<< Chapter < Page Chapter >> Page >

Blood loss anemias are fairly straightforward. In addition to bleeding from wounds or other lesions, these forms of anemia may be due to ulcers, hemorrhoids, inflammation of the stomach (gastritis), and some cancers of the gastrointestinal tract. The excessive use of aspirin or other nonsteroidal anti-inflammatory drugs such as ibuprofen can trigger ulceration and gastritis. Excessive menstruation and loss of blood during childbirth are also potential causes.

Anemias caused by faulty or decreased RBC production include sickle cell anemia, iron deficiency anemia, vitamin deficiency anemia, and diseases of the bone marrow and stem cells.

  • A characteristic change in the shape of erythrocytes is seen in sickle cell disease    (also referred to as sickle cell anemia). A genetic disorder, it is caused by production of an abnormal type of hemoglobin, called hemoglobin S, which delivers less oxygen to tissues and causes erythrocytes to assume a sickle (or crescent) shape, especially at low oxygen concentrations ( [link] ). These abnormally shaped cells can then become lodged in narrow capillaries because they are unable to fold in on themselves to squeeze through, blocking blood flow to tissues and causing a variety of serious problems from painful joints to delayed growth and even blindness and cerebrovascular accidents (strokes). Sickle cell anemia is a genetic condition particularly found in individuals of African descent.

Sickle cells

This photograph shows red blood cells of a person suffering from sickle cell anemia. Instead of being discoid shaped like healthy blood cells, sickle red blood cells are shaped like a sickle.
Sickle cell anemia is caused by a mutation in one of the hemoglobin genes. Erythrocytes produce an abnormal type of hemoglobin, which causes the cell to take on a sickle or crescent shape. (credit: Janice Haney Carr)
  • Iron deficiency anemia is the most common type and results when the amount of available iron is insufficient to allow production of sufficient heme. This condition can occur in individuals with a deficiency of iron in the diet and is especially common in teens and children as well as in vegans and vegetarians. Additionally, iron deficiency anemia may be caused by either an inability to absorb and transport iron or slow, chronic bleeding.
  • Vitamin-deficient anemias generally involve insufficient vitamin B12 and folate.
    • Megaloblastic anemia involves a deficiency of vitamin B12 and/or folate, and often involves diets deficient in these essential nutrients. Lack of meat or a viable alternate source, and overcooking or eating insufficient amounts of vegetables may lead to a lack of folate.
    • Pernicious anemia is caused by poor absorption of vitamin B12 and is often seen in patients with Crohn’s disease (a severe intestinal disorder often treated by surgery), surgical removal of the intestines or stomach (common in some weight loss surgeries), intestinal parasites, and AIDS.
    • Pregnancies, some medications, excessive alcohol consumption, and some diseases such as celiac disease are also associated with vitamin deficiencies. It is essential to provide sufficient folic acid during the early stages of pregnancy to reduce the risk of neurological defects, including spina bifida, a failure of the neural tube to close.
  • Assorted disease processes can also interfere with the production and formation of RBCs and hemoglobin. If myeloid stem cells are defective or replaced by cancer cells, there will be insufficient quantities of RBCs produced.
    • Aplastic anemia is the condition in which there are deficient numbers of RBC stem cells. Aplastic anemia is often inherited, or it may be triggered by radiation, medication, chemotherapy, or infection.
    • Thalassemia is an inherited condition typically occurring in individuals from the Middle East, the Mediterranean, African, and Southeast Asia, in which maturation of the RBCs does not proceed normally. The most severe form is called Cooley’s anemia.
    • Lead exposure from industrial sources or even dust from paint chips of iron-containing paints or pottery that has not been properly glazed may also lead to destruction of the red marrow.
  • Various disease processes also can lead to anemias. These include chronic kidney diseases often associated with a decreased production of EPO, hypothyroidism, some forms of cancer, lupus, and rheumatoid arthritis.

In contrast to anemia, an elevated RBC count is called polycythemia    and is detected in a patient’s elevated hematocrit. It can occur transiently in a person who is dehydrated; when water intake is inadequate or water losses are excessive, the plasma volume falls. As a result, the hematocrit rises. For reasons mentioned earlier, a mild form of polycythemia is chronic but normal in people living at high altitudes. Some elite athletes train at high elevations specifically to induce this phenomenon. Finally, a type of bone marrow disease called polycythemia vera (from the Greek vera = “true”) causes an excessive production of immature erythrocytes. Polycythemia vera can dangerously elevate the viscosity of blood, raising blood pressure and making it more difficult for the heart to pump blood throughout the body. It is a relatively rare disease that occurs more often in men than women, and is more likely to be present in elderly patients those over 60 years of age.

