Joseph R. Anticaglia, MD
Medical Advisory Board
Blood is a life force, a vital fluid that keeps us healthy. An adult has about five liters (ten pints) of blood that circulates throughout the body 24/7. It is slightly thicker than water, bright red when oxygenated, and dark red when deoxygenated. Too much, or too little blood, or atypical blood are signs of underlying medical problems.
Four Components of Blood:
1. Plasma (55% of Blood Volume)
Plasma is the liquid portion of blood that makes up fifty five per cent of the blood volume. The yellowish liquid is ninety per cent (90%) water with various dissolved substances contained in the liquid:
- Electrolytes, for example, sodium and potassium
- Hormones, for instance, insulin
- Proteins, e. g., antibodies, clotting factors, and albumin which binds to hormones, and help regulate the hormone levels in the blood
- Nutrients such as, amino acids, and glucose
- Waste products like carbon dioxide, and urea
Formed Elements (45% of blood Volume) include red blood cells, white blood cells and platelets.
2. Red Blood Cells (Erythrocytes)
RBCs contain hemoglobin which is the oxygen-carrying protein within the red blood cells. It is primarily responsible for transporting oxygen from the lungs to tissues and returning carbon dioxide to the lungs for exhalation. It has a lifespan of approximately 120 days (one hundred and twenty), and does not have a nucleus.
3. White blood Cells (Leucocytes)
These cells play a crucial role in the immune system being responsible for fighting infections, and protecting us against foreign substances. The different types of WBCs include basophils, eosinophils, lymphocytes, monocytes, and neutrophils.
4. Platelets (Thrombocytes)
Platelets are cell fragments, “protein packages” that work together to form blood clots that prevent excessive bleeding.
Blood Types
ABO System There are four main blood types, namely, A, B, AB, and O which are determined by the antigens on the surface of the RBCs.
Rh System
This system is determined by the presence (Rh positive), or absence (Rh negative) of the D antigen on
the surface of the red blood cell.
Blood Production (Hematopoiesis)
Blood cells are produced in the bone marrow, the soft, spongy part of the bone, where stem cells develop into RBCs, WBCs, and platelets.
Functions
Blood plays many roles in keeping us healthy. It transports oxygen from the lungs to tissues throughout the body, and sends carbon dioxide back to the lungs where it is then exhaled as a waste product. It delivers nutrients, and hormones to different parts of the body. It produces antibodies, an essential component of the immune system, that fight infections, and protect us against foreign substances.
It transports waste products to the lower digestive system, and kidneys, to be removed from the body. It forms blood clots to prevent blood loss, and by circulating throughout the body, it helps to regulate body temperature. Many concur, healthy blood is a “miracle fluid.”
References
- Guyton, C & Hall, J. E.; Textbook of Medical Physiology; Elsevier, 2016
This article is intended solely as a learning experience. Please consult your physician for diagnostic and treatment options.