The Science of Blood - Nurse Edition

The Science of Blood – Nurse Edition

In this episode, we will talk about the science of blood. It is precisely what it comprises, its different types, administer it, and what to watch out for.

What is Blood?

When people think of blood, it’s usually the red liquid that comes out of your cut, or what you see in gore movies. But blood is more than just that. For one it has three different components:

  • Red Blood Cells: 44%
  • White Blood Cells and Platelets: 1%
  • Plasma: 55%

Many people are not familiar with how blood works or what it is even made of. If you are interested in blood or work in this field (blood banks, labs, etc.), this episode will teach you everything you need to know about it. 

Red Blood Cells

Red blood cells are also called erythrocytes, and they account for 44% of your blood. These cells are round, flat, and look like a donut.
Hospitals check for red blood cells’ size, shape, and health when a person is in the hospital. It is also the first thing that doctors look into to identify a person’s health condition.

The RBCs have two crucial functions:

  • Takes oxygen from the lungs and delivers it to the rest of the body.
  • Removes carbon dioxide from the body, breathe it out, and returns it to the lungs.
RBC works with the help of hemoglobin, maintaining acid-base balance in the body. The red blood cells can live for 120 days and produce by the bone marrow. After 120 days, the spleen breaks them down, while the liver turns them into amino acids.
For RBCs to function they need nutrition to stay healthy. These cells survive and stay healthy with the help of Vitamins B12, B2, B3, folate, and iron.


The biggest problem that occurs with irregular red blood cells is anemia. This condition is when the RBC has low oxygenation. It leads to developmental delays in children. In severe cases, anemia leads to heart failure. The most common symptoms of anemia are tachycardia, lethargy, pale skin, and chills.

Common Types of Anemia:

Iron-deficiency Anemia – happens when your body does not have enough iron to produce red blood cells. It is also the most common form of anemia. The most common causes of iron deficiency are when you have:

  • A diet low in iron
  • Sudden blood loss 
  • Menstrual periods
  • Inability to absorb iron from food (ex. post-surgery)

Sickle Cell Anemia – is an inherited disease where the red blood cells look like a half-moon or sickle. This cell does not flow well in the blood vessels and causes blockage in the blood vessels. It can lead to organ damage, pain, and infection. Sickle cells also die after 20 days compared to normal RBC which is 120 days.  

Normocytic anemia – the RBC is normal in shape, but the number produced doesn’t meet the body’s needs. It usually causes long-term conditions in the body like cancer, kidney diseases, or rheumatoid arthritis.

Hemolytic Anemia – is a condition when the RBCs are destroyed even before their lifespan is over. When this happens, the body does not have enough red blood cells to function as your bone marrow cannot meet the demand. 

Fanconi Anemia – is the rarest form of anemia and is an inherited disorder like sickle cell. Anemia like this happens when the bone marrow cannot produce enough blood components. Red blood cells are also part of this blood component. Children born with this condition often develop leukemia [1].

Blood Types

There are eight blood types from the four blood groups. These are A, B, AB, and O. All red blood cells, positive or negative, have Rh factors except Type O.
The proteins can elicit an immune response when they contact their corresponding antibody. They stimulate the antibodies in the plasma to defend the body.
The antibodies in the blood protect your body from foreign invaders. Blood types have antibodies except for Type AB.
Type AB is in the plasma surrounding the RBCs. The recipient’s plasma antibodies must be the opposite of the antigen found on the donor’s red blood cell.

