Updated post about Red Blood Cells

Red Blood Cells

Introduction to Red Blood Cells.

-The name

Red blood cells are also known as RBCs, red blood corpuscles (an archaic term), haematids, erythroid cells or erythrocytes (from Greek erythros for "red" and kytos for "hollow", with cyte translated as "cell" in modern usage). The capitalized term Red Blood Cells is the proper name in the US for erythrocytes in storage solution used in transfusion medicine.

Information on Red Blood Cells.

-Life cycle

Human erythrocytes are produced through a process named erythropoiesis, developing from committed stem cells to mature erythrocytes in about 7 days. When matured, these cells live in blood circulation for about 100 to 120 days. At the end of their lifespan, they become senescent, and are removed from circulation.

-Life cycle (Erythropoiesis)

Erythropoiesis is the development process in which new erythrocytes are produced, through which each cell matures in about 7 days. Through this process erythrocytes are continuously produced in the red bone marrow of large bones, at a rate of about 2 million per second in a healthy adult. (In the embryo, the liver is the main site of red blood cell production.) The production can be stimulated by the hormone erythropoietin (EPO), synthesised by the kidney. Just before and after leaving the bone marrow, the developing cells are known as reticulocytes; these comprise about 1% of circulating red blood cells.

-Functional lifetime

This phase lasts about 100–120 days, during which the erythrocytes are continually moving by the blood flow push (in arteries), pull (in veins) and squeezing through microvessels such as capillaries as they compress against each other in order to move.

Relating to what we have learned- embryonic stem cells

-Artificially grown red blood cells

In 2008 it was reported that human embryonic stem cells had been successfully coaxed into becoming erythrocytes in the lab. The difficult step was to induce the cells to eject their nucleus; this was achieved by growing the cells on stromal cells from the bone marrow. It is hoped that these artificial erythrocytes can eventually be used for blood transfusions.

-How it looks like

-Red Blood Cell in the human blood

• Red Blood Cell in the blood vessel.

The artery that enters any organ divides and thins six to eight times before becoming an arteriole, the capillaries' control valve. Subsequently, the arteriole itself will branch two or three times, reducing its diameter to just 9 microns, and will continue on as a capillary. Some of these capillaries are so small that they cannot let even some large blood cells pass through them. Even red blood cells pass through such capillaries in single file, or else by distorting their shape.

The blood proceeding along the arteries at 1.5 kilometers an hour (0.93 miles per hour) slows down by a thousandth of that rate when it enters the capillaries. Every region of the body has been penetrated by an extraordinarily wide ranging network of capillaries. The capillaries in just one single person could stretch from one end of the USA to the other.109 This incomparable mechanism is brought into being to nourish all the cells in the body. In fact, a cell can be no further than 20 to 30 microns from a capillary—a distance of 0.02 millimeters (0.0007874 inch), which is sufficient to grasp the scale of this magnificent network that visits 100 trillion cells.

How does waste from the red blood cell goes into the lungs and how does oxygen molecules enters the red blood cell from the alveoli (tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place)

-Function of Red Blood Cells

Red blood cells (also referred to as erythrocytes) are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen (O₂) to the body tissues via the blood flow through the circulatory system. They take up oxygen in the lungs or gills and release it while squeezing through the body's capillaries.

-What are the organelles found in the cell?

The organelles found in red blood cells include a plasma membrane and the cells' cytoplasm is rich in hemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the blood's red color.

Hemoglobin

green = heme groups

red & blue = protein subunits

-List the structural features of the cell.

They are biconcave discs, having a depressed center on both sides. These depressed centers allow the cells to have more cell membrane surface which can be exposed to diffusing oxygen while transiting the lungs. This structure also allows them to be more flexible with the ability to twist and bend through the blood vessels.

-What are the functions of these organelles?

Hemoglobin facilitates transportation of oxygen and the plasma membrane keeps the hemoglobin in the cell.

-Why are these functions of the organelles important to the living cell?

Hemoglobin helps in transportation in oxygen so without hemoglobin, the cell will not carry oxygen so it would be useless and die. The person would also die.

