Blood

Anemia is condition in which person have abnormally low number of circulating red blood cells or level of hemoglobin or both, resulting in diminished oxygen-carrying capacity.

There are four primary causes of anemia:

1. excessive loss of red blood cells from bleeding;
2. destruction (hemolysis) of red blood cells;
3. defective red blood cell production;
4. inadequate red blood cell production because of bone marrow failure.

Manifestations (symptoms) → pathophysiology (the functional changes that accompany a particular syndrome/ disease)

Increased (↑); (↓) decreased/reduced; (→) due to/because of

Tissue hypoxia due to → The oxygen-carrying capacity of hemoglobin is reduced (↓)  

Tissue hypoxia can give rise to ←  fatigue, weakness, dyspnea^[1], and sometimes angina

Headache, faintness, and dim vision →  due to Hypoxia of brain tissue 

Pallor of the skin^[2], mucous membranes^[3], conjunctiva, and nail beds → Redistribution of the blood from cutaneous tissues or a lack of hemoglobin  

Tachycardia^[4] and palpitations^[5] may occur as → body tries to compensate with an increase in cardiac output.

Flow-type systolic heart murmur → changes in blood viscosity

Diffuse bone pain and sternal tenderness → due to accelerated erythropoiesis^[6] 

In hemolytic anemias: jaundice → caused by ↑ blood levels of bilirubin

Aplastic a.: petechiae and purpura → reduced platelet function.

[1] Dyspnea - Shortness of breath

[2] Pallor of the skin - unusual lightness of skin color compared with your normal complexion.

[3] Mucous membrane (mucosa) - is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs.

[4] Tachycardia - is the medical term for a heart rate over 100 beats a minute. 

[5] Heart palpitations are feelings of having a fast-beating, fluttering or pounding heart.

[6] Erythropoiesis is the process which produces red blood cells (erythrocytes)

Hemolytic anemia is characterized by the following:

• The premature destruction of red cells
• The  retention  in  the  body  of  iron  and  the  other  products  of  hemoglobin destruction
• An increase in erythropoiesis

Almost all types of hemolytic anemia are distinguished by normocytic^[1] and normochromic^[2] red cells. Because of the red blood cell’s shortened life span, the bone marrow is usually hyperactive, resulting in an increased number of reticulocytes^[3] in the circulating blood. As with other types of anemias, the person experiences easy fatigability, dyspnea, and other signs and symptoms of impaired oxygen transport. In hemolytic anemia, red cell breakdown can occur within or outside the vascular compartment.

[1] Normocytic cells - means you have normal-sized red blood cells, but you have a low number of them.

[2] Normochromic anemia - form of anemia in which the concentration of hemoglobin in the red blood cells is within the standard range, but there is an insufficient number of red blood cells.

[3] Reticulocytes are slightly immature red blood cells.

• A diet lacking in certain vitamins and minerals. A diet consistently low in iron, vitamin B-12
• Intestinal disorders. Having an intestinal disorder that affects the absorption of nutrients in your small intestine
• Pregnancy. Being pregnant and not taking a multivitamin with folic acid and iron
• Chronic conditions. If you have cancer, kidney failure
• Family history
• Menstruation

Different types of anemia have different causes. They include:

• Vitamin deficiency anemia. Besides iron, your body needs folate and vitamin B-12 to produce enough healthy red blood cells. A diet lacking in these and other key nutrients can cause decreased red blood cell production.
• Anemia of inflammation. Certain diseases — such as cancer, HIV/AIDS, rheumatoid arthritis, kidney disease
• Aplastic anemia. This rare, life-threatening anemia occurs when your body doesn't produce enough red blood cells
• Anemias associated with bone marrow disease. A variety of diseases, such as leukemia and myelofibrosis, can cause anemia by affecting blood production in your bone marrow.
• Hemolytic anemias. This group of anemias develops when red blood cells are destroyed faster than bone marrow can replace them. Certain blood diseases increase red blood cell destruction.
• Sickle cell anemia. This inherited and sometimes serious condition is a hemolytic anemia. It's caused by a defective form of hemoglobin that forces red blood cells to assume an abnormal crescent (sickle) shape.

• The causes of leukemia are largely unknown, but it thought to involve a comboination of genetic and environmental factors
• Higher chances for people who have been exposed to high levels of radiation 
• Exposure to benzene, many unknown toxins, drugs, chemicals and gases
• Viruses like the Human T-Cell leukaemia virus
• Leukemia as a second cause after aggressive chemotherapy for other cancers, such as Hodgkin's lymphoma (HL)
• Leukemia cells (hematopoietic precursor cells) have acquired mutations in their DNA that cause them to grow abnormally and lose functions of typical white blood cells.
• DNA Chromosome translocation and inversion mutations in cells

Most people diagnosed with chronic myeloid leukaemia have an abnormal chromosome called the Philadelphia chromosome.

Leukemia is suggested by the increased leukemia incidence among a number of congenital disorders [1], including Down syndrome, neurofibromatosis, and Fanconi anemia.

[1] Congenital disorder is a condition that is present from birth (Down syndrome, neurofibromatosis, and Fanconi anemia).

The leukemias are malignant neoplasms ^[1] of cells originally derived from hematopoietic precursor cells^[2]. They are characterized by diffuse replacement of the bone marrow with unregulated, proliferating, immature neoplastic cells^[3]. In most cases, the leukemic cells spill out into the blood, where they are seen in large numbers. The term leukemia (i.e., “white blood”) was first used by Virchow to describe a reversal of the usual ratio of red blood cells and white blood cells. The leukemic cells may also infiltrate the liver, spleen, lymph nodes, and other tissues throughout the body, causing enlargement of these organs.

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[1] malignant neoplasms is another term for a cancerous tumor. The term “neoplasm” refers to an abnormal growth of tissue. The term “malignant” means the tumor is cancerous and is likely to spread (metastasize) beyond its point of origin.

[2] hematopoietic precursor cells=hematopoietic stem cells (HSCs) are the stem cells that give rise to other blood cells. This process is called haematopoiesis.

[3] A neoplasm is an abnormal growth of cells, also known as a tumor. Neoplastic diseases are conditions that cause tumor growth. Growth can be either benign (noncancerous) or malignant (cancerous).

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Leukemias are cancers of the white blood cells, which begins in the bone marrow.