New Blood Trivia Quiz

Answer: Erythrocyte

A red blood cell (often abbreviated as RBC) has the scientific name of the erythrocyte. It comes from the Greek 'erythros' (meaning red) and 'kytos' (translated as cell). Sometimes they are referred to as red cells, corpuscles or even haematids.

An erythrocyte is pretty small - it is 7 micrometres in diameter or 7 thousandths of a millimetre. There are 20-30 trillion (that's 20-30 million million) erythrocytes in the adult body travelling around 100 000 km (60 000 mi) of blood vessels. Some of those blood vessels have a small diameter and at times those blood vessels have to squeeze through these smaller vessels. Fortunately, with their special shape, they are flexible enough to do that.

Answer: To carry oxygen from the lungs to all cells in the body

Nearly all cells in the body require oxygen to function. Oxygen that has been inspired (breathed in) sits in the smallest parts of the lung, the alveoli, and waits for red cells to move past the alveoli. The oxygenated blood then moves to the cells and tissues where the oxygen then drops off and moves into the cell.

Most of the time carbon dioxide, a waste product from the cells, attaches to the same red blood cell which takes the carbon dioxide back to the lungs where it detaches, moves into the alveoli and is expired. (This is not the only method in which carbon dioxide is taken out of the body).

The cycle then repeats itself.

The photo shows an oxygen tank and mask used by patients who cannot get enough oxygen into their lungs breathing on their own.

Answer: False

Most red blood cells are composed of a protein called haemoglobin. This protein (globulin) has four identical molecules called heme attached to it. Attached to each heme is an iron atom. The oxygen binds to this iron atom so each haemoglobin protein can carry four atoms of oxygen.

There are about 270 million haemoglobin molecules in every red blood cell. This means a red blood cell can have over one billion oxygen atoms attached to take to the cells and tissues where the oxygen is 'unloaded'.

The shape of the red blood cell is a biconcave disc (see photo). This means it is like a doughnut but instead of a hole in the centre, it has a thin membrane. This shape allows it to contain the largest number of haemoglobin molecules. it also makes the cell very flexible to fit through very narrow blood vessels.

The heme molecules on the haemoglobin molecule give the red blood cell its distinctive colour.

The photo depicts red blood cells as seen under a scanning electron microscope.

Answer: No nucleus

An erythrocyte loses its nucleus and its organelles In the final stage of maturation just before it is released into circulation. It loses its nucleus to enable it to contain more oxygen-carrying haemoglobin.

The disadvantage of this is the erythrocyte cannot repair itself nor can it reproduce. This means an erythrocyte has a very limited lifespan before it is, literally, taken out of circulation. This lifespan of a red blood cell is 100-120 days.

Therefore, the body has a continuous need for new blood. It needs to make 200 billion erythrocytes per day. This translates as 20 mL of blood produced daily, which contains 6 g of haemoglobin and 20 mg of iron. (This is why iron is an essential part of the human diet.)

The photo depicts onion skin where each demarcated cell has a distinct nucleus.

Answer: Bone marrow

We associate bones with structure and strength. Bones give us our form and shape and make movement possible as bones are hard and strong. However, some bones are hollow and filled with spongy tissue called bone marrow. These are the long bones of the arms and legs. All erythrocytes are made in this space, along with other types of blood cells. It takes two days for a mature erythrocyte to be made from a primitive cell.

The photo shows the head of a femur (thigh bone) with the outer bone removed, exposing the spongy bone marrow underneath.

Answer: Large cells called macrophages ingest them

Monocytes are the largest type of white blood cells. After they circulate for 1-3 days they then migrate into the tissues, particularly those in the liver, bone marrow and spleen. In the tissues, they are known as macrophages which means "big eater". These cells 'eat' damaged red blood cells by surrounding the damaged RBCs and then ingesting them. Hemoglobin and iron atoms are recycled and used in making new red blood cells.

The photo shows a macrophage (centre) ingesting red blood cells.

Answer: About half

Blood comprises red blood cells, other cells like leucocytes and platelets, as well as plasma which is a watery yellow colour and contains about one-tenth solids. These include ions, proteins, coagulating factors, nutrients, dissolved gases and waste products. The fraction that is erythrocytes is between 38-52% with males generally having a slightly higher ratio than females. The ratio is called the haematocrit. Low and high values are indicative of disease.

If you collect blood for testing in a collection tube and let it sit upright, the components will settle into three distinct layers (You can speed this separation process up with a centrifuge): The red cells are the heaviest and sink to the bottom, the white cells and platelets are comparatively low in number but lighter - they sit on top of the red blood cells. The plasma, with its dissolved substances, sits on top as shown in the photo.

Answer: They are involved with immunity and fighting infection

White blood cells or leucocytes/leukocytes try to rid the bloodstream of foreign invaders like bacteria and viruses before they become a problem (and before you go to the doctor for antibiotics!). They are bigger than red cells (see photo) and do not contain haemoglobin, so they appear white.

There are five types, with neutrophils (pictured) being the most prevalent. Neutrophils ingest bacteria before they can multiply and cause fever symptoms. Another type, lymphocytes, produce antibodies to invading bacteria, viruses and fungi. There are a thousand times fewer white cells than red cells, but should there be an 'invasion', white cells can multiply very quickly to try to fight the infection.

Answer: They clump together to form a clot whenever they come across damaged (eg cut) blood vessels

Like red and white blood cells, platelets are made in the bone marrow from a common stem cell. When they are released into the circulation (which they only do for around nine days), they are chemically attracted to damaged blood vessels and they stick to the damaged vessel and to each other to form a clot, plug the hole and stop the bleeding.

Thrombocytopenia is a medical condition with low levels of platelets which carries an increased risk of bleeding. However, a high number of platelets (thrombocythemia) increases the risk of forming blood clots within intact blood vessels. These could stop essential organs from receiving adequate blood supply, causing heart attacks or strokes.

Answer: When a transfusion is necessary, whole blood is transfused

A person's blood type is determined by different proteins on the person's erythrocytes. There are two main systems: ABO and Rh. If a person's erythrocytes have the A protein, they will be type A, If they have the B protein they are type B. If they have both they are type AB and if they have neither they are type O. If they have the Rh protein they are positive, if they do not they are negative. Worldwide O+ and A+ are the most prevalent types. AB- is rare. When a person receives a blood transfusion (because they are losing blood faster than they can make it), they are nearly always given the same ABO and Rh blood group donation as their own blood group (but there are a few exceptions).

When a person receives a blood transfusion they receive only the red cells from the donation; the plasma, white cells and platelets have been made into individual products. Each donation is about 470 mL of packed cells (red cells only). These red blood cells can be stored for between five and six weeks when properly refrigerated.

The photo depicts red cell donations stored in special bags before donation.