Plasma membrane keeps the hemoglobin inside the cell if not it would be all round our blood.

-Diseases involving the red blood cells

• Anemias (or anaemias) are diseases characterized by low oxygen transport capacity of the blood, because of low red cell count or some abnormality of the red blood cells or the hemoglobin.
• Iron deficiency anemia is the most common anemia; it occurs when the dietary intake or absorption of iron is insufficient, and hemoglobin, which contains iron, cannot be formed
• Sickle-cell disease is a genetic disease that results in abnormal hemoglobin molecules. When these release their oxygen load in the tissues, they become insoluble, leading to mis-shaped red blood cells. These sickle shaped red cells are rigid and cause blood vessel blockage, pain, strokes, and other tissue damage.

Affected by Sickle-cell disease, red blood cells alter shape and threaten to damage internal organs.

• Thalassemia is a genetic disease that results in the production of an abnormal ratio of hemoglobin subunits.
• Spherocytosis is a genetic disease that causes a defect in the red blood cell's cytoskeleton, causing the red blood cells to be small, sphere-shaped, and fragile instead of donut-shaped and flexible.
• Pernicious anemia is an autoimmune disease wherein the body lacks intrinsic factor, required to absorb vitamin B12 from food. Vitamin B12 is needed for the production of hemoglobin.
• Aplastic anemia is caused by the inability of the bone marrow to produce blood cells.
• Pure red cell aplasia is caused by the inability of the bone marrow to produce only red blood cells.Hemolysis is the general term for excessive breakdown of red blood cells. It can have several causes and can result in hemolytic anemia.
• Hemolysis is the general term for excessive breakdown of red blood cells. It can have several causes and can result in hemolytic anemia.

• The malaria parasite spends part of its life-cycle in red blood cells, feeds on their hemoglobin and then breaks them apart, causing fever. Both sickle-cell disease and thalassemia are more common in malaria areas, because these mutations convey some protection against the parasite.

• Polycythemias (or erythrocytoses) are diseases characterized by a surplus of red blood cells. The increased viscosity of the blood can cause a number of symptoms.

• In polycythemia vera the increased number of red blood cells results from an abnormality in the bone marrow.
• Hemolytic transfusion reaction is the destruction of donated red blood cells after a transfusion, mediated by host antibodies, often as a result of a blood type mismatch.
• Some other diseases have been removed as it is too difficult to understand. Those who are interested to know the hard ones can go to
• http://en.wikipedia.org/wiki/Red_blood_cell#Diseases_and_diagnostic_tools

Sources:

Information: http://web.buddyproject.org/web019/web019/blood.html and

http://en.wikipedia.org/wiki/Red_blood_cell

Picture (RBCs):

http://www.sciencequiz.net/jcscience/jcbiology/circulatorysystem/red_blood_cells.jpg

Picture (Blood):

http://images.google.com.sg/imglandingq=red%20blood%20cells&imgurl=

http://www.ich.ucl.ac.uk/gosh_families/

information_sheets/aplastic_anaemia/cells.gif&imgrefurl=

http://www.ich.ucl.ac.uk/gosh_families/information_sheets/

aplastic_anaemia/aplastic_anaemia_families.html&usg=__WzowWDOks0e1tCtfphX

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gbv=2&tbs=isch:1&start=4#tbnid=V1EOCbZVZLiKtM&start=8

Picture (Capillaries):

http://www.harunyahya.com/books/science/blood_heart/blood_heart_12.php

Picture (Capillaries drawn):

http://www.harunyahya.com/books/science/blood_heart/blood_heart_12.php

Definition of alveoli: New Oxford American Dictionary.

109 Biology Today, p. 202. :

http://www.harunyahya.com/books/science/blood_heart/blood_heart_12.php

Hemoglobin diagram: http://en.wikipedia.org/wiki/File:1GZX_Haemoglobin.png

Most information obtained from http://en.wikipedia.org/

Done by:

Christopher, Carisa, Yi Lin, Jaime, Pei Shan, Priyanka