BloodPlasma Is| Blood Composition | Function

July 6, 2020

Blood Plasma

What is the difference and how they are given Blood Plasma is?

Blood and Plasma | Blood Composition
Fresh Frozen Plasma

Blood and plasma is a part of pure blood

Blood represents about 8% of body weight composed of red blood cells, white blood cells, and platelets suspended in plasma, rich in proteins, sugars, fats, and minerals.

What are its functions?
Transport of substances in all areas of the body;
Defence against foreign agents, including pathogenic microorganisms such as viruses, bacteria, and fungi;
Repair of damage and wounds to the blood vessels, through blood coagulation, to avoid bleeding;
distribution of the heat generated mainly by muscle contraction through the control of peripheral circulation. In fact, when we are hot, the blood vessels dilate (vasodilation) and turn red, when we are cold. However, they are contracted (vasoconstriction).

What is it made of?

55% of the total volume of blood (the liquid part) is represented by plasma. The remaining 45% is made up of red blood cells, white blood cells, and platelets. Specifically, the white blood cells and platelets (also called buffy coat) are equal to 1%, the red blood cells to 44%.


With its natural straw yellow colour, it is 90% composed of water, in which salts and plasma proteins are dissolved. Among these, albumin, fibrinogen, factor VIII, factor IX and immunoglobulins (called plasma derivatives) can be obtained from the blood thanks to a process called fractionation.
Among its many functions is that of the medium of exchange of essential minerals and the maintenance of the pH of our body.
Plasma and its derivatives are commonly administered to traumatized patients and patients with severe liver disease.

Red blood cells

They are very numerous, one cubic millimetre of blood contains 4 to 5 million of them, and they live about 120 days (for this reason the blood donation is periodic). Thanks to the haemoglobin molecules contained in it, oxygen is transported from the lungs to the body’s tissues, also collecting the carbon dioxide that is brought back to the lungs and eliminated.
The patients most in need of red blood cell transfusion are those with chronic anaemia and those with acute bleeding.

White blood cells

They are much less numerous than red blood cells, the proportion is (approximately) 1 white blood cell for every 600 red blood cells. Their task is to defend against micro-mechanisms that can attack our body and everything that is recognized as foreign. They are divided into groups (neutrophils, lymphocytes, monocytes, eosinophils, basophils), each of which performs a specific defence action.


They intervene in stopping blood loss, they can be obtained by splitting or directly by a donor with a process known as apheresis, through which the platelets are separated from the blood collected, then re-infused into the donor.

Blood groups

The discovery of the blood groups dates back to 1900, by the Austrian Landsteiner (who was awarded the Nobel Prize for medicine in 1930).
There are eight different common blood types, determined by the presence or absence of specific antigens on the surface of red blood cells. Since some of these can trigger the patient’s immune system to attack the transfused blood, group compatibility is required in transfusions.
Blood and Plasma | Blood Composition
Red Blood Cells
What is given and in how many ways it can be given
To become a donor
There are four possible types of donation: blood, apheresis (plasma and platelets), dedicated, and self-donation. The analyzes that are made to aspiring donors are used to assess the suitability of the various types of donations.
It will be the doctor to determine, based on blood values, how many and which donations are best made during the year, bearing in mind that the main objective is always the health of the donor and recipient.
It may happen, in fact, that some donors, even if they do not have pathological situations, have haemoglobin (the pigment that carries oxygen in the blood) or hematocrit (percentage of red blood cells compared to the liquid part of the blood) or ferritin (iron reserve) at the minimum or lower limit of the suitable levels to donate whole blood.
In this case, the donor will be directed to donate plasma in order not to further reduce these blood components. Conversely, the donor with high red blood cell, haemoglobin, and hematocrit values ​​will be advised against plasmapheresis and prefer to donate whole blood and occasionally platelets.

Whole blood donation

Whole blood donation is the most common donation. The amount of blood donated is established by law and is 450 ml, with 10% variations about body weight, age, and gender. The interval between two whole blood donations must be at least 90 days. For women, up to menopause, the frequency is a maximum of 2 full blood donations per year.
A whole blood donation typically lasts around 15 minutes. The donor, in addition to meeting the general requirements, at the time of the gift must have a haemoglobin (Hb) value greater than 13.5 g / dl if male, more excellent than 12.5 g / dl if female.
Blood and Plasma | Blood Composition
Blood Composition

Plasma and apheresis donation

Plasma donation is one of those made using the apheresis procedure. In this case, we use an apparatus, called Cell Separator, which separates the different components of the blood in a sterile circuit, then re-infusing the remaining parts into the donor using a physiological solution. In this way it is possible to take only plasma (plasmapheresis), only platelets (plateletpheresis), or various combinations of two components (plasma and platelets, red blood cells and platelets, etc.).
An apheresis plasma donation lasts about 40-50 minutes and is given up to a maximum of 700ml, a platelet donation, however, reaches 50-60 minutes.
Not always providing for the collection of red and white blood cells, in apheresis it is possible to donate even if on the morning of the donation there are slightly lower haemoglobin values ​​than those required for whole blood.
Furthermore, since the plasma mainly consists of water, it regenerates faster. The minimum interval between one donation and another is therefore much shorter and is 35 days for both women and men.

Dedicated donation of Blood and plasma

Dedicated donation is a more antiquated and inadvisable method. It is carried out by a donor contacted directly by the recipient, based on the belief that being known by him, it offers more excellent safety than usual donors. This type of donation is not currently considered entirely safe and valid, as:
– it is difficult for anyone to get to know a person thoroughly, in particular, to bring up if they have had risky behaviours that can harm the recipient;
– the risk increases when more than one donor has to be used;
– the partner must not donate for a fertile woman who may have future pregnancies due to the risk of neonatal hemolytic disease;
– in the case of consanguinity, the donor lymphocytes attack the patient’s tissues causing a severe transfusion reaction.
Finally, it should not be forgotten that the blood of periodic donors whose health history is known from multiple guarantees.
Blood and Plasma | Blood Composition
Blood Donation


Self-donation is a transfusion procedure that consists of transfusing the subject with units of his own blood, it can be requested by the surgeon who will operate the patient. Patients who need to perform scheduled surgeries for whom significant blood loss is expected (≥ 20% of total blood volume).
The most used method for making this type of donation is the deposit. In the period preceding the operation, some units of blood are drawn from the patient (usually 2-3), in successive stages, at a distance of about 1 week from each other, until reaching the amount that is expected to be necessary during or after surgery.
The advantages of autotransfusion are as follows:
– elimination of incompatibility reactions;
– removal of the risk of transmission of infectious diseases;
– reduction of the risk of immunization from different antigens, with possible remote manifestations.

How donated blood and Plasma is used

Blood is used to replace that particular component that the patient is seriously deficient in. In particular:
– red blood cells, in acute anaemia for haemorrhage and chronic anaemias;
– platelets, in the patient with tumours or with bone marrow damaged by the effect of drugs;
– plasma, in the patient, burned or with serious coagulation problems.
Most of the plasma is used for the production of plasma derivatives so that a large amount of substance is concentrated in a small volume, and the treatment of particular pathologies is made more effective:
– albumin for shocked patients, burn victims, patients with liver or kidney failure and patients with severe protein deficiencies;
– coagulation factors for haemophiliacs and other severe forms of lack of these factors, with Hemorrhagic risks;
gammaglobulins for some infectious diseases such as tetanus, meningitis, viral hepatitis, and measles.
Video Courtesy: FuseSchool – Global Education