Chapter review

The most abundant formed elements in blood, erythrocytes are red, biconcave disks packed with an oxygen-carrying compound called hemoglobin. The hemoglobin molecule contains four globin proteins bound to a pigment molecule called heme, which contains an ion of iron. In the bloodstream, iron picks up oxygen in the lungs and drops it off in the tissues; the amino acids in hemoglobin then transport carbon dioxide from the tissues back to the lungs. Erythrocytes live only 120 days on average, and thus must be continually replaced. Worn-out erythrocytes are phagocytized by macrophages and their hemoglobin is broken down. The breakdown products are recycled or removed as wastes: Globin is broken down into amino acids for synthesis of new proteins; iron is stored in the liver or spleen or used by the bone marrow for production of new erythrocytes; and the remnants of heme are converted into bilirubin, or other waste products that are taken up by the liver and excreted in the bile or removed by the kidneys. Anemia is a deficiency of RBCs or hemoglobin, whereas polycythemia is an excess of RBCs.

Questions & Answers

What is ELISA
POULAMI Reply
(enzyme linked immunosorbent assay) is a test that uses antibodies and color change to identify a substance.
luke
difference between apocrine sweat glands and merocrine sweat glands
Binkheir Reply
I believe the apocrine sweat gland uses a sac under the hair follicle and the merocrine sweat gland releases directly on to the surface of the skin
Mark
normal blood volume in our body
pankaj Reply
5Litres
Albert
Normal blood volume in adults is 6 litres
Kedha's
4.7 to 5ltr.. normal for adult
Clangbhelle
what are the advantages of the concave shape of red blood cells?
Amy Reply
This structure is VERY flexible. It can allow these cells to get into the most tiny places in our bodies. a VERY good design! The advantage of red blood cells' biconcave shape is that the surface area is increased to allow more haemoglobin to be stored in the cell.
Saafi
They can stack so that they can move to capillaries
Nejat
action of gluteus medius and minimus
Green Reply
Lateral rotation of the hip joint
Hertzo
Briefly explain location of ecg on a patient
Prince Reply
it is a machine that gives a graphical representation of heart beat
Nani
Briefly explain location of ecg leads on a patient?
Prince
in ecg we use electrical leads over the chest ,ancle and wrist
Nani
what is the anatomical and function difference between paravertebral and prevertebral ganglia ?
Rada Reply
types of tissue in human
Preety Reply
charactetistic Of cartilaginous tissue
Preety
what is theRecurrent infection?
pankaj Reply
what do you mean about recurrent infection
pankaj
Recurrent or persistent infection is a manifestation of primary immuno deficiency
Kedha's
weakens the immune system, allowing infections and other health problems to occur more easily
Kedha's
lysis of RBC
Abdirizack
What is barometric pressure
Kedha's Reply
what is the agglutination advantage
Gopal Reply
the functions of the liver
Nana Reply
it produces bile juice which is used to make the food smaller
Kedha's
it also plays an important role in conversion of amino acid into urea
Komal
it also has role in gluconeogenesis in which amino acids and lipids convert into glucose.
Komal
during fetal life it's a center for hemopoiesis (formation of blood cells)
Komal
it filters, or removes, harmful substances from the blood
Kedha's
It stores nutrients, such as vitamins and iron,for the body
Kedha's
what is the largest gland in human body
Shahid Reply
liver
rachna
correct
Said
correct
dominic
thyroid gland
Kedha's
thyroid is largest endocrine gland
Komal
describe microscopic structures of the kidney
Nana Reply
kidney is covered by fibrous capsule, consists of an outer cortex and inner medulla with medullary pyramids. The microscopic structure is seen as 1-2 millions of nephrons and collecting tubule.
Komal
identify the four major tissue types
Binkheir Reply
connective epithelial
Nana
two ramining
Binkheir
muscle nervous
Nana
epithelial, connective, muscle, and nervous tissue
Mel

Get the best Anatomy & Physiology course in your pocket!





Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Anatomy & Physiology' conversation and receive update notifications?

Ask