a type of bodily fluid that exists outside of the cell (s). In humans, it makes up roughly 26% of total body water composition. Intravascular fluid (blood plasma), interstitial fluid, lymph, and transcellular fluid are all components of extracellular fluid. The most abundant fluid is interstitial fluid, which fills the spaces between cells, while the least abundant fluid is transcellular fluid, which fills the spaces of chambers produced by epithelial cell linings.

    2. Intracellular fluid – This is the bodily fluid that is contained within a cell (s). In humans, intracellular fluid accounts for 67% of total body water. Water, dissolved ions, and other molecules make up this substance.

    Types of body fluids


    • Vertebrates circulate blood in their bodies, which is a specific fluid connective tissue made up of blood plasma, fluid matrix, and formed elements (cells and cell fragments) that supply needed nutrients to the cells and remove waste.
    • The blood is mildly acidic (pH ranging from 7.3 to 7.4). It accounts for 20-30% of extracellular fluid and accounts for 8% of the total body mass.
    • An average-sized adult male’s blood volume is 5 to 6 litres, whereas an average-sized adult female’s blood volume is 4 to 5 litres.

    Components of blood

    Blood Plasma

    • About 45% of blood is made up of formed elements, while the other 55% is made up of blood plasma. Blood plasma contains 90-92% water and 8-10% solutes, the majority of which are proteins (approximately 7% by weight).
    • The primary proteins are fibrinogen, globulins, and albumins. Fibrinogens are required for blood clotting and coagulation. Globulins are primarily involved in the body’s defense processes, while albumins aid in osmotic balance.
    • Minerals, glucose, amino acids, lipids, and other substances are also found in minute amounts in plasma.

    Formed Elements

    • The formed elements of the blood include three major components

    Red blood cells/RBCs (Erythrocytes)-

    RBCs are oxygen transporters that are highly specialized. A healthy adult male has about 5.4 million RBCs per microlitre of blood, while a healthy adult female has about 4.8 million. The oxygen-carrying protein hemoglobin, which is also a pigment that gives blood its red color, is found in the cytoplasm of RBCs. The nucleus and other membrane-bound organelles are absent in mature RBCs. The form of RBCs is biconcave.

    White blood cells/WBCs (Leucocytes)-

    Unlike RBCs, WBCs contain no hemoglobin and have nuclei. WBCs are significantly less than red blood cells, with approximately 5000-10000 cells per microlitre of blood. Granular or agranular WBCs are the two types of WBCs.


    • The majority of total WBCs (60-65%) are neutrophils, while basophils make up the smallest percentage (0.5-1%).
    • Phagocytic cells such as neutrophils and monocytes (6–8%) scavenge foreign organisms that enter the body.
    • Basophils are inflammatory cells that emit histamine, serotonin, heparin, and a variety of other substances.
    • Eosinophils are immune cells that combat infections and have been associated with allergy reactions (2-3%). B and T lymphocytes, which account for 20-25% of all lymphocytes, are classified into two categories. Both B and T cells are in control of the organism’s immunological responses.

    Platelets (Thrombocytes) are tiny pieces of megakaryocytes rather than whole cells. Platelets form a platelet plug to help stop blood from leaking out of broken blood vessels.


    • Lymph (tissue fluid) is another fluid in the body that is used to transfer certain substances throughout the body.
    • After being filtered from the interstitial fluid, excess blood plasma is effectively recycled and returned to the lymphatic system (between cells).
    • The lymphatic system consists of lymph, lymph nodes, and lymph arteries, and it is responsible for returning filtered blood plasma from the interstitial fluid (between cells) as lymph.

    Blood Types

    • Despite its appearance of similarity, human blood differs in several ways. The blood has been divided into several groups.
    • The ABO and Rh classifications are two examples of such classifications that are widely used around the world.
    • Human blood is classified into four systems based on the presence or absence of two surface antigens, A and B, on RBCs: A, B, AB, and O.
    • Another blood grouping is determined by the presence or absence of another antigen on the surface of RBCs. This factor is termed as Rhesus Factor(Rh).

    Body fluids circulation

    • The circulatory system, also known as the cardiovascular or vascular system, is an organ system in our body that allows blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from the body’s cells in order to provide nourishment, aid in disease prevention, and maintain homeostasis(it is a self-regulating process which helps an individual to maintain stability).

    Classification of body fluids circulation

    • The blood circulatory system is divided into two parts: systemic circulation and pulmonary circulation.
    • Humans and other vertebrates have a closed cardiovascular system, whereas some invertebrate taxa have an open cardiovascular system (meaning blood never leaves the network of arteries, veins, and capillaries).
    • The lymphatic system, on the other hand, is an open system that allows excess interstitial fluid to be returned to the bloodstream.

    Mechanism of body fluid circulation

    • The mesodermally derived organ is the heart. The heart circulates oxygenated blood throughout the body while also transporting deoxygenated blood to the lungs.
    • Each circulation in the human heart has one atrium and one ventricle, for a total of four chambers for both the systemic and pulmonary circulations: left atrium, left ventricle, right atrium, and right ventricle.
    • The right atrium is the upper chamber of the heart on the right side. When blood returns to the right atrium, it is deoxygenated (low in oxygen) and pumped into the right ventricle, where it is re-oxygenated and carbon dioxide is removed before being pumped into the lungs via the pulmonary artery.
    • The left atrium receives newly oxygenated blood from the lungs as well as the pulmonary vein, which is then pushed through the aorta by the powerful left ventricle to the various organs of the body.

    Also read: Occupational Respiratory Disorders


    Describe body fluid blood? Describe its components.

    Blood is a complex connective tissue that is made up of two parts: Plasma is the extracellular fluid that makes up around 55 %of the volume of blood. Water makes up 91–92% of plasma, proteins make up 7%, inorganic materials make up 0.9%, glucose makes up 0.1%, and the rest is made up of other organic and inorganic compounds. Plasma's second-largest constituent is proteins.

    Name the blood vessel of the circulatory system which carries impure blood to the heart.

    Vena cava.

    Name one circulatory body fluid and its component?

    Circulatory fluid is blood and its components are hemoglobin, RBC, WBC.

    Define systemic circulation?

    Systemic circulation is the network of blood vessels that assures the flow of oxygenated blood from the left ventricle to all bodily organs and the return of deoxygenated blood to the right atrium.

    Describe the importance of pulmonary circulation.

    The circulatory system, which is connected to the lungs via arteries and veins, forms the circulatory system's pathway. Pulmonary circulation is the process of flow of blood from the heart to the lungs and then back to the heart. The heart receives regular oxygenated blood, whereas the pulmonary artery transports deoxygenated blood from the right ventricle to the lungs. It is the blood's path through arteries from the aorta, which rises from the heart to the right atrium.

    Chat on WhatsApp Call Infinity Learn

      Talk to our academic expert!


      Live ClassesBooksTest SeriesSelf Learning

      Verify OTP Code (required)

      I agree to the terms and conditions and privacy policy.