Blood Groups and Types

A blood type: has only A antigens on its surface but B antibodies in the plasma

  • Donates to: A and AB
  • Recipient of: O and A

B blood type: has only B antigens on its surface but A antibodies in the plasma

  • Donates to: B and AB
  • Recipients of: O and B

AB blood type: has both A and B antigens on its surface but NO antibodies in the plasma

  • Donates to: AB
  • Recipient of: O, A, B, and AB

O blood type: has NO antigens on its surface but has A and B antibodies in the plasma

  • Donates to: O, A, B, AB
  • Recipient of: O

Rh Factor

  • These factors are either found on the surface of a red blood cell or not. Either a person has them, or they don’t!
  • If the factors are present on the RBC, the person is Rh POSITIVE. If the elements are absent on the RBC, the person is Rh NEGATIVE.
  • Example: A+ (has factors present) or A- (no factors present)
  • IMPORTANT! If a patient is Rh-positive, they can receive either Rh+ or RH- blood. On the other hand, if a patient is Rh-negative, they can only receive Rh- blood.
The same RBC antigen and antibody cause an immune response called agglutination. This is when RBCs stick together and the donor’s red blood cells will lysis. When this happens, a reaction called hemolytic transfusion occurs. A donor’s RBC is then compared to the patient’s antibodies.

White Blood cells and Platelets

White blood cells account for 1% of your total blood. The main difference between leukocytes and RBCs or platelets is that they have a nucleus. White blood cells are responsible for your immunity.
You’d think there would be more than 1% of total blood for such an important role. There are also different types of blood cells with extra responsibilities [2].

Types of White Blood Cells

There are five main types of leukocytes.

  1. Neutrophils
    1. 62% of leukocytes are neutrophils. They are responsible for fighting off bacteria and fungi.
    2. They live for about 6hrs – to a few days.
  2. Lymphocytes
    1. 30% of leukocytes are lymphocytes. There are different types of lymphocytes.
      1. B cells: responsible for antibodies and activating T cells.
      2. T cells: are made in the thymus 
        1. Cytotoxic T cells: destroy infected cells (viral or cancer) through the use of granule sacs that contain digestive enzymes.
        2. Helper T cells: activate T cells, macrophages, and B cells.
        3. Regulatory T cells:  suppress the actions of B and T cells to decrease the immune response.
        4. Memory T cells protect against previously encountered antigens and provide lifetime protection against some pathogens.
        5. Natural Killer T cells: destroy infected or cancerous cells and attack cells that do not contain molecular markers that identify them as body cells.
  3. Monocytes
    1. 5.5% of leukocytes are monocytes.
      1. It is made in the bone marrow and travels through the blood to tissues in the body, where it becomes a macrophage or a dendritic cell. Macrophages surround and kill microorganisms, ingest foreign material, remove dead cells, and boost immune responses.
      2. During inflammation, dendritic cells stimulate immune responses by showing antigens on their surface to other immune system cells.
      3. A monocyte is a type of white blood cell and a type of phagocyte.
  4. Eosinophils
    1. 2% of all leukocytes are eosinophils. They are responsible for fighting off larger parasites and are part of the allergic inflammatory response. 
    2. They live for about 8-12 days.
  5. Basophils
    1. 0.5% of leukocytes are basophils. They are responsible for histamine release during inflammation. 


Platelets are thrombocytes produced by the bone marrow. They are responsible for coagulation which is crucial to wound healing. If one of your blood vessels gets damaged, it signals platelets. The platelets then rush to the site of damage and form a plug, or clot, to repair the damage  [3].

  • An average platelet count is 150,000 to 450,000 platelets per microliter of blood.
  • The risk for bleeding develops if a platelet count falls below 10,000 to 20,000.
    • Thrombocytopenia: IIs a condition when your bone marrow makes too few platelets, or your platelets are destroyed. If the platelet count gets too low, bleeding can occur under the skin. This is seen as bruising, inside the body as internal bleeding, or outside the body through a cut that won’t stop bleeding or from a nosebleed. Thrombocytopenia can be caused by many conditions, including several medications, cancer, kidney disease, pregnancy, infections, and an abnormal immune system.

Some people make too many platelets and can have platelet counts from 500,000 to more than 1 million.

