Specialized Cells- Erythrocytes

How to determine if RBC are performing well

Although the numbers of RBCs are important, it is the amount of hemoglobin in the bloodstream at any time that really determines how well the erythrocytes are performing their role of oxygen transport. The more hemoglobin molecules the RBCs contain, the more oxygen they will be able to carry. A single red blood cell contains about 250 million hemoglobin molecules, each capable of binding 4 molecules of oxygen, so each of these tiny cells can carry about 1 billion molecules of oxygen! However, much more important clinically is the fact that normal blood contains 12-18 grams (g) of hemoglobin per 100 milliliters (ml) of blood. The hemoglobin content is slightly higher in men (13-18 g/ml) than in women (12-16 g/ml).

Fate of RBC

Ave. life = 3-4 months Aged and damaged cells eaten by macrophages (WBC) in spleen, liver, bone marrow Cells kidneys detect low O2 (reflects RBC count) Releases ERYTHROPOIETIN to stimulate RBC formation Detecting low O2 which reflects the RBC count in a healthy individual

What type of structure do RBC have

Bi Concave Increase surface area for gas absorption Used as a packet of hemoglobin (Hb) Do not have their organelles (have very little inside them) Very important Erythrocytes are small, flexible cells shaped like biconcave discs—flattened discs with depressed centers on both sides. Because of their thinner centers, erythrocytes look like miniature doughnuts when viewed with a microscope. Their small size and peculiar shape provide a large surface area relative to their volume, making them ideally suited for gas exchange.

What are RBC filled with?

Hemoglobin (Hb) Carries oxygen ~280 mL per RBC Pigment When Hb is attache to Oxygen (RED) When Hb is not attached to Oxygen (PURPLE) Usually in veins Blood pigment +O2;-O2 Binds O2 at high concentration Hb blood passes though lungs High conc of Oxygen Releases O2 at low concentration Muscles, vital organs Hb releases oxygen Once CO binds it will never release oxygen All of its oxygen Hem groups will be taken up by CO and slowly suffocate

Hemoglobin

Hemoglobin (Hb), an iron-bearing protein, transports most of the oxygen that is carried in the blood. (It also binds with a small amount of carbon dioxide.) Recall that hemoglobin is an example of a globular protein. Globular, or functional, proteins have tertiary structure, meaning that they are folded into a very specific shape. In this case, the folded structure of hemoglobin allows it to perform the specific function of binding and carrying oxygen. The structure of globular proteins is also very vulnerable to pH changes and can be denatured (unfolded) by a pH that is too low (acidic); denatured hemoglobin is unable to bind oxygen.

What are the most abundant blood cells

RBC 1000 RBC: 1 WBC Kidney detects low levels Low oxygen levels WBC live more in tissue RBC cannot pass blood vessel wall Cells that carry oxygen RBCs outnumber white blood cells by about 1,000 to 1 and are the major factor contributing to blood viscosity. Although the numbers of RBCs in the circulation do vary, there are normally about 5 million cells per cubic millimeter of blood. (A cubic millimeter [mm3] is a very tiny drop of blood, almost too small to be seen.) When the number of RBC/mm3 increases, blood viscosity, or thickness, increases. Similarly, as the number of RBCs decreases, blood thins and flows more rapidly.

Hematocrit= % of RBC

Male % higher than Female % Testosterone helps to induce RBC formation Used as a blood enhancer if someone is going to blood dope Helps make more RBC

What organelles do RBC lack

No nuclei; No mitochondria; No ribosomes Mitochondria will steal oxygen Cell cannot do protein synthesis really Cannot repair, divide Really just a sac carrying oxygen Anaerobic respiration; do not make a lot of ATP RBCs differ from other blood cells because they are anucleate; that is, they lack a nucleus. They also contain very few organelles. In fact, mature RBCs circulating in the blood are literally "bags" of hemoglobin molecules. Moreover, because erythrocytes lack mitochondria and make ATP by anaerobic mechanisms, they do not use up any of the oxygen they are transporting, making them very efficient oxygen transporters indeed.

Iron in Hb is recycled back to liver

We get most of our iron when it is recycled Losing blood monthly should not be a reason to take iron unless you are iron deficient Dark leafy greens etc

Erythrocytes

red blood cells function primarily to ferry oxygen to all cells of the body.