  • Thrombocythemia – is a condition when the bone marrow makes too many platelets. The symptoms can include blood clots that form and block the blood supply to the brain or the heart. However, the cause of thrombocythemia is unknown.
  • Thrombocytosis –  is a condition caused by too many platelets. But platelet counts do not get as high as thrombocythemia. It is also more common and is not caused by the abnormal bone marrow. It is often caused by another disease in the body that stimulates the bone marrow to make more platelets. Those affected with thrombocytosis often have cancer, infections, inflammation, and reactions to medications. The symptoms of thrombocytosis are not usually severe, and the platelet count becomes normal again once the underlying condition becomes better. 


Plasma makes up 55% of the total blood volume. It contains water, protein, glucose, clotting factors, hormones, electrolytes, carbon dioxide, and oxygen. Generally, it carries nutrients, hormones, and proteins to different parts of the body. It also carries the waste products of cell metabolism away from tissues. Other than that, plasma is also the vehicle for blood cells to the blood vessels [4].

In addition, plasma is the vehicle for transporting blood cells through the blood vessels.

  • Coagulation – many essential proteins, such as fibrinogen, thrombin, and factor X, are present in plasma and play a vital role in the clotting process to stop a person from bleeding.
  • Immunity – blood plasma contains disease-fighting proteins, such as antibodies and immunoglobulins, which play a crucial role in the immune system by fighting pathogens.
  • Blood pressure and volume maintenance – a protein present in plasma called albumin helps maintain the oncotic pressure. This pressure prevents fluid from leaking into the body and skin where less water is present. It also helps ensure blood flow through blood vessels.
  • pH balance – substances present in blood plasma act as buffers, allowing plasma to maintain a pH within normal ranges, which helps to support cell function.
  • Transportation – plasma transports nutrients, electrolytes, hormones, and other essential substances all over the body. It also helps to remove waste products by transporting them to the liver, lungs, kidneys, or skin.
  • Body temperature – plasma helps maintain body temperature by balancing heat loss and heat gain in the body.

Blood Product Administration

Nurses should always follow the best standard practices when administering blood transfusions. They must also follow the standard policies and procedures of the healthcare facility.[5]

Blood transfusion consent, blood typing, and cross-matching are all needed before administering blood. But these are not required if the situation is an emergency. Checking blood products against the order and using two patient identifiers is critical. Blood must be given to patients within 30 minutes after being taken from the blood bank.

  • The patient and family members are informed about the procedure including what to expect during and after it is done.
  • Before administration, two licensed personnel must verify the correct blood product and patient. 
  • Blood products need a dedicated line for infusion and filtered intravenous tubing. Normal saline flushes the intravenous line, with no other solutions or medications. 
  • Need to take vital signs before initiating the transfusion. The nurse stays with the patient for the first 15 minutes of the transfusion. This is done to check for any immediate reaction. 
  • Vital signs are monitored for 15 minutes once the transfusion starts. It’s monitored during, after and one hour after the transfusion is complete.

Blood transfusion can create adverse reactions in the patient. The signs and symptoms of blood transfusion reactions for hemolytic and non-hemolytic reactions include:

  • Pain
  • Anxiety
  • Hematuria
  • Fever
  • Headache
  • Pruritus
  • Rash or hives
  • Nausea
  • Respiratory difficulties (common for non-hemolytic reactions)
The symptoms mentioned above, plus hypotension, bleeding, and oliguria shows hemolytic reactions. Blood transfusion should stop immediately but keep an IV line open for normal saline.
Patients are monitored by the healthcare provider and physicians must be noted immediately. The remaining blood products and tubing are then taken to the laboratory to be tested.

Want more blood? Click here 👇 to watch the full Episode 81:


0:00 Introduction
3:16 Episode Introduction
5:12 Red Blood Cells
11:20 Common Types of Anemia
19:50 Blood Types
26:45 Types of White Blood Cells
36:24 Platelets
47:00 Plasma
53:01 Blood Product Administration

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